Biomolecules and Enzymes

They are protective proteins which protect the body from ill effects of poisonous (toxic) substances and pathogenic invaders (virus, bacteria and other pathogens) by destroying the toxins and invaders. Important defence proteins are antibodies or immuno-globulins produced by lymphocytes in vertebrates. Interferon protects cells from the attack of viruses. Thrombin and fibrinogen form blood clots to prevent loss of blood and infection at sites of injuries. Certain proteins, called exploitive proteins, are normally toxic, but they may play a defensive role under certain conditions. These include snake venom, bacterial toxins and toxic plant protein called ricin.

These proteins transport specific substances from one part of body to the others. Most familiar is haemoglobin of red blood cells (erythrocytes or RBCs) of vertebrates. It transports oxygen from lungs to all tissues of the body. Likewise, lipo-proteins transport lipids in blood from liver to fatty tissues (fat deposits) and other tissues. Serum albumin transports fatty acids in blood from fatty tissues to other tissues.

These are filamentous proteins which enable cells and organisms to contract, to change shape, or to move about. For instance, actin and myosin are responsible for contraction and relaxation of muscle cells and occur in many other types of cells. Myosin also contains ATPase enzyme and is, therefore, both enzymatic and contractile. Tubulin protein is the major component of microtublules which form the locomotory organelles (flagella and cilia), basal bodies, centrioles and spindle apparatus in dividing cells.

This option is correct because aspartic acid acid contains one amino acid group and two carboxyl group while arginine contain two amino acid and one carboxyl group.

Ans : 2.

Ans :1.

Ans : 3.

Ans : 4.

Amino acids are the organic compounds that serve as the fundamental building blocks (monomers) of proteins.

Peptidoglycan is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, forming the cell wall.

Although a single peptide sequence, being a linear array of amino acids, by definition cannot fully represent a discontinuous epitope, it can comprise a part of such an epitope. However, because the epitope is incomplete, the peptide would probably only generate antibodies that have a relatively low affinity for the native antigen.

Macromolecular colloidal particles are formed when on dissolution in a suitable solvent, the macromolecules have sizes which are in the colloidal range. Naturally occurring macromolecules are starch, proteins and cellulose. Man made macromolecules are polymers such as polyethylene, nylon and polystyrene. These colloids are quite stable and resemble true solutions in many respects.

In this type of colloids sols, the dispersed phase has great attraction for the dispersion medium. In such colloids, the dispersed phase does not precipitate easily and the sols are quite stable. If the dispersion medium is separated from the dispersed phase, the sol can be reconstituted by simply remixing with the dispersion medium. Hence, these sols are called reversible sols. Examples of lyophilic sols include sols of gum, gelatine, starch, proteins and certain polymers in organic solvents.

About ten per cent of the peptides generated by the housekeeping proteasome are 8–9 residues in length, but the immunoproteasome is thought to be specialized to produce a greater proportion of peptides of this length which is optimal for insertion into the MHC class I groove.

H1 is least conserved during evolution.