Genetics

Question 1

Chromosomal abberations

Answer 1

= abnormalities
either aneuploidy (wrong #) or deletions, inversions, etc

Question 2

Aneuploidy

Answer 2

normal: 22 pairs of autosomal chromosomes + sex chromosomes
- identify in karyotypes
- can’t see point mutations or frameshifts

Question 3

Down’s

Answer 3

Trisomy 21

Question 4

Turner’s

Answer 4

XO / 45X

Question 5

Kleinfelter’s

Answer 5

XXY

Question 6

One X chromosome silenced in females

Answer 6

Barr bodies

Question 7

Trisomy 13 and 18

Answer 7

developmental impairments

Question 8

Karyotype bands

Answer 8

• dye stains

- if you can stain dye, dye permeates DNA = euchromatin

Question 9

alleles

Answer 9

• form of gene

- 2; one on each chrom (one from mom, one from dad)

Question 10

Crossing over

Answer 10

• prophase 1
• b/w homologous chromosomes of non-sister chromatids
• increase variation
• help pair homologous chromosomes

Question 11

Meiosis

Answer 11

• gametogenesis
• ploidy reduced at Anaphase 1 (homologous chromosomes separate
• sis chromatids separated at anaphase 2

(2 x 2n) -> 2(2 x 1n) ->4 (1n)

Question 12

Mendel’s law of segregation (1st) =

Answer 12

-alleles separate during anaphase 1

2nd- law of indep assortment- non-linked genes = recomb freq of 50%, otherwise linked closer to 0 (mom vs dad)

Question 13

spermatogonium

Answer 13

-stem cell: self-renewal OR commit to meiosis

spermatogonium = one mom, one dad
primary spermatocyte = it has been replicated

a mutation in a primary spermatocyte (during or after DNA repl) would result in either a 1:3 or 3:1 mutation

Question 14

test cross

Answer 14

a dominant of unknown genotype with recessive to figure out unknown genotype

Question 15

monohybrid cross

Answer 15

both parents are heterozygous

Question 16

Recessive pedigree

Answer 16

-generational skipping

Question 17

codominance example

Answer 17

blood type ABO

Question 18

Sex linked

Answer 18

-on MCAT, X linked
males more affected b/c HEMIZYGOUS- only have one X
-males cannot be carriers
-males are more likely to be colorblind; rhodopsin coded for on X chromosome

Question 19

X linked carrier mom, normal dad;

a) affected daughters?
b) affected sons?

Answer 19

• all daughters normal- 1/2 carriers, 1/2 fully fine

- 1/2 males affected; x from mom

Question 20

X linked affected dad, normal mom;

a) affected daughters?
b) affected sons?

Answer 20

a) all carrier daughters

b) none

Question 21

X linked affected dad, carrier mom;

a) affected daughters?
b) affected sons?

Answer 21

a) 1/2 carriers, 1/2 affected

b) 1/2 affected, 1/2 normal

Question 22

Huntington’s

Answer 22

-dominant, 100% penetrant

Question 23

CF

Answer 23

-recessive, 100% penetrant

Question 24

expressivity

Answer 24

-how bad will it be?
-given the phenotype, how much will you express it?
spectrum of severity / impairment

Question 25

if i tell you that it doesn’t express the trait or it’s lethal

Answer 25

you change the denominator / the probabilities shift
pay attention to wording

also just a reminder that you have an actual periodic table so

Question 26

Tay-Sachs

Answer 26

Muscle control (loss)
Blindness
Paralysis
Death