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Biology > Unit 8 - The control of gene expression > Flashcards

Unit 8 - The control of gene expression Flashcards

1
Q

base addition

A

one or more nucleotide are inserted

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2
Q

base deletion

A

one or more nucleotide are deleted

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3
Q

base substitution

A

a nucleotide is replaced with another base

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4
Q

duplication mutation

A

one or more bases is repeated

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5
Q

inversion mutation

A

a sequence of bases is reversed

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6
Q

translocation mutation

A

a sequence of bases is moved from one location to another

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7
Q

name the six types of base sequence mutations

A

addition, deletion, substitution, inversion, duplication, translocation

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8
Q

What is a mutagenic agent?

A

a factor that increases the rate of mutations

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9
Q

What are the three types of mutagenic agent?

A
  • acts as a base
  • alters bases
  • change the structure of DNA
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10
Q

What does a frameshift mutation do?

A

change the nature of all base triplets downstream from the mutation

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11
Q

What are the 4 types of stem cells?

A

totipotent, pluripotent, multipotent, unipotent

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12
Q

Totipotent

A

can mature into any type of body cell, found in the first few cell divisions of embryo

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13
Q

Pluripotent

A

can differentiate into any cell except placenta cells, found in embryo

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14
Q

Multipotent

A

able to differentiate into a few different types of cells, found in mature mammals (bone marrow)

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15
Q

Unipotent

A

can only differentiate into one type of cell, found in mature mammals (cardiomyocytes)

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16
Q

How can induced pluripotent stem cells (iPS) be formed?

A

produced from adult somatic cells using appropriate protein transcription factors

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17
Q

What are transcription factors?

A

Proteins that bind to promoter regions and control the transcription of genes

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18
Q

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

A

RNA polymerase can bind and allow transcription for that gene

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19
Q

What is an activator?

A

Transcription factor that increases the rate of transcription.

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20
Q

What is a repressor?

A

Transcription factor that decreases the rate of transcription.

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21
Q

Describe how oestrogen activates transcription.

A

Oestrogen diffuses through membrane.
Binds to oestrogen receptor.
Oestrogen –oestrogen receptor diffuses from cytoplasm into the nucleus
Binds to promoter region of DNA.
Activates transcription.

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22
Q

Why are not all cells affected by oestrogen?

A

Not all cells have oestrogen receptor in cytoplasm.

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23
Q

What is RNAi and what does it do? (basic)

A

RNA interference – blocks translation of mRNA at the ribosomes.

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24
Q

What does RNAi do?

A

complementary RNAi bind to the mRNA produced from a specific gene and prevent translation

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25
What are the two types of RNAi?
siRNA (small interference RNA) miRNA (micro interference RNA)
26
Epigenetics definition
Involves heritable changes in gene function without changes to the base sequence of DNA.
27
What are the two ways epigenetic can be done?
Methylation of DNA Acetylation of histones.
28
What is methylation of DNA?
methyl group added to nitrogenous base
29
What is acetylation of histones?
acetyl group added to histones
30
What does an increased methylation of DNA do?
changes the DNA structure so that the transcription factors and RNA polymerase can't interact with the gene, gene is not expressed
31
What happens when histones are acetylated?
the chromatin is less condensed meaning transcription factors and RNA polymerase can access the DNA allowing genes to be transcribed
32
What happens when acetyl groups are removed?
chromatin becomes highly condensed so that genes cannot be transcribed because the transcription factors and RNA polymerase can't access them
33
What genes control cell division?
tumour suppressor genes and oncogenes
34
What are malignant tumours?
grow rapidly and invade and destroy surrounding tissues, cells can break off the tumours and spread to other parts of the body
35
What are benign tumours?
grow slower and are often covered in fibrous tissue that stops cells invading other tissues
36
How do tumour cells look different to normal cells?
- nucleus is larger and darker - irregular shape - irregular shape - different antigens on their surface - divide more frequently
37
What are stem cells?
undifferentiated cells that can continually divide and become specialised
38
proto-oncogene
stimulates cell division by coding for proteins that make cells divide
39
tumour suppressor gene
slows cell division by coding for proteins that stop cells dividing or causes apoptosis, repairs mistakes in DNA
40
How do mutated oncogenes stimulate excessive cell division?
produce growth factors that activates genes that causes DNA to replicate and cell division
41
What is hypermethylation?
increases methylation, occurs in promoter region of TSG, inactivation of TSG, transcription is inhibited
42
What is hypomethylation?
decreases methylation in oncogenes, leads to their activation
43
What is the main difference between proto-oncogenes and tumour suppressor genes?
Oncogenes cause cancer as a result of ACTIVATION of proto-oncogenes Tumour suppressor genes cause cancer as a result of their INACTIVATION
44
What are the two factors that increase the risk of cancer?
genetic and environmental
45
What are the genetic risks of cancer?
inheriting alleles
46
What are some environmental risks of cancer?
radiation, carcinogens, high fat diet, obesity, lack of physical activity
47
How can you prevent cancer?
screen for the allele mutation, preventive steps, develop tests to detect mutations earlier
48
How can you treat cancer?
drugs that inhibit mutated enzymes which stops growth of cells, drugs that bind to receptors preventing growth factors binding
49
What is gene therapy?
faulty alleles are replaced by working versions of those alleles
50
Genome
all the genetic material/ DNA in a cell/ organism
51
How is DNA sequencing done?
a DNA sample is collected, many copies of the DNA are made, the copies are broken into many pieces, sequences are arranged in the correct order
52
Advantages of medical screening
quick identification of potential medical problems and for early intervention treatment
53
Proteome
Full range of different proteins that a cell is able to produce (at a given time)
54
How could determining the genome of a virus allow scientists to develop a vaccine?
Identify proteins or proteome of the virus then identify potential antigens to use in the vaccine
55
What does Recombinant DNA technology involve?
the transfer of fragments of DNA from one organism or species to another
56
What are the 5 steps for producing DNA fragments?
1. ISOLATION of DNA fragments (gene) 2. INSERTION of DNA fragment into a vector 3. TRANSFORMATION – DNA into host cells 4. IDENTIFICATION of host cells (gene markers) 5. GROWTH/CLONING of host cells
57
What are the 3 methods for producing DNA fragments?
a. Conversion of mRNA to cDNA using reverse transcriptase b. Using restriction endonucleases to cut fragments (gene) c. Creating the gene in a gene machine
58
What are the three steps for PCR?
- separation of DNA strands - annealing of primers - synthesis of DNA
59
How are DNA strands separated in PCR?
high temperature of 95
60
Describe the process of annealing primers in PCR?
55°C primers anneal to their complementary bases at the ends of the DNA fragments
61
What do the primers provide in PCR?
the starting sequence for the DNA polymerase to begin DNA replication
62
Explain the synthesis of DNA in PCR?
72°C Taq DNA polymerase joins adjacent nucleotides forming phosphodiester bond
63
What is a DNA probe?
single strand of DNA bases complementary to an allele/ gene
64
What are two types of genetic probe?
radioactive and fluorescent
65
What is DNA hybridisation?
DNA probes bind with the target sequence

Biology (8 decks)

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