More Ch. 26 and Ch. 27 Eukaryotes

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distinguish the major protists (in class), include their major characteristics that define them from other protists

(amoebozoa) Plasmodial Slime Molds- Lacy network that is visible to naked eye, large multinucleated cells, haploid cells fuse to form zygotes that subsequently undergo repeated rounds of mitosis, but not cell division, to form colorful, often lacy structures visible to the naked eye. These structures, called plasmodia, are coenocytic, which means they contain many nuclei within one giant cell. Cellular Slime Molds- Upon starvation, form large aggregates that resemble slugs.Cellular slime molds spend most of their life cycle as amoeboid cells feeding on bacteria in the soil. These slugs can move with the use of actin and myosin and forage for food. These structures also form sporangia that produce spores for dispersal (archaeplastida) - red algae = 5000 species mostly from marine environments. Most are multicellular and have differentiated tissues and complex morphology. Cell walls are made of cellulose, and they have photosynthetic pigments in the form of chlorophyll a and biliproteins (red pigment). Uses include toothpaste, ice cream, and agar (microbiology). green algae- 10,000 species living in freshwater. Includes seaweeds such as sea lettuce and large, complex seaweeds found in tropical and temperate oceans. United by two features the presence of chlorophyll a and chlorophyll b in chloroplasts that have two membranes unique attachment for flagella. (stramenopila) - giant kelps = One of the most impressive brown algae are the kelps, giant seaweeds that form forests above the seafloor. Kelps have evolved distinct organs specialized for attachment, photosynthesis, flotation, and reproduction. diatoms = ~ 10,000 species that thrive in environments that range from wet soil to the open ocean. Responsible for 25% of all photosynthesis on Earth. Skeletons of silica are now the principal means by which SiO2 is transferred from seawater to sediments.

analyze a phylogenetic to determine relatedness among organisms

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explain the evidence for why biologists believe that endosymbiosis and photosynthetic organisms happened several times

- A photosynthetic amoeba, Paulinella chromatophora, contains chloroplasts that originated from a different branch of cyanobacteria than the cyanobacteria that gave rise to the chloroplast in other photosynthetic eukaryotes. Research also suggests that the engulfment of cyanobacteria in Paulinella occurred long after the other endosymbiotic event that gave rise to chloroplasts. About one-third to one-half of the ancestral genome remains present in this organism, suggesting that chloroplast evolution is still in progress.

explain the role of 16S rRNA in determining relatedness in bacteria, archaea, and eukaryotic organisms

16S rRNA that is found in in all bacterial and archaeal ribosomes. The gene that codes for it is used to determine evolutionary relationships in prokaryotes. Process: Isolate DNA from bacteria Sequence region of DNA that codes for the RNA that works in ribosomes Compare that sequence to the rRNA sequence of known bacteria sequences to determine changes that occurred during the course of evolution Can analyze without being able to culture

describe plasmid and explain its role in bacterial diversity, evolution, and biotechnology

A bacterial cell's DNA is present as a single circular chromosome, and a bacterial cell can carry additional DNA in the form of plasmids. it is small circle of DNA that replicates independently of the cell's circular chromosome.... not essential for cell's survival but carry genes for antibiotic resistance, metal ion resistance

list the characteristics that are used to classify bacteria within that domain...

A. Shape (6 shapes) B. Type of Cell Wall - Gram-positive peptidylglycan, Gram-negative peptidyglycan, Mycolic acid No cell wall C. Arrangement- Tetrad-forming, Filament-forming D. Habitat- Water Soil Gut Oxygen Etc.... E. Metabolism How does it get its energy? How does it get its carbon? Can it fix nitrogen?

compare and contrast the characteristics of the organisms in the 3 domains of life

Eukarya= The defining characteristic of eukaryotic cells is the presence of a nucleus. However, it is quite another set of features that distinguishes eukaryotes in terms of function and the capacity for evolutionary innovation. Eukaryotic success lies in their remarkable capacity to form cells of diverse shape and size and to produce multicellular structures in which multiple cell types act in concert. A eukaryotic cell has an internal scaffolding of proteins made of actin filaments and microtubules that allows it to change shape and remodel itself quickly. These dynamic proteins make up the cell's cytoskeleton. Eukaryotes also have dynamic internal membranes that make up the endomembrane system. Bacteria = Bacteria have no membrane-bound nucleus, no energy-producing organelles, and no sex (these are defining features of eukaryotic cells). A bacterial cell's DNA is present as a single circular chromosome, and a bacterial cell can carry additional DNA in the form of plasmids. Because the DNA is not separated from the cytoplasm within a nucleus like that in the eukaryotic cell, transcription and translation both occur in the same location. Cellular processes are carried out in the cytoplasm or in the membrane of a bacterial cell by proteins that are free floating or membrane bound. The bacterial cell is supported by a cell wall made of peptidoglycan, a polymer of sugars and amino acids. Archaea = (physically similar to bacteria) -Use different lipids than bacteria - Different cell walls - RNA polymerase is more like Eukaryotes - Ribosomes are different than bacterial ribosomes (antibiotics) - methanogenesis -classified by habitat "extremophiles"

