5. Epigenetics

Question 1

What is a genotype? (Epigenetics B&B)

Answer 1

Genetic information from a DNA sequence

Question 2

What is a phenotype? (Epigenetics B&B)

Answer 2

The display of interaction of the genotype with the environment

Question 3

What are alleles? (Epigenetics B&B)

Answer 3

Variants of a gene

Question 4

What are the characteristics of fragile-X? (Epigenetics B&B)

Answer 4

• More commonly elicited in males

- Inherited in the form of mental retardation

Question 5

What causes fragile-X? (Epigenetics B&B)

Answer 5

• Mutation on one end of the fMRI gene

- Repeat of CGG codon

Question 6

Why is there a milder penetrance of fragile-X in females? (Epigenetics B&B)

Answer 6

X-inactivation

Question 7

How is gene activity adjusted throughout life? (Epigenetics B&B)

Answer 7

DNA methylation

Question 8

What is DNA methylation? (Epigenetics B&B)

Answer 8

• Methyl groups are added to the DNA molecule
• This changes the activity of a DNA (but not the sequence)
• When located in a gene promoter
• If too much, then the gene is turned off

Question 9

What is genomic imprinting? (Epigenetics B&B)

Answer 9

• Idea that gene expression is caused by other factors
• Genes are myelinated (turned off) depending on if they are inherited paternally or maternally
• Imprinting modification may be reversed in the next generation

Question 10

What chromosome does chromosomal deletion happen on? (Epigenetics B&B)

Answer 10

Chromosome 15

Question 11

What is chromosomal deletion? (Epigenetics B&B)

Answer 11

• During meiosis, spontaneous deletion of a part of the chromosome
• If deletion occurs on the paternal chromosome, then on maternal genes are present