Biology 2 Unit 1
Symbiosis
is an intimate relationship between partners of two or more species
artificial selection
many varieties of plants and animals could be developed in just a few generations
Which reproductive isolation mechanism explains why a large dog, such as a Newfoundland, would not normally mate with a small dog, such as a Chihuahua?
mechanical isolation
Pili
are appendages that are longer (and fewer) than fimbriae
Serial endosymbiosis hypothesis
assumes certain organelles arose from symbiotic relationships between larger cells and smaller bacteria incorporated to live within them
Phototrophs
capture energy from light
Spherical:
cocci (coccus) Occur singly, in groups of twos (diplococci),in long chains (streptococci), or clumps (staphylococci)
Some protists consist of a single cell with multiple nuclei. This condition is known as:
coenocytic
Which algal group contains individuals that are typically unicellular and form siliceous shells?
diatoms
Chromalveolates•Alveolates
dinoflagellates, apicomplexans, and ciliates
Transformation
A bacterial cell takes up fragments of foreign DNA (or RNA) released by another bacterium, exchanges DNA, resulting in a recombinant cell
Diatoms
Stramenopiles with shells composed of two parts•Cell wall consists of two overlapping silica shells with radial or bilateral symmetry•Some are plankton; others live on rocks or sediments
allopatric speciation
evolution of genetic reproductive barriers between populations that are geographically separated by a physical barrier
inbreeding increases the
frequency of homozygous genotypes
Conjugation
Two cells of different mating types come together; genetic material is transferred
habitat isolation
Two closely related species in the same geographic area live and breed in different habitats in that area
Gene transfer results in
genetic recombination
Zea mays is the scientific name of the corn plant. Zea represents the:
genus
the sum of all genotype frequencies
1.0
When faced with multiple possible cladograms, the criteria of ____ can be employed to pick the "best" hypothesis.
parsimony
Which hypothesis asserts that viruses are remnants of cellular organisms and evolved from small cells that were parasites in larger cells?
regressive hypothesis
if two alleles are dominant and recessive, the dominant phenotype is
the sum of two genotypes (AA and Aa)
Stramenopiles
water molds, diatoms, golden algae, and brown algae
viral reassortment leads to
rapid evolution
mutation
unpredictable change ion DNA
the first cells
vesicle like protobionts they divide by binary fission they maintain homeostasis some show beginnings of metabolism they are highly organized
Aristole
visualized organisms as 'moving toward a more perfect state' -- scale of nature
single stranded rna may have evolved into a more stable double stranded dna
DNA became information storage and rna remained involved in protein enzymes catalyzed most cell reactions
Four of the following ideas are consistent with Darwinian evolution. Which one is the exception?
Traits acquired during an individual's life are passed on to its offspring.
Under which mating condition is the Hardy-Weinberg principle applicable?
Matings between individuals are random.
What type of organism possesses multiple sets of chromosomes from different species?
an allopolyploid
An example of homologous structures is the wing of a bat and the:
arm of a human.
Alfred Wallace
arrived at the same conclusion at the same time as Darwin - Contributions to the Theory of Natural Selection
Prokaryotes reproduce
asexually
most viruses do not cause
disease
temperate viruses
do not always destroy host
Members of the alveolates are characterized by the presence of:
flattened vesicles under the plasma membrane
What best describes all of the alleles for all the loci present in a population?
gene pool
Black bears and brown bears co-occur but black bears spend their time in the woods and brown bears along the river. Which of the following best describes why they don't interbreed?
habitat isolation
diploid organisms
have two alleles at each genetic locus
macroevolution
involved large scale evolutionary changes
autotrophy
self feeding
Darwins four observations on the natural world
variation, overproduction, limits on population growth, differential reproductive success
Membership in a clade cannot be established by shared ancestral traits alone.
True
shortcomings of biological species concept
applies only to sexually reproducing organisms
What process has been used to produce many of today's vegetables, such as broccoli, kohlrabi and cauliflower, which are all derived from wild cabbage?
artificial selection
Mutualism
both partners benefit
macroevolution
changes among species over long periods
The surface of a Paramecium is covered with thousands of short, hair-like ____.
cilia
The bacterium that causes botulism disease is harmless until it:
contains a certain prophage DNA.
