Recently Added Biology Topics

· Variation and Mutation
· Inheritance Part 2
· Inheritance Part 1
· Cell Division Part 4
· Cell Division Part 3

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· Introduction of Cell Biology
· Cell Structure Part 1
· Cell Structure Part 2
· Cell Structure Part 3
· Cell Molecules Part 1
· Cell Molecules Part 2 - Organic Molecules
· Cell Molecules Part 3 - Proteins
· Cell Molecules Part 4 - Enzymes
· Cell Division Part 1
· Cell Division Part 3

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Cell Division Part 1

Cell Biology - Cell Division Part 1

Definition:
One cell divides and forms two new cells are called cell division

Importance of cell division:

Repeated cell division forms the body of an organism
Helps in replacement of degenerated and dead cells of body
Helps in wound healing
Require for formation of reproductive cells

Types of cell division:
1. Mitosis:
· Occurs in formation of somatic cells of body
· The number of chromosomes is the same in new cells as it was in the parent cell

2. Meiosis:
· Occurs during formation of reproductive cells
· The number of chromosomes is reduced to half the number in the parent cell

Cell cycle:
The sequence of events by which the cell is duplicated its contents and divides into two new cells is called cell cycle. The entire process is controlled by genes. Cell cycle is divides into two phases:
· Interphase
· Mitotic phase

Interphase:
The phase of cell cycle in which all the cell content gets duplicate and increases the size of cell is called Interphase.
· Genes are replicated and hence chromosomes are also replicated
· Chromosomes cannot be observed in their phase as it is dispersed in chromatin material
· Centrosome also replicates and two Centriole appear at right angle to each other

Sub-phases of Interphase:
1. G₁Phase:
· It is a gap-1 phase and starts at the end of previous cell division.
· RNA and protein synthesize in this phase

2. S Phase:
· It is a synthesis phase and synthesize DNA
· Replication of chromosome also occurs during this phase

3. G₂ Phase:
· It is a gap-2 phase and end of interphase
· It stops synthesis of DNA

Self Study:
Example- 1: Match the following

A	B
Mitosis	Process of one cell divides into two
Meiosis	Number of Chromosomes are half
Cell cycle	Number of chromosomes are same
Cell division	Process of duplication of cell content and division into two cells

Answer:

A	B
Mitosis	Number of chromosomes are same
Meiosis	Number of Chromosomes are half
Cell cycle	Process of duplication of cell content and division into two cells
Cell division	Process of one cell divides into two

Example-2: Which of the following phase synthesize RNA and protein?
a) Mitosis
b) Meiosis
c) G₁-Phase
d) Cell cycle

Answer: G₁-Phase synthesizes RNA and protein.
Example-3: ………….. is a process which replaces degenerated and dead cells of body
a) Cell molecules
b) Cell division
c) Mitosis
d) Meiosis

Answer: Cell division is a process which replaces degenerated and dead cells of body.