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OCR A level bio > Manipulating Genomes > Flashcards

Manipulating Genomes Flashcards

1
Q

Genome

A

All genetic info in an organism

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2
Q

What are introns

A

Large non-coding regions of DNA that are removed from mRNA and made into polypeptide chains

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3
Q

What are exons

A

Coding regions of DNA

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4
Q

What’s satellite DNA

A

Short sequences of DNA that are tandemly repeated as many as 10 million times in DNA- mainly located in telomeres

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5
Q

What’s microsatellite

A

Smaller region of just 2-4 bases repeated only 5-15 times

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6
Q

What’s DNA profiling?

A

Producing an image of the patterns in DNA of an individual

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7
Q

What’s the main steps for producing a DNA profile

A

Extraction
Digestion
Seperation
Hybridisation
Development
Seeing the evidence

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8
Q

What’s extraction

A

DNA extracted from tissue sample then amplified with DNA polymerase chain reaction

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9
Q

Digestion in DNA profiling

A

Restriction endonucleases enzymes cut DNA into small fragments at restriction sites

Different enzymes cut at different places but make two cuts, once through each strand of DNA

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10
Q

Seperation in DNA profiling

A

Separated using gel electrophoresis- utilised the way charged particles move under the influence of an electric current and gel is then immersed in alkali to seperation DNA double strands into single strand

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11
Q

Hybridisation in DNA profiling

A

Radioactive DNA probes bind to complementary strands of DNA under certain Ph and temperature

DNA probes- short

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12
Q

Development in DNA profiling

A

Radioactive labels- x ray images produced on paper/membrane

Fluorescent labels- UV light used to tag glow giving pattern of bars= DNA profile

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13
Q

What are the uses of DNA profiling

A

Forensic science

Paternity

Disease risk

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14
Q

Use of DNA profiling in forensic science and criminal investigation

A

PCR and DNA profiling performed on traces of DNA left at crime scene- from semen, blood and saliva
Trace identified from criminal DNA database

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15
Q

What is the use of gel electrophoresis

A

Seperate DNA fragments based on size

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16
Q

Seperation of nucleic acid fragments by electrophoresis

A
  1. DNA fragments placed in agarose gel strips
  2. Electric current passed through electrophoresis plate
  3. DNA has a slight negative charge due to negatively charged phosphate groups so move towards positive charged anode
    4.Smaller fragments move faster, fragments of same size form distinctive bands on gel
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17
Q

What is polymerase chain reaction

A

Artificial DNA rep
Method producing thousands of copies of DNA segment using enzyme DNA polymerase

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18
Q

What does PCR do

A

Make many copies of DNA at different length

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19
Q
  1. seperating strands
A

Temp in PCR machine increases to 95 degrees
Denatures DNA by breaking H bonds

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20
Q
  1. Annealing of the primers
A

Temp decreased to 55 degrees
Primers bind to the ends of the DNA strands needed for replication of strands to occur

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21
Q
  1. Synthesis of DNA
A

Temp increased again to 72 degrees- optimum temp for DNA polymerase
DNA polymerase adds bases to primer building up complementary strands of DNA

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22
Q

What is DNA sequencing used for

A

Determine sequence of nucleotides

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23
Q

Step 1 of DNA sequencing

A

DNA mixed with primer, DNA polymerase, excess nucleotides and terminator bases

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24
Q

Step 2 of DNA Sequencing

A

Mixture placed in thermal cycler
Double strands of DNA break at 95 degrees
At 55 degrees primer anneals to DNA strand

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25
Q

Step 3 of DNA Sequencing

A

At 60 degrees DNA polymerase starts to add free nucleotides using complementary base pairing to build up new DNA strands

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26
Q

Step 4 of DNA sequencing

A

Terminator bases randomly incorporated in growing DNA chains, DNA synthesis stops
Resulting in different sized fragments
DNA fragments ordered according to length (electrophoresis)

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27
Q

Why is electropherisis used in sequencing

A

Put DNA in size order and read order of DNA bases

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28
Q

Step 5 of DNA sequencing

A

Fluorescent markers on terminator bases used to find end of fragments, laseers detect different colors and order of sequence

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29
Q

Step 6 of DNA sequencing

A

Order of bases in the capillary tubes shows the sequence of the new, complementary strand of DNA made and used to build original DNA sequence

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30
Q

Step 7 in DNA sequencing

A

Data from sequencing process fed into computer resembling genomes by comparing all fragments and finding overlapping areas

When genome assembled scientists identify genes or parts of the genome which code for specific characterisitics

31
Q

What is paralell sequencing

A

DNA is fragmented and seperated into single strands

Millions of DNA fragments are attached to a flow cell

Flow cell is incubated with primers, DNA polymerase and other enzymes

Activated nucleotides are added and any light generated is detected and imaged

32
Q

What is bioinformatics

A

Development of the software and computing tools to organise and analyse large amounts of data

33
Q

What can computational bio be used for

A

Working out 3D structure of proteins
Identifying genes related to specific diseases in populations
Evolutionary relationships between organisms

34
Q
A
35
Q

What was the human genome project

A

International effort to map and sequence DNA of the entire human genome

Used in forensic science and genetic engineering

Automation of sequencing and development of faster computers meant it happened very quickly

