Explain the process of DNA replication with the help of a schematic diagram.
DNA replication is the phenomenon in which a duplicate copy of DNA is synthesized
The steps involved in the process of DNA replication are as follows:
i) DNA replication occurs in S-phase of the cell cycle.
ii) Enzyme involved: DNA polymerase (DNA-dependent DNA polymerase)
iii) Replication requires energy
Source of energy -Deoxyribonucleoside triphosphates (dNTPs)
dNTPs have dual purposes: act as substrates as well as provide energy
Replication initiates at specific regions in DNA called the origin of replication.
DNA polymerase polymerises a large number of nucleotides in a very short time.
During the course of replication, two parent strands do not completely open, but a small opening form in which replication occurs. This small opening forms a replication fork.
DNA polymerase can polymerize only in one direction, i.e,'
Therefore, replication occurs smoothly into end of DNA (continuous replication, but occurs discontinuously into end).
The discontinuous fragments so formed are joined by DNA ligase
Name the tropical sugar cane variety grown in South India. How has it helped in improving the sugar cane quality grown in North India?
Mendel published his work on inheritance of characters in 1865, but it remained unrecognized till 1900. Give three reasons for the delay in accepting his work.
Identify ‘a’, ‘b’ and ‘c’ in the following table:
|
No. |
Crop |
Variety |
Insect Pests |
|
1. |
Brassica |
Pusa Gaurav |
(a) |
|
2. |
Flat bean |
Pusa Sem 2 |
(b) |
|
3. |
(c) |
Pusa Sawani |
Shoot and fruit borer |
Why are beehives kept in a crop field during flowering period? Name any two crop fields where this is practiced.
How did the process of RNA interference help to control the nematode from infecting the roots of tobacco plants?
A colour-blind child is born to a normal couple. Work out a cross to show how it is possible. Mention the sex of this child.
Women are often blamed for producing female children. Consequently, they are ill-treated and ostracized. How will you address this issue scientifically if you were to conduct an awareness programme to highlight the values involved?
