Understanding Chromosomes: The Blueprint Of Life In Every Cell

Understanding Chromosomes: The Blueprint Of Life In Every Cell

Question 1. Chromosome.
Answer:

• A typical chromosome is made up of two rod-shaped chromatids which are placed more or less parallel to each other.
• Both chromatids are united to each other at a light staining area called centomere.
• Each chromatid has two arms – one on either side.

Chromosome Signficance:

• Each chromosome bears very large number of structures called genes which are made up of nucleic acid called deoxyribonucleic acid (DNA).
• These genes are involved in synthesis of proteins.
• Chromosome control the development and functioning of cells, by determining what types of proteins will be synthesized in them.

Question 2. DNA (Deoxyribonucleic acid).
Answer:

• It consists of two strands of fibers that are twisted to form double helix.
• The strands are linked to each other at regular intervals.
• Each strand consists of a chain of nucleotides.
• Each nucleotide molecule is made up of
  1. One molecule of sugar – deoxyribose.
  2. One molecule of phosphate.
     • It is attached to fifth carbon atom of sugar and third carbon atom of sugar of next nucleotide.
  3. A nitrogenous base [adenine, guanine, cytosine/thymine].
     • It is attached to the first carbon atom.
     • The DNA molecule is made up of two such polynucleotide chains running in opposite direction.
     • Adenine
       (A) always pairs with thymine
       (T) and cytosine
       (C) always pairs with guanine (G).