The most common outcome in interspecific hybrid offspring is no viable gametes. This happens because of:
defective meiosis
If allele frequencies do change over successive generations,
evolution is occurring
q2
frequency of aa
first cells were
heterotrophs
extreme halophiles
heterotrophs that require large amounts of na for growth
gemetic isolation
if mating takes place, molecular and chemical differences between species prevents fertilization
Variation
individuals in a population exhibit variation in traits; some improve an individuals chances of survival and reproductive success
Diplomonads
Excavates with one or two nuclei, no functional mitochondria, no Golgi complex, and up to eight flagella
genus
First part of scientific name.
Which is an example of adaptive radiation?
Four flowers of different species that evolved from a common ancestor due to selective pressures in slightly different niches
Unlike DNA in eukaryotic chromosomes, prokaryote DNA has
little protein
alveolates
dinoflagellates, apicomplexans, ciliates flattened vesicles inside plasma membrane
Nuclear area:
nucleoid
Commensalism
one partner benefits and the other is neither harmed nor helped
The specificity of viruses to different types of cells is due to ____ sites on the host cell.
receptor
Virus-first hypothesis
states that viruses predate cellular hosts. Viruses originated in a precellular world and were the first self-replicating entities
Which of the following can produce a population of individuals with a relatively high frequency of a harmful or rare allele?
the founder effect
species concepts
the morphological or phenetic species concept: into separate species based on their visible structural difference
An example of homoplastic structures is the wing of a butterfly and:
wing of a bird.
If an animal population is diploid, then each individual possesses:
two alleles for each locus.
Progressive hypothesis
viruses are mobile genetic elements that have evolved the added ability to escape from the cellular genome (escape hypothesis)
Five "informal" supergroups
Excavates •Chromalveolates •Rhizarians •Archaeplastids •Unikonts
A(n) paraphyletic group consists of several evolutionary lines that do not share a common ancestor.
False
If the allele or genotype frequencies deviate from the values predicted by the Hardy-Weinberg principle, the population is:
evolving.
Gram-negative bacteria
do not retain the stain
Which classification level contains the greatest number of species?
domain
Suppose a gene is transferred naturally by a bacterium from a plant genome to an insect genome within the same generation. What process does this illustrate?
horizontal gene transfer
viruses replicate inside
host cells
parapatric speciation
involved spatially distinct populations, between which there is gene flow, diverge and become reproductively isolated
Which is the only process that can lead to adaptations and directed genetic change of a population?
natural selection
Binary fission
one cell divides into two similar cells in which circular DNA replicates, then an ingrowth of plasma membrane and the cell wall forms a transverse wall
A taxon that diverges earlier and is sister to the other taxa being considered in cladistic analysis is a(n):
outgroup
Three Domains
Bacteria, Archaea, Eukarya
what is a population
a group of individuals of one species that live in the same geographic area at the same time
The term "clade" most closely refers to:
a group of organisms that share common characteristics inherited from a common ancestor.
At what stage of the lysogenic cycle would a prophage appear?
integration
Allopatric speciation is often exemplified in which type of geographical area or biome?
islands
Which best describes a population that forms a new species within the same geographical region as the original species?
sympatric speciation
Chromalveolates
A supergroup composed of extremely diverse protists with few shared characters •Probably originated by secondary endosymbiosis in which an ancestral cell engulfed a red alga •Most are photosynthetic •Include alveolates and stramenopiles •Contain alveoli (flattened vesicles) •Similar rDNA sequences
At what stage of the lysogenic cycle would a prophage appear?
Integration
enveloped virus
Virus that cannot infect other cells without a coat (envelope). If the envelope is destroyed (e.g., by heat or soap and water) it is unable to produce infection. Ex.
zooxanthellae
photosynthetic endosymbionts in marine invertebrates, such as corals
modes of selection
stabilizing, directional, disruptive
prezygotic barriers
Barriers that impede mating or hinder fertilization.
postzygotic barriers
Barriers that prevent the hybrid zygote from becoming a fertile adult. if an interspecific hybrid lives it may not reproduce
Parabasilids are excavates that lack functional mitochondria and lack a Golgi complex.
