Chapter 4

Question 1

Males are ____ for sex linked traits

Answer 1

hemizygous

Question 2

What created variation in homologs? When?

Answer 2

Crossing over, meiosis I

Question 3

Where does crossing over take place in sex chromosomes? When?

Answer 3

Pseudoautosomal regions (repeating sequences). Rare circumstances

Question 4

What does the SRY gene do?

Answer 4

Codes for protein needed for testes to develop. (Make testosterone, which creates more male structures, and mullerian inhibiting substance, which removes female structures)

Question 5

XX genotype male phenotype

Answer 5

SRY gene on X chromosome, crossover was too much

Question 6

Female phenotype, high tesoterone, anti mullerian hormone without uterus and ovaries

Answer 6

SRY gene with androgen insensitiveity (accidental crossover plus mutation). Normal X and Y chromosome with 2 copies of mutated gene

Question 7

XXY, XXXY, XXXXY

Answer 7

Kleinfelter syndrome. Male phenotype with single Y

Question 8

X

Answer 8

Turner syndrome, female phenotype. Fertility issues, ID

Question 9

Y

Answer 9

Nonexistent. X has genes critical for development

Question 10

Nondisjunction

Answer 10

Improper separation of chromosomes in meiosis