chap 19 + 24 bio 2 part 1 final exam

The Role of Oxygen in Metabolism see pic

see pic

analogous structures/features (define) vs. homologous structures

share similar function, but not common ancestry, while homologous features share common ancestry, but not necessarily similar function. pic explanation: The ability to glide through the air evolved independently in these two distantly related mammals.

most recent scientists on earth's origins (read)

However, some evidence suggests that the early atmosphere was made up primarily of nitrogen and carbon dioxide and was neither reducing nor oxidizing (electron removing). Recent Miller-Urey-type experiments using such "neutral" atmospheres have also produced organic molecules. In addition, small pockets of the early atmosphere, such as those near the openings of volcanoes, may have been reducing. Perhaps the first organic compounds formed near volcanoes or deep-sea vents, where hot water and minerals gush into the ocean from Earth's interior. In a 2008 test of the volcanic atmosphere hypothesis, researchers used modern equipment to reanalyze molecules that Miller had saved from one of his experiments. They found that numerous amino acids had formed under conditions that simulated a volcanic eruption (Figure 24.3).

read -- Let's now summarize some of the main ideas of natural selection: (2 points)

Natural selection is a process in which individuals that have certain heritable traits survive and reproduce at a higher rate than do other individuals because of those traits. Over time, natural selection can increase the frequency of adaptations that are favorable in a given environment

_____, ______, _____ organisms unlikely to leave fossils

Soft, small, less common

four types of data that document the pattern of evolution and illuminate how it occurs

direct observations, homology, the fossil record, and biogeography.

Although natural selection occurs through ______, _____

interactions between individual organisms and their environment, individuals do not evolve. Rather, it is the population that evolves over time.

endemic

native or confined to a particular region or people; characteristic of or prevalent in a field; found nowhere else in the world

natural selection can _____ or _____. Thus, even if a trait is _____, if all the _____, _____.

natural selection can amplify or diminish only those heritable traits that differ among the individuals in a population. Thus, even if a trait is heritable, if all the individuals in a population are genetically identical for that trait, evolution by natural selection cannot occur

As we saw in Unit Three, evolution cannot occur without genetic variation. The evolutionary changes seen in the prokaryotic fossil record and the diverse adaptations found in prokaryotes living today suggest that their populations must have considerable genetic variation—and they do. In this section, we'll examine three factors that give rise to high levels of genetic diversity in prokaryotes:

rapid reproduction, mutation, and genetic recombination.

examples of what vesicles can do Name the 4 simplified version of what vesicles can do + read the 4 complex descriptions

(a) Self-assembly (b) Reproduction. Vesicles can divide on their own, for ex. a vesicle "giving birth" to smaller vesicles (c) Absorption of RNA d) Finally, experiments have shown that some vesicles have a selectively permeable bilayer and can perform metabolic reactions using an external source of reagents—another important prerequisite for life. 1) For example, vesicles can form spontaneously when lipids or other organic molecules are added to water. When this occurs, molecules that have both a hydrophobic region and a hydrophilic region can organize into a bilayer similar to the lipid bilayer of a plasma membrane. Adding substances such as montmorillonite, a soft mineral clay produced by the weathering of volcanic ash, greatly increases the rate of vesicle self-assembly (Figure 24.4a). This clay, which is thought to have been common on early Earth, provides surfaces on which organic molecules become concentrated, increasing the likelihood that the molecules will react with each other and form vesicles. 2) Abiotically produced vesicles can "reproduce" on their own (Figure 24.4b), and they can increase in size ("grow") without dilution of their contents. 3) Vesicles also can absorb montmorillonite particles, including those on which RNA and other organic molecules have become attached (Figure 24.4c). 4) Finally, experiments have shown that some vesicles have a selectively permeable bilayer and can perform metabolic reactions using an external source of reagents—another important prerequisite for life.

A Comparison of the Three Domains of Life (see pic)

(see pic)

Three examples of beak variation in Galápagos finches (see pic)

(see pic) their beaks are adapted for specific diets

just read 1) Overall, summarize Darwin's 2 observations/inferences based on artifical selection but in nature 2) As these two inferences suggest, Darwin saw an important connection between _____ and _____ 3) He began to make this connection after ______

1) Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than do other individuals. Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations. 2) As these two inferences suggest, Darwin saw an important connection between natural selection and the capacity of organisms to "overreproduce." 3) He began to make this connection after reading an essay by economist Thomas Malthus, who contended that much of human suffering—disease, famine, and war—resulted from the human population's potential to increase faster than food supplies and other resources. Similarly, Darwin realized that the capacity to overreproduce was characteristic of all species. Of the many eggs laid, young born, and seeds spread, only a tiny fraction complete their development and leave offspring of their own. The rest are eaten, starved, diseased, unmated, or unable to tolerate physical conditions of the environment such as salinity or temperature.

Extreme halophiles 1) live where 2) Some species ________, while others ________ 3) for example, ________ (just read i guess)

1) (from the Greek halo, salt) live in highly saline environments, such as the Great Salt Lake and the Dead Sea. 2) Some species merely tolerate salinity, while others require an environment that is several times saltier than seawater (which has a salinity of 3.5%). 3) For example, the proteins and cell walls of archaea in the genus Halobacterium have unusual features that improve function in extremely salty environments but render these organisms incapable of survival if the salinity drops below 9%.

A fourth type of evidence for evolution comes from the field of ______ 1) define 2) read the rest

1) A fourth type of evidence for evolution comes from the field of biogeography, the scientific study of the geographic distributions of species. 2) (read all the rest of this) The geographic distributions of organisms are influenced by many factors, including continental drift, the slow movement of Earth's continents over time. About 250 million years ago, these movements united all of Earth's landmasses into a single large continent called Pangaea. Roughly 200 million years ago, Pangaea began to break apart; by 20 million years ago, the continents we know today were within a few hundred kilometers of their present locations. We can use our understanding of evolution and continental drift to predict where fossils of different groups of organisms might be found. For example, scientists have constructed evolutionary trees for horses based on anatomical data. These trees and the ages of fossils of horse ancestors suggest that the genus that includes present-day horses (Equus) originated 5 million years ago in North America. Geologic evidence indicates that at that time, North and South America were not yet connected, making it difficult for horses to travel between them. Thus, we would predict that the oldest Equus fossils should be found only on the continent on which the group originated—North America. This prediction and others like it for different groups of organisms have been upheld, providing more evidence for evolution.

heritable traits (read each time, just define it) 1) define 2) An organism's heritable traits can influence not only _____, but also ____. For example, ______ 3) When such advantages _______. 4) Thus, over time, _______.

1) A trait that can be passed on genetically from parent to offspring. 2) An organism's heritable traits can influence not only its own performance, but also how well its offspring cope with environmental challenges. For example, an organism might have a trait that gives its offspring an advantage in escaping predators, obtaining food, or tolerating physical conditions. 3) When such advantages increase the number of offspring that survive and reproduce, the traits that are favored will likely appear at a greater frequency in the next generation. 4) Thus, over time, natural selection resulting from factors such as predators, lack of food, or adverse physical conditions can lead to an increase in the proportion of favorable traits in a population.

1) who is capable of taxis 2) define taxis 3) example 4) read

1) About half of all prokaryotes are capable of taxis, 2) a directed movement toward or away from a stimulus (from the Greek taxis, to arrange). 3) For example, prokaryotes that exhibit chemotaxis change their movement pattern in response to chemicals. They may move toward nutrients or oxygen (positive chemotaxis) or away from a toxic substance (negative chemotaxis) 4) Some species can move at velocities exceeding μ 50 μm/sec up to 50 times their body length per second. For perspective, consider that a person 1.7 m tall moving that fast would be running 306 km (190 miles) per hour!

convergent evolution 1) although _____ share ____ because of _____, ____ can resemble one another _____ 2) define 3) example (just read)

1) Although organisms that are closely related share characteristics because of common descent, distantly related organisms can resemble one another for a different reason: convergent evolution 2) the independent evolution of similar features in different lineages 3) Consider marsupial mammals, many of which live in Australia. Marsupials are distinct from another group of mammals—the eutherians, or placental mammals—few of which live in Australia. (Eutherians complete their embryonic development in the uterus, whereas marsupials are born as embryos and complete their development while nursing, often in an external pouch.) Some Australian marsupials have eutherian look-alikes with superficially similar adaptations. For instance, as shown in Figure 19.18, the sugar glider, a forest-dwelling Australian marsupial, looks very similar to flying squirrels, gliding eutherians that live in North American forests. But the sugar glider has many other characteristics that make it a marsupial, much more closely related to kangaroos and other Australian marsupials than to flying squirrels or other eutherians. Once again, our understanding of evolution can explain these observations. Although they evolved independently from different ancestors, these two mammals have adapted to similar environments in similar ways. In such examples in which species share features because of convergent evolution, the resemblance is said to be analogous, not homologous. pic explanation: The ability to glide through the air evolved independently in these two distantly related mammals.

horizontal gene transfer 1) has played a key role in ______? 2) Over hundreds of millions of years, prokaryotes have acquired genes from ______, and ______ 3) read this and understand

1) Another important lesson from molecular systematics is that horizontal gene transfer has played a key role in the evolution of prokaryotes. 2) Over hundreds of millions of years, prokaryotes have acquired genes from even distantly related species, and they continue to do so today. 3) As a result, significant portions of the genomes of many prokaryotes are actually mosaics of genes imported from other species. For example, a study of 329 sequenced bacterial genomes found that an average of 75% of the genes in each genome had been transferred horizontally at some point in their evolutionary history. As we saw in Concept 20.5 , such gene transfers can make it difficult to determine phylogenetic relationships. Still, it is clear that for billions of years, the prokaryotes have evolved in two separate lineages: the bacteria and the archaea

1) Cooperation between prokaryotic cells allows them to 2) In some cases, this cooperation takes place between 3) for example 4) Most cells in a _______ carry out only ________, while a few specialized cells called _________ carry out only ______

1) Cooperation between prokaryotic cells allows them to use environmental resources they could not use as individual cells. 2) In some cases, this cooperation takes place between specialized cells of a filament which is (from google - a long chain comprised of protein subunits). 3) For example, the cyanobacterium Anabaena has genes that encode proteins for photosynthesis and for nitrogen fixation. However, a single cell cannot carry out both processes at the same time because photosynthesis produces O2, which inactivates the enzymes involved in nitrogen fixation. Instead of living as isolated cells, Anabaena forms filamentous chains. 4) Most cells in a filament carry out only photosynthesis, while a few specialized cells called heterocysts (sometimes called heterocytes) carry out only nitrogen fixation. Each heterocyst is surrounded by a thickened cell wall that restricts entry of O2 produced by neighboring photosynthetic cells. Intercellular connections allow heterocysts to transport fixed nitrogen to neighboring cells and to receive carbohydrates.

1) read 2) 1st way bacteria confers antibiotic resistance to antibiotics + example + read part in bold 3) 2nd way 4) read and understand very well

1) During the 1950s in Japan, physicians started noticing that some hospital patients with bacterial dysentery, which produces severe diarrhea, did not respond to antibiotics that had been effective in the past. Apparently, resistance to these antibiotics had evolved in some strains of Shigella, the bacterium that causes the disease. Eventually, researchers began to identify the specific genes that confer antibiotic resistance in Shigella and other pathogenic bacteria. 2) summary: mutation in a chromosomal gene of a pathogen confers resistance. for ex. a gene makes it less likely that a pathogen will transport an antibiotic into its cell. Sometimes, a mutation in a chromosomal gene of the pathogen can confer (allow - definition I got from google) resistance. For example, a mutation in one gene may make it less likely that the pathogen will transport a particular antibiotic into its cell. Read: Mutation in a different gene may alter the intracellular target protein for an antibiotic molecule, reducing its inhibitory effect. 3) In other cases, bacteria have "resistance genes," which code for enzymes that specifically destroy or otherwise hinder the effectiveness of certain antibiotics, such as tetracycline or ampicillin. Such resistance genes are often carried by plasmids known as R plasmids (R for resistance). 4) Exposing a bacterial population to a specific antibiotic will kill antibiotic-sensitive bacteria but not those that happen to have R plasmids with genes that counter the antibiotic. Under these circumstances, we would predict that natural selection would cause the fraction of the bacterial population carrying genes for antibiotic resistance to increase, and that is exactly what happens. The medical consequences are also predictable: Resistant strains of pathogens are becoming more common, making the treatment of certain bacterial infections more difficult. The problem is compounded by the fact that many R plasmids, like F plasmids, have genes that encode pili and enable DNA transfer from one bacterial cell to another by conjugation. Making the problem still worse, some R plasmids carry genes for resistance to as many as ten antibiotics.