False
Excavates
Group of unicellular protists with flagella and a deep (excavated) oral groove Have atypical, greatly modified mitochondria •Many are endosymbionts and live in anoxic environments •Obtain energy by glycolysis (anaerobic) •Include diplomonads, parabasalids, euglenoids, and trypanosomes
Brown Algae
Largest and most complex of all seaweeds; sizes range from a few centimeters to 75 m
the binomial system
Linnaeus, naming organisms according to genus and species
One critical requirement for life to arise on Earth was time for which to occur?
Molecules to accumulate and react with one another
Methods of obtaining nutrients differ widely among protists
Most algae are autotrophic photosynthesizers •Some heterotrophs obtain nutrients by absorption •Some heterotrophs ingest food •Some protists switch their modes of nutrition and are autotrophic at certain times and heterotrophic at others
Fermentation
Process by which cells release energy in the absence of oxygen
convergent evolution
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
Why is it believed that RNA was the first informational molecule to evolve?
RNA molecules are able to function as both enzymes and substrates for their own replication.
How do retroviruses differ from other RNA viruses?
Retroviruses have reverse transcriptase instead of RNA-dependent RNA polymerase.
Most protists are motile
Some move by pushing out cytoplasmic extensions (pseudopodia) along the leading edge •Others move by flexing individual cells; gliding over surfaces; waving cilia or flagella
_________ is the scientific study of the diversity of organisms and their evolutionary relationships.
Systematics
primary endosymbiosis
The engulfment of a cyanobacterium by a larger eukaryotic cell that gave rise to the first photosynthetic eukaryotes with chloroplasts.
sympatric speciation
The evolution of reproductive barriers within a single initially randomly mating population between two populations in the same geographic range change in ecology and ploidy
q= frequency of the recessive allele
a
prebiotic soup
a hypothetical solution of sugars, amino acids, nitrogenous bases, and other building blocks of larger molecules that may have formed in shallow waters or deep-ocean vents of ancient Earth and given rise to larger biological molecules
prions
a normally harmless protein (prp) sometimes fold into a different shape that causes disease
Evolution is genetic change in ____ that occurs over time.
a population
Which are evolutionary modifications that improve the survival and reproductive success of an organism?
adaptations
To cause disease, a pathogen must be
adapted to adhere to a specific cell type, multiply, and produce toxic substances (exotoxins)
oxygen poisoned obligate anaerobes
aerobic respiration evolved that used oxygen to increase the amount of energy extracted from food -- stabilized oxygen and carbon dioxide levels
behavorial isolation
also known as sexual isolation, many animal species exchange a distinct series of signals before mating
Adaptation
an evolutionary modification that improves the chances of survival and reproductive success in a given environment
Which type of protist is responsible for malaria in humans, parasitic to both humans and mosquitoes?
apicomplexans
bacteriophages infect
bacteria
Which protist group is characterized by having a micronucleus and a macronucleus?
ciliates
Phylogenetic systematics produce branching diagrams called:
cladograms
polyphyletic group
consists of several evolutionary lines that do not share the same recent common ancestor
Genetic equilibrium exists only when these conditions are met
diploid organisms, large population size random mating no natural selection no overlapping generations no net mutations no migrations
When phenotypes are favored at one extreme of a normal distribution, ____ selection occurs.
directional
Protists
eukaryotes that cannot be classified as animals, plants, or fungi mostly aquatic
2pq
frequency of Aa
founder effect
genetic drift that results when a few individuals from a large population found a new colony
Zea mays is the scientific name of the corn plant. Zea represents the:
genus.
taxon
group or level of organization into which organisms are classified
Prokaryotic cells do not
have a nucleus or other membrane-enclosed organelles
Most multicellular protists
have relatively simple body forms without specialized tissues
shared traits from a common ancestor are
homologous traits
iron-sulfur world hypothesis
hypothesis that the metabolic reactions that led to the first cells took place on the porous surface of iron-sulfide-rich rocks at hydrothermal vents
differential reproductive success
individuals with the most favorable combination of characteristics are more likely to survive and reproduce
postzygotic barriers
isolating barriers that act after a zygote begins to develop
natural selection changes allele frequiencies
member of a population that are better adapted to the environment have greater fitness- are more likely to survive and reproduce over generations, the proportion of favorable alleles increases in the population
A taxon that includes all the descendants of an ancestor is called:
monophyletic
A taxon that includes all the descendants of an ancestor is called:
monophyletic.
