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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
Step 3 of DNA Sequencing
At 60 degrees DNA polymerase starts to add free nucleotides using complementary base pairing to build up new DNA strands
26
Step 4 of DNA sequencing
Terminator bases randomly incorporated in growing DNA chains, DNA synthesis stops Resulting in different sized fragments DNA fragments ordered according to length (electrophoresis)
27
Why is electropherisis used in sequencing
Put DNA in size order and read order of DNA bases
28
Step 5 of DNA sequencing
Fluorescent markers on terminator bases used to find end of fragments, laseers detect different colors and order of sequence
29
Step 6 of DNA sequencing
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
30
Step 7 in DNA sequencing
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
What is paralell sequencing
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
What is bioinformatics
Development of the software and computing tools to organise and analyse large amounts of data
33
What can computational bio be used for
Working out 3D structure of proteins Identifying genes related to specific diseases in populations Evolutionary relationships between organisms
34
35
What was the human genome project
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
Why are genomes of pathogens analysed
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
What is DNA barcoding used for
Identifying species
38
How does DNA barcoding work
Comparing particular sections of the gene one that all organisms share but vary for different species
39
What part of plants have been used to identify different plant species
Region of DNA does not evolve quickly enough to distinguish plants but DNA of the chloroplasts of plants used to identify species
40
How is proteomics helpful
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
What are spliceosomes
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
Protein modification
Some proteins modified by other proteins after they’re synthesised May be shortened or lengthened to give variety of other proteins
43
What synthetic biology techniques are there
Genetic engineering Use of biology in industry Gene therapy Synthesis of new organism
44
Genetic engineering
May involve a single change in the biological pathway/ major genetic modification of an entire organism
45
What is genetic engineering
Manipulation of a genome
46
What does transgenic mean
Organism which contains a gene from another organism
47
Isolating the desired gene
1. Restriction endonuclease at specific base sequence leaving sticky ends OR 2. Isolate mRNA for desired gene and use reverse transcriptase enzyme to produce single complementary DNA strand
48
What’s a vector
An organism that carries genetic material into another cell
49
What are plasmids
Small circular molecules of DNA that can replicate independently
50
Recombinant DNA
DNA produced by combining DNA from different sources
51
How is recombinant DNA made
Isolated DNA is inserted into vector and put into host cell
52
Placing gene in vector
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
Why are two marker genes used
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
Why is the vector transferred
Plasmid with recombinant DNA transferred into host cell
55
Methods of transferring vector
1. Culture bacterial cells and plasmids in calcium- rich solution and increase temp causing bacterial membrane to become permeable
56
Method 2- Electroporation
Electric current applied to bacteria making membranes porous so plasmids move in Can also be used to get DNA fragments from eukaryotes
57
Problems with electroporation
Can permantly damage membrane Less useful in whole organism
58
Method 3- Electrofusion
Tiny electric currents applied to membranes of two different cells Fusing cells and nuclear membranes to from hybrid/polyploid animal cells
59
Polyploid cells
Each cell has more than two complete sets of chromosomes Don’t usually survive in body of living organisms
60
How have microorganisms been genetically modified
To produce many different substances useful to people e.g. insulin,HCG, clotting factors, antibiotics and vaccines/enzymes
61
Why are prokaryotes engineered
Produce substances useful to humans in large quantities e.g. insulin
62
Why are plants engineered
Herbicide resistance Higher yield Pesticide production
63
How are plants genetically engineered
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
Alternative method of plant engineering
Celluloses remove plant cell wall Electrofusion to form a polyploid cell Plant hormone used to grow cell and produce plant
65
Engineering animals
Much harder to engineer DNA of eukaryotic organisms Animal cell membranes less easy to manipulate
66
Genetic manipulation of microorganisms
Used to develop medical treatments
67
What is the worry of using GM pathogens
Could be used for biological warfare Not used so much because of health and safety risks but can be used for medical research
68
GM plants
May be able to feed ever growing population and overcome environmental issues like co2 production
69
What’s an example of GM crop
Soya beans with insect resistance
70
Insect resistance in GM soya beans
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
Benefits of GM crops
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
Cons of GM crops
Insects become resistance to pesticides Extended shelf life reduce demand and value People allergic to proteins in GM crops
73
What is pharming
Production of human medicines from genetic engineering in animals

OCR A level bio (10 decks)

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