Darwin's Focus on Adaptation 1) adaptation in relation to darwin + define it 2) explain finches on galapagos 3) natural selection + define it

1) During the voyage of the Beagle, Darwin observed many examples of adaptations - inherited characteristics of organisms that enhance their survival and reproduction in specific environments. 2) Later, as he reassessed his observations, he began to perceive adaptation to the environment and the origin of new species as closely related processes. Could a new species arise from an ancestral form by the gradual accumulation of adaptations to a different environment? From studies made years after Darwin's voyage, biologists have concluded that this is indeed what happened to a diverse group of finches found on the Galápagos Islands. The finches' various beaks and behaviors are adapted to the specific foods available on their home islands. Darwin realized that explaining such adaptations was essential to understanding evolution. 3) His explanation of how adaptations arise centered on natural selection, a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than do other individuals because of those traits.

Extreme thermophiles 1) what are they 2) example + explain (read i guess) 3) read about other example

1) Extreme thermophiles (from the Greek thermos, hot) thrive in very hot environments. 2) For example, the archaean Pyrococcus furiosus lives in geothermally heated marine sediments that reach temperatures of 100°C. At temperatures this high, the cells of most organisms die because their DNA does not remain in a double helix and many of their proteins denature. P. furiosus and other extreme thermophiles avoid this fate because they have structural and biochemical adaptations that make their DNA and proteins stable at high temperatures—a feature that has enabled P. furiosus to be used in biotechnology as a source of DNA polymerase for the PCR technique (see Figure 13.27). 3) Other examples of extreme thermophiles include archaea in the genus Sulfolobus, which live in sulfur-rich volcanic springs (Figure 24.21). One extreme thermophile that lives near deep-sea hot springs called hydrothermal vents is informally known as "strain 121," since it can reproduce even at 121°C.

The S. aureus and soapberry bug examples highlight three key points about natural selection.

1) First, natural selection is a process of editing, not a creative mechanism. A drug does not create resistant pathogens; it selects for resistant individuals that are already present in the population. 2) Second, in species that produce new generations in short periods of time, evolution by natural selection can occur rapidly—in just a few years (S. aureus) or decades (soapberry bugs). 3) Third, natural selection depends on time and place. It favors those characteristics in a genetically variable population that provide an advantage in the current, local environment. What is beneficial in one situation may be useless or even harmful in another. Beak lengths suitable for the size of the typical fruit eaten by members of a particular soapberry bug population are favored by natural selection. However, a beak length suitable for fruit of one size can be disadvantageous when the bug is feeding on fruit of another size.

1953 Miller Urey Experiments 1) who was working 2) results of experiment 3) post experiment 4) what does their experiment show?

1) In 1953, Stanley Miller, working with Harold Urey at the University of Chicago, tested the Oparin-Haldane hypothesis by creating laboratory conditions comparable to those that scientists at the time thought existed on early Earth. 2) His apparatus yielded a variety of amino acids found in organisms today, along with other organic compounds. 3) Many laboratories have since repeated Miller's classic experiment using different recipes for the atmosphere, some of which also produced organic compounds. 4) Miller-Urey-type experiments show that the abiotic synthesis of small organic molecules is possible under various conditions.

1) life on earth began ______ years ago with ______ (define) 2) read

1) Life on Earth began 3.5 billion years ago with the origin of single-celled prokaryotes. 2) Over this long history, a wide range of metabolic adaptations have evolved in prokaryotes, enabling them to thrive throughout the biosphere.

Euryarchaeota 1) what are in this clade 2)

1) Many extreme halophiles and all known methanogens are archaea in the clade Euryarchaeota (from the Greek eurys, broad, a reference to their wide habitat range). The euryarchaeotes also include some extreme thermophiles, though most thermophilic species belong to a second clade, Crenarchaeota (cren means "spring," such as a hydrothermal spring). Metagenomic studies have identified many species of euryarchaeotes and crenarchaeotes that are not extremophiles. These archaea exist in habitats ranging from farm soils to lake sediments to the surface waters of the open ocean.

stromatolites 1) something abt them 2) define 3) formed by (2) 4) The earliest stromatolites date to ______ years ago 5) read

1) Many of the oldest known fossils 2) layered rocks that form from the activities of certain prokaryotes 3) formed by cyanobacteria and several other types of photosynthetic bacteria 4) The earliest stromatolites date to 3.5 billion years ago. 5) For several hundred million years, all such fossils were similar in overall structure and all were from shallow marine bays. Stromatolites are still found in such bays today (see Figure 23.5), where they are formed by cyanobacteria and several other types of photosynthetic bacteria. By 3.1 billion years ago, stromatolites with two distinctly different morphologies had appeared, and by 2.8 billion years ago, stromatolites occurred in salty lakes as well as marine environments. Thus, early fossil stromatolites show signs of ecological and evolutionary change over time.

Subgroup: Alpha Proteobacteria 1) main thing abt this subgroup 2) NAME THE EXAMPLE + read this example

1) Many of the species in this subgroup are closely associated with eukaryotic hosts. 2) For example, Rhizobium species live in nodules within the roots of legumes (plants of the pea/bean family), where the bacteria convert atmospheric N2 to compounds the host plant can use to make proteins. Species in the genus Agrobacterium produce tumors in plants; genetic engineers use these bacteria to carry foreign DNA into the genomes of crop plants. Scientists hypothesize that mitochondria evolved from aerobic alpha proteobacteria through endosymbiosis.

binary fission 1)Many ______ can _______ quickly in _______ environments. by binary fission, a single _____ cell ______, which then _______. 2) Under optimal conditions, many ______ can divide how often? 3) in reality, ______ 4) Still, the potential of many prokaryotic species for rapid population growth emphasizes three key features of their biology: 5) As a result, ____

1) Many prokaryotes can reproduce quickly in favorable environments. By binary fission, a single prokaryotic cell divides into 2 cells, which then divide into 4, 8, 16, and so on. 2) Under optimal conditions, many prokaryotes can divide every 1-3 hours; some species can produce a new generation in only 20 minutes. At this rate, a single prokaryotic cell could give rise to a colony outweighing Earth in only two days! 3) In reality, of course, this does not occur. The cells eventually exhaust their nutrient supply, poison themselves with metabolic wastes, face competition from other microorganisms, or are consumed by other organisms. 4) Still, the potential of many prokaryotic species for rapid population growth emphasizes three key features of their biology: 1. They are small, 2. they reproduce by binary fission, 3. and they often have short generation times. 5) As a result, prokaryotic populations can consist of many trillions of individuals—far more than populations of multicellular eukaryotes, such as plants or animals.

biofilms 1) define 2) how they work 3) what they do in society

1) Metabolic cooperation among the cells of one or more prokaryotic species often occurs in surface-coating colonies known as biofilms. 2) Cells in a biofilm secrete signaling molecules that recruit nearby cells, causing the colonies to grow. The cells also produce polysaccharides and proteins that stick the cells to the substrate and to one another. Channels in the biofilm allow nutrients to reach cells in the interior and wastes to be expelled. 3) Biofilms are common in nature, but they can cause a wide range of problems for humans. 1. biofilms growing in pipes slow the flow of liquids such as water or oil and degrade the pipes themselves. 2. Biofilms also corrode boat hulls, oil platforms, and many other structures and industrial products. 3. In medical settings, biofilms can contaminate contact lenses, catheters, pacemakers, heart valves, artificial joints, and many other devices. 4. They also contribute to tooth decay and a wide range of chronic infections, some of which can be lethal. 5. Many biofilms can evade host immune responses and are extremely resistant to antibiotics, making them hard to treat. 6. Altogether, each year biofilms cause billions of dollars in damage and inflict tens of millions of people with chronic infections.

Throughout their long history, prokaryotic populations have been subjected to natural selection in all kinds of environments, resulting in their enormous diversity today. fossils of early prokaryotes document some of the major steps in their evolutionary history, including the appearance of the first photosynthetic organisms. However, prokaryotic populations have also evolved in ways that cannot be seen in the fossil record, including changes in the type and efficiency of their enzymes. Although we cannot trace the time course of such changes in the fossil record, we can examine their end results—the adaptations found in prokaryotes today. We'll survey those adaptations here, beginning with a description of prokaryotic cells. 1) most prokaryotes are _____ + read the disclaimer 2) are prokaryotes or eukaryotes smaller? 3) although prokaryotes are_____ and ____, prokaryotes are ______, ______

1) Most prokaryotes are unicellular, although the cells of some species remain attached to each other after cell division. 2) Prokaryotic cells typically have diameters of 0.5 to 5 μm, much smaller than the 10- to 100−μm diameter of many eukaryotic cells. (One notable exception, Thiomargarita namibiensis, can be as large as 750 μm in diameter—bigger than a poppy seed.) 3) Finally, although they are unicellular and small, prokaryotes are well organized, achieving all of an organism's life functions within a single cell

Subgroup: Epsilon Proteobacteria 1) describe this subgroup 2) name 2 examples and explain

1) Most species in this subgroup are pathogenic to humans or other animals. 2) Epsilon proteobacteria include Campylobacter, which causes blood poisoning and intestinal inflammation, and Helicobacter pylori, which causes stomach ulcers

nitrogen fixation 1) Nitrogen is essential for the production of (2) in ____ 2) the forms of nitrogen prokaryotes vs. eukaryotes can use 3) example (explain the vocab word here) 4) explain 1 example of the impact of this vocab word on other organisms

1) Nitrogen is essential for the production of amino acids and nucleic acids in all organisms. 2) Whereas eukaryotes can obtain nitrogen only from a limited group of nitrogen compounds, prokaryotes can metabolize nitrogen in a wide variety of forms. 3) For example, some cyanobacteria and some methanogens (a group of archaea) convert atmospheric nitrogen (N2) to ammonia (NH3), a process called nitrogen fixation. The cells can then incorporate this "fixed" nitrogen into amino acids and other organic molecules. In terms of their nutrition, nitrogen-fixing cyanobacteria are some of the most self-sufficient organisms, since they need only light, CO2, N2, water, and some minerals to grow. 4) Nitrogen fixation by prokaryotes has a large impact on other organisms. For example, it can increase the nitrogen available to plants, which cannot use atmospheric nitrogen but can use the nitrogen compounds that the prokaryotes produce from ammonia.

Like all organisms, prokaryotes can be categorized by how they obtain energy and the carbon used in building organic molecules. Every type of nutrition observed in eukaryotes is represented among prokaryotes, along with some nutritional modes unique to prokaryotes. In fact, prokaryotes have an astounding range of metabolic adaptations, much broader than that found in eukaryotes. (see table) 1) phototroph + chemotroph 2) autotroph 3) heterotrophs

1) Organisms that obtain energy from light are called phototrophs, and those that obtain energy from chemicals are called chemotrophs. 2) Organisms that need only CO2 (carbon dioxide) or related compounds as a carbon source are called autotrophs. 3) In contrast, heterotrophs require at least one organic nutrient, such as glucose, to make other organic compounds. (remember glucose GH for hetero likek in the alphabet GH)

endospores 1) Other ______ develop ______called endospores when they _____ or _____ 2) how are endospores formed + released 3) something unique abt endospores (explain)

1) Other bacteria develop resistant cells called endospores when they lack water or essential nutrients. 2) 1. The original cell produces a copy of its chromosome and surrounds that copy with a multilayered structure, forming the endospore. 2. Water is removed from the endospore, and its metabolism halts. 3. The original cell then lyses, releasing the endospore. 3) Most endospores are so durable that they can survive in boiling water; killing them requires heating lab equipment to 121°C under high pressure. In less hostile environments, endospores can remain dormant but viable for centuries, able to rehydrate and resume metabolism when their environment improves.

