DNA technology

Question 1

what are the 4 tool of dna technology

Answer 1

• restriction enzymes
  -electrophoresis
  -PCR
  -DNA primers and DNA probes

Question 2

What do restriction enzymes and restriction endonuclease do

Answer 2

• they hydrolyse phosphodiester binds in DNA or RNA producing smaller fragments

-hydrolyse phosphodiester bonds in both DNA strands

Question 3

What is a recognition sequence or recognition sites

Answer 3

-when restriction enzymes hydrolyse dna or RNA at specific base sequences

Question 4

What is a sticky end

Answer 4

when restriction enzymes hydrolyse dna or RNA at different locations pricing sticky ends

Question 5

what is a blunt end

Answer 5

-when some restriction enzymes hydrolyse dna at the same position of both dna strands

Question 6

what do sticky ends do

Answer 6

• enable dna to be joined onto different pieces of dna due to complementary base bonding between sticky ends

Question 7

what is gel electrophoresis

Answer 7

DNA or RNA fragments can be separated by gel elec

-based on the principle that smaller dna fragments will travel faster and further through the gel ( as less resistance) when an electric shock is applied

Question 8

why must an electric shock be used in gel electrophoresis

Answer 8

because it allows dna fragments to move through gel

-negativley charged dna fragments move towards the positively charged terminal.

Question 9

what happens after electro

Answer 9

• dna fragments are transferred to a nylon membrane
• radioactively tabled dna probes are then added to the membrane

-nylon membrane is placed on x-ray or photographic film

• radioactive fragments revealed as dark bands on photographic film(autoradiography
• DNA can also be identified using fluroscnet dna probes .

Question 10

what does the pcr technique allow

Answer 10

multiple copies of identical fragments of dna or genes to be produced from a small sample

Question 11

what 4 thing does the PCR reaction require

Answer 11

• Dna to be copied
  -heat stable DNA polymerase( thermostable)
  -free DNA nucleotide
  -primers

Question 12

describe the steps of PCR

Answer 12

STAGE1
-reactants are mixed and heated up to 95 degrees to break hydrogen bonds in dna
STAGE 2
-primers join to the specific target sequence and the mixture is cooled to 50-60 degrees to allow to stick

-free DNA nucleotides align to the DNA strands by complementary base pairing

STAGE 3
-Temperature is increased to 72 degrees so enzyme dna polymerase can join the individual dna nucleotides of a strand together to form a complementary strand.

Question 13

What are primers

Answer 13

-short single stranded molecules of DNA

Question 14

What is the purpose of a primer

Answer 14

-they provide a starting sequence for DNA polymerase as DNA polymerase cannot be a single strand at.a starting point

Question 15

What are DNA probes

Answer 15

• short single stranded molecules of DNA that are radioactively or flurescently labelled
• they’re used to locate a known sequence of DNA

Question 16

why may vectors not work

Answer 16

• cells may not take up the vector at all
  -the cell may not contain the gene as the plasmid may have joined back without foreign gene being taken up

Question 17

how can scientist check to see if a foreign gene has been taken up by the plasmid

Answer 17

• using marker genes

Question 18

What are marker genes

Answer 18

-enable successfully transformed bacteria or eukaryotic cells to be detected and isolated

-GFP gene which is added to the gene being transferred

Question 19

how does a vector work

Answer 19

-foreign dna is obtained by using restriction enzy bacteriaymes
-plasmid is extracted from bacterial cell and cut with the same restriction enzyme
-foreign dna and plasmid have complementary sticky ends
-DNA ligase forms phosphodiesterbonds bonding these together
- the recombinant plasmid is taken up by bacteria

Question 20

wha makes a blunt en d

Answer 20

hydrolysing dna at the same positions or base positins

Question 21

does epigenetics not involve ?

Answer 21

• mutation in dna and base codes

Question 22

what is the purpose of pcr

Answer 22

-specific samples of dna
-target cells
-many copies
-small sample size