Unit 8 - The control of gene expression Flashcards

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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.

24
Q

What does RNAi do?

A

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

25
Q

What are the two types of RNAi?

A

siRNA (small interference RNA)
miRNA (micro interference RNA)

26
Q

Epigenetics definition

A

Involves heritable changes in gene function without changes to the base sequence of DNA.

27
Q

What are the two ways epigenetic can be done?

A

Methylation of DNA
Acetylation of histones.

28
Q

What is methylation of DNA?

A

methyl group added to nitrogenous base

29
Q

What is acetylation of histones?

A

acetyl group added to histones

30
Q

What does an increased methylation of DNA do?

A

changes the DNA structure so that the transcription factors and RNA polymerase can’t interact with the gene, gene is not expressed

31
Q

What happens when histones are acetylated?

A

the chromatin is less condensed meaning transcription factors and RNA polymerase can access the DNA allowing genes to be transcribed

32
Q

What happens when acetyl groups are removed?

A

chromatin becomes highly condensed so that genes cannot be transcribed because the transcription factors and RNA polymerase can’t access them

33
Q

What genes control cell division?

A

tumour suppressor genes and oncogenes

34
Q

What are malignant tumours?

A

grow rapidly and invade and destroy surrounding tissues, cells can break off the tumours and spread to other parts of the body

35
Q

What are benign tumours?

A

grow slower and are often covered in fibrous tissue that stops cells invading other tissues

36
Q

How do tumour cells look different to normal cells?

A
  • nucleus is larger and darker
  • irregular shape
  • irregular shape
  • different antigens on their surface
  • divide more frequently
37
Q

What are stem cells?

A

undifferentiated cells that can continually divide and become specialised

38
Q

proto-oncogene

A

stimulates cell division by coding for proteins that make cells divide

39
Q

tumour suppressor gene

A

slows cell division by coding for proteins that stop cells dividing or causes apoptosis, repairs mistakes in DNA

40
Q

How do mutated oncogenes stimulate excessive cell division?

A

produce growth factors that activates genes that causes DNA to replicate and cell division

41
Q

What is hypermethylation?

A

increases methylation, occurs in promoter region of TSG, inactivation of TSG, transcription is inhibited

42
Q

What is hypomethylation?

A

decreases methylation in oncogenes, leads to their activation

43
Q

What is the main difference between proto-oncogenes and tumour suppressor genes?

A

Oncogenes cause cancer as a result of ACTIVATION of proto-oncogenes
Tumour suppressor genes cause cancer as a result of their INACTIVATION

44
Q

What are the two factors that increase the risk of cancer?

A

genetic and environmental

45
Q

What are the genetic risks of cancer?

A

inheriting alleles

46
Q

What are some environmental risks of cancer?

A

radiation, carcinogens, high fat diet, obesity, lack of physical activity

47
Q

How can you prevent cancer?

A

screen for the allele mutation, preventive steps, develop tests to detect mutations earlier

48
Q

How can you treat cancer?

A

drugs that inhibit mutated enzymes which stops growth of cells, drugs that bind to receptors preventing growth factors binding

49
Q

What is gene therapy?

A

faulty alleles are replaced by working versions of those alleles

50
Q

Genome

A

all the genetic material/ DNA in a cell/ organism

51
Q

How is DNA sequencing done?

A

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
Q

Advantages of medical screening

A

quick identification of potential
medical problems and for early
intervention treatment

53
Q

Proteome

A

Full range of different proteins that a cell is able to produce (at a given time)

54
Q

How could determining the genome
of a virus allow scientists to develop
a vaccine?

A

Identify proteins or proteome of the virus then
identify potential antigens to use in the vaccine

55
Q

What does Recombinant DNA
technology involve?

A

the transfer of fragments of DNA from
one organism or species to another

56
Q

What are the 5 steps for producing DNA fragments?

A
  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
Q

What are the 3 methods for producing DNA fragments?

A

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