Gnetic basis of complex inheritance

Question 1

Mendelian Inheritance (3)

Answer 1

Law of dominance
Law of segregation
Law of independent assortment

Question 2

Non- mendelian inheritance

Answer 2

Does not fit in with Mendelian inheritance due to gene conversion and the ability of an intermediate phenotype

Question 3

Anticipation

Answer 3

Eg triple repeat expansion

Question 4

Extracellular inheritance

Answer 4

Eg mitochondrial DNA

Question 5

Genomic printing

Answer 5

Variants from parents

Question 6

Incomplete penetrance

Answer 6

Environmental factor

Genetic modifiers

Question 7

Penetrance

Answer 7

Frequency with which trait is manifested by individuals carrying the gene
% with trait (mutant)/% with trait (wild) = RISK

Question 8

Genetic modifiers

Answer 8

Genes that have small quantitative effects on level of expression of another gene - many involve polymorphism

Question 9

Genomic imprinting

Answer 9

Genes expressed from only 1 chromosome so is parent of origin dependent and there is a higher risk of causing genetic disease

Question 10

Epigenetic modifications

Answer 10

Heritable changes in gene function not explained by changes in DNA

Question 11

Cytosine ( mC)

Answer 11

Induces structural adaption of chromosomal region so as to continue altered activity states

Question 12

Anticipation - triple repeat

Answer 12

Disease presents at earlier age and/or increasing severity with age eg Huntingtons and myotonic dystrophy

Question 13

Genetic mechanisms

Answer 13

Deletion, point mutation, imprinting error and uniparental disomy

Question 14

Imprinting error (P)

Answer 14

Loss of maternal expression causing Angleman syndrome - epilepsy, awkward gait and retardation

Question 15

Imprinting error (M)

Answer 15

Prader -wili syndrome - hypotonia short and obese

Question 16

Uniparental disomy

Answer 16

Inheritance of a chromosome pair from one parental origin

Question 17

Gyogenic

Answer 17

2 Maternal

Mass of embryo and ovarian teratoma

Question 18

Androgenic

Answer 18

2 Paternal

Mass of placenta and Hydatidiform male

Question 19

What does mitochondrial inheritance effect?

Answer 19

Tissue with high metabolic demand

Question 20

Does mitochondrial DNA have a higher or lower mutation rate than nuclear DNA?

Answer 20

Higher - 100 fold more
Lack of DNA repair system and protective histones
Oxygen release radicals that attack DNA (mtDNA)