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Biology Paper 2 > Topic 8 Mutations > Flashcards

Topic 8 Mutations Flashcards

1
Q

What is a mutation

A

Change in the DNA base sequence

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2
Q

What are the 6 types of gene mutations

A
  1. Addition
  2. Deletion
  3. Substitution
  4. Inversion
  5. Duplication
  6. Translocation of bases
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3
Q

What is addition mutation

A

One extra base is added

Results in frame shift so all the codons are now different

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4
Q

What is the deletion mutation

A

The deletion of a base sequence frame shift backwards

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5
Q

What is a substitution mutation

A

Where one base is swapped for another this could result in different amino acid or the same as genetic code is degenerate

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6
Q

What is inversion mutation

A

Section of bases when they re join they are inverted so this section of code is read backwards

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7
Q

What is duplication

A

Where one base is duplicated at least once also causes frame shift

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8
Q

What is translocation

A

Where a section of bases on one chromosome detaches and attached onto a different chromosome

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9
Q

What are stem cells

A

Undifferentiated cells that can continuously divide and become specialised

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10
Q

What are the 4 different types of stem cells

A

Totipotent, pluripotent, multipotent and unipotent

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11
Q

What is a totipotent stem cell

A

Divide and produce any type of body cell for a limited time in early embryos

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12
Q

What are pluripotent stem cells

A

Found in embryos can divide into unlimited numbers and be used in treating human disorders can turn into everything except placenta cells

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13
Q

What are multipotent and unipotent stem cells

A

Found in nature mammals and can divide to form limited number of different cells

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14
Q

What are induced pluripotent stem cells

A

(IPS) can be produced from adult somatic cells using appropriate protein transcription factors to overcome ethical issues

Genes that were switched off to make the cell specialised must be switched back on done using transcriptional factors

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15
Q

How is transcription controlled

A

In eukaryotes transcription of target genes stimulated or inhibited when specific transcriptional factored move from cytoplasm into nucleus

Can turn genes on or off

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16
Q

How does transcription factors occur (4)

A
  1. Transcription of gene occurs when molecule from cytoplasm enters nucleus binds to DNA
  2. These are proteins called transcription factors each binds to different base sequence on DNA and initiate transcription of genes
  3. Once bound transcription begins creating mRNA for the gene which is then translated in the cytoplasm to create protein
  4. Without binding transcription factors gene is inactive and protein won’t be made
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17
Q

What is oestrogen

A

A steroid hormone that can initiate transcription

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18
Q

What is epigenetics

A

Heritable change in gene function without changing the DNA base sequence caused by changes in environment

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19
Q

What is methylation of DNA

A

When methyl groups are added to DNA attach to base cytosine

Prevents transcription factors from binding and attracts proteins that condense the DNA histone complex so prevents a section of DNA from being transcribed

20
Q

What is acetylation of his tone proteins

A

Decreased acetylation of associated histones inhibits DNA transcription

If acetyl group removed from histones become more positive and attract phosphate group on DNA

Makes DNA and histones more strongly associated and hard for transcription factors to bind

21
Q

What is RNAi

A

RNA interference this inhibits translation

22
Q

What is the molecule that destroys mRNA

A

siRNA (small interfering RNA)

23
Q

How does siRNA work

A

An enzyme can cut the mRNA into siRNA

One strand-of the siRNA combines with another enzyme

This siRNA enzyme complex will bind via complementary base pairing to another mRNA molecule once bound enzyme with cut up mRNA so it can’t be translated

24
Q

How does cancer form

A

Mutation of genes and non functioning proteins or if mitosis is not regulated resulting in uncontrollable division

25
Q

What is a benign tumour

A

Grow large at a slow rate
Non cancerous
Produce adhesive sticky molecule so it can’t move
Impact is localised
Non life threatening normally

26
Q

What is a malignant tumour

A

Cancerous
Grow large and rapidly
The tumour can break off and spread to other tissues in body
Not encapsulated
Can reach blood supply

27
Q

For a tumour to develop what genes would need to have mutated

A

Tumour suppressor gene and/or the oncogene

28
Q

What are oncogenes

A

Mutated versions of protocogenes which creates proteins involved with the initiation of DNA replication

Oncogenes can mutate to cause cells to permanently activated to make cells divide continuously

29
Q

What are tumour suppressor genes

A

Produce proteins to slow down cell division and cause cell death

30
Q

What happens if there is a mutation in tumour suppressor gene

A

Gene not produced so cell division would continue and mutated cells Wouldn’t be identified

31
Q

How can oestrogen cause cancer

A

Once menopause is reached you no longer produce oestrogen from ovaries so instead fat cells in breast tissue produce oestrogen which has been linked with breast cancer

This could be due to oestrogen activating s gene that initiated transcription and if this is a proto oncogene so this grid permanently turned on activation cell division

32
Q

What are the 3 recombinant DNA technologies

A

-creating DNA fragments
- genetic fingerprinting
- genetic screening, counselling and locating genes

33
Q

What is recombinant DNA technology

A

Combining different organisms DNA which could enable scientists to manipulate and alter genes to improve industrial processes

34
Q

Explain the process of reverse transcription (6)

A
  1. Enzyme makes DNA copies from mRNA this enzyme is revers transcriptase
  2. A cell that naturally produced lots of the protein of interest
  3. These cells should have large amounts of mRNA for the protein
  4. The reverse transcriptase enzyme joins the DNA nucleotides with complementary base pairs to the mRNA sequence
  5. Single sensed DNA made
  6. To make DNA double stranded DNA polymerase used
35
Q

What are restriction endonucleases

A

Anyone’s that cut up DNA

36
Q

What is a promoter region

A

Sequence if DNA which is the binding site for RNA polymerase

37
Q

How do you insert DNA into a vector

A

Plasmid is cut open using restriction endonucleases

This creates sticky ends so DNA fragment sticky ends are complementary to the sticky ends of plasmid

38
Q

What are the 3 different marker genes that can be used to identify bacteria

A
  1. Antibiotic resistance
  2. Genes coding for fluorescent proteins
  3. Evened coding for enzymes
39
Q

How do the fluorescent markers work

A

Jellyfish contain glowing gene this gene can be inserted into bacteria plasmid

40
Q

What is in vitro fertilisation

A

Fragments of DNA can be amplified in vitro via the polymer as e chain reaction

41
Q

What is the method of PCR(3)

A
  1. Temperature is increased to 95° to break down hydrogen bonds and split DNA into single strands
  2. Temperature decreases so that primers can attach (annealing)
  3. Enzyme DNA polymerase attaches to complementary free nucleotides and makes new strand to align next to each template
    Temperature increases to the optimum for taq polymerase
42
Q

Give 3 advantages of PCR

A
  1. Automated - efficient
  2. Rapid - 100 billion copies of DNA made in hours
  3. Doesn’t require living cells
43
Q

What are DNA probes

A

Shirt single stranded pieces of DNA labelled radioactively or fluorescent ly so you can locate specific alleles see if they contain gene of interest

44
Q

What are VNTRS

A

variable number of tandem repeats

45
Q

What are VNTRS used for

A

Analysis of DNA fragments used to determine genetic relationships

46
Q

What is gel electrophoresis

A

Agar gel creates resistance for moving DNA and smaller pieces of DNA can move faster

This shows the lengths of VNTRS separates

47
Q

What is hybridisation

A

DNA probes added and they will mix with the single stranded VNTRS and bind to them

Biology Paper 2 (4 decks)

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