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Organisation of Life

Description: GATE LS Biochemistry Organization of Life
Number of Questions: 20
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Tags: GATE LS Biochemistry Organization of Life Organization of Life
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Which of the following characteristics best applies to the allosteric effector?

  1. It competes with the substrate for the catalytic site.

  2. It binds to a site other than the catalytic site.

  3. It changes the nature of the product formed.

  4. It changes the substrate specificity of the enzyme.


Correct Option: B
Explanation:

Allosteric enzyme, upon binding an effector, changes its shape, which in turn changes its affinity towards its product. The effector never binds with the catalytic site of the enzyme.

GABA is derived from which amino acid?

  1. Tryptophan

  2. TYrosin

  3. Glutamate

  4. Serine


Correct Option: C
Explanation:

GABA is systhesised from glutamate by the enzyme glutamic acid decarboxylase. It is an inhibitory neurotransmitter.

Alanine on transamination gives rise to

  1. pyruvic acid

  2. para-hydroxyphenylpyruvate

  3. phenylpyruvate

  4. hydroxypyruvate


Correct Option: A
Explanation:

Alanine transaminase transfers its amino group, which forms pyruvate.

Which enzyme uses NADP as a co-enzyme?

  1. Pyruvate carboxylase

  2. Pyruvate dehydogenase

  3. Glucose 6 phosphate dehydrogenase

  4. Lactate dehydrogenase


Correct Option: C
Explanation:

Glucose 6 phosphate dehydrogenase does not use NADP as its co-enzyme.

Which of the following statements is correct concerning Michales constant Km?

  1. It is measured in the same units as the rate of the enzyme-catalysed reaction.

  2. It varies with the amount of enzyme used in measuring the reaction rate.

  3. It can be considered to be a measure of affinity of an enzyme for its substrate.

  4. It has a low value to indicate a low affinity for the substrate.


Correct Option: C
Explanation:

The concentration of substrate when the velocity of the reaction is half of the maximum velocity is expressed as Michales Menten constant Km. The lower the value of Km, the greater the affinity of enzymes for the substrate.

Which of the following is a triose?

  1. Ribulose

  2. Ribose

  3. Glyceraldehyde

  4. Fructose


Correct Option: C
Explanation:

Glyceraldehyde consists of four 3-carbons, which is an intermediate component of the glycolysis.

Glycogen is a branched polymer of glucose. It has

  1. no reducing ends

  2. no non-reducing ends

  3. one reducing end and several non-reducing ends

  4. one non-reducing end and several reducing ends


Correct Option: C
Explanation:

Glycogen is a branched molecule of glucose subunit of glucose molecules, which are linked by á1-4 linkage and á1-6 linkage at the branching point. So, it has only one reducing end and several non-reducing ends.

The absence of vitamin B12 in human diet gives rise to.

  1. rickets

  2. pernicious anemia

  3. cataract

  4. beri beri


Correct Option: B
Explanation:

Pernicious anemia is a condition in which body cannot make enough red blood cells because it lacks vitamn B12.

Two proteins are having the same molecular mass and identical pH of 7. The best way to separate them will be

  1. SDS polyacrylamide gel electrophoresis

  2. Native gel electrophoresis

  3. Cation exchange chromatography

  4. Anion exchange chromatography


Correct Option: B
Explanation:

SDS PAGE is not used in if a particular protein has to be separated in the basis of their biological activity. As there is no treatment with SDS, all the proteins will carry their own charge at the pH and will move according to their different electrophoretic mobilities.

Myoglobin P. can carry oxygen Q. can carry hydrogen ions R. is allosterically regulated S. has a hyperbolic oxygen binding curve

  1. P only

  2. S only

  3. P, Q and S

  4. R and S


Correct Option: B
Explanation:

Myoglobin is not an allosteric protein. Myoglobin has a hoghe affinity for oxygen than haemoglobin, so it has a hyperbolic curve.

What is the ionisable group of DEAE Sephadex?

  1. Diethylaminoethyl

  2. Carboxymethyl

  3. Methyl sulfonate

  4. None of these


Correct Option: A
Explanation:

Diehtylaminoethyl is the positively charged group of DEAE.

In an enzyme mixture, both substrates and inhibitors have been added. Both of them interact with the same binding site of enzyme What is true in this situation?

