Gene Regulation (3.3)

Question 1

Describe gene regulation

Answer 1

Process that controls gene expression, turning genes on or off

Question 2

Describe gene expression

Answer 2

Process that leads to the transformation of the information stored in a gene into a functional gene product

Question 3

State whether or not gene regulation is tightly controlled in both prokaryotes and eukaryotes. True/False.

Answer 3

True. Gene regulation is tightly controlled in both prokaryotes and eukaryotes.

Question 4

Compare and contrast gene regulation in both eukaryotic and prokaryotic cells

Answer 4

Gene expression is more complex in eukaryotes and therefore occurs in a greater number of stages than in prokaryotes

Question 5

Describe gene regulation in eukaryotes

Answer 5

Gene expression - transcription, RNA processing and translation
- highly regulated (all stages)

Question 6

Describe gene regulation in prokaryotes

Answer 6

Gene expression - transcription and translation

- regulated during (transcription stage)

Question 7

Describe constitutive genes

Answer 7

Always switched on and are transcribed continually

Question 8

State two types of gene expression

Answer 8

• induced

- repressed

Question 9

Describe regulatory genes

Answer 9

Genes that code for transcription factors

Question 10

Describe transcription factors

Answer 10

Proteins that control gene expression at the transcription stage

Question 11

Describe structural genes

Answer 11

Genes that code for proteins and RNA that are not involved in gene regulation

Question 12

Describe the lac Operon

Answer 12

Contains genes which code for three proteins involved in the metabolism of lactose in E Coli.

Question 13

Describe the operon in prokaryotes

Answer 13

Unit of DNA under the regulation of a single promoter that codes for several proteins

Question 14

What can the lac operon be classified as?

Answer 14

Inducible operon

Question 15

Describe an inducible operon

Answer 15

Can be switched on/off

Question 16

State what the lac operon codes for

Answer 16

Three structural genes that code for three enzymes

Question 17

What do the enzymes produced by the lac operon break down?

Answer 17

Lactose -> glucose and galactose

Question 18

Provide a reason why these enzymes are not produced constantly

Answer 18

Misuse of energy as these enzymes are only required for the breakdown of lactose

Question 19

State what the lac operon consists of:

Answer 19

1. Promoter
2. Operator
3. Three structural genes

Question 20

Describe the operator

Answer 20

Binding site of the transcription factor

Question 21

State the three structural genes

Answer 21

1. lacZ
2. lacY
   3 lacA

Question 22

State what gene is adjacent to the lac Operon

Answer 22

lacI

Question 23

Describe what the lacI gene codes for

Answer 23

Transcription factor called the lac repressor

Question 24

State whether or not the lac repressor is always present

Answer 24

Yes. Always present.

Question 25

Describe the process that occurs in the lac operon model in the presence of lactose

Answer 25

Lactose binds to the lac repressor, inhibiting the transcription factors from binding to the operator. This enables RNA polymerase to attach to the promoter in the lac operon and transcribe the the three structural genes.

Question 26

Describe the process that occurs in the lac operon model in the absence of lactose

Answer 26

Transcription factors binds to the operator in the lac operon, blocking the RNA polymerase from binding to and transcribing the structural genes in the lac operon,

Question 27

Compare and contrast chromosome number in prokaryotes and eukaryotes

Answer 27

``` Prokaryotes = singule Eukaryotes = multiple ```

Question 28

Compare and contrast chromosomal structure in prokaryotes and eukaryotes

Answer 28

``` Prokaryotes = circular chromosomes Eukaryotes = linear chromosomes ```

Question 29

Compare and contrast plasmid presence in prokaryotes and eukaryotes

Answer 29

``` Prokaryotes = contain plasmids Eukaryotes = no plasmids (however have mitochondrial and chloroplast DNA) ```

Question 30

Compare and contrast gene arrangement in prokaryotes and eukaryotes

Answer 30

``` Prokaryotes = genes cluster in operon regions Eukaryotes = gene do not cluster in operon regions ```

Question 31

Describe nucleosome

Answer 31

The basic structural unit of chromatin, and is made up of a coil of DNA wound around a histone core

Question 32

Describe histone

Answer 32

Water-soluble protein in nucleus which DNA tightly coils around to form the nucleosome

Question 33

Describe chromatin

Answer 33

Complex of nucleic acids which condense to form a chromosome during cell division

Question 34

Describe what structure binds to the lac repressor in the lac operon model

Answer 34

Allolactose

Question 35

Describe gene induction

Answer 35

The increase in gene expression due to the presence of an inducer molecule

Question 36

Describe gene repression

Answer 36

The decrease in gene expression due to the activity of a repressor molecule

Question 37

Describe operator

Answer 37

A DNA sequence that acts as an on-off switch when interacting with a repressor molecule

Question 38

Describe operon

Answer 38

Section of prokaryotic DNA consisting of a cluster of related structural genes, a promoter and operator

Question 39

Describe promoter

Answer 39

DNA sequence that marks the binding site of RNA polymerase

Question 40

Describe regulatory gene

Answer 40

Gene involved in substance production which regulates gene expression

Question 41

Describe structural gene

Answer 41

A gene coding for the production of a specific protein involved in regulation

Question 42

Describe TATA box

Answer 42

A highly conserved region of the promoter to which the first transcription factor binds prior to transcription

Question 43

Describe transcription factors

Answer 43

Regulatory proteins that bind to DNA sequences to control transcription

Question 44

Compare and contrast structural and regulatory genes

Answer 44

Structural genes code for proteins required for cell structure or function whereas regulatory genes code for proteins that turn other genes on or off.