What is the only source of all new alleles in a closed (isolated) population?
mutation
there are five microevolutionary processes
nonrandom mating mutation genetic drift gene flow natural selection
Parasitism
one partner lives on or in the other; the parasite benefits and the host is harmed
Aerobic bacteria require
oxygen for cellular respiration
uv protection
oxygen reacted to form ozone layer organisms could live closer to land and not always in/around water
Given the diversity in protist ultrastructure and molecular data, biologists regard the protists as a(n) ____ group, meaning that some are descendants of a common eukaryote ancestor.
paraphyletic
a populations gene pool includes all the alleles for all the loci
present
Temporal and habitat isolation is classified as what type of reproductive barrier?
prezygotic barriers
The Hardy-Weinburg Principle
principle that allele frequencies in a population will remain constant unless one or more factors cause it to change.
The five stages of a lytic infection are attachment, penetration, __________, assembly, and release.
replication
node
represents the divergence of two or more groups from a common ancestor
In ____ selection, individuals with a phenotype near the mean are favored over those at the phenotypic extremes.
stabilizing
first cells were prokaryotic
stromatolites composed of layers of microbial biofilms
The first cells were most likely heterotrophic anaerobes because:
they utilized preformed organic molecules and did not need oxygen.
According to the serial endosymbiosis hypothesis, the ancestors of mitochondria are thought to be purple bacteria.
true
Autotroph
use inorganic compounds, such as CO2, to manufacture organic molecules
photosynthetic autotrophs
use light as an energy source cyanobateria
Fragmentation
walls develop within the cell, which then separates into several new cells
Protist classification
•Molecular analysis of the gene for small subunit ribosomal RNA, and other nuclear genes •Ultrastructure data revealed by electron microscopy
If a population of 2000 individuals has 120 aa genotypes, what would the genotype frequency of aa be?
0.06
the phylogenetic species concept
A definition of species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life. Shared derived characters
Protists
An informal group of primarily aquatic eukaryotic organisms with diverse body forms, types of reproduction, modes of nutrition, and lifestyles
What type of conversion occurs when a bacterium carrying viral genes takes on new, atypical characteristics?
Lysogenic
reverse transciptase
transcribes an RNA template into DNA
Phylogenetic systematics produce branching diagrams called:
cladograms.
Vertical gene transfer
transfers genetic material from parent to offspring
Gene Transfer Takes place by three different mechanisms:
transformation, transduction, conjugation
Currently, protists and other eukaryotes are split into five informal supergroups
Excavates, chromalvaeolates, rhizarians, archaeplastids, unikots
Ancestors of ____ may have possessed mitochondria, which were lost or reduced during evolutionary history.
Giardia
Prokaryotes:
Include two domains: Archaea and Bacteria
What is the outcome of the process of conjugation between two Paramecium cells?
Two new genetically identical cells that differ genetically from what they were before
Gram-positive bacteria
absorb and retain crystal violet stain
A cell wall
around the plasma membrane supports bacterium and keeps the cell from bursting under hypotonic conditions Includes peptidoglycan
Gregor Mendel
basic patterns of inheritance
The distinctive mating signals that have evolved as part of an animal's courtship illustrate what type of reproductive isolating mechanism?
behavioral isolation
Leonardo da Vinci
correctly interpreted fossils as the remains of once existing animals that had become extinct
Robert Koch
demonstrated that bacteria cause infectious disease
assortative mating
example of nonrandom mating in which individuals select mates by their phenotypes
p2
frequency of AA
What are the two major forces contributing to allopatric speciation?
genetic drift and natural selection
Subviral agents
infective agents that are smaller and simpler than viruses
inbreeding
mating of individuals who are more closely related than of they had been chosen at random from the population
linnaeus founded
modern taxonomy- the science of naming, describing, and classifying organisms
What is the only source of all new alleles in a closed population?
mutation
Neutral variation
not all mutations have an effect in the offsrping
Obligate anaerobes
only carry out anaerobic respiration
Heterophs
organisms that cannot make their own food and must feed on other organisms
A taxon that diverges earlier than the other taxa being considered in cladistic analysis is a(n):
outgroup.
