Epigenetics

Question 1

What is epigenetics?

Answer 1

The study of changes in gene expression or phenotype, caused by mechanisms other than changes in the DNA sequence

Epigenetics explores how environmental factors can influence gene activity.

Question 2

What is chromatin composed of?

Answer 2

• DNA
• Proteins called histones

Chromatin is essential for fitting DNA inside the nucleus and forming chromosomes.

Question 3

How is nuclear DNA structured?

Answer 3

Highly condensed and wrapped around histones in order to fit inside the nucleus

Question 4

Histones

Answer 4

positively charged proteins that help package DNA.

Question 5

What does chromatin look like in its extended form?

Answer 5

Beads on a string

This structure represents the arrangement of nucleosomes.

Question 6

Do all cells have active and inactive genes?

Answer 6

Yes

The specific genes that are active depend on the function of the cell.

Question 7

In stomach cells, which genes are inactive?

Answer 7

Genes for making hair

However, the gene for making the pepsin enzyme is active.

Question 8

What is euchromatin?

Answer 8

DNA coding genes that are actively transcribed and are more loosely packaged

Euchromatin is associated with RNA polymerases.

Question 9

What is heterochromatin?

Answer 9

DNA coding inactive genes that are more tightly packaged

Heterochromatin is associated with structural proteins.

Question 10

What causes DNA to be tightly packaged?

Answer 10

Methyl groups (CH3)

Methylation turns genes off.

Question 11

What causes DNA to be loosely packaged?

Answer 11

Acetyl groups (COCH3)

Acetylation turns genes on, allowing RNA polymerase to transcribe the gene.