1) Prokaryotes play a central role in many _________ + define i guess 2) one of these ________^^^ + 3 definitions 3) mutualism 4) commensalism 5) example of commensalism 6) parasitism 7) pathogen

1) Prokaryotes play a central role in many ecological interactions. ecology - (definition from google) the branch of biology that deals with the relations of organisms to one another and to their physical surroundings 2) Consider symbiosis (from a Greek word meaning "living together"), an ecological relationship in which two species live in close contact with each other. Prokaryotes often form symbiotic associations with much larger organisms. In general, the larger organism in a symbiotic relationship is known as the host, and the smaller is known as the symbiont. 3) There are many cases in which a prokaryote and its host participate in mutualism, an ecological interaction between two species in which both benefit. 4) Other interactions take the form of commensalism, an ecological relationship in which one species benefits while the other is not harmed or helped in any significant way. 5) For example, more than 150 bacterial species live on the outer surface of your body, covering portions of your skin with up to 10 million cells per square centimeter. Some of these species are commensalists: You provide them with food, such as the oils that exude from your pores, and a place to live, while they neither harm nor benefit you. 6) Finally, some symbiotic prokaryotes engage in parasitism, an interaction in which a parasite eats the cell contents, tissues, or body fluids of its host. As a group, parasites harm but usually do not kill their host, at least not immediately (unlike a predator). 7) Parasites that cause disease are known as pathogens, many of which are prokaryotic

ribozyme 1) RNA plays a central role in _______, but it can also function as _______ + (name) 2) a ______ is essentially a __________ 3) what they do

1) RNA plays a central role in protein synthesis, but it can also function as an enzyme-like catalyst (ribozymes) 2) a ribozyme is essentially a RNA catalyst 3) Some ribozymes can make copies of short pieces of RNA, if supplied with nucleotide building blocks

F plasmid 1) what is it 2) F+ cell is what + what is its function 3) F- cell what + what is its function 4) The F+ condition is ________ in the sense that ________ 5) Even if this does not occur, _____ 6) A donor cell's F factor can also be ______ + read the rest

1) The F factor in its plasmid form is called the F plasmid. 2) Cells containing the F plasmid, designated F+ cells, function as DNA donors during conjugation. 3) Cells lacking the F factor, designated F−, function as DNA recipients during conjugation. 4) The F+ condition is transferable in the sense that an F+ cell converts an F− cell to F+ if a copy of the entire F plasmid is transferred. 5) Even if this does not occur, as long as some of the F plasmid's DNA is transferred successfully to the recipient cell, that cell is now a recombinant cell. 6) A donor cell's F factor can also be integrated into the chromosome. READ: In this case, chromosomal genes can be transferred to a recipient cell during conjugation. When this occurs, homologous regions of the donor and recipient chromosomes may align, allowing segments of their DNA to be exchanged. As a result, the recipient cell becomes a recombinant bacterium that has genes derived from the chromosomes of two different cells—a new genetic variant on which evolution can act. picture: Conjugation and transfer of an F plasmid, resulting in recombination: explanation of pic: The DNA replication that accompanies the transfer of an F plasmid is called rolling circle replication. In effect, the intact circular DNA strand from the donor cell's F plasmid "rolls" as its other strand peels off and a new complementary strand is synthesized.

F factor 1) define + what does the F stand for 2) The F factor can exist either as a _______ or as a __________ 3) read i guess

1) The ability to form pili and donate DNA during conjugation results from the presence of a particular piece of DNA called the F factor (F for fertility) 2) The F factor can exist either as a plasmid or as a segment of DNA within the bacterial chromosome 3) The F factor of E. coli consists of about 25 genes, most required for the production of pili

decomposers 1) read 2) explain prokaryotes as decomposers 3) without this what would happen

1) The atoms that make up the organic molecules in all living things were at one time part of inorganic substances in the soil, air, and water. Sooner or later, those atoms will return to the nonliving environment. Ecosystems depend on the continual recycling of chemical elements between the living and nonliving components of the environment, and prokaryotes play a major role in this process. 2) For example, some chemoheterotrophic prokaryotes function as decomposers, breaking down dead organisms as well as waste products and thereby unlocking supplies of carbon, nitrogen, and other elements. 3) Without the actions of prokaryotes and other decomposers such as fungi, life as we know it would cease.

Evolutionary Origins of Bacterial Flagella (read) 1) parts of a flagellum 2) read and understand very well

1) The bacterial flagellum shown in Figure 24.10 has three main parts (the motor, hook, and filament) that are themselves composed of 42 different kinds of proteins. 2) How could such a complex structure evolve? In fact, much evidence indicates that bacterial flagella originated as simpler structures that were modified in a stepwise fashion over time. As in the case of the human eye (see Concept 23.4 ), biologists asked whether a less complex version of the flagellum could still benefit its owner. Analyses of hundreds of bacterial genomes indicate that only half of the flagellum's protein components appear to be necessary for it to function; the others are inessential or not encoded in the genomes of some species. Of the 21 proteins required by all species studied to date, 19 are modified versions of proteins that perform other tasks in bacteria. For example, a set of 10 proteins in the motor is homologous to 10 similar proteins in a secretory system found in bacteria. (A secretory system is a protein complex that enables a cell to produce and release certain macromolecules.) Two other proteins in the motor are homologous to proteins that function in ion transport. The proteins that comprise the rod, hook, and filament are all related to each other and are descended from an ancestral protein that formed a pilus-like tube. These findings suggest that the bacterial flagellum evolved as other proteins were added to an ancestral secretory system. This is an example of exaptation, the process in which structures originally adapted for one function take on new functions through descent with modification.

SEE PIC FOR capsule 1) capsule (where is it + what can it be made of + what structure does it have) 2) if not a capsule then what if it is ______ 3) 3 things/functions both kinds of sticky outer layers do

1) The cell wall of many prokaryotes is surrounded by a sticky layer of polysaccharide or protein. This layer is called a capsule if it is dense and well defined 2) or a slime layer if it is not as well organized. 3) 1. Both kinds of sticky outer layers enable prokaryotes to adhere/stick to their substrate or to other individuals in a colony. 2. Capsules and slime layers also protect against dehydration, 3. and some capsules shield pathogenic prokaryotes from attacks by their host's immune system.

1) The _____ of prokaryotes differ in structure from those of eukaryotes. 2) In eukaryotes that have cell walls, such as _____ and _____ the walls are usually made of ______ or ______ 3) In contrast, most _______ cell walls contain ________, a _____(define)____ 4) Archaeal cell walls contain _________ (MAKE SURE TO SAY HIGHLIGHTED PART)

1) The cell walls of prokaryotes differ in structure from those of eukaryotes. 2) In eukaryotes that have cell walls, such as plants and fungi, the walls are usually made of cellulose or chitin 3) In contrast, most bacterial cell walls contain peptidoglycan, (simplified: polymer [polymer is composed of macromolecules] made of modified sugars linked by polypeptides) a polymer composed of modified sugars cross-linked by short polypeptides. This molecular fabric encloses the entire bacterium and anchors other molecules that extend from its surface. 4) Archaeal cell walls contain a variety of polysaccharides and proteins but lack peptidoglycan.

1) The cells of ______ are simpler than those of _______ in both their _____ and the _____. 2) read the rest

1) The cells of prokaryotes are simpler than those of eukaryotes in both their internal structure and the physical arrangement of their DNA. 2) Prokaryotic cells lack the complex compartmentalization associated with the membrane-enclosed organelles found in eukaryotic cells. However, some prokaryotic cells do have specialized membranes that perform metabolic functions. These membranes are usually infoldings of the plasma membrane. Recent discoveries also indicate that some prokaryotes can store metabolic by-products in simple compartments composed of proteins; these compartments do not have a membrane.

1) earliest animals were (2 things) 2) what led to an explosive radiation of animals 3) what did the radiation of animals transform?

1) The earliest animals were microscopic and lived in marine environments. 2) By 530 million years ago, the origin of larger, mobile animals with complex nervous and digestive systems led to an explosive radiation of animals, 3) transforming the microorganism-only world to a world inhabited also by predators and other large eukaryotes.

extremophiles 1) which domain are they in 2) describe them 3) what are the 2 types

1) The first prokaryotes assigned to domain Archaea live in environments so extreme that few other organisms can survive there. 2) Such organisms are called extremophiles, meaning "lovers" of extreme conditions (from the Greek philos, lover), and 3) include extreme halophiles and extreme thermophiles.

1) genome of a prokaryote vs. eukaryote (2 things bolded) 2) prokaryote vs. eukaryote chromosomes (2 things) 3) eukaryote vs. prokaryote: nucleus 4) plasmids 5) Although DNA replication, transcription, and translation are fundamentally similar processes in prokaryotes and eukaryotes, some of the details differ. (explain example)

1) The genome of a prokaryote is structurally different from a eukaryotic genome and in most cases has considerably less DNA. 2) Prokaryotes typically have one circular chromosome, whereas eukaryotes usually have several to many linear chromosomes. In addition, in prokaryotes, the chromosome is associated with many fewer proteins than are the chromosomes of eukaryotes. 3) Unlike eukaryotes, prokaryotes lack a nucleus; their chromosome is located in the nucleoid, a region of cytoplasm that is not enclosed by a membrane. 4) In addition to its single chromosome, a typical prokaryotic cell may also have much smaller rings of independently replicating DNA molecules called plasmids most carrying only a few genes. 5) Although DNA replication, transcription, and translation are fundamentally similar processes in prokaryotes and eukaryotes, some of the details differ. - For example, prokaryotic ribosomes are slightly smaller than eukaryotic ribosomes and differ in their protein and RNA content. These differences allow certain antibiotics, such as erythromycin and tetracycline, to bind to ribosomes and block protein synthesis in prokaryotes but not in eukaryotes. As a result, people can use these antibiotics to kill or inhibit the growth of bacteria without harming themselves.

1) DNA molecules carry genetic information, including the instructions needed to replicate themselves accurately during reproduction. But DNA replication requires elaborate enzymatic machinery, along with an abundant supply of nucleotide building blocks that are provided by the cell's metabolism. This suggests that self-replicating molecules and a metabolic source of building blocks may have appeared together in early protocells. How did that happen? 2) define this word 3) Recent experiments show that abiotically produced _______ can exhibit ________, including (2):

1) The necessary conditions may have been met in vesicles 2) fluid-filled compartments enclosed by a membrane-like structure. 3) Recent experiments show that abiotically produced vesicles can exhibit certain properties of life, including: 1. simple reproduction 2. metabolism 3. the maintenance of an internal chemical environment different from that of their surroundings

Cyanobacteria 1) type of

1) These gram-negative photoautotrophs 2) are the only prokaryotes with plantlike, oxygen-generating photosynthesis. 3) (In fact, chloroplasts are thought to have evolved from an endosymbiotic cyanobacterium.) 4) Both solitary and filamentous cyanobacteria are abundant components of freshwater and marine phytoplankton, the collection of photosynthetic organisms that drift near the water's surface. 5) Some filaments have cells specialized for nitrogen fixation, the process that incorporates atmospheric N2 into inorganic compounds that can be used in the synthesis of amino acids and other organic molecules.

Subgroup: Delta Proteobacteria 1) name + explain main example 2) read about the other example

1) This subgroup includes the slime-secreting myxobacteria. When the soil dries out or food is scarce, the cells congregate into a fruiting body that releases resistant "myxospores." These cells found new colonies in favorable environments. 2) Another group of delta proteobacteria, the bdellovibrios, attack other bacteria, charging at up to 100 μm/sec (comparable to a human running 240 km/hr). The attack begins when a bdellovibrio attaches to specific molecules found on the outer covering of some bacterial species. The bdellovibrio then drills into its prey by using digestive enzymes and spinning at 100 revolutions per second.

Subgroup: Gamma Proteobacteria 1) name the main example + explain 2) Some heterotrophic gamma proteobacteria are ________ 3) read explanation

1) This subgroup's autotrophic members include sulfur bacteria, such as Thiomargarita namibiensis, which obtain energy by oxidizing H2S, producing sulfur as a waste product (the small globules in the photograph at right). 2) Some heterotrophic gamma proteobacteria are pathogens; 3) for example, Legionella causes Legionnaires' disease, Salmonella is responsible for some cases of food poisoning, and Vibrio cholerae causes cholera. Escherichia coli, a common resident of the intestines of humans and other mammals, normally is not pathogenic.

1) what can prokaryotes do for plants 2) in contrast to this what do prokaryotes do against plants 3) what archaeans can do

1) Under some conditions, prokaryotes can increase the availability of nutrients that plants require for growth, such as nitrogen, phosphorus, and potassium 2) Prokaryotes can also decrease the availability of key plant nutrients; this occurs when prokaryotes "immobilize" nutrients by using them to synthesize molecules that remain within their cells. Thus, prokaryotes can have complex effects on soil nutrient concentrations. 3) In marine environments, an archaean from the clade Crenarchaeota can perform nitrification, a key step in the nitrogen cycle. Crenarchaeotes dominate the oceans by numbers, comprising an estimated 10^28 cells. The sheer abundance of these organisms suggests that they may have a large impact on the global nitrogen cycle.

