D2.2 Gene Expression

Question 1

Phenotype

Answer 1

The functional and structural characteristics of an organism.

Question 2

Genotype

Answer 2

All the genetic information of an organism.

Question 3

Gene expression

Answer 3

The process of turning genotype into phenotype by protein synthesis.

Question 4

Promoters function

Answer 4

A sequence of DNA located upstream of a gene in the 5’ direction, ensure that RNA polymerase transcribes the gene in a 5’ to 3’ direction.

Question 5

Transcription Factors

Answer 5

Proteins that bind to specific base sequences of DNA and regulate gene transcription.

Question 6

What happens to mRNA after it is no longer required for translation?

Answer 6

It is broken down by nucleases.

Question 7

What are examples of protein synthesis in which DNA degradation regulation is important?

Answer 7

• Casein being produced for ling periods of time.
• Cyclins that are only needed briefly.

Question 8

State the relationship between the length of a poly-A tail and its lifespan:

Answer 8

• Shorter = higher nuclease activity
• Longer = lower nuclease activity

Question 9

Epigenesis

Answer 9

The development of a plant or animal from undifferentiated cells.

Question 10

How does differentiation occur in the context of gene expression control?

Answer 10

Activating some genes and deactivating others.

Question 11

Epigenetic tags

Answer 11

Chemical modifications of DNA that alter the phenotype of an organism.

Question 12

Genome

Answer 12

Whole genetic information of a cell.

Question 13

Transcriptome

Answer 13

The entire set of mRNAs transcribed in a cell.

Question 14

Proteome

Answer 14

The entire set of proteins produced by a cell.

Question 15

Methylation

Answer 15

The replacement of a hydrogen with a methyl group.

Question 16

Role of the methylation of the promoter:

Answer 16

• Prevents the binding of some transcription factors so that RNA polymerase does not transcribe the gene downstream of the promoter and is not expressed (usually adenine and cytosine).

Question 17

Role of methylation in histones of nucleosomes:

Answer 17

• Methyl can be added to an amino acid in histone proteins to activate or deactivate transcription.

Question 18

Epigenome

Answer 18

All of the genetic tags of an organism.

Question 19

What do epigenetic tags influence?

Answer 19

Gene expression and phenotypes.

Question 20

: How do epigenetic tags change during a cell’s life?

Answer 20

They change in response to environmental factors.

Question 21

What happens to epigenetic tags during cell division?

Answer 21

They can be passed to daughter cells, helping them perform the same functions (this applied only to mitosis and NOT gametogenesis).

Question 22

What was previously believed about epigenetic tags during meiosis?

Answer 22

They were thought to be removed, leaving a “blank canvas” in zygotes.

Question 23

What recent evidence suggests about epigenetic tags?

Answer 23

Some tags are not removed and can be passed to offspring (transgenerational epigenetic inheritance).

Question 24

How do epigenetic tags differ from base sequences?

Answer 24

Epigenetic tags can be easily changed, while base sequences are altered only by mutations.

Question 25

What is an example of transgenerational epigenetic inheritance?

Answer 25

1% of epigenetic tags persist to the next generation.

Question 26

Out of the blue

Answer 26

An epigenetic tag can prevent a dominant allele from being expressed.

Question 27

What are environmental factors that can affect gene expression

Question 27

Monozygotic Twins

Answer 27

Come from one zygote

Question 28

Dizygotic Twins

Answer 28

Twins that come from two separately fertilized zygotes. (Share 50% of DNA)

Question 29

How do environmental factors affect gene expression (lactase production):

Answer 29

- Absent: repressor proteins bind to the promoter of the lactase gene to prevent expression. - Present: The repressor does not bind to the promotor, so it can bind to the lactase gene and start transcription.

Question 30

How do environmental factors affect gene expression (oestrogen):

Answer 30

- Estrogen binds to a gene that produces progesterone receptor, and the endometrium becomes more responsive to progesterone.