  1. Substrate will bind to the active site of the enzyme with no inhibition.

  2. Both substrate and the inhibitor will compete for binding to the catalytic site of the enzyme.

  3. Substrate can never bind itself to the enzyme.

  4. None of the above


Correct Option: B
Explanation:

As both the substrate and the inhibitor share the same binding site in the enzyme, they will compete with each other in binding. This will exert an competitive inhibition. If substarte concentration is increased to a greater level, then the inhibition will be released.

Isoelectric focussing technique that is used to separate proteins works on the principle of

  1. electrophoretic separation based on relative content of acidic and basic residues

  2. mass of the protein molecules

  3. number of amino acids containing sulphur

  4. coagulation capacity of the protein molecules


Correct Option: A
Explanation:

Isoelectric focussing (IEF) is an electrophoretic method that separates proteins according to their isoeletric points(pI). proteins carry both positive and negative charges and their net charge depends highly on the pH of their surroundings. the pI is the specific pH at which the net charge on a protein molecule is zero. Thus, Isoelectric focussing technique used to separate proteins works on the principle of electrophoretic separation based on relative content of acidic and basic residues.

Which of the following statements is true?

  1. Both cytosolic and extracellular proteins have similar amount of disulphide bonds.

  2. Cytosolic proteins lack disulphide bonds, whereas extracellular proteins have more disulphide bonds.

  3. Extracellular proteins lack disulphide bonds, whereas cytosolic proteins have more disulphide bonds.

  4. None of these


Correct Option: B
Explanation:

The cytosol is a reducing environment whereas the extracellular milieu is an oxidising environment. Disulphide bonds are formed as a result of oxidation of thiol group and it requires an oxidising environment.

Ion exchange chromatography is applicable for the separation of molecules on the basis of their charge. It is based on the reversible exchange ions in the solution with the ions bound to supportive media.

If you want to separate a positively charged protein using ion exchange chromatography, what kind of chromatography will be suitable?

  1. Anion exchange chromatography

  2. Cation exchange chromatography

  3. Both 1 and 2

  4. None of these


Correct Option: B
Explanation:

To separate a positively charged protein, we should use a negatively charged resin. For example, commonly we use the resin Phosphocellulose, which is a negatively charged resin for the cation exchange chromatography.

Pfu polymerase is better than Taq polymerase because

  1. it has more efficient polymerse activity

  2. it has proof reading activity

  3. both 1 and 2

  4. none of these


Correct Option: B
Explanation:

Pfu polymerase has proof reading activity, so if there is any mispaired binding, it will repair this base pairing so that there will be no mispairing. Proof reading activity is absent in Taq polymerase, so it cannot repair any mispairing.

What characteristic domain is found in eukaryotic proteins that enable them to enter the endoplasmic reticulum?

  1. Stop transfer domain

  2. Signal sequence

  3. Signal sequence receptor

  4. Signal recognition protein


Correct Option: B
Explanation:

The proteins that are designated to enter endoplasmic reticulum for post translational modification bear a characteristic signal sequence generally on their N terminal that is used by specific receptor in ER membrane to make its entr yin to ER lumen.

Which amino acid gives rise to an inhibitory neurotransmitter?

  1. Histidine

  2. Tyrosine

  3. Glutamic acid

  4. Ornithine


Correct Option: C
Explanation:

Glutamic acid produces GABA, which is an inhibitory neurotransmitter.

Which of the following is the co-factor of Taq polymerase?

  1. Ca++

  2. K+

  3. Na+

  4. Mg++


Correct Option: D
Explanation:

Mg acts as a co-factor for Taq polymerase. With the increase of Mg, the specificity of Taq decreases.

Match the following:

 
A B
1. Alpha 1, 6 glucosidase a. Branching enzyme during glycogenesis
2. Alpha 1, 6, 1, 4 trans glucosidase b. Rate limiting enzyme of glycolysis
3. Alkaptonuria c. Debranching enzyme in glycolysis
4. Phospho fructo kinase1 d. Homogentisate 1, 2 dioxygenase
  1. 1 - c, 2 - a, 3 - d, 4 - b

  2. 1 - a, 2 - c, 3 - d, 4 - b

  3. 1 - d, 2 - a, 3 - c, 4 - b

  4. 1 - c, 2 - b, 3 - d, 4 - a


Correct Option: A
Explanation:

In an enzyme mix, both substrates and inhibitors have been added. Both of them interact with the same binding site of the enzyme.

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