RNA world Natural selection on the molecular level has produced ribozymes capable of self-replication in the laboratory. How does this occur (aka how does RNA self-replicate efficently? 4 steps/parts + explain RNA world

1) Unlike double-stranded DNA which is a helix, single-stranded RNA molecules assume a variety of specific 3D shapes mandated by their nucleotide sequences. 2) In a given environment, RNA molecules with certain nucleotide sequences may have shapes that enable them to replicate faster and with fewer errors than other sequences. 3) The RNA molecule with the greatest ability to replicate itself will leave the most descendant molecules. 4) Occasionally, a copying error will result in a molecule with a shape that is even more adept (aka more skilled) at self-replication. 5) Similar selection events may have occurred on early Earth. Thus, life as we know it may have been preceded by an "RNA world," in which small RNA molecules were able to replicate and to store genetic information about the vesicles that carried them.

1) read 2) Gram-positive ______ 3) gram-negative ______ 4) These differences in cell wall composition can have medical implications (3 implications for gram-negative, 1 for gram-positive)

1) Using a staining technique developed by the Dutch scientist Hans Christian Gram, biologists can categorize many bacterial species according to cell wall composition. 2) Gram-positive bacteria have relatively simple walls composed of a thick layer of peptidoglycan. 3) The walls of gram-negative bacteria have less peptidoglycan and are structurally more complex, with an outer membrane that contains lipopolysaccharides (carbohydrates bonded to lipids) 4) These differences in cell wall composition can have medical implications: 1. say: lipid portions of the walls of many gram-negative bacteria are toxic, causing fever or shock. The lipid portions of the lipopolysaccharides in the walls of many gram-negative bacteria are toxic, causing fever or shock. 2. Furthermore, the outer membrane of a gram-negative bacterium helps protect it from the body's defenses. 3. Gram-negative bacteria also tend to be more resistant than gram-positive species to antibiotics because the outer membrane impedes (delays/prevents) the entry of some drugs. 4. However, some gram-positive species have virulent strains that are resistant to one or more antibiotics. (Figure 19.15 discusses one example: methicillin-resistant Staphylococcus aureus, or MRSA, which can cause lethal skin infections.)

bioremediation 1) define 2) one way its used 3) 2 other ways it's used

1) Yet another way that humans harness prokaryotes is to carry out bioremediation, the use of organisms to remove pollutants from soil, air, or water. 2) For example, anaerobic bacteria and archaea decompose the organic matter in sewage, converting it to material that can be used as landfill or fertilizer after chemical sterilization. 3) Other applications of bioremediation include cleaning up oil spills (Figure 24.28) and precipitating radioactive material (such as uranium) out of groundwater.

vestigial structures 1) type of 2) they concern ___ 3) define 4) example (read)

1) another type of homology 2) concern "left-over" structures of marginal or little importance to the organism 3) vestigial structures are remnants of features that served a function in the organism's ancestors. 4) For instance, snakes arose from ancestors with legs, and the skeletons of some snakes retain vestiges of the pelvis and leg bones of their ancestors. Likewise, blind species of cave fishes descended from ancestors with eyes—which explains why these blind fishes have eye remnants buried under their scales. We would not expect to see these vestigial structures if snakes and blind cave fishes had origins separate from those of other vertebrate animals.

Endotoxins 1) what are they 2) when are they released 3) main example

1) are lipopolysaccharide components of the outer membrane of gram-negative bacteria. 2) In contrast to exotoxins, endotoxins are released only when the bacteria die and their cell walls break down. 3) Endotoxin-producing bacteria include species in the genus Salmonella, such as Salmonella typhi, which causes typhoid fever. You might have heard of food poisoning caused by other Salmonella species that can be found in poultry and some fruits and vegetables.

Mycoplasmas 1) 1st thing about them 2) 2nd thing about them 3) 3rd thing about them 4) 2 kinds of mycoplasmas

1) are the only bacteria known to lack cell walls. 2) They are also the tiniest known cells, with diameters as small as 0.1 m, only about five times as large as a ribosome. 3) Mycoplasmas have small genomes—Mycoplasma genitalium has only 517 genes, for example. 4) Many mycoplasmas are free-living soil bacteria, but others are pathogens.

flagella (see pic) 1) something specific about flagella (bolded part) 2) where are flagella located 3) Prokaryotic flagella differ greatly from eukaryotic flagella (3) 4) something about the history of flagella 5) flagella are what type of structure

1) flagella most commonly enable prokaryotes to move Of the various structures that enable prokaryotes to move, the most common are flagella. 2) Flagella (singular, flagellum) may be scattered over the entire surface of the cell or concentrated at one or both ends. 3) Prokaryotic flagella differ greatly from eukaryotic flagella: 1. They are one-tenth the width (they're skinnier lol) 2. and typically are not covered by an extension of the plasma membrane. 3. The flagella of prokaryotes and eukaryotes also differ in their molecular composition and their mechanism of propulsion. Among prokaryotes, bacterial and archaeal flagella are similar in size and rotational mechanism, but they are composed of entirely different and unrelated proteins. Overall, these structural and molecular comparisons indicate that the 4) flagella of bacteria, archaea, and eukaryotes arose independently. 5) Since current evidence shows that the flagella of organisms in the three domains perform similar functions but are not related by common descent, they are described as analogous, not homologous, structures

conjugation 1) first off what kind of mechanism is it? 2) what happens during it (4 parts to this) 3) explain the example (3 STEPS)

1) genetic recombination -- it's one of the mechanisms that can bring together prokaryotic DNA from different individuals (that is, different cells). 2) In a process called conjugation, 1. DNA is transferred DIRECTLY between two prokaryotic cells 2. (usually of the same species) 3. that are temporarily joined 4. In bacteria, the DNA transfer is always one-way: One cell donates the DNA, and the other receives it 3) We'll focus here on the mechanism used by E. coli. simplified version: in E. coli: 1. the donor cell attaches to a recipient by a pilus 2. pulls it closer like a grappling hook 3. (not 100% that this part happens) a temporary structure between the two cells forms called a "mating bridge" through which the donor may transfer DNA to the recipient. First, a pilus of the donor cell attaches to the recipient (Figure 24.17). The pilus then retracts, pulling the two cells together, like a grappling hook. The next step is thought to be the formation of a temporary structure between the two cells, a "mating bridge" through which the donor may transfer DNA to the recipient. However, the mechanism by which DNA transfer occurs is unclear; indeed, recent evidence indicates that DNA may pass directly through the hollow pilus.

In transformation, 1) first off what kind of mechanism is it? 2) thingy to remember transformation 3) define 4) example 5) transformation occurs when (describe) (4 ish parts to this) 5) just read

1) genetic recombination -- it's one of the mechanisms that can bring together prokaryotic DNA from different individuals (that is, different cells). 2) f in transformation = fresh environment DNA 3) the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings. definition from sata's slides: Some prokaryotic cells can take up and incorporate foreign DNA from the surrounding environment in a process called transformation 4) For example, a harmless strain of Streptococcus pneumoniae can be transformed into pneumonia-causing cells if the cells are exposed to DNA from a pathogenic strain 5) 1. This transformation occurs when a nonpathogenic cell takes up a piece of DNA carrying the allele for pathogenicity 2. and replaces its own allele with the foreign allele, 3. an exchange of homologous DNA segments. 4. The cell is now a recombinant: Its chromosome contains DNA derived from two different cells. 6) For many years after transformation was discovered in laboratory cultures, most biologists thought it was too rare and haphazard to play an important role in natural bacterial populations. But researchers have since learned that many bacteria have cell-surface proteins that recognize DNA from closely related species and transport it into the cell. Once inside the cell, the foreign DNA can be incorporated into the genome by homologous DNA exchange.

In transduction, 1) first off what kind of mechanism is it? 2) define 3) In most cases, transduction results from 4) explain how transduction happens see pic for transduction

1) genetic recombination -- it's one of the mechanisms that can bring together prokaryotic DNA from different individuals (that is, different cells). 2) phages (from "bacteriophages," the viruses that infect bacteria) carry prokaryotic genes from one host cell to another. 3) In most cases, transduction results from accidents that occur during the phage replicative cycle (Figure 24.16). A virus that carries prokaryotic DNA may not be able to replicate because it lacks some or all of its own genetic material. However, the virus can attach to another prokaryotic cell (a recipient) and inject prokaryotic DNA acquired from the first cell (the donor). If some of this DNA is then incorporated into the recipient cell's chromosome by crossing over, a recombinant cell is formed. explanation of pic: Phages may carry pieces of a bacterial chromosome from one cell (the donor) to another (the recipient). If crossing over occurs after the transfer, genes from the donor may be incorporated into the recipient's genome.

Fimbriae 1) define 2) function 3) singular 4) example 5) fimbriae vs. _____ + define this other thing (singular of this) + what it can also be called

1) hairlike appendages 2) some prokaryotes stick to their substrate or to one another by fimbriae 3) singular, fimbria 4) For example, the bacterium that causes gonorrhea, Neisseria gonorrhoeae, uses fimbriae to fasten itself to the mucous membranes of its host. 5) Fimbriae are usually shorter and more numerous than pili (singular, pilus), appendages that pull two cells together prior to DNA transfer from one cell to the other; pili are sometimes referred to as sex pili. (yellow strings in pic are fimbriae)

Spirochetes 1) type of _____ 2) something else abt them 3) shape (in bold) 4) what do they do 5) many are _____, but other are _____ + give example

1) heterotroph 2)are gram-negative 3) These helical gram-negative heterotrophs 4) spiral through their environment by means of rotating, internal, flagellum-like filaments. 5) Many spirochetes are free-living, but others are notorious pathogenic parasites: Treponema pallidum causes syphilis, and Borrelia burgdorferi causes Lyme disease.

Proteobacteria (see pic) 1) define 2) includes (3) 3) some are _____ while others are _____ (define both) 4) types of proteobacteria?

1) large and diverse clade of gram-negative bacteria 2) includes photoautotrophs, chemoautotrophs, and heterotrophs. 3) Some are anaerobic - Anaerobic bacteria are germs that can survive and grow where there is no oxygen, while others are aerobic - Requiring air or oxygen for life or survival 4) Molecular systematists currently recognize five subgroups of proteobacteria: (REMEMBER ABDEG (AB-DEG)) Alpha Beta Delta Epsilon Gamma

1) nearly all _____ have a _____ 2) 3 functions of this 3) why is salt used to preserve foods

1) nearly all prokaryotic cells have the cell wall 2) cell wall: 1. maintains cell shape 2. protects the cell 3. prevents it from bursting in a hypotonic environment 3) In a hypertonic environment, most prokaryotes lose water and shrink away from their wall (plasmolyze). Such water losses can inhibit (prevent) cell reproduction. Thus, salt can be used to preserve foods because it causes food-spoiling prokaryotes to lose water, preventing them from rapidly multiplying

Subgroup: Beta Proteobacteria (maybe just read) 1) describe this ssubgroup 2) name the main exammple + explain it 3) read the other examples

1) nutritionally diverse subgroup 2) includes Nitrosomonas, a genus of soil bacteria that play an important role in nitrogen recycling by oxidizing ammonium (NH4+), producing nitrite (NO2-) as a waste product. 3) Other members of this subgroup include a wide range of aquatic species, such as the photoheterotroph Rubrivivax, along with pathogens such as the species that causes the sexually transmitted disease gonorrhea, Neisseria gonorrhoeae.

cyanobacteria 1) are what types of organisms 2) early cyanobacteria did what read the rest

1) photosynthetic organisms 2) Early cyanobacteria began what is arguably the greatest impact organisms have ever had on our planet: the release of oxygen to Earth's atmosphere during the water-splitting step of photosynthesis. Cyanobacteria remained the main photosynthetic organisms for over a billion years, and they continue to be one of the most important groups of photosynthetic organisms alive today. Early cyanobacteria began what is arguably the greatest impact organisms have ever had on our planet: the release of oxygen to Earth's atmosphere during the water-splitting step of photosynthesis. In some of its chemical forms, oxygen attacks chemical bonds and can inhibit enzymes and damage cells. As a result, the rising concentration of atmospheric O2 probably doomed many prokaryotic groups. Some species survived in habitats that remained anaerobic, where we find their descendants living today. As we'll see, among other survivors, diverse adaptations to the changing atmosphere evolved, including cellular respiration, which uses O2 in the process of harvesting the energy stored in organic molecules.

molecular homology 1) define (2 ish definitions) 2) a gene organisms may have + define it

1) similar DNA (amino acid sequences) among different species from a common ancestor; a shared genetic code across all forms of life 2) It is also common for organisms to have genes that have lost their function, even though the homologous genes in related species may be fully functional. Like vestigial structures, it appears that such inactive "pseudogenes" may be present simply because a common ancestor had them. PSUEDOGENES DEFINITION FROM QUIZLET (NOT THE BOOK) - former genes that have accumulated mutations and are nonfunctional

the other scientist whose ideas were consistent with the old testament 1) name him/general time he lived/who he was 2) important thing he did 3) his version of classifying species (WHAT'S THIS CALLED) 4) how did he classify species

1) summary: Linnaean system - HE GROUPED SIMILAR SPECIES INTO INCREASINGLY GENERAL CATEGORIES. For example, similar species are grouped in the same genus, similar genera (plural of genus) are grouped in the same family, and so on 2) he developed the binomial system 3) his ideas are also consistent with the Old Testament These ideas were generally consistent with the Old Testament account of creation, which holds that species were individually designed by God and therefore perfect. In the 1700s, many scientists interpreted the often remarkable ways in which organisms are well suited for life in their environment as evidence that the Creator had designed each species for a particular purpose. Carolus Linnaeus 1) (1707-1778). a Swedish physician and botanist who sought to classify life's diversity, in his words, "for the greater glory of God." 3) In the 1750s, Linnaeus developed the two-part, or binomial, format for naming species (such as Homo sapiens for humans) that is still used today. 4) summary: Linnaean system - HE GROUPED SIMILAR SPECIES INTO INCREASINGLY GENERAL CATEGORIES. In contrast to the linear hierarchy of the scala naturae, Linnaeus adopted a nested classification system, grouping similar species into increasingly general categories. For example, similar species are grouped in the same genus, similar genera (plural of genus) are grouped in the same family, and so on 5) Linnaeus did not ascribe the resemblances among species to evolutionary kinship, but rather to the pattern of their creation. A century later, however, Darwin argued that classification should be based on evolutionary relationships. He also noted that scientists using the Linnaean system often grouped organisms in ways that reflected those relationships.

