Question 1

Identify the substances having glycosidic bond and peptide bond, respectively in their structure.

Accepted Answer

Inulin is a fructan (polysaccharide of fructose). Adjacent fructose units are linked through glycosidic bond. Insulin is a protein composed of 51 amino acids. Adjacent amino acids are attached through peptide bond.

Question 2

Which one of the following is the most abundant protein in the animals?

Accepted Answer

Collagen is the most abundant protein in animal world and RuBisCO is the most abundant protein in the whole of the Biosphere.

Question 3

What is meant by tertiary structure of proteins?

Accepted Answer

Tertiary structures are formed by coiling and folding of chains of proteins. The folding of the tertiary chains leads to the exposure of polar ends while it hides the non-polar amino acid chains. The tertiary structure is held together by the weak non-covalent interacting formed between various parts of the polypeptide chain.

Question 4

Proteins have primary structure. If you are given a method to know which amino acid is at either of the two termini (ends) of a protein, can you connect this information to purity or homogeneity of a protein?

Accepted Answer

Yes, if we are given a method to know the sequence of proteins, we can use this information to determine the purity of a protein. It is known that an accurate sequence of a certain amino acid is very important for the functioning of a protein. If there is any change in the sequence, it would alter its structure, thereby altering the function. So by knowing the sequence of a given protein, we can determine its structure and compare it with any of the known correct protein sequences. Any change in the sequence can be linked to the purity or homogeneity of a protein.For example, a single change in the sequence of haemoglobin in P chain at the 6th position can alter the normal haemoglobin structure to an abnormal structure that can cause sickle cell anaemia.

Question 5

Find out and make a list of proteins used as therapeutic agents. Find other applications of proteins (e.g., cosmetics, etc.)

Accepted Answer

Proteins used as therapeutic agents are as follows :1. Thrombin and fibrinogen – They help in blood clotting.2. Antigen (antibody) – It helps in blood transfusion.3. Insulin – It helps in maintaining blood glucose level in the body.4. Renin – It helps in osmoregulation.Proteins are also commonly used in the manufacture of cosmetics, toxins, and as biological buffers.

Question 6

Can you describe what happens when milk is converted into curd or yoghurt, from your understanding of proteins?

Accepted Answer

Microorganisms like lactobacillus, secrete lactic acid which changes the pH of milk and proteins, are very sensitive to change in pH. So this pH change due to lactic acid leads to the destruction of secondary and tertiary structures of protein (called denaturation), which leads to precipitation of milk proteins and curd formation.Milk has many globular proteins. Milk is converted into curd or yoghurt by the action of bacteria.

Question 7

Which of the following have carbohydrate as prosthetic group?

Accepted Answer

Glycoproteins are proteins that contain sugars like carbohydrates as prosthetic group. In most glycoproteins, the linkage is between asparagine and N-acetyl-D-glucosamine. Some glycoproteins are immunoglobulins, membrane proteins and muscle proteins. Lipoproteins are protein complexed with lipids like triglycerides, phospholipids etc. Nucleoproteins are proteins associated with nucleic acids and chromoproteins are proteins associated with pigments e.g., cytochrome, phytochrome.

Question 8

Assertion: The long protein chain folds upon itself like a hollow ball giving rise to the tertiary structure. Reason : Tertiary structure gives a 3-dimensional view of a protein.

Accepted Answer

The primary structure of protein depicts the sequence of amino acids in a chain or gives the positional information in a protein. Protein thread is folded in the form of a helix or in the sheet form in the secondary structure. The long protein chain is also folded upon itself like a hollow woolen ball, giving rise to the tertiary structure. This gives us a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for many biological activities of proteins.

Question 9

Proteins are formed by the condensation of

Accepted Answer

Proteins are formed by the condensation of amino acids.

Question 10

Name the most abundant protein in animal world.

Accepted Answer

Collagen is the most abundant protein in animal world.

Question 11

Identify the correct pair.

Accepted Answer

Option (B) contains the correct match. Rest of the matches are incorrect and can be corrected as

Question 12

The following statements describe three orders of structure of the insulin molecule.I. The molecule consists of two polypeptide chains joined and folded around one another.II. The sequence and number of amino acids in each polypetide chain is known.III. The amino acids in each chain are coiled into a helix and held in position by hydrogen bonds.Which order is described by each statement?

Accepted Answer

(d) Polypeptides can be divided into various levels of organisation. The primary structure refers to the linear arrangement of amino acid residues along a polypeptide chain.
The secondary structure refers to the folding of parts of these chains into regular structure.
The tertiary structure includes the folding of regions within the same polypeptide and quaternary structure refers to two or more polypeptide chains joined and wound around one another.

