Question 1

The essential chemical components of many coenzymes are:

Accepted Answer

Essential chemical components of many coenzymes are vitamins, e.g, coenzyme nicotinamide adenine dinucleotide (NAD) and NADP contain the vitamin niacin.

Question 2

Find out a qualitative test for proteins, fats and oils, amino acids. Test any fruit juice, saliva, sweat and urine for them.

Accepted Answer

(a) Test for proteinBiuret’s test – If Biuret’s reagent is added to the protein, then the colour of the reagent changes from light blue to purple.(b) Test for fats and oils Emulsion test - Add ethanol to a very small amount of the test substance. Shake in order to dissolve. Filter or dilute to obtain fairly clear liquid. Take another tube containing water and pour the ethanolic solution into the top. A white (milk like) emulsion indicates the presence of fats or oils.(c) Test for amino acidNinhydrin test – If Ninhydrin reagent is added to the solution, then the colourless solution changes to pink, blue, or purple, depending on the amino acid.1) Fruit juice Biuret’s test - Fruit juice + Biuret’s reagent -Colour changes from light blue to purple. Protein is present.Grease test - To a brown paper, add a few drops of fruit juice - No translucent spot. Fats and oils are absent or are in negligible amountsNinhydrin test - Fruit juice + Ninhydrin reagent + boil for 5 minutes - Colourless solution changes to pink, blue, or purple colour. Amino acids are present.2) SalivaBiuret’s test - Saliva + Biuret’s reagent - Colour changes from light blue to purple. Proteins are present.Grease test - On a brown paper, add a drop of saliva - No translucent spot. Fats/oils are absent.Ninhydrin test - Saliva + Ninhydrin reagent + boil for 5 minutes - Colourless solution changes to pink, blue, or purple colour. Amino acids are present.3) SweatBiuret’s test - Sweat + Biuret’s reagent- No colour change. Proteins are absent.Solubility test - Sweat + Water - Oily appearance - Fats/oil may be present.Ninhydrin test - Sweat + Ninhydrin reagent + boil for 5 minutes - No colour change, the solution remains colourless. Amino acids are absent.4) UrineBiuret’s test - Few drops of urine + Biuret’s reagent - Colour changes from light blue to purple- Proteins are present.Solubility test - Few drops of urine + Water - Little bit of oily appearance. Fats may or may not be present.Ninhydrin test - Few drops of urine + Ninhydrin reagent + boil for 5 minutes. Colourless solution changes to pink, blue, or purple colour depending on the type of amino acid- Amino acids are present.

Question 3

Select the correct constituents of protein

Accepted Answer

The proteins are composed of carbon, hydrogen, oxygen, nitrogen and sulphur. Certain proteins may contain phosphorous, iron or other elements also.

Question 4

The acid soluble pool, roughly represents

Accepted Answer

The acid soluble pool represents the cytoplasmic composition of cell. The macromolecules from cytoplasm and organelles becomes acid insoluble fraction. Together, they represent the entire chemical composition of living tissues or organisms.

Question 5

Proteins with catalytic power are known as

Accepted Answer

Proteins with catalytic power are called enzymes. Their basic function is their involvement in the change of rate of reaction either increase or decrease.

Question 6

Which one of the following is wrongly matched?

Accepted Answer

Almost all enzymes are basically made up of proteins. However, a small group of RNA molecules (e.g., ribozyme) have also been found to be enzymatic exceptionally.

Question 7

The left handed DNA is called

Accepted Answer

Five forms of DNA have been reported A, B, C and D forms are right handed, while the Z-DNA is left handed.

Question 8

One of the secondary structures exhibited by DNA is…..

Accepted Answer

Nucleic acids exhibit a wide variety of secondary structures. For example, one of the secondary structures exhibited by DNA is the famous Watson-Crick model. This model says that DNA exists as a double helix. The two strands of polynucleotides are antiparallel i.e., run in the opposite direction. The backbone is formed by the sugar-phosphate-sugar chain. The nitrogen bases are projected more or less perpendicular to this backbone but face inside.

Question 9

What is the approximate percentage of proteins in the cell contents?

Accepted Answer

In cell contents, the approximate percentage of proteins is 12%.

Question 10

Name the most abundant protein in animal world

Accepted Answer

Collagen is the most abundant protein in animal word.

Question 11

Richest source of protein is

Accepted Answer

Glycine max or soybean is the richest source of protein (36-44%). From its seeds edible oil and a milk-like substance is obtained, which is used as a substitute of milk.

Question 12

Histone octamer contains

Accepted Answer

Histones are a set of positively-charged, basic proteins. Histones are rich in the basic amino acid residuesl lysines and arginines. Both the amino acid residues carry positive charges in their side chains. Two molecules of each of the four types of histones -H2​ A,H2​ B,H3​ and H4​ are organized to form histone octamers. These form the inner core of nucleosome. The negatively charged DNA is wrapped around the positively - charged histone octamer to form a structure called nucleosome.

Question 13

Primary structure of proteins is due to the presence of

Accepted Answer

Primary structure of proteins is due to the present of peptide bond.

Question 14

Select the wrong statement

Accepted Answer

Collagen is the most abundant protein in animal world and Ribulose bisphosphate carboxylase-oxygenase (RUBISCO) is the most abundant protein in the whole of the biosphere.

Question 15

Identify X and Y in the given protein structure

Accepted Answer

X = N-terminal amino acidY = C-terminal amino acid

Question 16

The double helical model of the DNA was proposed by Watson and Crick based on what data produced by Wilkins and Franklin?

Accepted Answer

In 1953, James Watson and Francis Crick based on the X-ray diffraction data produced by Maurice, Wilkins and Rosalind Franklin, proposed a very simple but famous double helix model for the structure of DNA.

Question 17

The globular proteins undergo structural changes, in response to extremes of pH or temperature, the process called

Accepted Answer

Denaturation means deviation from natural form. Proteins or nucleic acids whenever exposed to extreme heat, pH or acids their structure become change. This process is known as denaturation.

Question 18

Many physiological functions are performed by proteins. One such function involves that some proteins discharge

Accepted Answer

Certain proteins form enzymes, some coenzymes and many hormones (insulin, parathormone) and regulate metabolism. They are called functional proteins.

Question 19

Which of the following is not a conjugated protein?

Accepted Answer

Peptone is any group of soluble and diffusable derived proteins formed by the action of enzymes on proteins, as in the process of digestion or by acid hydrolysis.

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