Chapter 3a - Extensions of Mendelian Inheritance: Sex-Linked Inheritance

Question 1

inheritane of a trait that is determined by a gene located on one of the sex chromosomes (X and Y)

Answer 1

sex-linked inheritance

Question 2

X-linked inheritance

Answer 2

1. X-linked dominant inheritance
2. X-linked recessive inheritance

Question 3

• generally only manifests in males
• usual transmission is from mother to son
• affected male cannot transmit disorder to male offspring, but would only make carrier daughters

Answer 3

X-linked recessive inheritance

Question 4

example of X-linked recessive genes

Answer 4

1. Red-green colorblindness
2. hemophilia
3. Lesch Nyhan Syndrome
4. Androgen Insensitivity Syndrome

Question 5

• rare disorder X-linked
• inborn error metabolism of purine
• deficiency of enzyme

Answer 5

Lesch Nyhan Syndrome

Question 6

clinical features of people with Lesch Nyhan Syndrome

Answer 6

• mental retardation
• microcephaly
• seizures
• choreoathetosis
• spasticity
• gout

Question 7

involuntary movement of fingers

Answer 7

choreoathetosis

Question 8

rigid muscles

Answer 8

spasticity

Question 9

excessive uric acid in blood

Answer 9

gout

Question 10

occurs when someone is genetically male but is insensitive to androgens (male sex hormones)

Answer 10

Androgen insensitivity syndrome (AIS)

Question 11

• more common in female than males
• all daughters of affected father but none of his sons are affected
• heterozygous mother will pass the trait equally to half of sons and half of daughters

Answer 11

X-linked dominant inheritance

Question 12

example of X-linked dominant inherited diseases

Answer 12

Hypophosphatemic rickets

Question 13

• disorder of bone mineralization caused due to defects (inherited/acquired) in the renal handling of phosphorus
• does not result from vitamin D deficiency
• gene coding bone protein never receive vitamin D message to function

Answer 13

Hypophosphatemic rickets

Question 14

affect males only

Answer 14

Y-linked genes

Question 15

Y-linked genes are also known as

Answer 15

Holandric genes

Question 16

example of Y-linked genes

Answer 16

1. porcupine man-skin
2. webbed toes
3. hypertrichosis

Question 17

• characterized by normal skin at birth that develops striking spiny hyperkeratotic lesions within a few months
• there is sparing of the face, palms, and soles, and affected individuals do not experience blistering

Answer 17

Lambert type of ichthyosis hystrix (IHL) or porcupine man

Question 18

web-like connection between 2nd and 3rd toes

Answer 18

webbed toes

Question 18

excessive hair development in the outer rim of ears

Answer 18

hypertrichosis pinnae auris

Question 19

occur in moths and chicken

Answer 19

Z-linked inheritance

Question 20

homogametic ZZ

Answer 20

males

Question 21

heterogametic ZW

Answer 21

females

Question 22

example of Z-linked inheritance

Answer 22

barred feathers (dominant)

Question 23

barred feathers

Answer 23

dominant

Question 24

nonbarred feathers

Answer 24

recessive