Modes of Inheritance

Question 1

Autosomal dominant

Answer 1

Found in chromosome pairs 1-22. A single defective allele is enough to produce a disease phenotype.  Every generation on a pedigree diagram is affected. Affects males and females equally.

Question 2

What pedigree pattern is autosomal dominant

Answer 2

vertical

Question 3

Dominant autosomal mutations tend to be…

Answer 3

Gain of function
Dominant negative effect
Insufficient

Question 4

Gain of function

Answer 4

gene now makes a protein with a new function eg longer lifespan/new location thus increasing their effect

Question 5

dominant negative effect

Answer 5

the mutated form interferes with the activity of proteins it binds eg dimers or multimers which reduces activity

Question 6

insufficient

Answer 6

mutant in one gene results in ½ the amount of a protein that is not enough for normal function

Question 7

autosomal recessive disorders

Answer 7

Two defective alleles are required to produce a disease phenotype. Skips generations in pedigree diagrams. Affects males and females equally. Horizontal pedigree pattern

Question 8

X linked dominant

Answer 8

Every generation on a pedigree diagram is affected. Affects males and females, equally.

Question 9

X linked recessive

Answer 9

Affects males more than females because females are only affected if homologous recessive, while males are affected even if heterozygous. Females tend to be carriers.

Affected boys may have affected uncles

Question 10

why are x linked dominant conditions often more milder and variable in females than males

Answer 10

Random X inactivation (lyonisation). This is a method of dosage compensation. Dosage compensation ensures that the same amount of gene expression occurs in males and females. In females, this process works by condensing one of the females X chromosomes into heterochromatin- genes are not transcribed

Question 11

Y linked disorders

Answer 11

Affects only males and all sons of an affected father have it- vertical pedigree pattern

Question 12

Mitochondrial

Answer 12

Can only be transmitted from mothers. Affects males and females equally. all children of an affected woman may be affected. But mitochondrial conditions are typically extremely variable due to random segregation - vertical degree pattern.

Question 13

how do the severity of symptoms in mitochondrial conditions vary

Answer 13

amount of wild type to mutant dna. Severity of mutation - mitochondria have multiple copies , genome some normal, some mutant (heteroplasmy)

Question 14

common characteristic of mitochondrial disease

Answer 14

can present as unrelated multi-system symptoms . Motor and nerve function affected