Class notes
GENE3734 Semester TEST 2 Questions
- Course
- Behavioural Genetics
- Institution
- University Of The Freestate (UFS)
This document contains Semester TEST 2 Questions for GENE3734.
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SEMESTER TEST 2 QUESTIONSPOSSIBLE QUESTIONS AND ANSWERS
1.1. Discuss the variations on Mendelian inheritance patterns. (3)
Any 3, with correct definitions:
- Incomplete dominance
- Co-dominance
- Epigenetics
- Y-chromosome inheritance
- Mitochondrial Inheritance
1.2. Discuss the threshold model by using an example. (3)
Any 2, plus appropriate example.
- Discontinuous variation discrete classes
- Degree of relatedness can increase incidence
- Additive genetic and environmental influences
- Crossing over threshold, fall into affected class
- E.g. Schizophrenia (predisposing additive genes, plus traumatic environmental influence). 2
1.3. Discuss the sources of genetic variation to a phenotype. (3)
Any 3, plus correct definitions:
- Mutations
- Silent / synonymous
- Missense / Nonsynonymous
- Nonsense / Null mutations
- Indels
- Frameshift
- Lethal mutations
- Hypomorphic mutations
- Hypermorphic mutations
1.4. In a homogenous population, a percentage of individuals show the same phenotype. This is an
example of: (1)
a. Pleiotropy
b. Inbreeding
c. Penetrance
d. Expressivity
1.2. Name and define the forms of inheritance that does not follow Mendelian principles. (4)
List & define any 4:
Incomplete dominance
Co-dominance
Epigenetics
Complex / Poligenic / Multifactorial
Epistasis
Pleiotropy
, GEC / GEI
Y-chromosome / Mitochondrial
Genomic imprinting
1.3. Explain how additive and interactive genetic mechanisms work by applying it to the Gene-
Environment Correlation and Gene-Environment Interaction. Make use of examples. (5)
GEC = additive genes for IQ + studying more = higher IQ
GEI = interactive alcoholism genes + alcohol = alcoholic (both necessary for phenotype!)
1.4. Discuss the evolutionary significance of mutations. (3)
Define mutation
Adaptation to environment
Natural selection
Example
2.1. Explain how genetic engineering works, as well as its application. (4)
Change genes in living cell by putting desired gene in by means of viral vector
• Somatic
• Targets the genes in specific organs and tissues of the body of a single existing person
without affecting genes in their gametes.
• Still under trial
• Germline
• Targets the gametes, or very early embryos.
• Alterations affect every cell in the body of the resulting individual, and are passed on to all
future generations.
• Banned in most countries.
2.2. Discuss additive and interactive genetic mechanisms. (6)
Additive:
- Accumulation of genetic and/or environmental influenced on a phenotype, increasing the severity
of the disease or disorder
- Co-dominance and Incomplete dominance
- Intermediate phenotypes
- Gene-environment correlation
Interactive:
- Dependence between genes and/or environmental influences for the manifestation of a phenotype
- Epistasis and Dominance
- Masking of one gene or allele by another gene or allele
- Gene-environment Interaction
2.3. Explain how epigenetics can contribute to penetrance and expressivity. (8)
- Epigenetics: Change in phenotypic expression with no change to DNA sequence
- Penetrance: Percentage of individuals sharing a genotype displaying the phenotype. DNA
methylation.
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