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Biology- OCR > Chapter 19- Gene Expression > Flashcards

Chapter 19- Gene Expression Flashcards

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1
Q

What is a gene mutation?

A

Change in DNA’s base sequence

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2
Q

When can gene mutations happen?

A

Can happen spontaneously during DNA replication

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3
Q

What can increase the rate of mutations?

A

Mutagenic agents

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4
Q

What are the three types of gene mutations?

A
  • DELETION
  • SUBSTITUTION
  • INSERTION
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5
Q

What is deletion?

A

Occurs when a nucleotide is removed from a DNA sequence

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6
Q

What does deletion cause?

A
  • causes a frame shift which changes the sequence of triplets.
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7
Q

What is substitution?

A

Occurs when a base is swapped for another base

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8
Q

What can substitution cause?

A
  • only affects a single triplet in DNA sequence
  • can result in a different amino acid being coded for and therefore changes primary structure.
  • Or amino acid coded for stays the same so no difference to primary structure.
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9
Q

What is insertion?

A

Occurs when one or more nucleotides are added to DNA sequence

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10
Q

What can insertion cause?

A
  • Either results in a FRAMESHIFT
  • or an addition of an amino acid
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11
Q

What can mutations that change the primary structure of a protein cause (in terms of different levels of proteins)?

A
  • Can alter bonds within its tertiary structure.
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12
Q

Name one possible negative and one possible positive of a mutation:

A

NEGATIVE: can result in a non functioning protein- could be harmful for organism

POSITIVE: Can result in a new protein which is beneficial for organism.

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13
Q

What does every cell in the body contain?

A

-ALL genes

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14
Q

Why are genes not active at all times?

A
  • they are only activated when needed
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15
Q

What activates genes?

A

Hormones can activate genes when they need to work.

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16
Q

What is an active gene?

A

A gene that has been TRANSCRIBED and TRANSLATED, resulting in a polypeptide.

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17
Q

Define gene expression

A

When a gene has been transcribed and translated into a protein.

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18
Q

Give an example of gene expression products:

A
  • The tertiary structure of protein
  • enzyme
  • polypeptide chain
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19
Q

State an example of a gene that will always be expressed

A

Enzymes needed for respiration

  • respiration never stops
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20
Q

What is the difference between gene expression and protein synthesis?

A
  • gene expression refers to the ENTIRE process of TRANSCRIPTION and TRANSLATION.
  • Whereas, protein synthesis just refers to the part of the TRANSLATION process (where amino acids are assembled into polypeptide, forming a protein)
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21
Q

What are the 2 types of genes involved in transcriptional control?

A

Structural gene and Regulatory gene

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22
Q

Define a structural gene:

A
  • A gene that codes for a protein that has a function in the cell
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23
Q

Define a regulatory gene:

A

A gene that codes for proteins that CONTROL structural genes.

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24
Q

How many structural genes does a regulatory gene normally control?

A

Many structural genes

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25
Q

What is a PROMOTER?

A
  • A DNA sequence

-that sits between the regulatory gene and first structural gene

-binding site for RNA polymerase.

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26
Q

What does the promoter do?

A
  • enables transcription of the structural genes
  • does this as it is the binding site of RNA Polymerase (enzyme) to carry out transcription
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27
Q

Do promoters exist is both prokaryotes and eukaryotes or one or the other?

A

BOTH

  • however the way RNA polymerase interacts with promoters is different in prokaryotes and eukaryotes
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28
Q

In prokaryotes, how does RNA polymerase bind to the promoter?

A
  • RNA polymerase binds straight away to the promoter and transcribes the structural genes.
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29
Q

How do prokaryotes control gene expression at the transcriptional level?

A

OPERATORS
- a DNA sequence

  • sits between the promoter and the first structural gene
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30
Q

What is a transcription factor?

A

A protein coded by a regulatory gene that controls structural genes

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31
Q

What is a REPRESSOR protein?

