Type of Inheritance

Question 1

Sex Linked Recessive

Answer 1

Genes on the X chromosome
Expression:
Males: One recessive allele results in expression.
Females: Need two recessive alleles (homozygous) for expression; otherwise, they are carriers.
Examples: Hemophilia, color blindness.

Question 2

Autosomal Recesive

Answer 2

Location: Genes on autosomes (non-sex chromosomes).
Expression:
Need two recessive alleles for expression.
Carriers have one recessive allele and usually show no symptoms.
Inheritance: Both parents must be carriers for 25% risk of offspring being affected.
Examples: Cystic fibrosis, sickle cell anemia.

Question 3

Y-linkage

Answer 3

Y Linkage:

Location: Genes on the Y chromosome.
Expression:
Passed from father to son; males only.
Females cannot have Y-linked traits.

Question 4

Sex Linked Dominant

Answer 4

Location: Genes located on the X chromosome.
Expression:
Both males and females can express the trait.
In males (XY), a single dominant allele on the X chromosome leads to expression.
In females (XX), one or two dominant alleles result in expression.

Question 5

Autosomal Dominant

Answer 5

Location: Genes on autosomes (non-sex chromosomes).
Expression:
A single dominant allele from one parent leads to expression.
Homozygous dominant or heterozygous individuals express the trait.
Inheritance:
One affected parent is enough for a 50% chance of offspring being affected.
Every affected individual has at least one affected parent.
Examples: Huntington’s disease, Marfan syndrome.