Although new mutations are a major source of variation in prokaryotic populations, additional diversity arises from genetic recombination 1) define 2) eukaryote vs. prokaryote 3) define horizontal gene transfer 4) mechanisms described above can transfer DNA within and between species in which domains? however, ________

1) the combining of DNA from two sources. 2) In eukaryotes, the sexual processes of meiosis and fertilization combine DNA from two individuals in a single zygote. But meiosis and fertilization do not occur in prokaryotes. Instead, three other mechanisms—transformation, transduction, and conjugation—can bring together prokaryotic DNA from different individuals (that is, different cells). 3) When the individuals are members of different species, this movement of genes from one organism to another is called horizontal gene transfer. 4) Scientists have found evidence that each of these mechanisms can transfer DNA within and between species in both domain Bacteria and domain Archaea. To date, however, most of our knowledge comes from research on bacteria.

1) define phylogeny just to remember it 2) One lesson from studying ___________ is that the _________ of ________ is immense. 3) read the rest

1) the evolutionary history of a species or group of species 2) One lesson from studying prokaryotic phylogeny is that the genetic diversity of prokaryotes is immense. 3) When researchers began to sequence the genes of prokaryotes, they could investigate only the small fraction of species that could be cultured in the laboratory. In the 1980s, researchers began using the polymerase chain reaction (PCR; see Figure 13.27) to analyze the genes of prokaryotes collected from the environment (such as from soil or water samples). Such "genetic prospecting" is now widely used; in fact, today entire prokaryotic genomes can be obtained from environmental samples using metagenomics (see Concept 18.1). Each year, these techniques add new branches to the tree of life. While only about 16,000 prokaryotic species have been assigned scientific names, a single handful of soil could contain 10,000 prokaryotic species by some estimates. Taking full stock of this diversity will require many years of research.

Paleontology 1) define 2) developed by 3) explain

1) the study of fossils 2) was developed in large part by French scientist Georges Cuvier (1769-1832). 3) summary: observed strata, saw that the older the stratum, the more dissimilar its fossils were to current life-forms. saw species disappear from one layer to next. opposed evolution. said there were extinctions he reasoned organisms were later repopulated by different species immigrating from other areas. In examining strata near Paris, Cuvier noted that the older the stratum, the more dissimilar its fossils were to current life-forms. He also observed that from one layer to the next, some new species appeared while others disappeared. He inferred that extinctions must have been a common occurrence, but he staunchly opposed the idea of evolution. Cuvier speculated that each boundary between strata represented a sudden catastrophic event, such as a flood, that had destroyed many of the species living in that area. Such regions, he reasoned, were later repopulated by different species immigrating from other areas.

Ideas from The Origin of Species: In his book, Darwin amassed evidence that descent with modification by natural selection explains three broad observations about nature:

1) the unity of life 2) the diversity of life 3) the striking ways in which organisms are suited for life in their environments

methanogens 1) type of _____ 2) explain 3) Although some methanogens live in _______, such as ______, others live in ______ and ______ where _______. 4) 2 ways they are useful

1) type of archaea 2) Many other archaea live in more moderate environments. Consider the methanogens, archaea that release methane as a by-product of their unique ways of obtaining energy. Many methanogens use CO2 to oxidize H2, a process that produces both energy and methane waste. Among the strictest of anaerobes, methanogens are poisoned by O2. 3) Although some methanogens live in extreme environments, such as around deep-sea hydrothermal vents (Figure 24.22), others live in swamps and marshes where other microorganisms have consumed all the O2. The "marsh gas" found in such environments is the methane released by these archaea. 4) 1. Other species inhabit the anaerobic guts of cattle, termites, and other herbivores, playing an essential role in the nutrition of these animals. 2. Methanogens are also useful to humans as decomposers in sewage treatment facilities.

Chlamydias 1) type of _____ 2) also is a ____ 3) how does it survive + describe chlamydias 4) two things chlamydias cause in people

1) type of bacteria 2) also is a parasite 3) can survive only within animal cells, depending on their hosts for resources as basic as ATP. The gram-negative walls of chlamydias are unusual in that they lack peptidoglycan. 4) blindness and nongonococcal urethritis, the most common sexually transmitted disease in the United States: One species, Chlamydia trachomatis, is the most common cause of blindness in the world and also causes nongonococcal urethritis, the most common sexually transmitted disease in the United States.

The earliest fossils are of prokaryotes that lived 3.5 billion years ago. But how did the first living cells appear? Observations and experiments in chemistry, geology, and physics have led scientists to propose one scenario that we'll examine here. They hypothesize that chemical and physical processes could have produced simple cells through a sequence of four main stages:

1. The abiotic (nonliving) synthesis (production) of small organic molecules, such as amino acids and nitrogenous bases 2. The joining of these small organic molecules into macromolecules, such as proteins and nucleic acids 3. The packaging of these molecules into protocells, droplets with membranes that maintained an internal chemistry different from that of their surroundings 4. The origin of self-replicating molecules that eventually made inheritance possible

Formation of sedimentary strata with fossils (2) tbh just read and view the picture

1. rivers carry sediment into aquatic habitats such as seas and swamps. overtime sedimentary rock layers (strata) form under water. some strata contain fossils. 2. as water levels change and geological activity pushes layers of rock upward, the strata and their fossils are exposed.

Homology (just define -- text in bold)

A second type of evidence for evolution comes from analyzing similarities among different organisms. As we've discussed, evolution is a process of descent with modification: Characteristics present in an ancestral organism are altered (by natural selection) in its descendants over time as they face different environmental conditions. As a result, related species can have characteristics that have an underlying similarity yet function differently. Similarity resulting from common ancestry is known as homology. As we'll describe in this section, an understanding of homology can be used to make testable predictions and explain observations that are otherwise puzzling.

All _______ prokaryotes known to date are ______ : just say what's in bold + read the rest

All the pathogenic prokaryotes known to date are bacteria, and they deserve their negative reputation. Bacteria cause about half of all human diseases. For example, more than 1 million people die each year of the lung disease tuberculosis, caused by Mycobacterium tuberculosis. And another 2 million people die each year from diarrheal diseases caused by various bacteria. Some bacterial diseases are transmitted by other species, such as fleas or ticks. In the United States, the most widespread pest-carried disease is Lyme disease, which infects 300,000 people each year (Figure 24.25). Caused by a bacterium carried by ticks that live on deer and field mice, Lyme disease can result in debilitating arthritis, heart disease, nervous disorders, and death if untreated.

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Although the best-known prokaryotes tend to be the bacteria that cause human illness, these pathogens represent only a small fraction of prokaryotic species. Many other prokaryotes have positive interactions with people, and some play essential roles in agriculture and industry.

The Evolution of Drug-Resistant Bacteria 1) An example of ongoing natural selection that dramatically affects humans is ______

An example of ongoing natural selection that dramatically affects humans is the evolution of drug-resistant pathogens (disease-causing organisms and viruses). This is a particular problem with bacteria and viruses because they can produce new generations in a short period of time; as a result, resistant strains of these pathogens can proliferate very quickly. Consider the evolution of drug resistance in the bacterium Staphylococcus aureus. About one in three people harbor this species on their skin or in their nasal passages with no negative effects. However, certain genetic varieties (strains) of this species, known as methicillin-resistant S. aureus (MRSA), are formidable pathogens. Most MRSA infections are caused by recently appearing strains such as clone USA300, which can cause "flesh-eating disease" and potentially fatal infections

Another valuable application of bacteria

Another valuable application of bacteria is to reduce our use of petroleum. Consider the plastics industry. Globally, each year about 350 billion pounds of plastic are produced from petroleum and used to make toys, storage containers, soft drink bottles, and many other items. These products degrade slowly, creating environmental problems. Bacteria can produce natural plastics. For example, some bacteria produce a type of organic polymer known as PHA (polyhydroxyalkanoate), which they use to store chemical energy (Figure 24.27). The PHA can be extracted, formed into pellets, and used to make durable, yet biodegradable, plastics. Researchers are also seeking to reduce use of petroleum and other fossil fuels by engineering bacteria that can produce ethanol from various forms of biomass, including agricultural waste, switchgrass, and corn.

valuable application of bacteria: read and understand

Another valuable application of bacteria is to reduce our use of petroleum. Consider the plastics industry. Globally, each year about 350 billion pounds of plastic are produced from petroleum and used to make toys, storage containers, soft drink bottles, and many other items. These products degrade slowly, creating environmental problems. Bacteria can produce natural plastics. For example, some bacteria produce a type of organic polymer known as PHA (polyhydroxyalkanoate), which they use to store chemical energy (Figure 24.27). The PHA can be extracted, formed into pellets, and used to make durable, yet biodegradable, plastics. Researchers are also seeking to reduce use of petroleum and other fossil fuels by engineering bacteria that can produce ethanol from various forms of biomass, including agricultural waste, switchgrass, and corn.

Mutualistic Bacteria

As is true for many other eukaryotes, human well-being can depend on mutualistic prokaryotes. For example, our intestines are home to an estimated 500-1,000 species of bacteria; collectively, their cells outnumber all human cells in the body by a factor of ten. Different species live in different portions of the intestines, and they vary in their ability to process different foods. Many of these species are mutualists, digesting food that our own intestines cannot break down. The genome of one of these gut mutualists, Bacteroides thetaiotaomicron, includes a large array of genes involved in synthesizing carbohydrates, vitamins, and other nutrients needed by humans. Signals from the bacterium activate human genes that build the network of intestinal blood vessels necessary to absorb nutrient molecules. Other signals induce human cells to produce antimicrobial compounds to which B. thetaiotaomicron is not susceptible. This action may reduce the population sizes of other, competing species, thus potentially benefiting both B. thetaiotaomicron and its human host.

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As surveyed in Figure 24.20, on the next two pages, bacteria include the vast majority of prokaryotic species familiar to most people, from the pathogenic species that cause strep throat and tuberculosis to the beneficial species used to make Swiss cheese and yogurt. Every major mode of nutrition and metabolism is represented among bacteria, and even a small taxonomic group of bacteria may contain species exhibiting many different nutritional modes. The diverse nutritional and metabolic capabilities of bacteria—and archaea—are behind the great impact these organisms have on Earth and its life.

Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life (just read)

As the 19th century dawned, it was generally thought that species had remained unchanged since their creation. A few clouds of doubt about the permanence of species were beginning to gather, but no one could have forecast the thundering storm just beyond the horizon. How did Charles Darwin become the lightning rod for a revolutionary view of life?

read abt darwin publishing on the origin of species

By the early 1840s, Darwin had worked out the major features of his hypothesis. He set these ideas on paper in 1844, when he wrote a long essay on descent with modification and its underlying mechanism, natural selection. Yet he was still reluctant to publish his ideas, in part because he anticipated the uproar they would cause. During this time, Darwin continued to compile evidence in support of his hypothesis. By the mid-1850s, he had described his ideas to Lyell and a few others. Lyell, who was not yet convinced of evolution, nevertheless urged Darwin to publish on the subject before someone else came to the same conclusions and published first. In June 1858, Lyell's prediction came true. Darwin received a manuscript from Alfred Russel Wallace (1823-1913), a British naturalist working in the South Pacific islands of the Malay Archipelago (Figure 19.7). Wallace had developed a hypothesis of natural selection nearly identical to Darwin's. He asked Darwin to evaluate his paper and forward it to Lyell if it merited publication. Darwin complied, writing to Lyell: "Your words have come true with a vengeance. . . . I never saw a more striking coincidence . . . so all my originality, whatever it may amount to, will be smashed." On July 1, 1858, Lyell and a colleague presented Wallace's paper, along with extracts from Darwin's unpublished 1844 essay, to the Linnean Society of London. Darwin quickly finished his book, titled On the Origin of Species by Means of Natural Selection (commonly referred to as The Origin of Species), and published it the next year. Although Wallace had submitted his ideas for publication first, he admired Darwin and thought that Darwin had developed and tested the idea of natural selection so extensively that he should be known as its main architect.

Darwin's Research (read)

Charles Darwin (1809-1882) was born in Shrewsbury, England. He had a consuming interest in nature—reading nature books, fishing, hunting, and collecting insects. Darwin's father, a physician, could see no future for his son as a naturalist and sent him to medical school in Edinburgh. But Charles found medicine boring and surgery before the days of anesthesia horrifying. He quit medical school and enrolled at Cambridge University, intending to become a clergyman. (At that time many scholars of science belonged to the clergy.) At Cambridge, Darwin became the protégé of John Henslow, a botany professor. Soon after Darwin graduated, Henslow recommended him to Captain Robert FitzRoy, who was preparing the survey ship HMS Beagle for a long voyage around the world. FitzRoy, who was himself an accomplished scientist, accepted Darwin because he was a skilled naturalist and because they were of similar age and social class.

Comparing early stages of development in different animal species reveals additional anatomical homologies not visible in adult organisms.

Comparing early stages of development in different animal species reveals additional anatomical homologies not visible in adult organisms. For example, at some point in their development, all vertebrate embryos have a tail located posterior to (behind) the anus, as well as structures called pharyngeal (throat) arches (Figure 19.17). These homologous throat arches ultimately develop into structures with very different functions, such as gills in fishes and parts of the ears and throat in humans and other mammals. see pic read: At some stage in their embryonic development, all vertebrates have a tail located posterior to the anus (referred to as a post-anal tail), as well as pharyngeal (throat) arches. Descent from a common ancestor can explain such similarities.

In contrast to ____ emphasis on sudden events, other scientists suggested that profound change could take place through the cumulative effect of slow but continuous processes. 1) scientist #1 2) scientist #2 3) explain these two scientists effects

Cuvier's 1) James Hutton says geologic feautures could be explained by gradual mechanisms, such as valleys being formed by rivers wearing through rocks. In 1795, Scottish geologist James Hutton (1726-1797) proposed that Earth's geologic features could be explained by gradual mechanisms, such as valleys being formed by rivers wearing through rocks. 2) The leading geologist of Darwin's time, Charles Lyell (1797-1875), incorporated Hutton's thinking into his proposal that the same geologic processes are operating today as in the past, and at the same rate. 3) Hutton's and Lyell's ideas strongly influenced Darwin's thinking. Darwin agreed that if geologic change results from slow, continuous actions rather than from sudden events, then Earth must be much older than the widely accepted age of a few thousand years. It would, for example, take a very long time for a river to carve a canyon by erosion. He later reasoned that perhaps similarly slow and subtle processes could produce substantial biological change. However, Darwin was not the first to apply the idea of gradual change to biological evolution.

What impelled Darwin to challenge the prevailing views about Earth and its life? skip

Darwin developed his revolutionary proposal over time, influenced by the work of others and by his travels. As we'll see, his ideas also had deep historical roots.

The Voyage of the Beagle (read)

Darwin embarked from England on the Beagle in December 1831. The primary mission of the voyage was to chart poorly known stretches of the South American coastline. Darwin, however, spent most of his time on shore, observing and collecting thousands of plants and animals. He described features of organisms that made them well suited to such diverse environments as Brazil's humid jungles, Argentina's broad grasslands, and the Andes' towering peaks. Darwin observed that the plants and animals in temperate regions of South America more closely resembled species living in the South American tropics than species living in temperate regions of Europe. Furthermore, the fossils he found, though clearly different from living species, distinctly resembled the living organisms of South America. Darwin also read Lyell's Principles of Geology during the voyage. He experienced geologic change firsthand when a violent earthquake shook the coast of Chile, and he observed afterward that rocks along the coast had been thrust upward by several meters. Finding fossils of ocean organisms high in the Andes, Darwin inferred that the rocks containing the fossils must have been raised there by many similar earthquakes. These observations reinforced what he had learned from Lyell: Physical evidence did not support the traditional view that Earth was only a few thousand years old.

read -- How rapidly do such changes (favorable traits that are heritable/natural selection) occur?

Darwin reasoned that if artificial selection can bring about dramatic change in a relatively short period of time, then natural selection should be capable of substantial modification of species over many hundreds of generations. Even if the advantages of some heritable traits over others are slight, the advantageous variations will gradually accumulate in the population, and less favorable variations will diminish. Over time, this process will increase the frequency of individuals with favorable adaptations, hence increasing the degree to which organisms are well suited for life in their environment.

Darwin's drawing (see pic)

Darwin reasoned that over a long period of time, descent with modification eventually led to the rich diversity of life we see today. He viewed the history of life as a tree, with multiple branchings from a common trunk out to the tips of the youngest twigs (Figure 19.8). In his diagram, the tips of the twigs that are labeled A through D represent several groups of organisms living in the present day, while the unlabeled branches represent groups that are extinct. Each fork of the tree represents the most recent common ancestor of all the lines of evolution that subsequently branch from that point. Darwin reasoned that such a branching process, along with past extinction events, could explain the large morphological gaps (differences in form) that sometimes exist between related groups of organisms.

Beagle's stop at the Galápagos (December 1831-October 1836)

Darwin's interest in the species (or fossils) found in an area was further stimulated by the Beagle's stop at the Galápagos, a group of volcanic islands located near the equator about 900 km west of South America. Darwin was fascinated by the unusual organisms there. The birds he collected included several kinds of mockingbirds. These mockingbirds, though similar to each other, seemed to be different species. Some were unique to individual islands, while others lived on two or more adjacent islands. Furthermore, although the animals on the Galápagos resembled species living on the South American mainland, most of the Galápagos species were not known from anywhere else in the world. Darwin hypothesized that the Galápagos had been colonized by organisms that had strayed from South America and then diversified, giving rise to new species on the various islands.

How do you date fossils?

Date using radiometric dating: "parent" isotope decays to a "daughter" isotope at a known rate Half life: amount of time it takes to decay halfway

1920s scientists (read)

During the 1920s, Russian chemist A. I. Oparin and British scientist J. B. S. Haldane independently hypothesized that Earth's early atmosphere was a reducing (electron-adding) environment, in which organic compounds could have formed from simpler molecules. The energy for this synthesis could have come from lightning and UV radiation. Haldane suggested that the early oceans were a solution of organic molecules, a "primitive soup" from which life arose.

1) Following the _____ of prokaryotes, the origin of ________ ________ years ago led to the _______ of ________—the ______, ______, _______, and _______ that fill our world today.

Following the metabolic diversification of prokaryotes, the origin of eukaryotes 1.8 billion years ago led to the evolution of a vast array of structurally complex organisms—the protists, plants, fungi, and animals that fill our world today.

Fossil record is ______.

Fossil record is incomplete. Most organisms don't fossilize, many fossils are destroyed, and few are ever discovered.

Gram-Positive Bacteria (just read for now)

Gram-positive bacteria rival the proteobacteria in diversity. Species in one subgroup, the actinomycetes (from the Greek mykes, fungus, for which these bacteria were once mistaken), form colonies containing branched chains of cells. Two species of actinomycetes cause tuberculosis and leprosy. However, most actinomycetes are free-living species that help decompose the organic matter in soil; their secretions are partly responsible for the "earthy" odor of rich soil. Soil-dwelling species in the genus Streptomyces (top) are cultured by pharmaceutical companies as a source of many antibiotics, including streptomycin. Gram-positive bacteria include many solitary species, such as Bacillus anthracis, which causes anthrax, and Clostridium botulinum, which causes botulism. The various species of Staphylococcus and Streptococcus are also gram-positive bacteria.

Natural Selection in Response to Introduced Species (read)

Herbivores, animals that eat plants, often have adaptations that help them feed efficiently on their primary food sources. What happens when herbivores switch to a new food source with different characteristics? An opportunity to study this question in nature is provided by soapberry bugs, which use their "beak," a hollow, needlelike mouthpart, to feed on seeds located within the fruits of various plants. In southern Florida, the soapberry bug (Jadera haematoloma) feeds on the seeds of a native plant, the balloon vine (Cardiospermum corindum). In central Florida, however, balloon vines have become rare. Instead, soapberry bugs in that region now feed on seeds of the goldenrain tree (Koelreuteria elegans), a species recently introduced from Asia. Soapberry bugs feed most effectively when the length of their beak is similar to the depth at which seeds are found within the fruit. Goldenrain tree fruit consists of three flat lobes, and its seeds are much closer to the fruit surface than are the seeds of the plump, round fruit of the native balloon vine. These differences led researchers to predict that in populations that feed on goldenrain tree, natural selection would result in beaks that are shorter than those in populations that feed on balloon vine (Figure 19.14). Indeed, beak lengths are shorter in the populations that feed on goldenrain tree. Can a change in a population's food source result in evolution by natural selection? Field Study Soapberry bugs feed most effectively when the length of their "beak" is similar to the depth of the seeds within the fruit. Scott Carroll and his colleagues measured beak lengths in soapberry bug populations feeding on the native balloon vine. They also measured beak lengths in populations feeding on the introduced goldenrain tree. The researchers then compared the measurements with those of museum specimens collected in the two areas before the goldenrain tree was introduced. Results: Beak lengths were shorter in populations feeding on the introduced species than in populations feeding on the native species, in which the seeds are buried more deeply. The average beak length in museum specimens from each population (indicated by red arrows) was similar to beak lengths in populations feeding on native species. Conclusion: Museum specimens and contemporary data suggest that a change in the size of the soapberry bug's food source can result in evolution by natural selection for a corresponding change in beak size.

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If people were to disappear from the planet tomorrow, life on Earth would change for many species, but few would be driven to extinction. In contrast, prokaryotes are so important to the biosphere that if they were to disappear, the prospects of survival for many other species would be dim.

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In 2013, researchers succeeded in building a vesicle in which copying of a template strand of RNA could occur—a key step toward constructing a vesicle with self-replicating RNA. On early Earth, a vesicle with such self-replicating, catalytic RNA would differ from its many neighbors that lacked such molecules. If that vesicle could grow, split, and pass its RNA molecules to its "daughters," the daughters would be protocells that had some of the properties of their parent. Although the first such protocells likely carried only limited amounts of genetic information, specifying only a few properties, their inherited characteristics could have been acted on by natural selection. The most successful of the early protocells would have increased in number because they could exploit their resources effectively and pass their abilities on to subsequent generations. Once RNA sequences that carried genetic information appeared in protocells, many additional changes would have been possible. For example, RNA could have provided the template on which DNA nucleotides were assembled. Double-stranded DNA is a more chemically stable repository for genetic information than is the more fragile RNA. DNA also can be replicated more accurately. Accurate replication was advantageous as genomes grew larger through gene duplication and other processes and as more properties of the protocells became coded in genetic information. Once DNA appeared, the stage was set for a blossoming of new forms of life— a change we see documented in the fossil record.

Adaptations of Prokaryotes: A Summary (say what's in bold)

Let's step back and examine the big picture of the adaptations that have arisen in various prokaryotic populations. We've described some of their key structural features, such as cell walls, endospores, fimbriae, and flagella. But prokaryotic cells are simpler structurally than are eukaryotic cells—they do not vary as much in shape or size, and they lack the complex compartmentalization associated with the membrane-enclosed organelles of eukaryotic cells. Indeed, the ongoing success of prokaryotes is not primarily a story of structural diversification; rather, their success is an extraordinary example of physiological and metabolic diversification. As we've seen, prokaryotes thrive under a wide variety of physical and chemical conditions, and they have an astonishing range of metabolic adaptations that allow them to obtain energy and carbon in these environments. Overall, the metabolic diversification of prokaryotes can be viewed as a first great wave of adaptive radiation in the evolutionary history of life. Bearing that broad perspective in mind, we turn now to the genetic diversity that has enabled the adaptations found in prokaryotic populations.

