Paper 2- processes

Question 1

Method for producing cultures from cauliflower explants

Answer 1

1. Wipe all surfaces with disinfectant and soak all apparetus- no fungi contamination which would mean we see fungal growth, not explant
2. Break of a small floret of cauliflower using scalpal- cut a thin section
3. steralise the explant by soaking in solution for 15 mina- make sure to swirt
4. add to agar growth medium
5. leave for 3 weeks on sunny windowsill

Question 2

Oestrogen Stimulation Pathway

Answer 2

1. Oestrogen diffuses through the cell surface membrane into the cytoplasm
2. Oestrogen diffuses through nuclear pore and attaches to a ERa receptor causing it to undergo a change
3. The new shape of the ERa receptor allows it to detach from the protein complex and diffuse toward gene to be expressed
4. Receptor binds to cofactor enabling it to bind to the promotor region stimulating RNA polymerase binding and gene transcription

Question 3

Steps of making recombinant DNA

Answer 3

Identification- of gene
Isolation
Multiplication
Transfer- using vector
Identification- using marker gene

Question 4

Polymerase Chain Reaction Process

Answer 4

Denaturation- he double-stranded DNA is heated to 95°C which breaks the hydrogen bonds that bond the two DNA strands together

Annealing- the temperature is decreased to between 50 - 60°C so that primers (forward and reverse ones) can anneal to the ends of the single strands of DNA

Elongation- the temperature is increased to 72°C for at least a minute, as this is the optimum temperature for Taq polymerase to build the complementary strands of DNA to produce the new identical double-stranded DNA molecules

Question 5

In vivo method of DNA replication

Answer 5

• isolation
• Inserted into vectors
• transported into bacterial host cells
• bacteria multiply in number
• marker genes help identify
• remaining bacteria are cultured

Question 6

how to use DNA probes to locate specific alleles

Answer 6

• sample is taken from patient
• DNA extracted and purified
• amplified
• restriction endonucleases digest amplified test DNA
• rest is separated in gel electrophoresis
• bands transfered to nylon membrane and labelled DNA probes complementary to harmful allele is added
• washed

Question 7

Gel Electropherisis

Answer 7

1. pipette DNA samples into wells on the gel plate
2. connect the negative electrode to the end of the plate with the wells and cconnect positive at far end
3. the smaller mass/ shorter pieces of DNA will move faster and further from the wells than larger fragments
4. proves added so UV light can view the DNA samples

Question 8

Non-Cyclic phosphorylation

Answer 8

1. photoionisation- energy is absorbed by PSII which excites the electrons to a higher energy level to be released from the chlorophyll
2. these need to be replaces- photo-lysis of water into protons and electrons and oxygen
3. excited electrons move down the chain loosing energy to PSII. This energy transports H+ into thylakoids making a higher concentration than the stroma. Protons now move down via ATP synthase molecules making ATP
4. at PSI, more energy absorbed which excited electrons to an even higher energy level so they are transfered to NADP reducing it

Question 9

Cyclic Phosphorylation

Answer 9

Produces ATP using energy from PSI- doesnt pass hydrogen to NADP

Question 10

Calvin Cycle

Answer 10

1. CARBON DIOXIDE FIXATION- Carbon dioxide combines with ribulose bisphosphate catalysed by the enzyme rubisco. This forms an unstable 6 carbon molecule which immediatley splits into two G3P
2. Molecules of G3P are reduced by NADP with energy provided by ATP forming 2 molecules of triose phosphate. this step uses some ATP and all the NADP
3. The rest of the ATP is used to regenerate the ribulose bisphosphate or combined with fructose to form glucose

Question 11

Investigating the effect of light intensity on photosynthesis in pond weed

Answer 11

ensure all the water is well aerated before use by bubbling air through ensuring oxygen produced isnt absorbed

1. set up in a dark room, add distilled water and sodium hydrogencarbonate to a boiling tube
   2.cut pondweed stem at an angle
2. place light at a set distance from the tube and measure the volume of gas collected in the gas syringe over a set period of time
3. repeate
4. repeate over a range of distances

Question 12

Glycolysis

Answer 12

1. Glucose is phosphorylated into glucose phosphate using 2 molecules of ATP
2. GP splits into two molecules of triosephosphate
3. TP is oxidized into pyruvate where the electrons and hydrogens are transported to NAD

Produces- 2x pyruvate, 2x ATP, 2x NADH

Question 13

Ethanol Fermentation

Answer 13

1. pyruvate is decarboxylated to ethanal giving off Co2
2. ethanal is reduced to ethanol from NADH

Question 14

Lactate Fermentation

Answer 14

pyruvate accepts hydrogen from NADH forming lactate

Question 15

The Link Reaction

Answer 15

1. pyruvate is oxidised to acetate making NADH and oxygen
2. acetate combines with coenzyme A forming acetyl CoA

Question 16

The Krebs Cycle

Answer 16

1. Acetyl CoA releases oxyloacetate 2C to combine with a four carbon molecule making a 6 carbon molecule
2. The CoA returns to the link reaction
3. A series of oxidation reduction reactions convert this molecule back to 4C and it reduces NAD and FAD as well as produces ATP and looses Co2