describe the major parts of the sulfur cycle and the organisms that play a role in each part

Our bodies are made up of mostly carbon, oxygen, and hydrogen, but we also contain about 0.2% sulfur by weight. Sulfur is present in the amino acids cysteine and methionine and, as a result, present in many proteins. It is also found in enzymes in electron transfer, some membranes, vitamins, and cofactors. But where do we get the sulfur we need? from the food we eat The primary producers take in sulfur. On land, plants take up sulfate ions from the soil and reduce them to hydrogen sulfide that can be incorporated into cysteine and other biomolecules in a process called assimilation. After cell death, fungi and bacteria decompose cells, returning carbon, sulfur, and other compounds to the environment. Reduced sulfur compounds released from decomposing cells are then oxidized by bacteria and archeons, completing the cycle.

describe the general principles of life cycles of single-celled eukaryotes, animals, and plants including haploid and diploid phases

Sexual reproduction involves meiosis and the formation of gametes, and the subsequent fusion of gametes during fertilization. Sex promotes genetic variation in two simple ways: First, meiotic cell division results in gametes or spores that are genetically unique. Second, in fertilization, new combinations of genes are brought together by the fusion of gametes. The cell cycle of eukaryotes differs depending on whether the organism reproduces sexually or asexually. Cells with one copy of each gene are haploid, while sexual fusion between two haploid cells results in a diploid cell (two copies of each gene). The life cycle of sexually reproducing eukaryotes alternates between haploid and diploid states. The life cycles of single-celled eukaryotes differ in the proportion of time spent as haploid (1n) versus diploid (2n) cells. Animals, plants, and other complex multicellular organisms have life cycles with the same features as those just discussed. The big difference is that in animals, the zygote divides many times to form a multicellular diploid body before a small subset of cells within the body undergoes meiotic cell division to form haploid gametes (eggs and sperm). During fertilization, the egg and sperm combine sexually to form a zygote. In animals, as in diatoms, the only haploid phase of the life cycle is the gamete. Plants either have a dominant multicellular haploid phase OR dominant multicellular diploid phase. One example...moss....

describe the evolutionary relatedness of the 3 domains and the 7 superkingdoms in the Eukarya domain

relatedness of the 3 domains= endosymbiotic theory... 7 superkingdoms = the evolution of photosynthesis & cyanobacteria.. endosymbiosis of green or red algae

distinguish the major protists (in class), include their major characteristics that define them from other protists

Superkingdom Alveolata.. Unifying feature: cortical alveoli - small vesicles packed beneath the cell The group is united by the presence of cortical alveoli, small vesicles packed beneath the cell surface that, in some species at least, store calcium ions for use by the cell 1. Dinoflagellates are responsible for red tides (toxic blooms in coastal water) that occur naturally or because of human activities such as sewage seeps and fertilized cropland runoffs. 2. Ciliates- paramecium found in pond scum 3. Most popular of the avelotates is the third group, the apicomplexans. This group includes the species Plasmodium falciparum, which causes malaria and was responsible for 600,000 deaths worldwide in 2013. Superkingdom Rhizaria= Unifying feature: pseudopodia - "false feet" Vary considerably in form, having no clear morphological distinctive characters, but for the most part they are amoeboids Many produce complex shells or skeletons Make up the vast majority of protozoan fossils Some are photosynthetic Superkingdom Excavates = Many are missing "true" mitochondria Some are photosynthetic Includes many human parasites Trypanosomes - some species cause African Sleeping sickness Giardia (STD) Trichomonas (STD)

explain the endosymbiotic theory of mitochondria and chloroplast, including the likely identity of the cells that underwent endosymbiosis

The endosymbiotic hypothesis proposes that the chloroplasts and mitochondria of eukaryotic cells were originally free-living bacteria... both have closely similar internal membranes that organize the light reactions of photosynthesis mitochondria- proteo bacteria was engulfed by either an archae or very early eukaryote chloroplasts- was engulfed by eukaryotic cell that already had mitochondria (mitochondria came first)

describe the major parts of the nitrogen cycle and the organisms that play a role in each part