Archaea 1) say part in bold + just read the rest

Microbiologists began comparing the sequences of prokaryotic genes in the 1970s. For example, using small-subunit ribosomal RNA as a marker for evolutionary relationships, researchers concluded that many prokaryotes once classified as bacteria are actually more closely related to eukaryotes and belong in a domain of their own: Archaea. Microbiologists have since analyzed larger amounts of genetic data—including more than 1,700 entire genomes—and have concluded that a few traditional taxonomic groups, such as cyanobacteria, are monophyletic. However, other traditional groups, such as gram-negative bacteria, are scattered throughout several lineages

2009 scientist experiments (read)

Miller-Urey-type experiments show that the abiotic synthesis of small organic molecules is possible under various conditions. However, the presence of small organic molecules, such as amino acids and nitrogenous bases, is not sufficient for the emergence of life as we know it. Every cell has many types of macromolecules, including enzymes and other proteins and the nucleic acids needed for self-replication. Could such macromolecules have formed on early Earth? A 2009 study demonstrated that one key step, the abiotic synthesis of RNA monomers, can occur spontaneously from simple precursor molecules. In addition, by dripping solutions of amino acids or RNA nucleotides onto hot sand, clay, or rock, researchers have produced polymers of these molecules. The polymers formed spontaneously, without the help of enzymes or ribosomes. Unlike proteins, the amino acid polymers are a complex mix of linked and cross-linked amino acids. Still, it is possible that such polymers acted as weak catalysts for a variety of chemical reactions on early Earth.

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New findings continue to inform our understanding of archaeal phylogeny. For example, recent metagenomic studies have uncovered the genomes of many species that are not members of Euryarchaeota or Crenarchaeota. Moreover, phylogenomic analyses show that three of these newly discovered groups—the Thaumarchaeota, Aigarchaeota, and Korarchaeota—are more closely related to the Crenarchaeota than they are to the Euryarchaeota. These findings have led to the identification of a "supergroup" that contains the Thaumarchaeota, Aigarchaeota, Crenarchaeota, and Korarchaeota (see Figure 24.19). This supergroup is referred to as "TACK" based on the names of the groups it includes. The importance of the TACK supergroup was highlighted by the recent discovery of the lokiarchaeotes, a group that is closely related to TACK archaea and that could possibly represent the long sought-after sister group of the eukaryotes. As such, the characteristics of lokiarchaeotes may shed light on one of the major puzzles of biology today—how eukaryotes arose from their prokaryotic ancestors. The pace of these and other recent discoveries suggests that as metagenomic prospecting continues, the tree in Figure 24.19 will likely undergo further changes.

Darwin then argued that a similar process occurs in nature. He based his argument on two observations, from which he drew two inferences. what is observation #1? + see pic

Observation #1: Members of a population often vary in their inherited traits (SEE PIC + EXPLANATION OF PIC) pic expanation: Individuals in this population of Asian ladybird beetles vary in color and spot pattern. Natural selection may act on these variations only if (1) they are heritable and (2) they affect the beetles' ability to survive and reproduce.

Darwin then argued that a similar process occurs in nature. He based his argument on two observations, from which he drew two inferences. what is observation #2? + see pic

Observation #2: All species can produce more offspring than their environment can support (Figure 19.12), and many of these offspring fail to survive and reproduce. pic explanation: A single puffball fungus can produce billions of spores that give rise to offspring. If all of these offspring and their descendants survived to maturity, they would carpet the surrounding land surface.

Prokaryotes in Research and Technology

On a positive note, we reap many benefits from the metabolic capabilities of both bacteria and archaea. For example, people have long used bacteria to convert milk to cheese and yogurt. Bacteria are also used in the production of beer and wine, pepperoni, fermented cabbage (sauerkraut), and soy sauce. In recent decades, our greater understanding of prokaryotes has led to an explosion of new applications in biotechnology. Examples include the use of E. coli in gene cloning and the use of DNA polymerase from Pyrococcus furiosus in the PCR technique Through genetic engineering, we can now modify bacteria to produce vitamins, antibiotics, hormones, and other products In addition, naturally occurring soil bacteria have potential as sources for new antibiotics, as you can explore in the Scientific Skills Exercise.

Exotoxins 1) Pathogenic prokaryotes usually cause illness by _______, which are ______ (2) 2) define exotoxin + give one main example

Pathogenic prokaryotes usually cause illness by producing poisons, which are classified as exotoxins or endotoxins. Exotoxins are proteins secreted by certain bacteria and other organisms. Cholera, a dangerous diarrheal disease, is caused by an exotoxin secreted by the proteobacterium Vibrio cholerae. The exotoxin stimulates intestinal cells to release chloride ions into the gut, and water follows by osmosis. In another example, the potentially fatal disease botulism is caused by botulinum toxin, an exotoxin secreted by the gram-positive bacterium Clostridium botulinum as it ferments various foods, including improperly canned meat, seafood, and vegetables. Like other exotoxins, the botulinum toxin can produce disease even if the bacteria that manufacture it are no longer present when the food is eaten. Another species in the same genus, C. difficile, produces exotoxins that cause severe diarrhea, resulting in more than 15,000 deaths per year in the United States alone.

In the first edition of The Origin of Species, Darwin never used the word evolution (although the final word of the book is "evolved"

Rather, he discussed descent with modification - unity of life comes from organisms havving common ancestors. the descendants of those ancestors lived in various habitats so overtime they accumulate modifications aka adaptations. Rather, he discussed descent with modification, a phrase that summarized his view of life. Organisms share many characteristics, leading Darwin to perceive unity in life. He attributed the unity of life to the descent of all organisms from an ancestor that lived in the remote past. He also thought that as the descendants of that ancestral organism lived in various habitats, they gradually accumulated diverse modifications, or adaptations, that fit them to specific ways of life. Thus, Darwin thought of evolution as a process in which both descent (shared ancestry, resulting in shared characteristics) and modification (the accumulation of differences) can be observed.

just read for now AHHHHH

Recently, the prokaryotic CRISPR-Cas system, which helps bacteria and archaea defend against attack by viruses (see Figure 17.6), has been developed into a powerful new tool for altering genes in virtually any organism. The genomes of many prokaryotes contain short DNA repeats, called CRISPRs, that interact with the so-called Cas (CRISPR-associated) proteins. Cas proteins, acting together with "guide RNA" made from the CRISPR region, can cut any DNA sequence to which they are directed. Scientists have been able to exploit this system by introducing a Cas protein (Cas9) and guide RNA into cells whose DNA they want to alter (see Figure 13.32). Among other applications, the CRISPR-Cas9 system has already opened new lines of research on HIV, the virus that causes AIDS (Figure 24.26). While the CRISPR-Cas9 system can potentially be used in many different ways, care must be taken to guard against the unintended consequences that could arise when applying such a new and powerful technology.

just read for now

Since the 19th century, improved sanitation systems in the industrialized world have greatly reduced the threat of pathogenic bacteria. Antibiotics have saved a great many lives and reduced the incidence of disease. However, resistance to antibiotics is currently evolving in many bacterial strains. As you read earlier, the rapid reproduction of bacteria enables cells carrying resistance genes to quickly give rise to large populations as a result of natural selection, and these genes can also spread to other species by horizontal gene transfer. Horizontal gene transfer can also spread genes associated with virulence, turning normally harmless bacteria into potent pathogens. E. coli, for instance, is ordinarily a harmless symbiont in the human intestines, but pathogenic strains that cause bloody diarrhea have emerged. One of the most dangerous strains, O157:H7, is a global threat; in the United States alone, there are 75,000 cases of O157:H7 infection per year, often from contaminated beef or produce. Scientists have sequenced the genome of O157:H7 and compared it with the genome of a harmless strain of E. coli called K-12. They discovered that 1,387 out of the 5,416 genes in O157:H7 have no counterpart in K-12. Many of these 1,387 genes are found in chromosomal regions that include phage DNA. This suggests that at least some of the 1,387 genes were incorporated into the genome of O157:H7 through phage-mediated horizontal gene transfer (transduction). Some of the genes found only in O157:H7 are associated with virulence, including genes that code for adhesive fimbriae that enable O157:H7 to attach itself to the intestinal wall and extract nutrients.

What Is Theoretical About Darwin's View of Life? (just read)

Some people dismiss Darwin's ideas as "just a theory." However, as we have seen, the pattern of evolution—the observation that life has evolved over time—has been documented directly and is supported by a great deal of evidence. In addition, Darwin's explanation of the process of evolution—that natural selection is the primary cause of the observed pattern of evolutionary change—makes sense of massive amounts of data. The effects of natural selection also can be observed and tested in nature. What, then, is theoretical about evolution? Keep in mind that the scientific meaning of the term theory is very different from its meaning in everyday use. The colloquial use of the word theory comes close to what scientists mean by a hypothesis. In science, a theory is much more comprehensive than a hypothesis. A theory, such as the theory of evolution by natural selection, accounts for many observations and explains and integrates a great variety of phenomena. Such a unifying theory does not become widely accepted unless its predictions stand up to thorough and continual testing by experiment and additional observation (see Concept 1.3 ). As the rest of this unit demonstrates, this has certainly been the case with the theory of evolution by natural selection. The skepticism of scientists as they continue to test theories prevents these ideas from becoming dogma. For example, although Darwin thought that evolution was a very slow process, we now know that this isn't always true. Populations can evolve rapidly, and new species can form in relatively short periods of time—a few thousand years or less. Furthermore, evolutionary biologists now recognize that natural selection is not the only mechanism responsible for evolution. Indeed, the study of evolution today is livelier than ever as scientists use a wide range of experimental approaches and genetic analyses to test predictions based on natural selection and other evolutionary mechanisms.

The colonization of land by ______ and ______ _______ years ago transformed _______ from a "_______" consisting of ______ and ______ to ________ and ________.

The colonization of land by plants and fungi 500 million years ago transformed terrestrial (earthly) environments from a "green slime" consisting of bacteria and single-celled eukaryotes to lush forests and other plant communities

What else can fossils tell us about cetacean origins? read

The earliest cetaceans lived 50-60 million years ago. The fossil record indicates that prior to that time, most mammals were terrestrial. Although scientists had long realized that whales and other cetaceans originated from land mammals, few fossils had been found that revealed how cetacean limb structure had changed over time, leading eventually to the loss of hind limbs and the development of flukes (the lobes on a whale's tail) and flippers. In the past few decades, however, a series of remarkable fossils have been discovered in Pakistan, Egypt, and North America. These fossils document steps in the transition from life on land to life in the sea, filling in some of the gaps between ancestral and living cetaceans. pic explanation: Multiple lines of evidence support the hypothesis that cetaceans (highlighted in yellow) evolved from terrestrial mammals. Fossils document the reduction over time in the pelvis and hind limb bones of extinct cetacean ancestors, including Pakicetus, Rodhocetus, and Dorudon. DNA sequence data support the hypothesis that cetaceans are most closely related to hippopotamuses.

The first genetic material was most likely ____, not ____.

The first genetic material was most likely RNA, not DNA.

geologic record

The geologic record is a standard time scale dividing Earth's history into four eons•The Phanerozoic eon encompasses most of the time that animals have existed on Earth•It is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic•The boundaries between the eras correspond to major extinction events

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The story begins in 1943, when penicillin became the first widely used antibiotic. Since then, penicillin and other antibiotics have saved millions of lives. However, by 1945, over 20% of the S. aureus strains seen in hospitals were resistant to penicillin. These bacteria had an enzyme, penicillinase, that could destroy penicillin. Researchers responded by developing antibiotics that were not destroyed by penicillinase, but resistance to each new drug was observed in some S. aureus populations within a few years. Then, in 1959, doctors began using a promising new antibiotic, methicillin. But within two years, methicillin-resistant strains of S. aureus were observed. How did these resistant strains emerge? Methicillin works by deactivating an enzyme that bacteria use to synthesize their cell walls. However, some S. aureus populations included individuals that were able to synthesize their cell walls using a different enzyme that was not affected by methicillin. These individuals survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common, leading to the spread of MRSA. Initially, MRSA could be controlled by antibiotics that work differently from the way methicillin works. But this has become less effective because some MRSA strains are resistant to multiple antibiotics—probably because bacteria can exchange genes with members of their own and other species (see Figures 24.16 and 24.18). Thus, the multidrug-resistant strains of today may have emerged over time as MRSA strains that were resistant to different antibiotics exchanged genes.