species
second part of scientific name
synapomorphy
shared derived character shared by two or more groups and originated in their last common ancestor
A monophyletic group is defined by:
shared derived characters
plasmids
small circular fragments of DNA that may contain genes for catabolic enzymes, genetic exchange, or antibiotic resistance
mechanical isolation
structural differences in reproductive organs prevent successful mating between species
satellites
subviral agents that depend on co-infection of a host cell with a helper virus
outgroup
taxon considered top have branched off earlier than the taxa under investigation allows identification of changes
One group of fruit flies reproduces in August and one group reproduces in September. Which of the following mechanisms is preventing them from cross breeding?
temporal isolation
prezygotic barriers
temporal, habitat, behavioral, mechanical, gametic
gene flow generally increases variation within a population
the migration of breeding individuals between populations with a corresponding movement of alleles increasing genetic variability in the recipient population
population genetics
the study of genetic variability within a population and of the evolutionary forces that act on it
horizontal gene transfer
transfer of genes between species of the same generation
Horizontal gene transfer
transfers genetic material to another organism that is not its offspring
p= frequency of dominant allele
A
p+q =
1
thermophiles
which require very high or very low temperature for growth
classification
The process of grouping things based on their similarities
maximum likelihood
A principle that states that when considering multiple phylogenetic hypotheses, one should take into account the one that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time. STATISTICAL
Ciliates
Complex unicellular alveolates with a pellicle that gives them a definite but changeable shape •Hairlike cilia coordinate movement in motile forms, or draw in food in sessile forms •Two kinds of nuclei: diploid micronuclei function in reproduction; polyploid macronucleus controls growth and metabolism •Reproduce sexually by conjugation •Example: Paramecium
Trypanosomes
Excavate with a single mitochondrion that has an organized deposit of DNA (kinetoplastid) •Colorless•Many are parasitic and cause disease, often live in blood •Example: Trypanosoma brucei, a human parasite that causes African sleeping sickness transmitted by the bite of infected tsetse flies
limits on population growth
Organisms compete for limited resources; not all survive to reproduce
homologous structures
Structures in different species that are similar because of common ancestry.
Which statement describes a temperate virus?
A temperate virus does not always destroy its host.
modern synthesis
A comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution.
shared derived characters
An evolutionary novelty that is unique to a particular clade. = synapomorphy
adaptive radiation
An evolutionary pattern in which many species evolve from a single ancestral species
Endospores
Dormant, extremely durable cells
Antibiotic Resistance
Drug resistance may result from accumulation of mutations in plasmid or chromosomal DNA Overuse of antibiotics is the main cause of drug resistance
Chemoheterotrophs
Energy and carbon from other organisms •Includes decomposers that obtain carbon and energy from dead organic matter •The majority of bacteria are chemoheterotrophs
Chemoautotrophs
Energy from oxidation of inorganic chemical substances such as ammonia (NH3) and hydrogen sulfide (H2S). •Most archaea and some bacteria are chemoautotrophs •Carbon from inorganic compounds
Photoheterotrophs (purple nonsulfur bacteria)
Energy from sunlight •Carbon from other organisms
Photoautotrophs (cyanobacteria)
Energy from sunlight •Carbon from inorganic compounds
restriction enzymes
Enzyme that cuts DNA at a specific sequence of nucleotides
Protists are members of domain
Eukarya
Euglenoids
Most are unicellular flagellates •Some photosynthetic (autotrophic). Chloroplasts acquired by secondary endosymbiosis (three membranes!) •Some heterotrophic species absorb organic compounds by phagocytosis and digest prey in food vacuoles
Which statement about viruses is FALSE?
Viruses can manufacture proteins.
Which characteristic defines a virus?
Viruses cannot metabolize.
Spirals:
spirochete (flexible) or spirillum (rigid)• A comma-shaped spirillum is a vibrio
Phylogeny
the pattern or relatedness among evolutionary units such as individuals, genes, populations. or species
Pleisomorphies
"primitive" ancestral characters
In a certain population, the allele causing sickle cell anemia has an allele frequency of 0.3. If the population is in genetic equilibrium for this locus, what fraction of the population would be carriers for the allele (heterozygous individuals)?
