Regulation of Transcription and Translation

Question 1

What binds to the DNA promoter region?

Answer 1

Transcription Factors

These are proteins with specific tertiary structures

Question 2

The promoter region is located BEFORE or WITHIN the gene?

Answer 2

Before

Sometimes this is referred to as ‘upstream’ of the gene

Question 3

transcription factors are found in the [1] and upon activation can enter the [2].

Answer 3

[1] cytoplasm

[2] nucleus

Question 4

What happens after the transcription factor binds to the promoter region?

Answer 4

stimulates RNA polymerase;

transcription begins and mRNA increases;

Question 5

TRUE or FALSE:

Transcription factors binding to the promoter regions always increase transcription.

Answer 5

FALSE

Some transcription factors inhibit transcription

Question 6

How does oestrogen enter cells?

Answer 6

1. Lipid-soluble (steroid hormone);
2. Diffuses through the phospholipid bilayer;

Question 7

What does oestrogen bind to?

Answer 7

oestrogen receptor (ER alpha)

Question 8

What happens to the oestrogen receptor (ER alpha) upon binding with oestrogen?

Answer 8

Changes its tertiary structure;

The receptor now acts as a transcripton factor;

Question 9

TRUE or FALSE:

Oestrogen is a transcription factor

Answer 9

FALSE

Its receptor when activated by oestrogen binding = transcription factor

Question 10

Osterogen binds to its receptor becuase it has a _____________ shape

Answer 10

complementary

Question 11

The activiated ooestrogen receptor (ER alpha) is a [1] and binds to the [2] region.

This stimulates [3] and leads to transcription of a gene. This increases [4] and leads to more protein synthesis.

Answer 11

[1] transcription factor

[2] promoter

[3] RNA polymerase

[4] mRNA

Question 12

Steroid hormones are hydrophobic.

Explain why steroid hormones can rapidly enter a cell by passing through its cell-surface membrane [2 marks].

Answer 12

1. Lipid soluble;
2. Diffuse through phospholipid bilayer;

Question 13

In the cytoplasm, testosterone binds to a specific androgen receptor (AR).

An AR is a protein.

Suggest and explain why testosterone binds to a specific AR (2 marks).

Answer 13

1. Testosterone has a specific tertiary structure;
2. This has a complementary shape to the receptor;

Many hormones are ‘modified’ proteins

Question 14

The binding of testosterone to the androgen receptor (AR) changes the shape of the AR.

This AR molecule now enters the nucleus and
stimulates gene expression.

Suggest how the AR could stimulate gene expression (2 marks)

Answer 14

1. AR is a transcription factor;
2. Binds to DNA promoter region;
3. Stimulates RNA polymerase;

Question 15

RNA interference (RNAi) inhibits the ________________ of mRNA

Answer 15

translation

Question 16

Types of RNA interfering molecules

Answer 16

small interfering RNA (siRNA)

micro RNA (miRNA)

Question 17

Are siRNA and miRNAs single OR double stranded?

Answer 17

single stranded

Question 18

siRNA binds to specific [1] molecules via [2] base pairing.

This guides enzymes which [3] mRNA.

[4] is prevented.

Answer 18

[1] mRNA
[2] complementary
[3] destory
[4] translation

Question 19

If a specific protein is still produced in smaller quantities this could be because not all mRNA has been __________________ by RNA interference

Answer 19

destroyed

Question 20

Define epigenetics

Answer 20

Inheritable changes in gene function;

without changes to the DNA base sequence;

Question 21

Types of epigenetic changes

Answer 21

Methylation

Acetylation

Question 22

TRUE or FALSE:

Changes in the environment lead to changes in methylation and acetylation which determine whether a gene is expressed.

Answer 22

TRUE

Question 23

During methylation, a methyl group is added to a ______ _______.

Answer 23

DNA base

Question 24

Methylation of DNA bases in the [1] region, prevents transcription [2] from binding.

This [3] transcription.

Answer 24

[1] promoter

[2] factors

[3] decreases / inhibits

Question 25

Chromosomal DNA in eukaryotes is wrapped around _____________

Answer 25

histones

Question 26

**TRUE or FALSE: ** During acetylation DNA bases are modified

Answer 26

FALSE

Question 27

Acetylation of histone makes them [1] packed. This makes the promoter region and target gene more accessible to transcription factors and [2]. This [3] transcription.

Answer 27

[1] loosely [2] RNA polymerase [3] increases

Question 28

Decreasing methylation, ________________ transcription

Answer 28

stimulates / increases

Question 29

Explain why decreasing acetylation of histones decreases transcription.

Answer 29

1. Histones are more tightly packed; 2. Prevents transcription factors from binding to the promoter region; 3. Prevents RNA polymerase from accessing the target gene;