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Biology Part 2 > Unit 8: Gene expression and DNA technology pt 2 > Flashcards

Unit 8: Gene expression and DNA technology pt 2 Flashcards

(51 cards)

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1
Q

What are DNA ladders?

A

has DNA fragments of known size and are used to calculate the size of unknown samples

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1
Q

What is a polymerase chain reaction?

A

enables multiple copies of identical fragments of DNA/genes to be produced from a small sample

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2
Q

outline a polymer chain reaction

A
  • Primers and DNA are mixed and heated at 95°/ 5 minutes (breaks hydrogen bonds s)
  • cool to 55°/2 minutes allows primers to anneal to specific target sequence
  • free DNA nucleotide align to DNA strands by CBP
  • temperature is increased to 72° (optimum for DNA polymerase) enzyme joins nucleotides to form new complementary strand
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3
Q

how do you calculate the number of molecules produced in PCR?

A

2^n

n= number of cycles

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4
Q

What is a DNA primer?

A

short single standard molecules of DNA

Provide starting sequence for DNA polymerase
- Important because DNA polymerase can’t begin at a single stranded starting point

Prevent original DNA strands joining back together

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5
Q

What is a DNA probe?

A

short single standard molecules of DNA that are radioactively/fluorescently labelled

Used to identify/locate known sequences of DNA

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6
Q

What is recombinant DNA technology?

A

transfer of fragments of DNA from one organism/species to another

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7
Q

What is a transgenic organism?

A

organism that has received transferred DNA

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8
Q

how can you obtain a required fragment/gene using reverse transcriptase?

A
  • mRNA uses as a template to produce required chain/fragment of DNA
  • mRNA is mixed with free nucleotides and reverse transcriptase
  • free DNA nucleotides align next to
    complementary bases on mRNA
  • reverse transcription joins DNA nucleotide together to produce a fragment/gene
  • DNA strand produced by this is called complementary DNA
  • Double stranded DNA is produced from cDNA using DNA nucleotides and DNA polymerase
  • No introns
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9
Q

How can you obtain a fragment using restriction enzymes?

A

required gene/fragment can be removed from the DNA using restriction endonuclease enzymes

-Contains introns

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10
Q

How can you produce fragments using a gene machine?

A
  • doesn’t need pre-existing DNA or mRNA as a template
  • amino acid sequence of a protein is used as a template to determine the sequence of DNA nucleotides for a specific gene
  • automated process — required nucleotide sequence is programmed into the gene machine

No introns

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11
Q

Why must introns not be present in gene transfers?

A

If the source of the gene is eukaryotic and the recipient is prokaryotic introns can’t be present

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12
Q

what are promoter and terminator regions?

A

sections of DNA which must be added to the gene/fragment of DNA for successful transcription of the transferred genes in the recipient cells

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13
Q

What is a promoter region?

A

initiate transcription by promoting the binding of RNA polymerase

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14
Q

What is a terminator region?

A

marks the end of a gene and triggers release of the mRNA transcribed

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15
Q

What does it mean to amplify fragments of DNA?

A

Increase the number by replication

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16
Q

what is invivo?

A

copies are made inside the living organism

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17
Q

What is invitro?

A

copies are made outside a living organism

Usually by PCR

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18
Q

What are the two techniques of amplification?

A

in vivo
In vitro

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19
Q

What is a vector used for?

A

Transfers genes

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20
Q

What vector is used in bacteria?

21
Q

What are some other vectors?

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A

Viruses and liposomes (phospholipid sack)

22
Q

What is bacteria used for?

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A
  • producing a protein code for by a transferred gene
  • clone genes/fragments (invivo cloning)
23
Q

How does bacteria clone gene/fragments?

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A

in vivo cloning

the rapid reproduction rate of bacteria allows a transferred gene to be quickly copied so a large amount of gene product can be obtained

