Genetics

Question 1

Complete dominance

Answer 1

When only one dominant and one recessive allele exist for a given gene. Dominant will mask recessive.

Question 2

Codominance

Answer 2

When more than one dominant allele exists for a given gene. Example: AB blood type.

Question 3

Incomplete dominance

Answer 3

When a heterozygote expresses a phenotype that is intermediate between the 2 homozygous genotypes. Example: Mating of certain Red and White flowers to get Pink.

Question 4

Penetrance

Answer 4

proportion of the population with a given genotype who actually express the phenotype

Question 5

Expressivity

Answer 5

Different manifestations of the same genotype across the population

Question 6

Mendel’s 1st law

Answer 6

Law of segregation

Genes exist as alleles.
An organism has 2 alleles for each gene
Separation of homologous chromosomes during anaphase I

Question 7

Mendel’s 2nd law

Answer 7

Law of independent assortment

The inheritance of one gene does not affect the inheritance of another gene

Question 8

Wild type allele

Answer 8

The alleles that are considered normal or natural in the population

Question 9

Point mutations

Answer 9

When a nucleotide in DNA is swapped for another

Silent, missense, or nonsense

Question 10

Silent mutation

Answer 10

when the change in nucleotide has no effect on the final protein synthesized from the gene

Question 11

Missense mutation

Answer 11

When the change in nucleotide results in substituting one amino acid for another in final protein

Question 12

Nonsense mutation

Answer 12

Change in nucleotide results in substituting in a stop codon for an amino acid in final protein

Question 13

Frameshift mutations

Answer 13

When nucleotides are inserted into or deleted from the genome. This shifts the reading frame and changes the sequence or results in premature truncation

Question 14

Chromosomal mutations

Answer 14

Larger scale mutation in which large segments of DNA are affected

Deletion, duplication, inversion, insertion, translocation

Question 15

Deletion mutation

Answer 15

When a large segment of DNA is lost from a chromosome

Question 16

Duplication mutation

Answer 16

When a segment of DNA is copied multiple times in the genome

Question 17

Inversion mutation

Answer 17

When a segment of DNA is reversed within the chromosome

Question 18

Insertion mutation

Answer 18

When a segment of DNA is moved from one chromosome to another

Question 19

Translocation mutation

Answer 19

When a segment of DNA from one chromosome is swapped with a segment of DNA from another chromosome

Question 20

Genetic leakage

Answer 20

Flow of genes between species.

Can produce hybrid offspring

Question 21

Genetic drift

Answer 21

Refers to changes in the composition of the gene pool due to chance

Question 22

How do you perform a test cross?

Answer 22

Used to determine an unknown genotype. You cross the unknown genotype with an organism with a known homozygous recessive genotype.

Question 23

What should you assume for sex linked traits on the MCAT?

Answer 23

Assume that all sex linked traits are X-linked recessive

Question 24

Hardy-Weinburg Equation

Answer 24

p^2 + 2pq + q^2 =1

p+q=1

Question 25

Modern synthesis model

Answer 25

Sometimes called Neo-Darwinism Adds knowledge of genetic inheritance and changes in the gene pool to the original theory of natural selection

Question 26

Differential reproduction

Answer 26

Those traits passed on by one or more successful organisms will become ubiquitous in the gene pool

Question 27

Inclusive fitness

Answer 27

A measure of an organisms success in the population, based on the number of offspring, success in supporting offspring, and the ability of offspring to then support others

Question 28

Stabilizing selection

Answer 28

Keeps phenotypes within a specific range by selecting against extremes

Question 29

Directional selection

Answer 29

Adaptive pressure that leads to the emergency and dominance of an initially extreme phenotype

Question 30

Disruptive selection

Answer 30

To extreme phenotypes are selected over the norm

Question 31

Prezygotic mechanisms

Answer 31

Prevent formation of those I go completely

Question 32

Postyzygotic mechanisms

Answer 32

Allow for gamete fusion but yield either non-viable or sterile offspring

Question 33

Divergent evolution

Answer 33

The independent development of dissimilar characteristics in two or more lineages sharing a common ancestor

Question 34

Parallel evolution

Answer 34

The process whereby related species evolve in similar ways for a long period of time in response to analogous environmental selection pressures

Question 35

Convergent evolution

Answer 35

The independent development of similar characteristics in two or more lineages not sharing a recent common ancestor