We get nitrogen from the foods we eat. The air we breathe consists of 78% nitrogen gas; however, many primary producers cannot make use of nitrogen in this form. Only bacteria and archaeons can reduce nitrogen gas to its usable form, ammonia, through a process called nitrogen fixation. It is one of the most important reactions ever evolved by organisms. The nitrogen cycle begins with nitrogen fixation and continues to many additional metabolisms, most of which are confined to bacteria and archaeons. Ammonia released by the decomposition of dead cells can be taken up by primary producers, but it is commonly oxidized to nitrate by chemoautotrophic bacteria in a process called nitrification. This process works in both soil and water, therefore nitrate is the most common form of nitrogen in both locations. Anaerobic respiration completes the cycle by returning nitrogen gas to the atmosphere. Some bacteria can use nitrate as an electron acceptor in respiration in a process known as denitrification. This process is so efficient that nitrogen fixation must continually make nitrogen available for organisms.

describe what the human microbiome is and explain its relationship to a human's diet and their health.. include the effect of antibiotics and probiotics on the microbiome

You were born without any bacteria in your body. Within minutes, microbes were starting to colonize your body. Now, you have ~10X more non-human cells (bacteria, archaea, protest) in you than human cells Vast majority are neutral or helpful. Only a few can make us sick. The colonization of bacteria to our guts varies based on what we eat. In African children raised on a low-fat, low-animal-protein diet that is rich in plant matter, their gut microbiota is enriched with species known to help digest cellulose. In European children raised on a Western diet rich in sugar and animal fat, the same bacteria that are present in African children are absent. probiotic= yogurt, beneficial bacteria prebiotic= food that good bacteria eats antibiotic= The bacteria that are not resistant to the antibiotic are eliminated

describe choanoflagellates and the relationship between them and humans

are a group of unicellular protists (group optisthokonta) characterized by a ring of microvilli that form a collar around the cell's single flagellum. About 150 choanoflagellate species have been described from marine and freshwater environments, where they prey on bacteria These species are the most evolutionarily similar protistan species to animals. Molecular sequence comparisons confirm the close relationships between animals and choanoflagellates. Many genes once thought to be unique to animals have now been identified in choanoflagellates

explain the role of cell surface area and cell volume in the transport of nutrients in and out of the cell

cells need to be small because they rely on diffusion for getting substances into and out of their cells. When a cell grows, there is comparatively less membrane for the substances to diffuse through resulting in the center of the cell not receiving the substances that it needs. Diffusion is less efficient, cell processes slow down and the cell stops growing. The cell then needs to divide into two smaller cells, which each have a larger SA:V ratio and can diffuse materials more efficiently again

list common shapes of bacteria. explain the role of diffusion in cell shape

coccus (round), bacillus (rod), coccobacillus (short stubby rod), vibrio (gently curved rod), sprillium (helix), spirochete (flexible helix) SLIDE 10 CH. 26

distinguish between meotic cell division, mitotic cells division, binary fission, conjunction, sexual reproduction, asexual reproduction, and horizontal gene transfer

meotic cell division- form of cell division that includes two rounds of nuclear division.. by producing haploid gametes, meotic cell division makes sexual reproduction possible mitotic cell division- division of the nucleus in which the chromosomes are separated into two nuclei binary fission- the process by which cells of bacteria or archaeons divide conjugation- the direct cell to cell transfer of DNA, usually in form of a plasmid sexual reproduction- process if producing offspring that receive genetic material from two parents; in eukaryotes, the process occurs through meiosis and fertilization asexual reproduction- the reproduction of cells or single celled organisms by cell division; offspring are clones of the parent horizontal gene transfer= allows bacterial cells to gain beneficial genes from organisms distributed throughout the bacterial domain and beyond (conjugation, transformation, transduction)

compare and contrast prokaryotic vs eukaryotic cells

prokaryotic = no nucleus, membrane bound organelles, most are single celled, no complex multicellularity, circular chromosomes, plasmids eukaryotic = can form simple & complex multicellular organisms, nucleus, organelles derived from endosymbiotic relationships, RNA processing

define protozoa and algae.. describe the relationship

protozoa= heterotrophic protists, almost exclusively single celled algae= photosynthetic protists, may be microscopic single celled organisms or the highly visible, multicelled organisms we called seaweed both are protists


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