0.42
four requirements of chemical evolution
1. little or no free oxygen: oxygen oxidizes the organic molecules necessary for life 2. a source of energy: lightning; cosmic and UV radiation 3. availability of chemical building blocks: water; dissolved inorganic minerals; gases in the early atmosphere 4. time: earth is approximately 4.6 billion years old
unikont
A eukaryotic cell with a single flagellum; thought to be the ancestor of all animals
bikont
A eukaryotic cell with two flagella; thought to be the ancestor of all plants
Transduction
A phage carries bacterial genes from one bacterial cell into another •Chromosome of new host becomes recombination of its own DNA and DNA from another bacterium
Whose findings of evolution by natural selection were presented with those of Darwin?
Alfred Wallace
the metabolism first hypothesis
An explanation of the origin of life, in which life began as a self-sustaining, organized system consisting of chemical reactions between simple molecules enclosed within a boundary
Parabasilids
Anaerobic, flagellated excavates that live in animals •Examples: Trichonymphs and trichomonads •Trichonymphs have hundreds of flagella and live in the guts of termites and wood-eating cockroaches - endosymbiotic bacteria digest cellulose in the wood •A trichomonad, Trichomonas vaginalis, causes trichomoniasis, a sexually transmitted disease in humans
At what stage of a lytic infection are phage components put together to make new viruses?
Assembly
Fimbriae and Pili
Bacteria use fimbriae and pili to attach to cell surfaces or to each other
Euglenoids and Trypanosomes
Euglenoids and trypanosomes have an unusual flagellum with a crystalline rod in addition to the 9+2 flagellum characteristic of eukaryotes •Have atypical mitochondria
Eukaryotic
Eukaryotic cells have nuclei and other membrane-enclosed organelles such as mitochondria and plastids, 9 + 2 flagella, and multiple chromosomes •Sexual reproduction, meiosis, and mitosis are also characteristic of eukaryotes
A characteristic that is independently acquired by reversal or convergent evolution exhibits homology.
False
Apicomplexans
Group of parasitic, spore-forming alveolates, some of which cause serious diseases in humans•Lack specific structures for locomotion and move by flexing •Have an apical complex of microtubules that attaches the parasite to its host •Produce sporozoites transmitted to next host •Example:•Plasmodium falciparum, which causes malaria •Toxoplasma gondii, which causes toxoplasmosis
What is a prophage?
It is phage DNA that is integrated into bacterial DNA.
Dinoflagellates
Marine plankton that are generally unicellular; a few are colonial•Alveoli contain interlocking cellulose plates with silicates; typically have two flagella; many are bioluminescent•Species may be photosynthetic, heterotrophic, or endosymbionts
What are the viruses that attack bacteria?
Phages
Retroviruses
RNA viruses that have a DNA polymerase (reverse transcriptase)
Stramenopiles: Water Molds
Stramenopiles once classified as fungi•Have a mycelium with coenocytic hyphae that digests organic material•Body consists of a single multinucleate cell•Asexual reproduction: zoosporangium develops into a new mycelium-> biflagellate zoospore•Sexual reproduction: fusion of male and female nuclei; produces thick-walled oospores
Dolphins share synapomorphies with mammals.
True
Prions induce normal Prp on the surface of brain cells to misfold and cause brain damage.
True
Budding
a cell develops a bulge (bud) that enlarges, matures, and eventually separates from the mother cell
homoplasy
a characteristic that appears homologous but is acquired by convergent evolution or reversal
Methanogens
a diverse group that inhabit oxygen-free environments
After a fire, a population of ants was reduced from 1 million to 1000. What type of genetic drift will occur in the gene pool of this population when it expands again?
a genetic bottleneck
The term clade most closely refers to:
a group of organisms that share common characteristics inherited from a common ancestor.
species
a group of similar organisms that are capable of interbreeding with one another
bottlenecks
a population may rapidly and severely decrease due to disease, exploitation, or sudden environmental change
secondary endosymbiosis
a process in eukaryotic evolution in which a heterotrophic eukaryotic cell engulfed a photosynthetic eukaryotic cell which survived in a symbiotic relationship inside the heterotrophic cell
viroid
a very small infectious piece of RNA responsible for some serious diseases in plants
lysogenic cycle
a viral reproductive cycle in which the viral DNA is added to the host cell's DNA and is copied along with the host cell's DNA
In the accompanying figure, note the variation in these closely related birds. What does this illustrate?