A

A type of transcriptional factor

32
Q

State how prokaryotes control gene expression at the transcriptional level

A
  1. Regulatory gene produces a REPRESSOR PROTEIN
  2. REPRESSOR protein BINDS to OPERATOR
  3. RNA POLYMERASE unable to bind to PROMOTER
  4. REPRESSOR protein PREVENTS RNA polymerase from transcribing structural genes.
33
Q

What is a CLUSTER?

A

A group of structural genes

34
Q

What is an OPERON?

A

An Operon is a cluster of structural genes that is under the control of 1 promoter

  • It consists of the CLUSTER (structural genes), OPERATOR and PROMOTER
35
Q

Where can the Lac Operon be found?

A

In bacteria

36
Q

What does the Lac Operon contain?

A
  • the genes needed to digest LACTOSE
37
Q

Outline the process of an inactive lac Operon (when no lactose is present)

A
  1. Regulatory gene produces REPRESSOR PROTEIN
  2. REPRESSOR protein BINDS to the OPERATOR
  3. As a result, the RNA POLYMERASE is unable to bind to the promoter
  4. So RNA POLYMERASE cannot transcribe structural genes
38
Q

Outline the process of an ACTIVE lac Operon (when lactose is present)

A
  1. Regulatory gene produces a REPRESSOR PROTEIN
  2. Lactose in cell binds to REPRESSOR protein which causes the protein to change its TERTIARY STRUCTURE
  3. As a result, REPRESSOR protein unable to bind to operator
  4. RNA POLYMERASE binds to promoter
  5. Means RNA POLYMERASE transcribes structural genes
39
Q

What is the difference between eukaryotes and prokaryotes when it comes to transcriptional factors and control of gene expression?

A

Eukaryotes DON’T contain an OPERATOR

40
Q

Describe the transcription factor process in eukaryotes

A
  1. Regulatory gene produces TRANSCRIPTION FACTOR
  2. TRANSCRIPTION FACTOR binds to the promoter
  3. This enables RNA POLYMERASE to also bind to promoter
  4. RNA POLYMERASE transcribes structural genes
41
Q

In eukaryotes, do transcriptional factors inhibit or stimulate gene expression?

A

STIMULATE (always)

42
Q

When transcriptional factors in eukaryotes are produced, are they active or inactive?

A

INACTIVE - meaning they can’t bind to the promoter

43
Q

In order to active the transcription of structural genes, a transcription factor must be activated. How do they become activated?

A

A hormone enters the cell to activate transcription factor.

44
Q

Describe how hormones activate transcription factors in order to transcribe structural genes in eukaryotes:

A
  1. Regulatory gene reduces INACTIVE transcription factor
  2. Hormone enters cell and diffuses into nucleus
  3. Hormone binds to inactive transcription factor
  4. Causes a change in tertiary structure of transcription factor which therefore ACTIVATES the transcription factor.
  5. Active transcription factors BIND to promoter
  6. Enables RNA polymerase to bind to promoter
  7. Then starts transcribing structural genes
45
Q

What is the difference between transcription control in prokaryotes and eukaryotes?

  • RNA POLYMERASE
A

PROKARYOTES:
- Can bind to promoter WITHOUT transcription factor

EUKARYOTES:
- Can ONLY bind to promoter with transcription factor

46
Q

What is the difference between transcription control in prokaryotes and eukaryotes?

  • BINDING SITE OF TRANSCRIPTION FACTOR
A

PROKARYOTES:
- OPERATOR

EUKARYOTES:
- PROMOTER

47
Q

What is the difference between transcription control in prokaryotes and eukaryotes?

  • EFFECT OF TRANSCRIPTION FACTOR
A

PROKARYOTES:
- inhibits transcription

EUKARYOTES:
- Stimulates transcription

48
Q

What is the difference between transcription control in prokaryotes and eukaryotes?

