Sex linked traits

Question 1

What determins if the baby is a boy or not

Answer 1

The SRY gene

Question 2

What happens if the SRY gene is present

Answer 2

Testes form

Question 3

What happens if the SRY gene is absent

Answer 3

Ovaries form

Question 4

Why is the x chromosome bigger than the y chromosome

Answer 4

The x chromosome has way more genes than the y chromosome

Question 5

Do both men and women have x chromosomes

Answer 5

Yes, women have 2 x chromosomes and men have 1 x chromosome

Question 6

What are sex linked traits

Answer 6

Traits on sex chromosomes, usually on the x chromosome

Question 7

Does a recessive trait on the x chromosome show more on men or women and why?

Answer 7

Men because they only need 1 copy of the recessive allele while females need 2

Question 8

Do recessive x linked disorders happen more in men or women, why?

Answer 8

men because the Y chromosome can not help as it does not have a superscript

Question 9

Can sons inherit x-linked disorders from their father? why?

Answer 9

No because the father only gives their son the Y chromosome

Question 10

How are dominant alleles in sex linked traits represented

Answer 10

With capital chromosomes and capital alleles (ex: X ᴴX ᴴ or X ᴴ Y)

Question 11

How are recessive alleles in sex linked traits represented

Answer 11

With capital chromosomes and lower case alleles (X ʰX ʰ or X ʰ Y)

Question 12

What is a carrier

Answer 12

Someone who does not have a sex linked disorder but have it in their genotype and can pass it to their kids
(ex: Xᴴ Xʰ)

Question 13

In humans, the recessive allele that causes a form of red-green colour blindness (b) is found on the X chromosome. Find the genotype and phenotype of the F1 gen from a father who had colour vision and a mother who is heterozygous for colour vision.

Answer 13

Genotypes: 25% X ᴮ X ᴮ
25% X ᴮ Y
25% X ᴮ X ᵇ
25% X ᵇ Y

Phenotypes: 100% girls have colour vision
50% boys have colour blindness

Question 14

What are pedigrees

Answer 14

Family tree of phenotypes

Question 15

What do the roman numerals on the left side of the pedigrees mean

Answer 15

The generations

Question 16

What do the numbers under each shape mean

Answer 16

The individuals in that generation

Question 17

What does the square shape represent

Answer 17

men

Question 18

What do the circles represent

Answer 18

Women

Question 19

What do the coloured in shapes mean

Answer 19

Affected individuals, have the trait/disease

Question 20

What do we track using pedigrees

Answer 20

Autosomal dominant and autosomal recessive

Question 21

How can we know if a pedigree is autosomal dominant

Answer 21

-There is atleast one affected parent
-genotypes of affected individuals are either homozygous or heterozygous dominent

Question 22

How can we know if a pedigree is autosomal recessive

Answer 22

-Parents dont have to be affected -genotypes of affected individuals are homozygous recessive

Question 23

How do we solve pedigrees

Answer 23

1. Determine if it is autosomal dom or autosomal recessive
2. Determine who has the disorder and fill in their genotypes
3. Determine who doesnt have the disorder and fill in their genotypes