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The very existence of an ecosystem can depend on prokaryotes. For example, consider the diverse ecological communities found at hydrothermal vents. These communities are densely populated by many different kinds of animals, including worms, clams, crabs, and fishes. But since sunlight does not penetrate to the deep ocean floor, the community does not include photosynthetic organisms. Instead, the energy that supports the community is derived from the metabolic activities of chemoautotrophic bacteria. These bacteria harvest chemical energy from compounds such as hydrogen sulfide (H2S) that are released from the vent. An active hydrothermal vent may support hundreds of eukaryotic species, but when the vent stops releasing chemicals, the chemoautotrophic bacteria cannot survive. As a result, the entire vent community collapses.

Anatomical and Molecular Homologies + define homologous structures. (read)

The view of evolution as a remodeling process leads to the prediction that closely related species should share similar features—and they do. Of course, closely related species share the features used to determine their relationship, but they also share many other features. Some of these shared features make little sense except in the context of evolution. For example, the forelimbs of all mammals, including humans, cats, whales, and bats, show the same arrangement of bones from the shoulder to the tips of the digits, even though the appendages have very different functions: lifting, walking, swimming, and flying. Such striking anatomical resemblances would be highly unlikely if these structures had arisen anew in each species. Rather, the underlying skeletons of the arms, forelegs, flippers, and wings of different mammals are homologous structures that represent variations on a structural theme that was present in their common ancestor. (see pic) READ THIS PART: Even though they have become adapted for different functions, the forelimbs of all mammals are constructed from the same basic skeletal elements: one large bone (purple), attached to two smaller bones (orange and tan), attached to several small bones (gold), attached to several metacarpals (green), attached to approximately five digits, each of which is composed of multiple phalanges (blue).

read again don't skip

We can also use our understanding of evolution to explain biogeographic data. For example, islands generally have many plant and animal species that are endemic. Yet, as Darwin described in The Origin of Species, most island species are closely related to species from the nearest mainland or a neighboring island. He explained this observation by suggesting that islands are colonized by species from the nearest mainland. These colonists eventually give rise to new species as they adapt to their new environments. Such a process also explains why two islands with similar environments in distant parts of the world tend to be populated not by species that are closely related to each other, but rather by species related to those of the nearest mainland, where the environment is often quite different.

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Within a decade, Darwin's book and its proponents had convinced most scientists that life's diversity is the product of evolution. Darwin succeeded where previous evolutionists had failed, mainly by presenting a plausible scientific mechanism with immaculate logic and an avalanche of supporting evidence.

However it is defined, we can view evolution in two related but different ways:

as a pattern and as a process. summary: the pattern is revealed by data via biology, geology, physics, etc. this data is facts--they're observations about the natural world that show that life has evolved over time. The pattern of evolutionary change is revealed by data from many scientific disciplines, including biology, geology, physics, and chemistry. These data are facts—they are observations about the natural world—and these observations show that life has evolved over time. summary: the process of evolution includes the mechanisms that cause the observed pattern of change The process of evolution consists of the mechanisms that cause the observed pattern of change. These mechanisms represent natural causes of the natural phenomena we observe. Indeed, the power of evolution as a unifying theory is its ability to explain and connect a vast array of observations about the living world.

hypotonic environment

environment in which there is less solute outside the cell than inside the cell water moves into the cell, Cell bursts

hypertonic environment

environment in which there is more solute outside the cell than inside the cell more "salt" outside, more water inside, Cell shrinks (think that the water is hyper to get out to where the salt is)

A third type of evidence for evolution comes from _____. 1) the ____ record does what? read this stuff 2) show what? + example 3) can shed light on _____ + example

fossils (The Fossil Record) 1) documents the pattern of evolution, showing that past organisms differed from present-day organisms and that many species have become extinct. 2) show the evolutionary changes that have occurred in various groups of organisms. for example: , researchers found that over several thousand years, the pelvic bone in fossil stickleback fish became greatly reduced in size. The consistent nature of this change over time suggests that the reduction in the size of the pelvic bone may have been driven by natural selection. 3) Fossils can also shed light on the origins of new groups of organisms. An example is the fossil record of cetaceans, the mammalian order that includes whales, dolphins, and porpoises. As shown in Figure 19.19, some of these fossils provided strong support for a hypothesis based on DNA sequence data: that cetaceans are closely related to even-toed ungulates, a group that includes hippopotamuses, pigs, deer, and cows. pic explanation: Comparing fossils and present-day examples of the astragalus (a type of ankle bone) indicates that cetaceans are closely related to even-toed ungulates. (a) In most mammals, the astragalus is shaped like that of a dog, with a double hump on one end (indicated by the red arrows) but not at the opposite end (blue arrow). (b) Fossils show that the early cetacean Pakicetus had an astragalus with double humps at both ends, a shape otherwise found only in (c) pigs, (d) deer, and all other even-toed ungulates.

Among other sources of information, Darwin drew from the work of scientists studying ______ + define (just read)

fossils - the remains or traces of organisms from the past

read

four types of data/evidence that document the pattern of evolution and illuminate how it occurs: direct observations, homology, the fossil record, and biogeography. In The Origin of Species, Darwin marshaled a broad range of evidence to support the concept of descent with modification. Still—as he readily acknowledged—there were instances in which key evidence was lacking. For example, Darwin referred to the origin of flowering plants as an "abominable mystery," and he lamented the lack of fossils showing how earlier groups of organisms gave rise to new groups. In the last 150 years, new discoveries have filled many of the gaps that Darwin identified. The origin of flowering plants, for example, is much better understood (see Concept 26.4 ), and many fossils have been discovered that signify the origin of new groups of organisms (see Concept 23.1 ). In this section, we'll consider four types of data that document the pattern of evolution and illuminate how it occurs: direct observations, homology, the fossil record, and biogeography.

Rapid Reproduction and Mutation

sort of summary of info below: In eukaryotes, sexual reproduction is a source of genetic variation, but prokaryotes do not reproduce sexually. Moreover, when a prokaryotic cell divides (by binary fission) to form two daughter cells, the generation of a novel allele by a new mutation is rare for any particular gene. How, then, does the extensive genetic variation of prokaryotes arise? new mutations, though rare on a per gene basis, can increase genetic diversity quickly in species with short generation times and large populations. this diversity, in turn, can lead to rapid evolution: Individuals that are genetically better equipped for their environment tend to survive and reproduce at higher rates than other individuals. The ability of prokaryotes to adapt rapidly to new conditions highlights the point that although the structure of their cells is simpler than that of eukaryotic cells, prokaryotes are not "primitive" or "inferior" in an evolutionary sense. They are, in fact, highly evolved: For 3.5 billion years, prokaryotic populations have responded successfully to many types of environmental challenges. In eukaryotes, sexual reproduction is a source of genetic variation, but prokaryotes do not reproduce sexually. Moreover, when a prokaryotic cell divides (by binary fission) to form two daughter cells, the generation of a novel allele by a new mutation is rare for any particular gene. How, then, does the extensive genetic variation of prokaryotes arise? In many species, the key is rapid reproduction combined with mutation, even at a low rate. Consider the bacterium Escherichia coli as it reproduces by binary fission in a human intestine, one of its natural environments. After repeated rounds of division, most of the offspring cells are genetically identical to the original parent cell. However, if errors occur during DNA replication, some of the offspring cells may differ genetically. The key point is that new mutations, though rare on a per gene basis, can increase genetic diversity quickly in species with short generation times and large populations. This diversity, in turn, can lead to rapid evolution: Individuals that are genetically better equipped for their environment tend to survive and reproduce at higher rates than other individuals (Figure 24.15). The ability of prokaryotes to adapt rapidly to new conditions highlights the point that although the structure of their cells is simpler than that of eukaryotic cells, prokaryotes are not "primitive" or "inferior" in an evolutionary sense. They are, in fact, highly evolved: For 3.5 billion years, prokaryotic populations have responded successfully to many types of environmental challenges.

1) where are many fossils found? 2) how is strata formed 3) explain this term further

summary: 1. Many fossils are found in sedimentary rocks 2. sediment covers old layers and compress into layers called strata (singular, stratum) 3. erosion can carve thru young strata and reveal older strata that was buried 1) Many fossils are found in sedimentary rocks formed from the sand and mud that settle to the bottom of seas, lakes, and swamps (Figure 19.3). 2) New layers of sediment cover older ones and compress them into layers of rock called strata (singular, stratum). 3) The fossils in a particular stratum provide a glimpse of some of the organisms that populated Earth at the time that layer formed. Later, erosion may carve through upper (younger) strata, revealing deeper (older) strata that had been buried.

Lamarck's Hypothesis of Evolution (3 things)

summary: 1. proposed principle of use and disuse: the idea that parts of the body that are used extensively become larger and stronger, while those that are not used deteriorate. Among many examples, he cited a giraffe stretching its neck to reach leaves on high branches. 2. The second principle, inheritance of acquired characteristics, stated that an organism could pass these modifications to its offspring 3. Lamarck also thought that evolution happens because organisms have an innate drive to become more complex 1) Although some 18th-century naturalists suggested that life evolves as environments change, only one proposed a mechanism for how life changes over time: French biologist Jean-Baptiste de Lamarck (1744-1829). Alas, Lamarck is primarily remembered today not for his visionary recognition that evolutionary change explains patterns in fossils and how organisms are well suited for life in their environments, but for the incorrect mechanism he proposed. 2) Lamarck published his hypothesis in 1809, the year Darwin was born. By comparing living species with fossil forms, Lamarck had found what appeared to be several lines of descent, each a chronological series of older to younger fossils leading to a living species. 3) He explained his findings using two principles that were widely accepted at the time. The first was use and disuse, the idea that parts of the body that are used extensively become larger and stronger, while those that are not used deteriorate. Among many examples, he cited a giraffe stretching its neck to reach leaves on high branches. 4) The second principle, inheritance of acquired characteristics, stated that an organism could pass these modifications to its offspring. Lamarck reasoned that the long, muscular neck of the living giraffe had evolved over many generations as giraffes stretched their necks ever higher. 5) Lamarck also thought that evolution happens because organisms have an innate drive to become more complex. Darwin rejected this idea, but he, too, thought that variation was introduced into the evolutionary process in part through inheritance of acquired characteristics. Today, however, our understanding of genetics refutes this mechanism: Experiments show that traits acquired by use during an individual's life are not inherited in the way proposed by Lamarck

Scala Naturae

summary: ancient greek philosopher Aristotle viewed species as fixed (unchanging). Through his observations of nature, Aristotle recognized certain similar characteristics among organisms. he arranged organisms on the scala naturae aka scale of nature. each form of life, perfect and permanent, had its specific rung on the ladder. this was consistent with the old testament account of creation saying that species were individually designed by God and therefore perfect. These ideas were generally consistent with the Old Testament account of creation Long before Darwin was born, several Greek philosophers suggested that life might have changed gradually over time. But one philosopher who greatly influenced early Western science, Aristotle (384-322 bce), viewed species as fixed (unchanging). Through his observations of nature, Aristotle recognized certain "affinities" among organisms. He concluded that life-forms could be arranged on a ladder, or scale, of increasing complexity, later called the scala naturae ("scale of nature"). Each form of life, perfect and permanent, had its allotted rung on this ladder. These ideas were generally consistent with the Old Testament account of creation, which holds that species were individually designed by God and therefore perfect. In the 1700s, many scientists interpreted the often remarkable ways in which organisms are well suited for life in their environment as evidence that the Creator had designed each species for a particular purpose.

artificial selection + explain the background behind it and define it

summary: artificial selection: Humans have modified species over many generations by selecting and breeding individuals that possess desired traits for example crops livestock and pets look very diff to their wild ancestors Darwin proposed the mechanism of natural selection to explain the observable patterns of evolution. He crafted his argument carefully, hoping to persuade even the most skeptical readers. First he discussed familiar examples of selective breeding of domesticated plants and animals. Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits, a process called artificial selection (Figure 19.10). As a result of artificial selection, crops, livestock animals, and pets often bear little resemblance to their wild ancestors. Darwin then argued that a similar process occurs in nature. He based his argument on two observations, from which he drew two inferences. description of picture: These different vegetables have all been selected from one species of wild mustard. By selecting variations in different parts of the plant, breeders have obtained these divergent results.

overall the fossil record shows ______

that over time, descent with modification produced increasingly large differences among related groups of organisms, ultimately resulting in the diversity of life we see today.

The fossil record is biased in favor of species that

•Existed for a long time •Were abundant and widespread• Had hard shells, skeletons, or other parts The relative ages of fossils can be determined by their sequence in the rock strata•The absolute ages of fossils can be determined by radiometric dating•A radioactive "parent" isotope decays to a "daughter" isotope at a constant rate•Each isotope has a known half-life, the time required for half the parent isotope to decay