Inheritance and sex linkage

Question 1

What are sex-linked genes?

Answer 1

Genes located on a sex chromosome

Question 2

Male vs female alleles

Answer 2

Males have 1 allele per gene whereas females have 2

Question 3

If a male has a recessive allele from his mother does he express the trait?

Answer 3

Yes

Question 4

Do females express the recessive trait from their mothers?

Answer 4

Only in homozygous recessive

Question 5

Name the 4 systems for sex determination

Answer 5

• X-Y (XX=female, XY=male)
• X-O (XX=female, X=male)
• Z-W (ZW=female, ZZ=male)
• haplo-diploid (no sex chromosomes)

Question 6

Autosomal recessive in pedigree analysis

Answer 6

• Effects males and females
• Both parents must carry allele
• Parent may not display trait
• 1/4 children effected

Question 7

Sex-linked recessive

Answer 7

• Effects males more than females
• Effected male passes allele to daughter
• Trait skips a generation
• Females must be homozygous for allele to be effected

Question 8

Autosomal dominant

Answer 8

• Effects males and females
• One parent carries allele
• If child displays trait parent does too
• 1/2 children effected