Practical 3 Quiz – Transamination PDF

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Practical 3 Quiz – Transamination...

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Started on State Completed on Time taken Marks 11.50/12.00 Grade 95.83 out of 100.00 Question 1 Partially correct Mark 0.50 out of 1.00

In the transamination experiment the extract was dialysed to remove free amino acids. Dialysis removes small molecules by allowing their difussion through a semi permeable membrane whilst retaining the large molecules in the dialysis bag.. We have protein in a dialysis bag of 10ml volume. The concentration of free amino acids in the bag with the protein is 10mM. The bag is placed in 1L of bu!er and stirred for 1 hour. After 1 hour the amino acids are distributed evenly over the entire volume of the system. The dialysis bag is then removed and placed in 1L of fresh bu!er and the process repeated, followed by one more repeat. What is the concentration of amino acids in the dialysis bag at the end of this process? Express your answer in nM. (nano molar) Answer: !

During dialysis the amino acids all start out in the 10ml inside the dialysis tube. This is added to 1L of bu!er so after incubation they are then found spread equally over the total volume (1000ml + 10ml). After the "rst dialysis step the concentration will therefore be: 10mM x 10/1010 = 0.099mM = 99uM The step is repeated twice so carry out the same calculation, changing the starting concentration each time: Step 2 - 99uM x 10/1010 = 0.98uM = 980nM Step 3 - 980nM x 10/1010 = 9.70nM The correct answer is: 9.7

Question 2 Correct Mark 2.00 out of 2.00

Look at the transamination reaction below: GLUTAMIC ACID + A → α keto-glutarate + B Identify the correct substrate (A) and product (B) combination from the list below. Select one: a. oxaloacetic acid and alanine b. oxaloacetic acid and aspartic acid c. pyruvate and alanine

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d. citric acid and aspartic acid

Your answer is correct. The correct answers are: pyruvate and alanine, oxaloacetic acid and aspartic acid

Question 3 Correct Mark 4.00 out of 4.00

Look at the TLC below of amino acids. The plate shows the TLC after spraying with nihydrin and heating. M is a tri-peptide, 1 = asp, 2 = tyr, 3 = glu, 4 = phe and 5 =pro. Aminopeptidase produces an amino acid coloured brown and carboxypeptidase one coloured bright purple. Answer the following questions relating to the tripeptide.

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Which amino acid is at the N-terminus?

Pro

Using normal rules, what is the tri-peptide sequence?

Pro,asp,phe

Which amino acid is at the C-terminus?

Phe

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For part one you needed to match the three spots under M to the matching amino acids in tracks 1-5. The question tells you that the carboxypeptidase produces a bright purple spot so this identi"es the C-terminal residue. Similarly you are told that amino peptidase gives a brown spot hence this is the N-terminal amino acid. The correct answer is: Which amino acid is at the N-terminus? → Pro, Using normal rules, what is the tri-peptide sequence? → Pro,asp,phe, Which amino acid is at the C-terminus? → Phe

Question 4 Correct Mark 1.00 out of 1.00

Select the enzyme group from the drop down menu which correctly de"nes the enzymes in extract used in the transamination experiment. Glutamate amino transferase

Transferase

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Glutamate dehydrogenase

oxidoreductase (deaminating)

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The transaminase is stated to be an amino TRANSFERASE and therefore is a transferase class of enzyme. The deaminase removes an amine group and therefore splits it away from the amino acid and is thus a LYASE. The correct answer is: Glutamate amino transferase → Transferase, Glutamate dehydrogenase → oxidoreductase (deaminating)

Question 5 Correct Mark 1.00 out of 1.00

Look at the statements below select the ONE answer that correctly relates to the use of dintrophenyl hydrazine. Select one: a. DNPH was used to label the oxo acids purple by produsing a hydrazone by reaction with free keto groups. b. DNPH was used to label the amino acids purple and produce a hydrazone by reaction with free amino groups. c. DNPH was used to label the amino acids yellow and produce a hydrazone by reaction with the free alpha-carboxyate group. d. DNPH was used to label the oxo acids yellow and produce a hydrazone by reaction with the free keto group.

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We used ninhydrin to stain the amino acids and this produced a purple spot whereas the dinitrophenyl hydrazine labelled the oxo-acids yellow. The correct answer is: DNPH was used to label the oxo acids yellow and produce a hydrazone by reaction with the free keto group.

Question 6 Correct Mark 1.00 out of 1.00

Look at the following statements which describe the possible colour forming mechanism of the ninhydrin reaction. Select the ONE correct description from the list. Select one: a. Ninhydrin reacts with the R groups of the free amino acid to form a complex which cross links the R group and the alpha-carboxyl group to form a purple colour. b. Ninhydrin reactions with the carboxylate group of the free amino acid which upon further deamination and removal of an aldehyde group produces an adduct which forms a purple complex with another molecule of ninhydrin. c. Ninhydrin reacts with the amino group of the free amino acid which upon further decarboxylation and removal of an aldehyde produces an adduct which forms a purple complex with another molecule of ninhydrin.

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d. Ninhydrin reacts with the R groups of the free amino acid to form a complex which cross links the R group and the alpha-amino group to form a purple colour. e. Ninhdrin reacts with the peptide bond resulting in a the removal of the R group and the formation of a complex with other molecules of ninhydrin.

Your answer is correct. The correct answer is: Ninhydrin reacts with the amino group of the free amino acid which upon further decarboxylation and removal of an aldehyde produces an adduct which forms a purple complex with another molecule of ninhydrin.

Question 7 Correct Mark 2.00 out of 2.00

Which cofactors do the transaminase (A) and dehydrogenase (B) enzymes use: Select your answer from the list cofactors for transamination (A) and Deamination (B) Select one: a. Lipoic acid and NAD b. NAD and Pyridoxal phosphate c. Pyridoxal phosphate and thiamine d. NAD and FAD e. Pyridoxal phosphate and NAD

Your answer is correct. The correct answer is: Pyridoxal phosphate and NAD

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