Test: Biomolecules 4 - From Past 28 Years Questions - NEET MCQ

The two chains comprising the DNA are sprially coiled around a common axis to form a regular, right handed double helix.

In RNA, pyrimidine thymine is replaced by uracil.

The ratios  for the (A+ G)/ (T+C) are constant at approximately  1.0 for the different organisms. Each of these organisms contains a double  stranded genome. The percentage of Guanine and Cytosine are almost equal to each other, similarly the percentages of Adenine and Thymine are almost equal to each other as well. In other words, the percentage of purines should be equal to the percentage of pyrimidines for double stranded  DNA. This means that (A + G) = (C + T)
The (A+T) / (C + G) ratios are not constant. The relative numbers of (A + T) base pairs and (G + C) base pairs are unique to each organism and can  vary between the different species.

The nucleic acid (DNA and RNA) are repeating units of nucleotides i.e. polynucleotides. Each nucleotide comprises of nitrogenous heterocyclic bases viz. purines or pyrimidi

Cytochromes are a type of chromoproteins. Chromoproteins are conjugated proteins which are composed of a protein molecule joined to nonprotein group (Prosthetic group).

RNA is a single chain of ribonucleotides. Each ribonucleotide consists of nitrogenous bases (adenine, guanine, cytosine and uracil), ribose sugar and phosphoric acid.

Nucleic acid (DNA and RNA) comprises of polynucleotides. Each nucleotide consist of nitrogenous bases, pentose sugar and phosphoric acid.

According to Chargaff ’s rule, the amount of adenine is always equal to thymine and that of guanine equal to cytosine. Moreover, A + G = T + C.
120 + 120 = 120 + 120
240 = 240
So there will be 480 nucleotides in all.

DNA is a long, double helix consisting of repeating units of deoxyribonucleotides.

There are certain enzymes which have slightly different molecular structure but have similar catalytic function such enzymes are known as isoenzymes. Holoenzymes is the active compound formed by combination of a coenzyme and an apoenzyme. Apoenzyme is the protein component of an enzyme, to which the coenzyme attaches to form an active enzyme. Coenzyme are organic non-protein molecules  that bind with the protein molecule (apoenzyme) to form the active enzyme (holoenzyme).

The nitrogenous bases are constituents of DNA. The nitrogenous bases may be pruines or pyrimidines. Purines are 9 membered, double winged structures eg. adenine or guanine.

Water is the most abundant compound in the most majority of cells. About 65-70% of human body is water. Major portion of water found in human body occurs in the cells as intracellular water.

An amino acid molecule consists of a central a carbon bonded to an amino group (–NH2), a carboxylic group (–COOH), a hydrogen atom and a carbon chain or ring on its sides.

Bulk of RNA occurs in the cytoplasm and a small amount in the nucleus in eukaryotic cells. In prokaryotic cell RNA is found in the cytoplasm.

Length of one helix is 34Å in B-DNA.

Enzymes accelerate chemical reaction by lowering the activation energy.

Principal or major elements include oxygen, carbon, hydrogen and nitrogen. They are so named because they alone constitute 99% of living system.

The pyrimidine bases include cytosine, thymine and uracil.

In a phosphodiester bond, linkage takes place between the phosphate group of one nucleotide and the hydroxyl group of sugar (ribose or deoxyribose) of the adjacent nucleotide.

Glycogen is a polysaccharide, which is synthesized and stored in the liver. It is released into the blood by breakdown of simple glucose, and energy is released.

The pyrenoids are small spherical protein bodies, surrounded by starch deposition found singly or in numbers embedded in the chloroplast of many algae and bryophytes.

The nitrogenous bases forming the nucleoside in RNA are adenine, guanine  (purines) and cytosine and uracil (pyrimidines).

Polysaccharides are complex carbohydrates formed by polymerization of a large number of units called monosaccharides, starch is a glucosan polysaccharide and is the major reserve food  of animals. Cellulose is the structural polysaccharide of  plant cell wall. Sucrose is a disaccharide formed of one unit of D-glucose and one unit of D-fructose. Maltose is a disaccharide formed of two molecules of glucose held together, lactose is disaccharide formed through condensation of  D-glucose and  D-glucose. Glucose and  fructose are monosaccharides.

Proteins are polymers of amino acids. There are only 20 amino acids which can be arranged in different orders in a polypeptide chain to form a wide array of proteins.

Bacteria are prokaryotic organisms. Polyamines (basic proteins) like spermidine and cadaverine (instead of histones) are associated with DNA packaging in bacteria.