Topic 1

Question 1

characteristics in the pedigree of a X-linked recessive rare disease?

Answer 1

• more males affected than females (bc it is easier for them to show the mutation Xm/Y instead of the decreased in probability in females from heterozygosity)
• all affected females: all male offspring will be affected
• all unnaffected father: no daughter will be affected

Question 2

what is the phenotypic ratio of a monohybrid cross for independent assortment?

Answer 2

3:1 dominant:recessive

Question 3

what does Mendel’s first law of equal segregation?

Answer 3

in meiosis, members of a gene pair separate equally into the germ cells

Question 4

what is a monohybrid cross

Answer 4

a cross where both organisms are heterozygous for 1 gene

Question 5

what is the genetic ratio of a monohybrid cross?

Answer 5

1:2:1 AA:Aa:aa

Question 6

what is the result of meiosis?

Answer 6

4 haploid daughter cells (tetrad)

Question 7

what is the result of mitosis?

Answer 7

two daughter cells with the same genotype as the original cell

Question 8

what pairs up in meiosis vs mitosis

Answer 8

in mitosis, chromatids line up in prophase and metaphase

in meiosis, two homologous chromosomes line up in prophase 1 and metaphase 1

Question 9

what is a meiocyte?

Answer 9

a transient diploid which forms only from the union of haploid cells of different mating type

Question 10

what phase does replication occur?

Answer 10

S phase in the interphase

Question 11

what is a dominant trait

Answer 11

the trait that determines the phenotype in heterozygotes

Question 12

what is haplosufficient

Answer 12

when one gene copy (one wild type allele) is enough to produce a wild-type phenotype (wild-type dominant)

Question 13

what is haploinsufficient

Answer 13

when one gene copy of the wild type allele is not enough to produce wild-type phenotype (wild-type recessive)

Question 14

what is the phenotypic ratio of doing a test cross with a heterozygote

Answer 14

1:1

Question 15

which is considered as the homogametic sex

Answer 15

females (XX)

Question 16

chromosome with telomere in the middle

Answer 16

meta centric

Question 17

chromosome with telomere on end

Answer 17

telocentric

Question 18

chromosome where one end is longer than other

Answer 18

anacentric

Question 19

what is the expected phenotypes when doing a first cross for an X-linked trait and the mutation is recessive?

Answer 19

female wild type x male mutant
all wild-type phenotype

Question 20

what is a first cross for x-linked traits

Answer 20

female wild-type x male mutant

Question 21

what is the expected phenotypes when doing a first cross for an X-linked trait and the mutation is dominant?

Answer 21

all females will be mutants and all male will be wild-type

Question 22

what is the expected phenotypes when doing a reciprocal cross for an X-linked trait and the mutation is dominant?

Answer 22

all children mutants

Question 23

what is the expected phenotypes when doing a reciprocal cross for an X-linked trait and the mutation is recessive?

Answer 23

only male offspring will be mutant all female will be wild type

Question 24

what is a reciprocal cross?

Answer 24

mutant female, wild type male

Question 25

what is the pattern for first cross and reciprocal cross for x-linked

Answer 25

1:0 or 1:1 for either reciprocal or first cross and only one gender for 1:1 all the time

Question 26

what gets replicated in the S phase

Answer 26

chromatids

Question 27

what are sister chromatics

Answer 27

chromatids with exact same alleles

Question 28

what are non-sister chromatids

Answer 28

chromatids that can either be the same or different (homozygous or heterozygous)

Question 29

what is the pathway before mitosis and meiosis

Answer 29

G1(gap), S phase (replication), G2 (gap)

Question 30

What are the characteristics of an X-linked dominant trait

Answer 30

• no skipping generation
• all affected male: all daughters will be affected
• all unaffected mother: no sons will be affected