6.1.3 - manipulating genomes

Question 1

genome

Answer 1

all the genetic material it contains

Question 2

introns

Answer 2

the non coding regions of DNA

Question 3

satellite DNA

Answer 3

short sequences of DNA that are repeated many times

Question 4

minisatellite

Answer 4

sequence of 20-50 base pairs that will be repeated from 50 to several hundred times

Question 5

VNTRs

Answer 5

variable number tandem repeats (minisatellites)

Question 6

DNA profiling

Answer 6

technique to produce an image of the patterns of DNA of an individual

Question 7

5 stages of producing a DNA profile

Answer 7

1. extracting the DNA
2. digesting the sample
3. separating the DNA fragments
4. hybridisation
5. seeing the evidence

Question 8

stage 1 of DNA profiling- extracting the DNA

Answer 8

DNA must be extracted from a DNA sample, a technique called PCRs are used to give scientists enough DNA from a tiny tissue sample

Question 9

stage 2 of DNA profiling - digesting the sample

Answer 9

the strands are cut into small fragments using restriction endonucleases which cut DNA at restriction sites

Question 10

stage 3 of DNA profiling - separating the sample

Answer 10

the cut fragments need to be separated using eletrophoresis where the shorter fragments move towards the bottom of the gel and longer fragments remain at the top

they are then transferred from the gel into nylon membrane in a process known as southern blotting

Question 11

stage 4 in DNA profiling - hybridisation

Answer 11

DNA probes (radioactive or flourescent) bind to complimentary strands of DNA - identify the regions that are more varied

Question 12

stage 5 in DNA profiling - seeing the evidence

Answer 12

radioactive - x ray images taken
fluorescent - UV light so the tage slow

Question 13

PCR

Answer 13

polymerase chain reaction - allows scientists to produce a lot of DNA from the tiniest original sample

Question 14

PCR process

Answer 14

step one - separating the strands by increasing the temperature and breaking the hydrogen bonds

step two - annealing of the primers by decreasing the temperature and primers bind to end of DNA strands

step three - synthesis of DNA where temperature is increased to optimum temperature for DNA polymerase to work, to replicate the DNA strands.

Question 15

uses of DNA profiling

Answer 15

• forensic science (traces of DNA left at crime scene)
• prove paternity of a child
• identifying individuals who are at risk of developing particular diseases

Question 16

DNA sequencing

Answer 16

process of determining the precise order of nucleotides within a DNA molecule

Question 17

who developed the first DNA sequencing process?

Answer 17

Fredrick Sanger

Question 18

Human Genome Project

Answer 18

international project in which scientists from a number of countries worked to map the entire human genome.

Question 19

what are terminator bases?

Answer 19

modified versions of the four nucleotide bases. (a,t,c,g), that stops DNA synthesis when they are included (e.g a A terminator base will stop DNA synthesis at a location that an A base would go.
These are given coloured flourescent tag

Question 20

stages of DNA sequencing

Answer 20

1. Dna sequence mixed with primer, DNA polymerase and normal nucleotides
2. PCR steps 1 and 2
3. at 60C DNA polymerase starts to build up new DNA strands by adding nucleotides with the complementary base to DNA template strand
4. terminator bases stop the synthesis of DNA, resulting in different fragment lengths
5. eletropheresis - flourescent markers used to identify the final base on each fragment, which can then show the sequence of DNA

Question 21

next generation sequencing

Answer 21

DNA sequencing technologies have led to new automated high thoroughput sequencing processes. All the clusters can be sequenced an imaged at the same time.

Question 22

bioinformatics

Answer 22

development of software and computing tools needed to organise and analyse raw biological data

Question 23

computational biology

Answer 23

uses data from bioinformatics to then predict what will happen in different circumstances

Question 24

significance of analysing genomes of pathogens

Answer 24

• doctors to find out source of an infection
• doctors to identify antibiotic resistant strains of bacteria
• to track the progress of an outbreak

Question 24

DNA barcoding

Answer 24

identifying particular sections of the genome that are common to all species but vary between them and compare them.
e.g cytochrome c ocxidase

Question 25

proteomics

Answer 25

study and amino acid sequencing of an organisms enture protein complement

Question 26

genetic engineering

Answer 26

the manipulation of a genome

Question 27

basic principles of genetic engineering

Answer 27

involves isolating a gene for a desirable characteristic in one organism and placing it into another organism using a suitable vector.

Question 28

transgenic

Answer 28

an organism that carries a gene from another organism

Question 29

first stage of genetic engineering

Answer 29

isolating the desired gene

Question 30

techniques to isolate the desired gene

Answer 30

• restriction endonucleases to cut the required gene from the DNA of the organism
• isolating mRNA and then using reverse transcriptase to turn it into a DNA strand (cDNA)

Question 31

sticky ends

Answer 31

regions with unpaired exposed bases after restriction endonucleases have cut it.
easier to insert desired genes into DNA of different organism

Question 32

formation of recombinant DNA

Answer 32

the DNA is isolated and now must be inserted into vectors that can carry it into the host cell

Question 33

most commonly used vectors

Answer 33

bacterial plasmids - small circular molecules of DNA separate from the chromosomal DNA that can replicate independently.

Question 34

recombinant DNA

Answer 34

plasmid combining with the host DNA

Question 35

marker gene

Answer 35

in plasmids - enables scientists yo determine that the bacteria have taken up the plasmid.

Question 36

how is the DNA fragment inserted into plasmid

Answer 36

cut open, use a restriction endonuclease, resulting in the plasmid having the same sticky ends as the DNA.
DNA ligase forms phosphodiester bonds, joining them together.

Question 37

transferring the vector process

Answer 37

culture the bacterial cells and plasmids in calcium rich solution and increase temperature - causes bacterial membrane to become permeable and plasmids can enter

electroporation

Question 38

electroporation

Answer 38

small electrical current is applied to the bacteria, making the membranes porous and plasmids move into cells

Question 39

electrofusion

Answer 39

tiny electric currents are applied to membranes of two different cells. this fuses the cell and nuclear membranes to form a hybrid or polyploid cell.

Question 40

genertically modifying plants example

Answer 40

agrobacterium tumefaciens - a bacteria that causes tumors in healthy plants.

can make crops resistant herbicides etc.

trasgenic plant cells form a callus which can be grown into a new transgenic plant

Question 41

somatic cell gene therapy

Answer 41

involves replacing the mutant allele with a healthy allele in the affected somatic body cells

Question 42

vectors used in gene therapy

Answer 42

in vivo - plasmids
in vitro - viruses

Question 43

why is somatic cell gene therapy only temporary?

Answer 43

somatic cells have limited life and are replaced from stem cells, which will have the faulty allele

Question 44

germ line cell gene therapy

Answer 44

insert a healthy allele into the germ cells - usually eggs - and this will b passed down to own offspring

Question 45

why is germ line gene therapy illegal in this country?

Answer 45

human rights violation - no consent
impact on whole organism
designer babies

Question 46

how can scientists use a gene to study relationships between organisms

Answer 46

sequence the gene for different organisms
compare the base sequences - those that are more similar are more likely to be closely related