genome projects and gene technology Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Describe how DNA is replicated in a cell.

A
  • DNA strands separate / hydrogen bonds broken;
  • Parent strand acts as a template / copied / semi-conservative replication;
  • Nucleotides line up by complementary base pairing; (Adenine & Thymine etc)
  • Role of DNA polymerase: joins adjacent nucleotides on the developing strand via condensation and formation of phosphodiester bond;
  • 5’ to 3’ direction
  • Each new DNA molecule has 1 template and 1 new strand
  • Formed by semi-conservative replication.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe and explain how the polymerase chain reaction (PCR) is used to amplify a DNA fragment.

A
  • (Requires DNA fragment) (Taq) DNA polymerase, (DNA) nucleotides and primers;
  • Heat to 95°C to break hydrogen bonds (and separate stands);
  • Reduce temperature (40-65°C) so primers bind to DNA/strands;
  • Increase temperature (70-75°C), DNA polymerase joins nucleotides (and repeat method);
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is the DNA heat to 95°C during PCR?

A
  • Produce single stranded DNA
  • Breaks WEAK hydrogen bonds between strands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why do you add primers during PCR?

A
  • Attaches to / complementary to start of the gene / end of fragment;
  • Replication of base sequence from here;
  • Prevents strands annealing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Explain why ‘base-pairs’ is a suitable unit for measuring the length of a piece of DNA.

A
  • DNA = 2 chains / joined by linking of 2 bases / A with T and G with C/ purine pairs with pyrimidine;
  • Bases are a constant distance apart / nucleotides occupy constant distance;
  • each base-pair is same length / sugar-phosphate is a constant distance;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Name one mutagenic agent.

A
  • high energy radiation /ionising particles e.g. named particles/α, β, γ & X-rays;
  • benzene;
  • x rays/cosmic rays;
  • uv (light);
  • carcinogen / named carcinogen;
  • mustard gas / phenols / tar (qualified);
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

A deletion mutation occurs in gene 1.
Describe how a deletion mutation alters the structure of a gene.

A
  • removal of one or more bases/nucleotide;
  • frameshift/(from point of mutation) base sequence change;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the main stages in the copying, cutting and separation of the DNA.

A
  • heat DNA to 95°C / 90°C;
  • strands separate;
  • cool so that primers bind to DNA;
  • add DNA polymerase/nucleotides;
  • use of restriction enzymes to cut DNA at specific base sequence/ breaks phosphodiester bonds
  • use of electric current and agar/gel;
  • shorter fragments move further;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the polymerase chain reaction.

A
  • Heat DNA;
  • Breaks hydrogen bonds/separates strands;
  • Add primers;
  • Add nucleotides;
  • Cool;
  • (to allow) binding of nucleotides/primers;
  • DNA polymerase;
  • Role of (DNA) polymerase;
  • Repeat cycle many times;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe a plasmid.

A
  • circular DNA;
  • separate from main bacterial DNA;
  • contains only a few genes;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Suggest one reason why DNA replication stops in the polymerase chain reaction.

A
  • Limited number of primers/nucleotides; /
    Primers / nucleotides ‘used up’.
  • DNA polymerase (eventually)denatures
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Suggest why the restriction enzyme has cut the human DNA in many places but has cut the plasmid DNA only once.

A
  • enzymes only cut DNA at specific base sequence/recognition site/specific point;
  • sequence of bases/recognition site/specific point (on which enzyme acts)
  • occurs once in plasmid and many times in human DNA;
  • (max 1 if no reference to base sequence or recognition site)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe how the bacteria containing the insulin gene are used to obtain sufficient insulin for commercial use.

A
  • use of fermenters;
  • provides nutrients plus suitable conditions for optimum growth/named
  • environmental factor;
  • reproduction of bacteria;
  • insulin accumulates and is extracted;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Explain what is meant by a vector.

A
  • Carrier;
  • DNA/gene; (context of foreign DNA)
  • Into cell/other organism/host;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Explain how modified plasmids are made by genetic engineering and how the use of markers enable bacteria containing these plasmids to be detected.

A
  • isolate TARGET gene/DNA from another organism/mRNA from
  • cell/organism;
  • using restriction endonuclease/restriction enzyme/reverse transcriptase to
  • get DNA;
  • produce sticky ends;
  • use DNA ligase to join TARGET gene to plasmid;
  • also include marker gene;
  • example of marker e.g. antibiotic resistance;
  • add plasmid to bacteria to grow (colonies);
  • (replica) plate onto medium where the marker gene is expressed;
  • bacteria/colonies not killed have antibiotic resistance gene and (probably) the TARGET gene;
  • bacteria/colonies expressing the marker gene have the TARGET gene as well;
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

mRNA may be described as a polymer. Explain why.

A
  • Made up of many (similar) molecules/monomers/nucleotides/units;
17
Q

What is a DNA probe?

A
  • (Short) single strand of DNA;
  • Bases complementary (with DNA/allele/gene);
18
Q

Name three techniques used by scientists to compare DNA sequences.

A
  • Polymerase Chain Reaction
  • DNA fingerprinting
  • Gel electrophoresis