electrophoresis

Question 1

what is electrophoresis

Answer 1

separating different dna sized fragments of dna.

Question 2

what is the name of the gel used for electrophoresis

Answer 2

agarose gel

Question 3

describe the electrophoresis process

Answer 3

1- dna sample broken down with restriction enzymes

2- get a tank and pour agarose gel into it whilst combs are in place at one end

3- when gel is set, cover gel with buffer solution

4- remove combs which will create wells in the gel

5- add loading dye to tubes with broken down DNA

6- add DNA and dye to buffer solution by pipette. the density of the dye will carry DNA down wells.

7- place electrodes in tank and connect with a power supply and let them run for 6 hours

8- remove buffer solution and replace with a dye, dye will adhere to the DNA fragments which have travelled in the gel and stain them

Question 4

what is the name of the liquid poured over the agarose gel

Answer 4

buffer soultion

Question 5

what is the purpose of loading dye being added to the broken down DNA sample

Answer 5

loading dye is dense, therefore when dna is added to the buffer solution, the dye carries it down the wells.

Question 6

how come when electrodes are connected to a power supply, DNA moves through gel

Answer 6

current passes through gel
dna has a negative charge, therefore migrates towards the anode.

Question 7

what group in dna, makes the molecule negatively charged

Answer 7

phosphate groups

Question 8

describe dna structure

Answer 8

double helix
deoxyribose sugar
phosphate group
nitrogenous base

Question 9

what enzymes break up dna

Answer 9

restriction enzymes

Question 10

what is the other process which is similar to electrophoresis

Answer 10

separating proteins

Question 11

what is SDS and what is it used in

Answer 11

used when separating proteins
SDS- sodium dodecyl sulfate
charged detergent

Question 12

what is the function of sds

Answer 12

equalises the surface charge on the molecules and allows proteins to separate as they move through agarose gel

Question 13

what is a factor which determines movement of proteins and their separation through agarose gel (separating proteins)

Answer 13

the movement of proteins through gell is dependent on the molecular mass of proteins

Question 14

what is the point in separating proteins

Answer 14

it can be used to analyse different haemoglobin proteins and diagnose conditions

Question 15

what are the two conditions which can be diagnosed by separating proteins

Answer 15

sickle cell anaemia

aplastic anaemia

Question 16

what is a dna probe

Answer 16

a single strand length of dna, complementary to sample dna

Question 17

what are the two ways we can label DNA probes

Answer 17

radioactive markers- reveals colour when exposed to photographic film
fluorescent markers- emit colour when exposed to uv light

Question 18

why are dna probes helpful

Answer 18

can locate gene needed when genetically engineering organisms

can identify specific allele for disease

can identify the same gene in a variety of different genomes when comparing genomes of animals

Question 19

what is a dna microarray

Answer 19

when scientists place several different probes on a fixed surface

Question 20

how can dna microarrays detect mutations

Answer 20

dna containing mutated alleles will bind to the mutant probe

Question 21

what process can amplify dna

Answer 21

PCR

Question 22

what is the process of a dna microarray

Answer 22

• DNA test samples are marked with fluorescent markers
• marked DNA is revealed when DNA anneals to probes
• computer analysis indicates the presence of DNA sequence.