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Biology > Control of Gene Expression > Flashcards

Control of Gene Expression Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are the causes of mutation?

A

Mutagenic chemicals
Spontaneous mutation
Radioactive materials

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2
Q

Insertion / deletion

A

one or more nucleotide pairs are inserted or deleted from the sequence, altering the sequence of nucleotides causing a frameshift

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3
Q

Duplication

A

one or more bases are repeated, causing a frameshift

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4
Q

Inversion

A

A group of bases is seperated from DNA and rejoin at the same position but in reverse order

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5
Q

Translocation

A

A group of DNA base become seperated from the sequnce and are inserted into the DNA sequence of another chromosome.

Significant effects on the phenotype

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6
Q

Totipotent stem cells

A

Can differentiate into any cell type

Found in zygotes

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7
Q

Pluripotent stem cells

A

Form almost any cell type

Early stages of embryo

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8
Q

Multipotent stem cells

A

Can differentiate into limited cell types

Found in bone marrow and umbilical cord

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9
Q

Unipotent stem cells

A

Can only differentiate into one cell type

Germ line stem cells
Epidermal stem cells

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10
Q

What are pluripotent stem cells useful for?

A

repairing damaged tissue

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11
Q

Why is the genetic code degenerate?

A

there are multiple tRNA molecules for each amino acid

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12
Q

Where are transcription factors produced?

A

Cytoplasm

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13
Q

How do repressors prevent the transcription of genes?

A

They stop RNA polymerase from binding to DNA

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14
Q

Which 2 types of hormones are involved in the regulation of transcription?

A

Peptide Hormones

Lipid-soluble Steroid Hormones

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15
Q

What is the benefit of oestrogen being lipid-soluble?

A

It can pass through the phospholipid bilayer

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16
Q

What does the receptor-hormone complex bind to in order to activate transcription?

A

Promotor region of DNA

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17
Q

What is the effect of Methylation on transcription?

A

Methylation inhibits transcription

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18
Q

What is the role of tumour suppressor genes?

A

Inhibit cell division

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19
Q

What type of RNAi is complementary to the mRNA sequence

A

siRNA

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20
Q

What charge do histone proteins have?

A

Positive

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21
Q

What charge does DNA have?

A

Negative

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22
Q

What are the 2 techniques used to diagnose disease using DNA probes?

A

Electrophoresis

Microarray

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23
Q

What does electrophoresis do?

A

Seperates DNA fragments according to size

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24
Q

What is a microarray?

A

it is a plate with many indents with DNA probes for a specific gene in each indent

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25
Q

What labels are used on DNA probes to diagnose disease?

A

Radioactive phosphate tag

Fluorescent tag

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26
Q

How are patients advised about genetic screening?

A

Genetic Counselling

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27
Q

2 types of gene therapy

A

Germline Therapy

Somatic Therapy

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28
Q

At what end of the gel is DNA inserted in gel electrophoresis?

A

The negative end

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29
Q

Totipotent stem cells in development

A

Translate only part of their DNA, meaning the cells remain unspecialised

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30
Q

Example of unipotent stem cells

A

Cardiomyocytes produce new muscle cells

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31
Q

When do totipotent stem cells become specialised?

A

During embryonic development

When the cells become specialised, onlu some genes are activated and only the activated genes are expressed

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32
Q

Proteins in differentiation

A

If a gene is expressed, it is transcribed into mRNA and translated into a protein

Differentiation happens as certain proteins are made

The presence of certain proteins means a cell has become specialised

33
Q

Sources of stem cells

A

Adult stem cells

Embryonic stem cells

Induced Pluripotent stem cells

34
Q

Uses of stem cells in disease

A

Grow organs for organ transplants

Replace damaged cells in the spinal cord causing paralysis

35
Q

How are IPS produced?

A

Somatic cells converted to iPS by activating genes using appropriate protein transcription factors

This makes somatic cells become unspecialised so they can be used to treat disease

36
Q

Bone Marrow Transplants

A

Used to treat blood and immune disorders

Contain multipotent stem cells that can produce all types of blood cell

37
Q

Stem cells in drug research

A

Used to grow artificial tissue

Drugs can be tested on these artificial tissues before being tested on humans

38
Q

Stem cells in developmental biology

A

Learn about how an embryo develops and how organs are formed

Improve medicines by learning about why organs have abnormalities

39
Q

Stem cells - potential future research

A

Produce new organs or tissues for transplants

Treat irreversible diseases, such as diabetes or paralysis

40
Q

Transcription Factors

A

Proteins that control gene expression by stimulating or inhibiting the transcription of target genes

In the nucleus, transcription factors bind to a specific region of DNA to stimulate or inhibit the gene

41
Q

Activators

A

Transcription Factors that stimulate gene expression

Promote the transcription of genes by interacting with RNA polymerase and allowing it to bind to DNA

42
Q

Repressors

A

Transcription factors that inhibit gene expression

Prevent the transcription of genes by stopping RNA polymerase from binding to DNA

43
Q

Peptide Hormones

A

Bind to the cell surface membrane and trigger a secondary messenger response

The secondary messenger will lead to the activation or inhibition of transcription of some genes

44
Q

Lipid-soluble steroid hormones

A

Pass through the phospholipid bilayer

Steroid hormones interact directly with DNA to promote or inhibit gene expression

45
Q

Why can oestrogen pass through the phospholipid bilayer?

