Mendelian inheritance & Genetic basis of complex Inheritance Flashcards
1
Q
- Describe the characteristics of Medelian Inheritance, both autosomal and sex-linked.
A
- Autosomal
-
Dominant
- Each generation is affected
- Both sexes affected in equal proportion
- Equally transmitted by both sexes
- Transmitted through affected individuals
- 50% chance of inheriting mutation (Only need 1 dominant allele)
-
Recessive
- Affected individuals in a single generation
- Generations “skipped”
- Both sexes affected in equal proportions
-
Dominant
2
Q
- Describe the characteristics of Medelian Inheritance, both autosomal and sex-linked.
A
- Sex Linkage
-
X-Linked Recessive
- Males affected more than females, who have 2 copies of the X Chromosomes (hope for a dominant allele)
- Transmitted through affected/unaffected females
- Males cannot transmit disorders to sons
- Daughters of affected males will be carriers
-
X-Linked Dominant
- Both sexes affected
- Females usually less severely affected than males
- Affected males cannot transmit disorder to their sons
- Daughters of affected males will be affected
-
Y-Linked
- Affects males only
-
X-Linked Recessive
3
Q
Anticipation- Triplet Repeat Expansion
A
Anticipation: Disease presents at earlier age and/or increasing severity in succeeding generations.
Triplet repeat diseases:
- Huntington’s disease
- Myotonic dystrophy (muscle wasting)
- Fragile X syndrome (learning disabilities and cognitive impairment)
4
Q
Homoplasmy and Heteroplasmy
A
Polyploidy: up to thousands mitochondria per cell.
Polyploid cells and organisms are those containing more than 2 homologous pair sets of chromosomes.
2 - 10 copies per mitochondrion.
5
Q
Genetic modifiers
A
Genes that have small quantitative effects on the level of expression of another gene. May involve polymorphism.