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36 Cards in this Set
- Front
- Back
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Virion or virus particle |
The extracellular form of a virus |
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Reverse transcriptase |
A viral enzyme that can synthesize DNA from an RNA template |
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What is the result when helper T cells fall below about 200 cells per cubic milliliter of blood?
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Inability to defend the body against opportunistic infections as well as the onset of AIDS.
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In what sense is evolution of AZT resistance "automatic" rather than directed or planned? Is it accurate to think of HIV as "trying" to evolve? |
Evolution is "automatic" because it is simply an inevitable consequence of the mathematics of mutation, differential survival, and reproduction in large populations. In the case of HIV resistance, whenever AZT is applied to a large, dividing population of HIV, sooner or later AZT resistance will inevitably evolve. This process occurs simply due to mathematics, without any guidance, planning, or "desire" on the part of the HIV virions, so it is not correct to think of HIV, or of any evolving population, as "trying to evolve." |
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Which is the best definition of Darwinian fitness? |
The ability of an individual to survive and reproduce in a certain environment, compared to other individuals. |
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An adaptation is best defined as _______________. |
any trait that increases fitness |
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Successful biology research often depends on choosing a good "model" - a particular species, population, or locality that is particularly amenable to study, and/or is a particularly clear case of the research question. Why were the finches of Daphne Major a good choice for an evolution study? |
The fact that Daphne Major is an island made it unlikely that migration would have a great effect. The size of the island made it possible to catch and measure the entire population of medium ground finches, while still having a large enough population for genetic drift to not have a major effect. |
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Natural selection acts directly on ______, and only indirectly on _____. |
phenotype, genotype |
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Which of the following attributes does not relate to homoplasy? |
SINE and LINE data sets |
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A growing body of literature suggests that mutations are surprisingly frequent on a per genome/per generation basis; most are ___________ or ___________. |
neutral/slightly deleterious |
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Gene |
stretch of DNA that codes for a distinctive type of RNA or protein product |
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Alleles |
versions of the same gene that differ in their base sequences |
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Mutation |
any change in the base sequence of DNA |
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Point mutation |
a change in a single base sequence of a gene |
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monophlyetic group, or clade |
A group that contains an ancestor and all of its descendants |
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paraphyletic group |
A group that contains an ancestor and some, but not all, of its descendants |
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homology |
The occurrence of shared traits that were inherited from a common ancestor |
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homoplasy |
The occurrence of shared traits that were not inherited from a common ancestor |
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Derived |
Modified from an ancestral state to a new state |
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synapomorphy |
A shared trait that was modified (changed from an older ancestral state) in the most recent common ancestor |
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outgroup |
A close relative of the groups under study, but one that is known to have branched off earlier than all the other groups |
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Reversal |
A change of a modified trait back to its ancestral state |
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Parsimony |
fewest number of assumptions in phylogenetic trees. Most accurate and preferable. evolution occurs slowly, and therefore evolutionary changes should be, in general, rare. |
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What is an exact method, and what limits its use? |
An exact method, or an exhaustive search, is an analysis that examines every possible tree. Exact methods are computationally intensive and take so long that they can only be used on small data sets, because of the astronomical number of possible trees in large data sets. |
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If trees derived from different data sets are in conflict, what are some commonly used criteria for deciding which tree is more likely to be correct? |
The tree most likely to be correct is the one that was derived from a larger data set, is corroborated by multiple analysis methods, has an obviously better choice of outgroup, and/or was based on well-understood characters known to be resistant to homoplasy. |
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SINE or LINE |
They are segments of DNA that occasionally insert themselves into new locations in the genome |
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At what level do the processes of evolution act? |
evolution acts on individuals. individuals do not evolve but populations do. |
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modern synthesis |
new synthesis of ideas from different biological perspectives that provide proof of evolution |
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What were the two main objectives/hypotheses of Darwin’s On the Origin of Species by Means of Natural Selection? |
descent with modification & natural selection |
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Darwin's observations (4) |
-individuals have heritable traits -more population than resource= competition -adaptation -same population can have different traits |
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Distance method |
looses a lot of information. puts characteristics into numerical numbers |
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Bayesian/maximum likehood method |
uses statistical methods with nucleotides. allows to incorporate other findings |
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how long has phylogenetic trees been used? |
1800s because the first one was found in Darwin's notebook |
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data used to reconstruct evolutionary trees |
molecular data |
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What are two types of proteins that can cause point mutations? |
Point mutations can occur whenever DNA has to be replicated (for cell division) or repaired. Therefore most common sources of point mutations are errors made by DNA polymerase during replication prior to cell division, and errors by DNA repair enzymes in detecting or repairing DNA damage. |
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Which of the following is not a reason why analyses of loss-of-function mutations underestimate actual mutation rates? |
large-scale phenotype mutations cannot be caused by point mutation |
