Probability and Pedigree Rules

Question 1

What do we assume when a trait is rare and autosomal recessive?

Answer 1

-we assume that individuals who marry/mate into the pedigree are not carriers but are homozygous for the ‘normal’ (dominant) allele
-(homozygous dominant)
-only changes if we are given different evidence or info from future generations

Question 2

What are types of Recessive Mutations?

Answer 2

-often involve lost of gene function
1. Null /Amorphic Alleles
2. Hypomorphic Alleles

Question 3

What does the Null/Amorphic Alleles mutation mean?

Answer 3

-enzyme is encoded in the nucleotide sequence
-mutation in the promotor region
-1. A nonfunctional protein in produced null=nothing amorphic=weird shape OR
2. No protein is produced
-if 50% of protein pool is normal it is good enough to be normal
-50% is non functioning

Question 4

What does the hypomorphic Alleles mutation mean?

Answer 4

-determined by the producer
1. A poorly functioning protein is produced OR
2. Reduced amounts of a normal functioning protein is produced
-only need 50% toward the protein pool
-mutation in promotor (dim switch) that doesn’t fully start

Question 5

What is the multiplication rule?

Answer 5

-multiply chances together when you see the AND indicator in the question

Question 6

What is the addition rule?

Answer 6

-add all probabilities/ chances together when you see the OR indicator in the question

Question 7

What is autosomal dominant traits and an example?

Answer 7

-dominant mutation overrides the normal gene
-if you have one copy of the affected gene it is dominant
-does not matter that you have a normal copy
-Ex: Huntington disease

Question 8

What are types of dominant mutations and what do they involve?

Answer 8

-often involve gain/change of gene function
1. Dominant Hypermorphic Alleles
2. Neomorphic Alleles

Question 9

What does the dominant hypermorphic alleles mutation mean?

Answer 9

-too much of a protein makes it dominant over the phenotype (over-production)
(in promotor region)
-negative phenotypic consequences due to production of a protein with increased activity levels (too low or too high)

Question 10

What does the neomorphic alleles mutation mean?

Answer 10

-presence of an altered protein has a new function causing negative phenotypic consequences
-mutation occurs when the altered protein interferes with the wildtype protein (dominant-negative allele)