adaptive radiation
Fimbriae
are hundreds of hairlike appendages (shorter than flagella) made of protein
At what stage of a lytic infection are phage components put together to make new viruses?
assembly
Rod-shaped:
bacilli (bacillus) Occur as single rods or long chains of rods
microevolution
changes in allele frequencies that occur within populations
microevolution
changes within the populations over a few generations
paraphyletic group
contains a common ancestor and some, but not all, of its descendants
allopolyploidy
contains multiple sets of chromosomes from two or more species
Apomorphy
derived character
speciation
evolution of a new species
disruptive selection
extreme changes in the environment may favor two or more different phenotypes selects against the average phenotypes occurs only if alleles favored under the new circumstances are already present in the population results in a divergence of distinct groups of individuals within a population increases variation in the population
When the reproductive cells of different species are incompatible and cannot accomplish fertilization, it is referred to as:
gametic isolation.
reproductive isolation
gene flow between two species may be prevented by prezygotic or postzygotic barriers
temporal isolation
genetic exchange is prevented because two groups reproduce at different times of the day, season or year
The evolutionary species concept states that for a population to be declared a separate species, it must:
have diverged significantly from other populations.
polyploidy
having more than 2 sets of chromosomes reproductive isolation occurs in a single generation
If individuals in the same town continue to only mate with other individuals from the same town, one would expect to see an increase in ____ within the population.
homozygosity
Archaea have no peptidoglycan
in cell walls or simple RNA polymerase
Overproduction
in every generation each species has the capacity to produce more offspring than can survive
monophyletic group
includes ancestor and all descendants shared derived characters and sister taxa
Aerobes appeared after oxygen
increased in the atmosphere
virus
infective agent consisting of a core or nucleic acid and is dependent on a living host
peripatric speciation
is the divergence of a small population from a widely distributed ancestral form
viruses are considered a obilgate intracellular parasite
must depend on a living host to survive and replicate
Which process provides the genetic variability that natural selection acts on during evolution?
mutation
neutral variation
not all mutations have an effect on the offspring
Evolution occurs in populations
not individuals
Heterotrophs
obtain carbon atoms from organic compounds made by other organisms
Chemotrophs
obtain energy from chemical compounds
The traditional class Reptilia is ____ because it does not include all descendants of the most recent common ancestor of reptiles.
paraphyletic
principle of parsimony
parsimony requires the cladogram with the fewest changes in characters to be accepted as most probable
Darwin
proposed that all species currently living on our planet arose from earlier ones by a process of gradual evolution HMS Beagle
rna world model
proposed that the earliest life forms were mostly RNA
capsid
protein coat surrounding a virus- determine a shape
antigenic drift
seasonal evolution caused by natural selecting altering the structure of surface proteins
negative assortative mating
selection of mates with opposite phenotypes
positive assortative mating
selection of mates with the same phenotype
stabilizing selection
selects against phenotypic extremes, favors individuals with average phenotypes narrows the bell curve reduces variation
Because whales breathe via lungs, have a little hair when born, and nurse their young, these ____ characters allow us to classify them as mammals.
shared derived
the biological species concept
species are groups of interbreeding populations which are reproductively isolated from other such groups not based on attributes of the individual rather delinates species by properties possessed by populations
Thomas Malthus
suggested that limited food supply slows population growth
Jean Baptiste de Lamarck (1744-1829)
suggested that organisms pass traits they acquired during their lifetimes to their offspring
seriel endosymbiosis
suggests that early eukaryotic cells were assemblages of formerly free living prokaryotes chloroplast may have evolved from cyanobacteria that lived inside larger heterotrophic cells mitochondria may have evolved from aerobic bacteria inside larger anaerobic cells
The scientific study of the diversity of organisms and the evolutionary relationships between them is referred to as:
systematics
The scientific study of the diversity of organisms and the evolutionary relationships between them is referred to as:
systematics.
