Bio 5 - Inheritance

Question 1

What are three diseases caused by Mitochondrial Inheritance defects?

Answer 1

Mitochondrial myopathies (ragged-red muscle fibers seen on biopsy). Leber hereditary optic neuropathy. Leigh syndrome (subacute sclerosing encephalopathy).

Question 2

What is anticipation in terms of inheritance?

Answer 2

Age of onset is earlier and earlier in successive generations. Severity of the disease worsens with successive generations.

Question 3

What is incomplete penetrance?

Answer 3

How often a genotype causes a particular phenotype; not all who have the gene will show the phenotype. Therefore it might seem like it skips generations.

Question 4

What is Codominance?

Answer 4

2 alleles, and neither of them is dominant.

Question 5

What is Variable expression?

Answer 5

Severity of the phenotype varies from one individual to another. Like tuberous sclerosis.

Question 6

What is Pleiotropy?

Answer 6

A single gene has more than one effect on the individual’s phenotype.

Question 7

What is Locus heterogeneity?

Answer 7

Mutations at different loci that can produce the same phenotype.

Question 8

What is Mosaicism?

Answer 8

Cells in the body have different genetic make-up.

Question 9

What is imprinting?

Answer 9

Phenotype differences depend on whether the mutation comes from the mother or the father’s genetic material.

Question 10

What is the difference between Prader-Willi and Angelman syndrome?

Answer 10

[MAMA and POP]

Maternal gene. Angelman. Mood (inappropriate laughter). Ataxia. / Prader-Willi. Overeating. Paternal gene deletion.

Question 11

What is the cause and symptoms of Prader-Willi syndrome?

Answer 11

Deletion of proximal portion of chrom 15q11-q13 from paternal origin. Presents in infancy: hypotonia, poor feeding, characteristic facial features (almond-shaped eyes, downward turned mouth). They have hyperphagia, obesity, short stature (partial GH deficiency), intellectual disability, behavioral disorders (tantrums, skin picking, OCD), hypogonadotrophic hypogonadism, osteoporosis, delayed menarche.

Question 12

How do we diagnose Prader-Willi Syndrome?

Answer 12

Confirmed with FISH (fluorescence in-situ hybridization).

Question 13

What is the Hardy-Weinberg Equation?

Answer 13

It is p+q=1. Or p^2+2pq+q^2=1. The p^2 is the frequency of homozygosity for p. The q^2 is the frequency of homozygosity for q. 2pq is the frequency of heterozygosity.

Question 14

What is the frequency of the BB phenotype and the Bb phenotype of the frequency of allele B is 70%?

Answer 14

If P is 0.7, then Q is 0.3. Therefore P^2 is 0.49 and 2PQ is 2(0.7)(0.3) which equals to 0.42.

Question 15

What is the frequency of the Aa genotype and the AA genotype if the frequency of allele A is 0.95?

Answer 15

AA: (0.95)^2 = 0.9025. Aa: 2(0.95)(0.05) = 0.095.

Question 16

If 49% of a particular population is homozygous for a curly hair gene that is dominant to a straight hair gene, what percentage of the population has curly hair?

Answer 16

P:0.7, P^2: 0.49, Q:0.3. 2PQ: 2(0.7)(0.3)= 0.42. Therefore P^2 + 2PQ = all the curly hair = 0.49 + 0.42 = 0.91.

Question 17

A male infant is born to a woman that is heterozygous for an X-linked disease. The father is normal. What is the probability that the son will be affected?

Answer 17

50%.

Question 18

A female infant is born to a woman that is heterozygous for X-linked disease. The father is normal. What is the probability that the daughter is a carrier?

Answer 18

50%.

Question 19

What is the probability that a female carrier of an X-linked disease will have a child with that disease assuming she mates with a normal male?

Answer 19

25%.

Question 20

If aa symbolizes a recessive disease, what is the likelihood that parents Aa and Aa will have a phenotypically normal child?

Answer 20

75%.

Question 21

Cystic fibrosis is an autosomal recessive disorder. Two parents that are heterozygous for cystic fibrosis have a normal, non-affected child. What is the probability that the child is homozygous normal?

Answer 21

33.3%. We remove the homozygous recessive because we know the kid does not have it.

Question 22

Upon examination of a pedigree, you note that both males and females are affected with a disease in every generation. What type of genetic disease is this?

Answer 22

Autosomal dominant.

Question 23

What are nine X-linked recessive disorders?

Answer 23

[Oblivious Female Will Give Her Boys Her X-Linked Disoders]
Ocular albinism. Fabry disease. Wiskott-Aldrich. G6PD deficiency. Hunter syndrome. Brunton agammaglobulinemia. Hemophilia A and B. Lesch-Nyhan syndrome. Duchenne muscular dystrophy.