Gene Technologies

Question 1

Recombinant DNA

Answer 1

Fragments of foreign dna are inserted into other sections of dna

Question 2

Universal code

Answer 2

DNA is made from a sequence of four bases (A,T,C,G) and every organism uses the four bases - this means that any section of DNA can be taken from organism into another

Question 3

Transcription and translation

Answer 3

Once dna has been inserted, it is then transcribed and translated to produce proteins - transcription and translation are also a universal process

Question 4

What is the organism that has received the fragments of dna called

Answer 4

Transgenic

Question 5

Producing fragments for recombinant dna

Answer 5

-Inserting a specific gene (target gene )of interest into which normally encodes a protein that has useful properties

Question 6

Reverse transcriptase

Answer 6

Enzyme that converts single stranded mRNA into double stranded DNA.
Can be used in producing dna fragments by converting the mRNA for the target gene into double stranded DNA
The DNA produced from reverse transcriptase is called complimentary DNA

Question 7

E.g insulin

Answer 7

DNA fragments of insulin are isolated from pancreatic cells in the following steps :
mRNA for insulin is isolated from the pancreatic cells, mRNA is mixed with reverse transcriptase which converts mRNA into cDNA which can now be used to produce recombinant DNA

Question 8

Recognition sequences

Answer 8

Sections of DNA where the base sequence has palindromic base pairs which have a sequence of base pairs that are the same but in opposite directions - these can be used to isolate the target gene if there are two sets of sequences either side of the gene

Question 9

Restriction endonuclease

Answer 9

Enzymes bind to a specific recognition sequence
If two restriction endonucleases bind to two recognition sequences surrounding a target gene which can be cut out of the DNA

Question 10

How do restriction endonuclease produce fragments

Answer 10

• DNA containing the target gene is mixed with the restriction endonucleases which bind to the recognition sequences on either side of the target gene which can be cut out of the dna

Question 11

Gene machines

Answer 11

DNA fragments can be produced by synthesising the target gene sequence form a database using free floating nucleotides
Nucleotides are added in the correct order to synthesise the correct base sequence
Protecting groups are added to make sure the correct nucleotides are added and no side branches are produced

Question 12

In Vivo

Answer 12

Inside the organism , in vitro is outside the organism

Question 13

Marker genes

Answer 13

Genes that are inserted along with the recombinant dna and confer antibiotic resistance

Question 14

PCR in vitro amplification step 1

Answer 14

1. Set up the reaction mixture - the DNA fragments are mixed with primers , DNA polymerase and free floating nucleotides

Question 15

In vivo amplification: the DNA fragment is inserted into the vector

Answer 15

The vector dna is cut open using the same restriction endonuclease that was used to isolate the target DNA so that they produce complementary sticky ends
The vector and the dna fragment are mixed together with dna ligament which joins the sticky ends

Question 16

In Vivo amplification : plasmid vector

Answer 16

Host cells have to be persuaded to take in the plasmid vector and it’s dna so the host bacterial cells are placed in ice cold calcium carbonate then the plasmids are added and the mixture is heat shocked (42°c)

Question 17

In vivo amplification : bacteriophage vector

Answer 17

The bacteriophage will infect the heat bacterium by injecting its dna into it

Question 18

In vivo amplification: identifying transformed cells

Answer 18

Marker genes can be inserted into the vectors at the same time as the gene to be cloned and host cells are grown on agar plates where the marker gene can code for antibiotic resistance

Question 19

In vitro amplification step 2

Answer 19

The dna mixture is heated to 95° to break the hydrogen bonds between the two strands

Question 20

In vitro amplification step 3

Answer 20

The mixture is then cooled to between 50° and 65° so that primers can bind

Question 21

In vitro amplification step 4

Answer 21

The reaction mixture is heated to 72° so DNA polymerase can work by lining up free dna nucleotides alongside each template stand and joins the nucleotides together. Specific base pairing means new complementary strands are formed

Question 22

Agriculture

Answer 22

Can be transformed so that they give higher yields or are more nutritious which means the risk of famine and malnutrition is reduced
Crops can also be transformed to have pest resistance

Question 23

Golden rice

Answer 23

Contains one gene from a maize plant and one gene from a soil bacterium which enables the rice to produce beta-carotene that is used by our bodies to produce vitamin a
It is being developed to help reduce vitamin a deficiency in areas where there’s a shortage of dietary vitamin a such as South Asia and africa : in these areas up to 500000 children per year worldwide go blind due to vitamin a deficiency

Question 24

Industry

Answer 24

Industrial processes often use biological catalysts which can be produced from transformed organisms so they can be produced in large quantities for less money e.g chymosin is an enzyme in cheese-making

Question 25

Medicine

Answer 25

Many drugs and vaccines are produced by using recombinant DNA technology e.g insulin is used to treat type 1 diabetes which used to come from animals which didn’t work as well so now human insulin is now made using a cloned human insulin gene