Unit 2 Day 4

Question 1

What is AD?

Answer 1

mutation rate

Question 2

What is AR?

Answer 2

carrier rate

Question 3

population genetics

Answer 3

the study of allele frequencies and changes in allele frequencies in populations

Question 4

mutation rates

Answer 4

a measure of the rate at which various types of mutations occur over time. Mutation rates are typically given for a specific class of mutation, for instance point mutations, small or large scale insertions or deletions.

Question 5

fitness

Answer 5

individual reproductive success and is equal to the average contribution to the gene pool of the next generation that is made by an average individual of the specified genotype or phenotype.

Question 6

consanguinity

Answer 6

the property of being from the same kinship as another person. In that aspect, consanguinity is the quality of being descended from the same ancestor as another person.

Question 7

hardy Weinberg principle

Answer 7

allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

Question 8

population genetics

Answer 8

the study of allele (mutation) frequencies and changes in allele (mutations) frequencies in populations
-we are interested in deleterious mutations and a few beneficial ones

Question 9

what are population genetics important for?

Answer 9

understanding allele frequency in populations and how those frequencies change

Question 10

population sampling by phenotype leads to what?

Answer 10

estimates of allele frequency the underlying genetic mechanism

Question 11

what are the basic principles of population genetics?

Answer 11

estimate mutation rates
determine fitness
effects of consanguinity
addition of new mutations to gene pool

Question 12

hardy weinberg frequency

Answer 12

p+q=1

Question 13

hardy weinberg equation

Answer 13

p² + 2pq + q² = 1

Question 14

what is q in the hardy weinberg equation

Answer 14

q equals all of the alleles in individuals who are homozygous recessive (aa) and the other half of the alleles in people who are heterozygous (Aa)

Question 15

what is p in the hardy weinberg equation

Answer 15

p equals all of the alleles in individuals who are homozygous dominant (AA) and half of the alleles in people who are heterozygous (Aa) for this trait in a population.

Question 16

what can we learn from hardy weinberg principles?

Answer 16

• new mutations occur regularly
• most mutations are benign
• next gen DNA sequencing will determine whether the estimates we derive of mutation rates are correct
• by observing the number of cases of disease in a pop, it is possible to calculate rates of mutation for diff conditions

Question 17

Assumptions of Hardy Weinberg principle

Answer 17

population matings are random

allele frequencies remain constant over time

Question 18

why do allele frequencies remain constant over time?

Answer 18

• No appreciable rate of mutation
• All genotypes are equally fit (equal chance to pass alleles to next generation)
• No significant immigration/emigration of individuals with different allele frequencies

Question 19

allele frequency estimation is useful for?

Answer 19

• autosomal recessive where you estimate carrier rates

- applied genetic counseling for couples (integrate family history)

Question 20

what is the carrier frequency

Answer 20

2pq

Question 21

what is prevalence of disease

Answer 21

q^2

Question 22

why sex?

Answer 22

allows introduction of genetic variation to propagate new genetic traits
-benefits organisms who live in changing env., need to fend off disease, need to purge deleterious mutations

Question 23

variation occurs due to ?

Answer 23

parental genomes

recombination in meiosis

Question 24

sexual dimorphism

Answer 24

phenotypic differences btw males and females

reproductive organs, body habitus

Question 25

Jacob’s syndrome

Answer 25

47, XYY
learning disabilities
speech delay
developmental delay
behavioral/emotional difficulties
autism
tall
1/1000 boys

Question 26

Triplet X syndrome

Answer 26

47XXX
tall
risk of:
learning disabilities, delayed speech
delayed motor milestones
seizures
kidney abnormalities
1/1000 newborn girls

Question 27

gonad determination is…?

Answer 27

chromosomal
-y=male
-x and no y=female
(normal cases)

Question 28

are fetuses inherently female?

Answer 28

no.
both ovaries/testes result from common, bipotent gonad
gene directed processes

Question 29

what do the gonads tell the body to develop?

Answer 29

secondary sex charachteristics

phenotypic features

Question 30

genital ducts

Answer 30

2 in males and females
mesonephric/wolffian ducts=male structures
paramesonephric/mullerian ducts=female structures

Question 31

Mesonephric/Wolffian ducts

Answer 31

-SRY on Y chromosome; SOX9 gene
(transcription factors produce MIS, regression of paramesonephric ducts)
-FGF9 (causes tubes from mesonephric duct to penetrate gonadal ridge, differentiation testes)
-SF1/NR5A1 (differentiation sertoli and leydig cells)

Question 32

what effect does testosterone have on wolffian ducts?

Answer 32

elongate to form epididymis, seminal vesicles, vas deferens

Question 33

Mullerian/paramesonephric ducts

Answer 33

• WNT4 protein (signaling factor for ovary, inhibited by SOX9)
• DHH gene (nuclear hormone receptor, upregualted WNT4, downregulated SOX9)
• RSPO1 gene (coactivator of WNT path)

Question 34

what effect does estrogen have on mullein ducts?

Answer 34

female structures

forms uterus, cervix, broad ligament, fallopian, upper 1/3 of vagina

Question 35

androgen exposure for males results in what?

Answer 35

penis
scrotum
location of urethral opening

Question 36

estrogen exposure for females results what?

Answer 36

clitoris
labia majora/minora
lower 2/3 of vagina

Question 37

when does external genitalia develop?

Answer 37

at 3 weeks
from mesenchymal cells
form genital tubercle, genital swelling

Question 38

what tests are ordered for disorders of sexual differentiation

Answer 38

first day of life
FISH (sex chromosomes)
karyotype (chromosome microarray)
hormone studies
ultrasound
surgical consult with urology

Question 39

Androgen insensitivity syndrome (AIS)

Answer 39

46 XY (genetically male)
X-linked AR
abnormality of androgen receptor (doesn't recognize/respond)
phenotypes range from mild to full reversal of sexualization

Question 40

5-alpha reductase deficiency

Answer 40

46 XY
mutation means body can’t convert testosterone to dihydrotestosterone
phenotype=undervirilized male with increased virilization at puberty

Question 41

SRY Gene disorders

Answer 41

46 XY, 46 XX
Y linked gene
-deletion/absence of gene=phenotypically normal female
-ectopic presence of SRY gene in 46XX is a phenotypically normal male
-mutations in 46 XY= decreased/absent production of anti mullein hormone

Question 42

Denys-Drash and Frasier Syndrome

Answer 42

Sex reversal w/ 46XY
mutations in WT1 gene
different chronic kidney diseases
increased risk wilms tumor

Question 43

congenital adrenal hyperplasia

Answer 43

ambiguous genitalia 46XX
21-hydroxylase deficiency
salt wasting