Question 13

Direction: Read the following and answer the questions that follow
Proteins are most abundant intracellular organic biomolecules. These are polypeptides having chains of amino acids that are linked by peptide bonds. These amino acids are either essential or non-essential on the basis of their utility. Proteins are the heteropolymers and their structure exist at four different levels viz, primary, secondary, tertiary and quaternary. These four levels differ in the degree of complexity in the polypeptide chain. On the basis of structural function in animal body, proteins are either fibrous or globular. Depending upon these structural characteristics proteins perform various functions linked to immune system, blood clotting, muscle movement, etc.
(i) An essential amino acid is:
(a) leucine
(b) proline
(c) serine
(d) All of these
(ii) An example of globular protein is:
(a) keratin
(b) collagen
(c) albumin
(d) All of these
(iii) In an alkaline solution, amino acids become:
(a) positively charged
(b) negatively charged
(c) neutral
(d) zwitter ion
(iv) The type of bond that forms the α-helix secondary structure of protein is:
(a) glycosidic bond
(b) disulphide bond
(c) phosphodiester bond
(d) hydrogen bond
(v) Assertion (A) Lipoprotein is a type of conjugated protein.
Reason (R) Conjugated proteins are exclusively made up amino groups.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) Both A and R are false

Accepted Answer

(i) (a) Leucine is essential amino acids that is not synthesised in animal body.
(ii) (c) Albumin is globular protein.
(iii) (b) Amino acids contain both amino and carboxylic group. In an alkaline solution, the amino acid donates H+ions to the medium and becomes negatively charged.
(iv) (d) In the secondary structure of proteins, hydrogen bonding occurs between −C=O and - NH groups.
(v) (c) A is true, but R is false because Conjugated proteins are those containing non-amino prosthetic groups like metals or ions, e.g. phosphoproteins, lipoproteins, etc.

Question 14

Assertion (A) A protein is a heteropolymer. Reason (R) Dietary proteins are the source of non-essential amino acids.

Accepted Answer

A is true, but R is false.Each protein is a polymer of amino acids. As there are 20 types of acid, a protein is a hetropolymer and not a homopolymer. Amino acids can be essential or non-essential Certain amino acids are essential for our health and they have to be supplied through our diet. Hence, dietary proteins are the source of essential amino acids. Non-essential amino acids are those amino acids which are synthesised in our body.

Question 15

Assertion (A) The long protein chain is folded upon itself like a hollow ball giving rise to the tertiary structure. Reason (R) Tertiary structure gives a 3-dimensional view of a protein.

Accepted Answer

Both A and R are true, but R is not the correct explanation of AThe primary structure of protein is the sequence of amino acids in a chain. i.e., the positional information in a protein. In the secondary structure protein thread is folded in the form of helix or in the sheet form. The long protein chain is also folded upon itself like a hollow woollen ball, giving rise to the tertiary structure This gives us a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for many biological activities of proteins.

Question 16

Protein structure depends on its amino acid sequence and local, low-energy chemical bonds between atoms in both the polypeptide backbone and in amino acid side chains. Protein structure plays a key role in its function, if a protein loses its shape at any structural level, it may no longer be functional. Primary structure is the amino acid sequence. Secondary structure is local interaction between stretches of a polypeptide chain and includes α-helix and β pleated sheet structures. Tertiary structure is the overall three-dimension folding driven largely by interactions between R groups. Quaternary structures is the orientation and arrangement of subunits in multi-subunit protein In a protein structure, the first amino acid and the last amino acid are respectively called as

Accepted Answer

N-terminal amino acid, C-terminal amino acid

Question 17

Protein structure depends on its amino acid sequence and local, low-energy chemical bonds between atoms in both the polypeptide backbone and in amino acid side chains. Protein structure plays a key role in its function, if a protein loses its shape at any structural level, it may no longer be functional. Primary structure is the amino acid sequence. Secondary structure is local interaction between stretches of a polypeptide chain and includes α-helix and β pleated sheet structures. Tertiary structure is the overall three-dimension folding driven largely by interactions between R groups. Quaternary structures is the orientation and arrangement of subunits in multi-subunit proteinThe primary structure of a protein molecule has

Accepted Answer

two ends

Question 18

Protein structure depends on its amino acid sequence and local, low-energy chemical bonds between atoms in both the polypeptide backbone and in amino acid side chains. Protein structure plays a key role in its function, if a protein loses its shape at any structural level, it may no longer be functional. Primary structure is the amino acid sequence. Secondary structure is local interaction between stretches of a polypeptide chain and includes α-helix and β pleated sheet structures. Tertiary structure is the overall three-dimension folding driven largely by interactions between R groups. Quaternary structures is the orientation and arrangement of subunits in multi-subunit protein Which structural level enables the proteins to function as enzymes?

Accepted Answer

Tertiary

Question 19

Protein structure depends on its amino acid sequence and local, low-energy chemical bonds between atoms in both the polypeptide backbone and in amino acid side chains. Protein structure plays a key role in its function, if a protein loses its shape at any structural level, it may no longer be functional. Primary structure is the amino acid sequence. Secondary structure is local interaction between stretches of a polypeptide chain and includes α-helix and β pleated sheet structures. Tertiary structure is the overall three-dimension folding driven largely by interactions between R groups. Quaternary structures is the orientation and arrangement of subunits in multi-subunit protein Which of the following statements about the structure of proteins is true?

Accepted Answer

Proteins are heteropolymers containing strings of amino acids

Question 20

Protein structure depends on its amino acid sequence and local, low-energy chemical bonds between atoms in both the polypeptide backbone and in amino acid side chains. Protein structure plays a key role in its function, if a protein loses its shape at any structural level, it may no longer be functional. Primary structure is the amino acid sequence. Secondary structure is local interaction between stretches of a polypeptide chain and includes α-helix and β pleated sheet structures. Tertiary structure is the overall three-dimension folding driven largely by interactions between R groups. Quaternary structures is the orientation and arrangement of subunits in multi-subunit protein Upon denaturation, a protein loses its

Accepted Answer

three dimensional shape

Filters

Filters

class

subject

topic

concept

difficulty

Solutions for Proteins Important Questions

Found the solution, but did not understand the concept?

Ask my first question