Describe the structure of the DNA molecule?
Answers
Answer:
The DNA molecule consists of two strands that wind around one another to form a shape known as a double helix. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups. Attached to each sugar is one of four bases--adenine (A), cytosine (C), guanine (G), and thymine (T).
Answer:
The DNA is a right handed double helix. It consists of two polydeoxyribonucleotide chains (strands) twisted around each other on a common axis.
2. The two strands are antiparallel, i.e., one strand runs in the 5 to 3 other in 3 to 5 direction while the direction.
3. The width of a double helix is 20 A° (2 nm).
4. Each turn of the helix is 34 A° (3.4 nm) with 10 pairs of nucleotides, each pair placed at a distance of about 3.4 A°.
5. Each strand of DNA has a hydrophilic deoxyribose phosphate backbone (3-5 diester bonds) on the outside (periphery) of the molecule while the hydrophobic bases are stacked inside (core).
6. The two polynucleotide chains are not identical but complementary to each other due to base pairing. 7. The two strands are held together by hydrogen bonds formed by complementary base pairs.
7. The A-T pair has 2 hydrogen bonds while G-C pair has 3 hydrogen bonds. The hydrogen bonds are formed between a purine and a pyrimidine only. If two purines face each other, they would not fit into the allowable space. And two pyrimidines would be too far to form hydrogen bonds.
8. The content of adenine equals to that of thymine (A = T) and guanine equals to that of cytosine (G = C).
9. The genetic information resides on one of the two strands known as template strand or sense strand. The opposite strand is antisense strand. The double helix has (wide) major grooves and (narrow) minor grooves along the phosphodiester backbone. Proteins interact with DNA at these grooves, without disrupting the base pairs and double helix.