A

It is lipid-soluble

46
Q

How does Oestrogen enter the nucleus

A

Binds to receptors on transcription factors in the cytoplasm, causing the transcription factors to change shape

Receptor-hormone complex formed which can now enter the nucleus

47
Q

Oestrogen Stimulates protein synthesis

A

Receptor-hormone complex binds to the promotor region of DNA

Binding to DNA activates transcription

48
Q

Chromatin

A

The combination of proteins and histones

49
Q

Epigenome

A

The chemical layer surrounding chromatin

50
Q

Effect of the epigenome on chromatin

A

Chromatin becomes more condensed, preventing TFs from binding to DNA transcription is inhibited

Chromatin becomes less condensed, allowing easier access to TFs, promoting transcription

51
Q

Epigenetic Markers

A

Do not alter the base sequence, but alter chromatin structure

52
Q

What do methyl groups bind to?

A

CpG sites on DNA - Where cytosine and guanine are together in the base sequence

53
Q

Effect of methyl groups on chromatin

A

Chromatin becomes more condensed, meaning Tfs can’t reach DNA and transcription is inhibited

54
Q

Decreased Acetylation

A

Acetyl groups are removed from histone proteins, which increases the positive charge on histone proteins, increasing the attraction to the phosphate groups on DNA

Causes chromtin to condense, so RFs can’t reach DNA

55
Q

Effect of Increased Methylation

A

Decrease the expression of tumour suppressor genes more than normal

Cells divide uncontrollably and tumours are produced

56
Q

Effect of decreased methylation

A

Increase gene expression of proto-oncogenes more than normal

Cells divide uncontrollably and tumours are produced

57
Q

What can translation be inhibited by?

A

RNAi

58
Q

Translation

A

synthesising proteins using the genetic code

After transcription, mRNA moves from the nucleus to the cytoplasm

Translation reads the sequence of bases on mRNA and joins corresponding amino acids together to produce a protein

59
Q

RNAi

A

Small molecule of double-stranded RNA

Interfered with mRNA by binding to the mRNA moolecule and breaking it down, preventing it from being translated

60
Q

siRNA

A

A type of RNAi that is complementary to the mRNA sequence it inhibits

Targets a specific sequence of mRNA, breaking it down to smaller fragments upon binding

The fragments of mRNA are degraded

61
Q

miRNA

A

Not fully complementary to the mRNA sequence

Target multiple sequences of mRNA

After miRNA has bound to mRNA, the mRNA is either degraded or stored for future

62
Q

Oncogenes

A

Mutations in a proto-oncogene

Capable of transforming a cell into a cancerous cell because they cause excessive cell division

Normally stimulate cell divison

Decreased methylation of a proto-oncogene causes proto-oncogenes to be overexpressed, stimulating cell division

63
Q

Drug used to treat HER2 mutation

A

Herceptin

64
Q

DNA Fragments

A

The sections of DNA that are transferred to make recombinant DNA

65
Q

Recombinant DNA

A

The process of transferring sections of DNA from one organism to another

66
Q

Transgenic

A

The name given to the organism that has recieved fragments of DNA

67
Q

Universal code

A

The name given to DNA due to the fact every organism uses the same 4 bases to produce proteins

68
Q

3 ways of producing DNA fragments

A

Reverse transcriptase

restriction Endonuclease

Gene machine

69
Q

Reverse Transcriptase

A

Coverts single-stranded mRNA into double-stranded DNA

Producing DNA fragments

Produces cDNA

70
Q

Recognition Sequences

A

Sections of DNA where the base sequence has palindromic base pairs

Used to isolate the target gene if there are 2 sets of sequences either side of the gene

71
Q

How can a target gene be cut out of a recognition sequence?

A

Binding of 2 restriction endonuclease

72
Q

How can DNA fragments be produced in a gene machine?

A

Synthesising the target gene sequence using free-floating nucleotides

73
Q

Usefulness of a gene machine

A

DNA template isn’t necessary

Sequence for target gene is obtained from a database

74
Q

Producing Fragment in gene machine

A

sequence for the target gene is obtained from a database

Nucleotides added in correct order to synthesise correct base sequence

Protecting groups added throughout to ensure correct nucleotides are added and no side branches are produced

75
Q

Why are Sticky ends on DNA fragments complementary to sticky ends on vector DNA?

A

Cut using the same restriction endonuclease

Seversal nucleotides have been added onto the end of the fragment

76
Q

DNA ligase

A

Attaches sticky ends together

77
Q

Vector - Plasmid

A

The host cell takes up the recombinant DNA via heat-shock, this is where the cells are heated to 42’C for one minute

78
Q

Vector - Bacteriophage

A

Recombinant DNA is injected into host cells

79
Q

How are transformed cells identified?

A

Marker genes

Biology (7 decks)

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