Peptidoglycan is absent in
the archaean cell wall
systematics
the study of relationships postulated to exist among species or higher taxa
chi squared test
to see of observed and expected frequencies are very close
microspheres
type of protobiont formed by adding water to abiotically formed polypeptides
Frequencies of alleles and genotypes in a population do not change from generation to generation
unless influenced by outside factors
directional selection
when an environment changes, phenotypes at one extreme of the normal distribution are favored occurs only if alleles favored under the new circumstances are already present in the population no effect on the amount of genetic variation in a population
outcomes of allopolyploids
• Selective pressures cause one of three outcomes in a new population of allopolyploids: 1. The new species may not compete successfully against established species, and becomes EXTINCT. 2. The new species may assume a new role in the environment and COEXIST with both parental species. 3. If it has greater fitness than one or both parental species, the new species may REPLACE the parent(s).
How Did Eukaryotes Evolve?
•Mitochondria and chloroplasts probably originated from endosymbionts: •Serial endosymbiosis hypothesis assumes certain organelles arose from symbiotic relationships between larger cells and smaller bacteria incorporated to live within them •Mitochondria may have originated as aerobic bacteria and chloroplasts may have originated as a cyanobacterium within a host cell
Diversity in the Protists
•Most are unicellular •Some form colonies •Some are coenocytic (multinucleate mass of cytoplasm) •Some are multicellular
Major Groups of Bacteria
•Proteobacteria (gram-negative) •Cyanobacteria (gram-negative) •Chlamydias (gram-negative) •Spirochetes (gram-negative) •Gram-positive bacteria
lytic reproductive cycle
(Virus)many copies of the phage are made within the bacterial cell and then the bacterium lyses, or breaks open. (the common cold)
Refer to the accompanying table. What is the allele frequency of allele D? Genotype Number DD 200 Dd 700 dd 100
0.55
If a population of 1000 individuals has 120 aa genotypes, 460 Aa genotypes, and 420 AA genotypes, what is the allele frequency of the dominant allele (A)?
0.65
Koch's Postulates
1.The pathogen must be present in every individual with the disease 2.A sample of the microorganism taken from the diseased host can be grown in pure culture 3.A sample of the pure culture causes the same disease when injected into a healthy host 4.The microorganism can be recovered from the experimentally infected host
The allele freqs. of the M and N blood group alleles are 0.6 and 0.4. How many of a population of 500 would be expected to have MN blood type if the population is in HW equilibrium
240
symplesiomorphy
A character shared by a number of groups, but inherited from ancestors older than the last common ancestor
shared ancestral character
A character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade.
phylogenetic tree
A graphic representation of lines of descent among organisms or their genes.
Which statement describes a virulent phage?
A virulent phage destroys bacteria.
Who is responsible for the first concept regarding the passing on traits or characteristics that were acquired during the lifetime of an organism to its offspring?
Jean Baptiste de Lamarck
Capsules and Slime Layers
Many prokaryote species produce a capsule or slime layer of polysaccharide or protein that surrounds the cell wall
taxonomy
The science of classifying organisms
For the relative proportions of alleles and genotypes in successive generations to stay the same, which condition must be met for the population?
There can be no natural selection.
How many domains form the three main branches of the tree of life?
Three
Three of the following ideas are consistent with Darwinian evolution. Which one is the exception?
Traits acquired during an individual's life are passed on to its offspring.
Golden Algae
Unicellular biflagellates•Freshwater or marine; contain chloroplasts•Primarily asexual reproduction (zoospores)•Make up a significant portion of marine nanoplankton•Important role as producers in marine environment•Classification is controversial•Some biologists group golden algae with diatoms; some with brown algae; some divide them into two phyla•Example: coccolithophorids ("scales" of silica or calcium carbonate)
Carl Woese
two groups - prokaryotes and eukaryotes
cladogram
type of phylogenetic tree in which each branch represents a clade, a group of organisms with a common ancestor
Most protists are ____, with each cell forming a complete organism capable of performing all the functions characteristic of life.
unicellular
mutation
unpredictable change in DNA the source of genetic variation in a population only mutations in reproductive cells are inherited
Facultative anaerobes
use oxygen for cellular respiration if available, but use anaerobic respiration when necessary
neutral variation
variation that does not alter the ability of an individual to survive and reproduce and is, therefore, not adaptive
viruses are not classified in any of the three domains
viruses classified based on host range and size shape etc
regressive hypothesis
viruses may have evolved from small independent cells that were parasites in larger cells and unneeded genes were gradually lost through evolution
pathogens
viruses responsible for serious diseases such as rabies, influenza, and AIDS
