Sheet 14--Final Exam Flashcards
(54 cards)
What is balancing selection, and what is balanced polymorphism?
balancing selection–number of selective processes by which multiple alleles are actively maintained in the gene pool of a population at frequencies above that of gene mutation
balanced polymorphism- situation in which two different versions of a gene are maintained in a population of organisms because individuals carrying both versions are better able to survive than those who have two copies of either version alone—-This is maintained through balancing selection
what is frequency dependent selection?
fitness of a genotype depends on its frequency
what is kin selection and what is altruism?
apparent strategies in evolution that favor the reproductive success of an organism’s relatives, even at a cost to their own survival
altruism-selflessness is the principle or practice of concern for the welfare of others
what kinds of evidence support the existence of microevoultion?
.
what is industrial melanism?
darkness—of the skin, feathers, or fur—acquired by a population of animals living in an industrial region where the environment is soot-darkened.
what is the best example of microevolution in human beings?
aids resistence with CCR5
why do we think that the frequency of sickle cell anemia is much higher in central africa?
Selective force in Africa is presence of malaria. Maintenance of allele has adaptive value in Africa
since sickle cell anemia is usually lethal, why hasnt it been eliminated by natural selection?
.
why do humans living in tropical regions have dark skins while those in the north have light skins?
.
What are the two general ways in which DNA is altered?
radiation and chemical mutagens
What are the 3 ways mutations arise?
1) DNA damage
2) chromosomal Rearrangement
3) Transposition
what are four types of mutations?
1) point mutations–base changes
2) small deletions or insertions– frame shifts
3) large deletions or insertions
4) rearrangements of large pieces of DNA
What are point mutations?
involve small numbers of bases
- -can include base substitutions and indels–both insertions and deletions
- -affect one gene
what is an indel?
short way to refer to insertions or deletions
what are base substitution mutations?
chagne in the base that results in:
- -change in the amnino acid sequence
- -change in the stop codon
- add or remove an intron splice site
- –substitution is a type of point mutation
what are indels? what are they lumped together?
- -mutations resulting from an insertion or a deletion of bases
- -causes a frameshift
why are indels usually more deleterious than base substitutions?
indels change the entire message
–CAT CAT CAT
—-remove A
CTC ATC ATC
What are the two ways DNA gets damaged?
- -mistakes during DNA replications
- -chemical decomposition
what sorts of spontaneous mutations occur during and what occur after DNA replication?
During DNA replication:
- –mispaired bases
- – misaligned bases
After DNA replication:
- -Deaminatino of C to U
- -depurination–loss of A or G
what are the two classes of mutagens?
radiation and chemicals
what sorts of mutations are caused by X-Rays?
double stranded breaks cause deletions, insertions, and rearrangements
What mutations are cuased by sun tanning?
UV causes formation of thymine dimers
–point mutatinos
what sorts of mutations are cause by cigarette smoke?
base substitution
what sorts mutations caused by intercalating chemicals?
insert into DNA and cause frame shift mutations
