Lecture 15 - Genetics and the Study of Variation

Question 1

What is a gene?

Answer 1

The functional unit of heredity, which carries information from one generation to the next; a segement of DNA

Question 2

Differ genotype from phenotype

Answer 2

Genotype is the specific allelic constitution of an organism (either of the organism itself or a set of genes).

Phenotype is the properties of an organism resulting from a specific set of genotype (and its interaction with the environment).

Question 3

Variation between species and within individuals may be inherited. Mention three factors that may lead to variation.

Answer 3

Enviromental, Genetic, and a combination of Both.

Question 4

Foetal Alcohol Spectrum Disorder is caused by alcohol consumption during pregnancy. This is characterized by the offspring experiencing growth retardation and CNS anomalies. This variation is most likely caused by a ______ factor.

Answer 4

Environmental

Question 5

Huntington Disease is an example of variation in an individual may possess through genetic inheritance. What differs between a Huntington sufferer and a healthy individual?

Answer 5

Normally, the gene for the protein huntingtin consist of up to 35 repeats of the base sequence CAG.

In HD, there are 42 repeats or more.

Question 6

Epigenetics are changes in gene expression that do not involve changes in DNA. Name a process that describes this event in the context of gene expression. Explain.

Answer 6

Methylation involves the addition of the methyl group to the promoters (which controls gene expression).

Methylated promoters leads to the gene not being expressed (silenced).

Question 7

Does epigenetic events involve changes in the DNA sequence of the individual? Is it inheritable?

Answer 7

No, it only affects the expressivity of the gene, not the gene sequence itself. However, it can be passed from cell to cell, parent to offspring.