24
How is the plasmid used to transfer a fragment/gene?
* plasma is cut using the same restriction endonuclease that cut the gene * plasma DNA and foreign DNA join by base pairing as they have complementary sticky ends * **ligase** is used to form the phosphodiester bonds * the plasma with the foreign DNA is referred to as a **recombinant plasmid**
25
What is transformation?
process in which bacteria take up the recombinant plasmid This allows these plasma vectors to be added to a culture of bacteria
26
Why may the use of vectors not work?
- cells may not take up the vector - Cells may take up the vector with the vector might not contain the gene (plasma may have joined back together without the foreign DNA being taken up)
27
What is marker gene?
Allows successfully transformed bacteria/eukaryotic cells to be **detected and isolated for subsequent culturing**
28
How does GFP gene detect bacteria/eukaryotes?
GFP gene codes for the production of **green fluorescent protein** GFP gene added to the gene being transferred bacterial/eukaryotes can be identified as they fluorescence when viewed with **UV light** under a microscope
29
What are some humanitarian benefits of using recombinant DNA technology?
- Reducing famine and malnutrition by developing GM plants/animals which **produce high yields and are resistant to disease** - producing vaccines and drugs - Treating genetic diseases by gene therapy
30
what are some drawbacks of using recombinant DNA that come from environmentalists and anti globalisation activists?
- possible transfer of foreign genes to non target organisms - An irreversible process with no certainty of economic benefits - Ethical considerations with regard to permanently altering the genome of animals - Long-term ecological and evolutionary consequences are unknown
31
what is gene therapy?
Uses recombinant DNA technology for the **treatment of genetic diseases**
32
How does gene therapy work?
Involves the introduction of **functional copies** of an allele into an organism which possesses **defective alleles** of the same gene
33
What are the stages of gene therapy?
• identify gene causing the disease • obtaining and cloning copies of the functional allele • transferring these functional values into the patient (by use of a vector) • ensuring that the values reached the target cells and function normally
34
What is DNA sequencing?
involves techniques to determine the sequence of DNA nucleotide bases (genome) This allows the sequence of proteins (proteome) to be determined
35
what are applications of DNA sequencing?
Can identify potential antigens for use vaccines
36
Why can the genome not be translated into proteom in some organisms?
these organisms are more **complex** presence of **non coding DNA** and **regulatory genes** means the genome can’t easily be translated into the proteome
37
What is used to screen people for specific alleles
DNA probes and DNA hybridisation
38
What is the procedure before screening?
* a DNA probe is made that is complementary to the DNA sequence of the allele being investigated * multiple copies of the DNA probe are made using PCR * the sample of DNA is obtained from the person/organism being tested
39
Outline screening
- The DNA that’s being tested is fragmented by restriction endonucleases - Fragments are separated by gel electrophoresis - Fragments are treated and split into single strands - Single strands are transferred to nylon membrane and probes are added - Membrane is **washed** remove unattached probes - If allele is present labelled DNA probe will bind to a complementary base on **one** of its strands presents for as position of probe can be **identified by the radioactivity/fluorescence** it admits
40
what can patients be screened for?
- Heritable conditions - individual drug responses people respond differently to particular drugs due to differences in their alleles — this leads to personalised medicine - Health risks
41
what is genetic counselling?
uses information concerning the **presence of identified mutant alleles**
42
What is genetic counselling used for?
- understand the **probability** of people developing a disease - Advise parents who may be **carriers** of a disease causing allele - decide the **best course** of drug treatment for genetic diseases
43
What is a variable number Tandem Repeat
many **repetitive non-coding sequences** of nucleotide bases in a genome
44
what are VNTRs used for?
Analysis of these can be used to: - determine the relatedness between individuals - match the identity of a DNA sample to an individual
45
Outline the procedure of genetic fingerprinting
1. PCR is used to amplify the sample DNA 2. It’s then cut into fragments using restriction endonucleases cut DNA at sites close to, but not within the VTNRs giving a large number of DNA fragments (some fragments will be the same length others different) 3. fragments are separated by gel electro forces. 4. Fragments are treated using alkali to form single strands 5. Singles strands are transferred to a nylon membrane 6. Radioactive probes are added that are complimentary to the repeated sequences. Many probes are used and each bind with the VNTRs by DNA hybridisation 7. Radioactive probes allowed the position of fragments to be identified when the membrane is placed onto an x-ray film (the genetic fingerprint is obtained).
46
How can genetic fingerprints be compared?
if fingerprints have bands at the same position on the gel it means they have the same number of nucleotides and repetitive sequences
47
How is genetic fingerprint used in forensic science?
By comparing DNA samples from crime scene with DNA of suspects
48
How is genetic fingerprinting used to diagnose?
Certain diseases involve unique patterns of several areas and can be identified by fingerprinting
49
How is genetic fingerprinting used to determine genetic relationships?
it can determine genetic relationships and genetic variability in a population as more closely related species have **more similar VNTRs**
50
how is genetic fingerprinting used in animal and plant breeding?
**ensuring genetic diversity is maintained** by screening organisms to **prevent inbreeding** between closely related individuals

Biology Part 2 (16 decks)

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