Genetic Inheritence

Question 1

Allele Def.

Answer 1

Copy of a gene with slight variation in DNA base sequences

Question 2

Homozygote Def

Answer 2

Alleles are perfectly identical

Question 3

Heterozygous Def

Answer 3

Alleles are different by a few base sequences

Question 4

Genotype Def.

Answer 4

Genetic constitution

Question 5

Phenotype def.

Answer 5

Physical appearance

Question 6

How inheritence patterns are identified

Answer 6

Pedigree analysis and DNA sequencing

Question 7

Mendelian Inheritance Patterns List

Answer 7

Autosomal dominant, autosomal recessive, x-linked dominant, x-linked recessive and y-linked

Question 8

Autosomal Dominant

Answer 8

Dominant allele in non-sex pair is defective. Physical disease presents in both heterozygous (most frequent) and homozygous (more intense) conditions. Patients tend to die before reproductive maturity. Both sexes effect and both transmit. Offspring have disease phenotype 50% of the time

Question 9

Autosomal Dominant Disease Example

Answer 9

Familia Hypercholesteremia: Increase in cholesterol due to damaged LDL receptors. Leads to

Question 10

Exceptions to Autosomal Dominant Disease Progression

Answer 10

Mutation, Reduced penetration and variable expression

Question 11

Reduced Penetration Outline

Answer 11

The reduction in proportion of people with given genotype presenting specific phenotype

Question 12

Variance in Expression Outline

Answer 12

Difference in diasease phenotype severity

Question 13

Carriers Def.

Answer 13

Individuals with 1 disease allele and 1 compensating allele. Don’t present with disease phenotype

Question 14

Haploinsufficiency Def.

Answer 14

Disease requires > 50 % of protein produced by chromosome pairs to not appear in phenotype. Presents in both hetero and homzygous

Question 15

Dominant Effect def.

Answer 15

Protein produced by disease gene impedes normal allele function

Question 16

How 1 gene can cause disease phenotype

Answer 16

Haploinsufficiency, Dominant effect, gain of function and loss of hetrozygosy

Question 17

Gain of Function Outline

Answer 17

Disease allele has improved function. Eg Huntington’s blockage of protein at end of neurons results in damage

Question 18

Loss of Heterozygosity Outline

Answer 18

Carcinogens damage DNA containing healthy allele thus body depends on diseased allele

Question 19

Autosomal Recessive Outline

Answer 19

Disease phenotype in recessive homozygotes. Heterozygotes are carriers. Tend to affect all siblings in 1 generation (doesn’t effect multiple generations). All sexes equally effected. Carrier and Non have 50% chance of offspring disease phenotype and 50% carrier

Question 20

Why do males and females produce same amount of sex-linked protein though males are hemizygous

Answer 20

1 of females 2 X-chromosomes is wound too tightly around a histone for transcription to occur

Question 21

Barr Body Def

Answer 21

Permanently condensed heterochromatic chromosome. Stains darkly

Question 22

Adult female mosaic

Answer 22

Mass of cells that both cells withactive x-chromosomes from the paternal line and cells with active x-chromosomes from the maternal line

Question 23

Intermediate Effect Def.

Answer 23

Patient is clinically unaffected (no disease symptoms) but has biochemical abnormalities

Question 24

Skewed x inactivation

Answer 24

More genes programming for diseased protein is inactive

Question 25

Manifesting Heterozygote

Answer 25

Clinically affected. More genes coding for diseased protein are activated then inactivated

Question 26

x-linked recessive

Answer 26

Carrier mother gives birth to effected son and carrier daughter. No male to male transmissions. Eg Hemophilia A

Question 27

x-linked dominant diseases

Answer 27

No male to male transmiisson. Females are effected. 1 parent effected, 50% chance of having offspring effected

Question 28

mtDNA Outline

Answer 28

mitochondrial DNA passed solely through maternal line. Diseased causes skeletal muscle damage and neurological impairment. Homoplasmy = all mtDNA is mutated. Heteroplasmy = mix of altered and non DNA

Question 29

Genetic Drift Def.

Answer 29

Change in frequency of an allele through generations randomly

Question 30

Genetic Migration

Answer 30

Movement of an allele between populations. Changes gene pool of recieving populations

Question 31

Selection

Answer 31

Change in gene frequency due to survival of fittest