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Biology Alevels > control of gene expression topic 8 > Flashcards

control of gene expression topic 8 Flashcards

1
Q

when does gene mutation normally occur

A

during DNA replication

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2
Q

what are the types of mutations

A

addition
deletion
substituition
inversion
duplication
translocation

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3
Q

what is inversion

A

a sequence of bases is reversed

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4
Q

what is duplication

A

when one or more bases is repeated
e.g ACTG becomes ACTCTG

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5
Q

what is translocation

A

a sequence of bases is moved from one location of the genome to another

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6
Q

what do mutagenic agents do

A

they increase the rate of mutation

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7
Q

what are examples of mutagenic agents

A

uv radiation
ionising radiation
some viruses

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8
Q

why is it an advantage that genetic code is degenerate

A

if a mutation occurs it may not change the proteins amino acid sequence
since they code for the same amino acid

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9
Q

what is a frame shift

A

a change in all the following base triplets

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10
Q

why are muscle cells different to hair cells

A

muscle cell has same DNA as a hair cell

but different portions of DNA is translated which makes the cells different

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11
Q

what is a stem cell

A

they are the types of cells which can differentiate into many kinds of cells

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12
Q

what are the different types of stem cells

A

totipotent
pluripotent
unipotent
induced pluripotent

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13
Q

what is a totipotent cell

A

they can divide to produce any type of body cell

they go on to develop but only translate a portion of the DNA

found in short term embryos

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14
Q

what are pluripotent cells

A

stem cells found in embryo but can differentiate into fewer cells than totipotent

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15
Q

what are unipotent cells

A

stem cells that can differentiate into only one kind of cell
e.g cardiac stem cells can only differentiate into cardiomyocytes

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16
Q

what are induced pluripotent stem cell

A

can be produced from adult somatic stem cells
can be done adding appropriate protein transcription factors

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17
Q

how can the transcription of target genes be stimulated

A

occurs due to transcription factors move from the cytoplasm to the nucleus

once in the nucleus ,they bind to specific DNA sites near the target genes

this has the effect of activating transcription / repressing transcription

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18
Q

describe the steroid oestrogen as a transcription factor

A

oestrogen binds to oestrogen receptor to form an oestrogen -oestrogen receptor complex

complex(the transcription factor) moves from cytoplasm to the nucleus where it binds to its DNA target site
the complex acts as an activator of transcription

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19
Q

what is epigenetics

A

involves heritable changes in gene function ,without changes to the base sequence of DNA

determines whether the gene is switched off or switched on by changing ho easily the gene can be transcribed

20
Q

how can you ‘switch off’ of a gene

A

when more methyl groups are added to the DNA

making it harder to transcribe

21
Q

how can you switch on a gene

A

when you add more acetyl groups to the DNA

22
Q

How can epigenetics lead to the development of genetic disease

A

fragile X ray syndrome is a condition where there is increased methylation of FMR 1 gene due to deletion mutation

causing gene to be switched off and the protein it codes for ,to not be produced

23
Q

what is RNA interference

A

they inhibit the translation of the mRNA produced from target genes

24
Q

what is responsible for RNA interference

A

miRNA and siRNA

25
Q

how does miRNA and siRNA inhibit translation

A

siRNA cuts up the mRNA so it cant be translated

miRNA binds to the mRNA to block translation

26
Q

what is a tumour

A

a mass of abnormal cells

27
Q

what are the two types of tumours

A

benign -not cancerous ,they grow slowly and are often harmless

malignant - grow rapidly and invade surrounding tissues

28
Q

what causes tumours

A

changes to genes called tumour suppressor genes and proto-oncogenes

  1. if many methyl groups/acetyl bind to tumour suppressor genes/proto-oncogenes ,it becomes harder to transcribe the gene
  2. mitosis isn’t regulated
  3. leads to cancer
29
Q

what are the two types of genes involved in the production of tumours

A

tumour suppressor gene

proto-oncogene

30
Q

what causes breast cancer

A

increase concentration of oestrogen

31
Q

What is recombinant DNA technology

A

Recombinant DNA technology involves the transfer of fragments of DNA from one organism, or species, to another

32
Q

Why can DNA fragments be transferred

A

The genetic code is universal,

so the transferred DNA will be translated in the cells of the recipient organism

33
Q

What does transgenic mean

A

An organism that has had DNA transferred to it is called transgenic

34
Q

How can fragments of DNA be produced

A

Using reverse transcriptase to convert mRNA to cDNA

Using restriction enzymes to cut a fragment containing the gene from the DNA

Using a ‘gene machine’ to create the desired section of DNA

35
Q

How can DNA fragments be amplified

A

Fragments of DNA can be amplified by vitro and in vivo techniques.

36
Q

How can DNA fragments be amplified (cloned)

A

Fragments of DNA can be amplified by in vitro and in vivo techniques.

37
Q

Describe in vitro techniques

A

In vitro refers to techniques that involve a lab

38
Q

What is PCR

A

The polymerase chain reaction (PCR) is an example of an in vitro method

PCR makes millions of copies of a DNA fragment in a few hours

39
Q

What is required for polymer chain reaction

A

A reaction mixture containing the DNA sample, free nucleotides, DNA polymerase, and DNA primers (short pieces of DNA that are complementary to the ends of the DNA strand) is set up

40
Q

What is required for polymer chain reaction

A

A reaction mixture containing the DNA sample, free nucleotides, DNA polymerase, and DNA primers (short pieces of DNA that are complementary to the ends of the DNA strand) is set up

41
Q

Describe the procedure for PCR

A

1.The mixture is heated to 90C to break the hydrogen bonds between the complementary strands of DNA

2.The mixture is then cooled to between 50 and 65C so that primers can (bind) to the strands

3.The mixture is heated again to 72C for the DNA polymerase joins nucleotide

4.In every cycle of PCR, the volume of DNA doubles

42
Q

Describe in vivo method as an example of recombinant technology

A

The required DNA fragment is isolated using restriction endonucleases, reverse transcriptase, or a gene machine.
The DNA is cut to form ‘sticky ends’ that allow it to join to other DNA strands

The DNA is inserted into a loop of plasmid DNA that acts as a vector. Ligases are used that act as ‘glue’ to join the DNA to the strands by forming complementary sticky ends

This recombinant plasmid is transferred to a bacterium and the transformed bacteria are identified and isolated.

43
Q

Describe three ways DNA fragment is isolated

A

Restriction endonucleases
Reverse transcriptase
Gene machine

44
Q

How can the plasmid taken up by bacteria be identified

A

Marker genes’ can be inserted into the plasmid as well so that bacteria that have taken up the plasmid can be identified

45
Q

Describe how enzymes could be used to insert genes in a plasmid

A

Restriction endonucleases to cut plasmid

Ligase joins genes

Biology Alevels (13 decks)

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