36
Q

Why are genomes of pathogens analysed

A

Find out sources of infection

Identify antibiotic resistant strains

Track progress of outbreak of potentially serious disease and monitor epidemics

Identify region in genome of pathogens which may be useful targets in development of new drugs

37
Q

What is DNA barcoding used for

A

Identifying species

38
Q

How does DNA barcoding work

A

Comparing particular sections of the gene one that all organisms share but vary for different species

39
Q

What part of plants have been used to identify different plant species

A

Region of DNA does not evolve quickly enough to distinguish plants but DNA of the chloroplasts of plants used to identify species

40
Q

How is proteomics helpful

A

Enable you to predict the amino acid sequence of all proteins it produces
BUT
Sequence of amino acids can be different and some gene code for many different proteins

41
Q

What are spliceosomes

A

Introns are removed from pre-mRNA
-Exons joined together by enzyme complexes

Can join to exons in different ways

Result- single gene may produce several versions of the functional mRNA coding for different AA giving different proteins and phenotypes

42
Q

Protein modification

A

Some proteins modified by other proteins after they’re synthesised

May be shortened or lengthened to give variety of other proteins

43
Q

What synthetic biology techniques are there

A

Genetic engineering

Use of biology in industry

Gene therapy

Synthesis of new organism

44
Q

Genetic engineering

A

May involve a single change in the biological pathway/ major genetic modification of an entire organism

45
Q

What is genetic engineering

A

Manipulation of a genome

46
Q

What does transgenic mean

A

Organism which contains a gene from another organism

47
Q

Isolating the desired gene

A
  1. Restriction endonuclease at specific base sequence leaving sticky ends

OR

  1. Isolate mRNA for desired gene and use reverse transcriptase enzyme to produce single complementary DNA strand
48
Q

What’s a vector

A

An organism that carries genetic material into another cell

49
Q

What are plasmids

A

Small circular molecules of DNA that can replicate independently

50
Q

Recombinant DNA

A

DNA produced by combining DNA from different sources

51
Q

How is recombinant DNA made

A

Isolated DNA is inserted into vector and put into host cell

52
Q

Placing gene in vector

A
  1. Plasma (vector) cut ion with same restriction endouclease- complementary sticky ends to DNA fragment
  2. DNA lignite joins them together forming phosphodiester bonds

3.Plasma contains two marker genes

53
Q

Why are two marker genes used

A

E.g. antibiotic resistance and fluorescence

One shows if bacteria has taken up plasmid successfully- marker gene will function

The other will show if the gene has inserted into the plasmid successfully- marker gene wont function

54
Q

Why is the vector transferred

A

Plasmid with recombinant

DNA transferred into host cell

55
Q

Methods of transferring vector

A
  1. Culture bacterial cells and plasmids in calcium- rich solution and increase temp causing bacterial membrane to become permeable
56
Q

Method 2- Electroporation

A

Electric current applied to bacteria making membranes porous so plasmids move in

Can also be used to get DNA fragments from eukaryotes

57
Q

Problems with electroporation

A

Can permantly damage membrane

Less useful in whole organism

58
Q

Method 3- Electrofusion

A

Tiny electric currents applied to membranes of two different cells

Fusing cells and nuclear membranes to from hybrid/polyploid animal cells

59
Q

Polyploid cells

A

Each cell has more than two complete sets of chromosomes

Don’t usually survive in body of living organisms

60
Q

How have microorganisms been genetically modified

A

To produce many different substances useful to people e.g. insulin,HCG, clotting factors, antibiotics and vaccines/enzymes

61
Q

Why are prokaryotes engineered

A

Produce substances useful to humans in large quantities e.g. insulin

62
Q

Why are plants engineered

A

Herbicide resistance

Higher yield

Pesticide production

63
Q

How are plants genetically engineered

A

Using a bacteria which causes tumours in plants

Desired gene place placed in plasmid with marker gene and put directly in plant gene

Transgenic plant cells form callus and can be grown into new plant

64
Q

Alternative method of plant engineering

A

Celluloses remove plant cell wall

Electrofusion to form a polyploid cell

Plant hormone used to grow cell and produce plant

65
Q

Engineering animals

A

Much harder to engineer DNA of eukaryotic organisms

Animal cell membranes less easy to manipulate

66
Q

Genetic manipulation of microorganisms

A

Used to develop medical treatments

67
Q

What is the worry of using GM pathogens

A

Could be used for biological warfare

Not used so much because of health and safety risks but can be used for medical research

68
Q

GM plants

A

May be able to feed ever growing population and overcome environmental issues like co2 production

69
Q

What’s an example of GM crop

A

Soya beans with insect resistance

70
Q

Insect resistance in GM soya beans

A

Inserted gene in soya beans so that they produce Bt protein which is toxic to many insects

Some soya beans made resistant to common weed killers so farmers can used it but not kill plants

71
Q

Benefits of GM crops

A

Pest resistance so yield increase and do not died from pesticide

Disease resistance reducing crop loss

Herbicide resistance so less competition with weeds

Extended shelf life so reduces waste

72
Q

Cons of GM crops

A

Insects become resistance to pesticides

Extended shelf life reduce demand and value

People allergic to proteins in GM crops

73
Q

What is pharming

A

Production of human medicines from genetic engineering in animals

OCR A level bio (10 decks)

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