  • NAME OF TRANSCRIPTION FACTOR
A

PROKARYOTES:
- REPRESSOR protein

EUKARYOTES:
- transcription factor

49
Q

What does post transcriptional control describe?

A
  • describes the changes in mRNA goes through after transcription
  • the changes ensure the mRNA is ready for translation
50
Q

Transcription in eukaryotes produces a type of mRNA, what is it called?

A

PRIMARY mRNA

51
Q

How does primary mRNA become ready for translation?

A
  1. RNA SPLICING- the non coding ITRONS are removed
  2. RNA EDITING- some RNA bases are substituted, deleted or addd in
52
Q

What happens after primary mRNA goes through rna splicing and rna editing?

A

A mature RNA is created and is ready for translation

53
Q

When does control at the post translation level occur?

A

It occurs AFTER the gene has been TRANSLATED.

54
Q

Why is there a POST TRANSLATION CONTROL?

A
  • changes ensure Perot is are ready to perform functions in cell
55
Q

What happens after a protein is translated?

A

It needs to be activated

56
Q

How are proteins activated?

A

PHOSPHORYLATION

57
Q

Outline how phosphorylation activates a protein:

A
  1. Cyclic AMP binds to and activates protein KINASE
  2. Protein KINASE then phosphorylation the protein (phosphate group added to protein) and changes the proteins tertiary structure and so activates.
  3. As a result, activated protein can perform specific functions in cell.
58
Q

Define HOMEOBOX GENE:

A

A gene that controls the initial development of an organism body plan.

59
Q

What organism contain Homeobox genes?

A

Humans, Animals, plants and fungi all contain Homeobox genes due to all having body plans.

60
Q

What do Homeobox genes code for?

A

Transcription factors that control the expression of structural genes

  • when structural genes expressed, they ensure various parts of body plan develop correctly
  • so Homeobox genes are a type of regulatory gene
61
Q

Are Homeobox genes a type of structural or regulatory gene?

A

Regulatory gene

62
Q

When Homeobox genes code for transcriptional facts and they are produced, what do they need to bind to, to allow the expression of the structural genes?

A

DNA

63
Q

What is the binding site called on transcription factors produced by Homeobox genes?

A

HOMEODOMAIN

64
Q

A specific DNA sequence within the Homeobox gene codes for the Homeodomain, what is this DNA sequence called?

A

Homeobox

65
Q

What is a HOMEOBOX?

A

Transcribes for the transcription factors Homeodomain

66
Q

All human Homeobox genes contain the same Homeobox, animals also have similar ones.

WHY?

A
  • Homeobox genes control an organism body plan

-so if organism has any mutation in its Homeobox genes, its unlikely to survive.

67
Q

What does ‘mutations in Homeobox genes are selected AGAINST by natural selection’ mean?

A

Means over course of natural selection, the Homeobox is likely NOT to change much at all

  • So they are said to be highly CONSERVED by natural selection.
68
Q

What type of Homeobox gene is involved in the symmetry of an animal?

A

Hox gene

69
Q

Define a Hox gene

A

A type of Homeobox gene that are only found in animals

70
Q

What is a body plan?

A

The observable, spatial arrangement of an organism body parts.

71
Q

When does the body plan develop?

A

Embryonic stage

72
Q

What 2 cellular processes control the development of body plan?

A

Mitosis and apoptosis

73
Q

What is mitosis?

A

Mitosis causes cells to divide

This produces new cells for growth, repair and reproduction

74
Q

What is apoptosis?

A

Causes cells to die

Removes old cells or cells that no longer work

75
Q

Give an example of mitosis and apoptosis working together in embryonic stage

A
  • in early embryo, mitosis produces 5 finger s
  • also produced a layer of skin that holds all 5 fingers together
  • when human embryo matures, apoptosis removes the layer of skin between the fingers
  • as a result, hands develop 5 separate fingers.
76
Q

What gene controls both mitosis and apoptosis?

A

Hox genes

Biology- OCR (5 decks)

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