Question

1. Please discuss cellular growth and development

Answer 1

Ans) Cell growth: the use of genetic info in DNA to make the structural & functional proteins needed for cell survival.

Normal Cell Growth
The Cell Cycle:

- The outer layer of the skin is approximately two dozen cells thick. Under normal circumstances, cells at the bottom of this layer, called the basal layer, divide at exactly the same rate as dead cells are shed from the surface. Each time one of these basal cells divides, it produces two cells. One remains in the basal layer and goes on to divide again. The other migrates out of the basal layer and can no longer divide. This way, the number of dividing cells in the basal layer, and the number of non-dividing cells in the outer layer stays the same.

In order for this process to unfold with such precision, 2 important cellular processes must balance each other perfectly:

Proliferation
Apoptosis
Proliferation refers to the growth and reproduction of cells. Apoptosis (cell suicide) is the mechanism by which old or damaged cells normally self-destruct. If these carefully balanced processes are disrupted and cells proliferate uncontrollably, fail to die off at the appropriate time, or both, the end result may be cancer.

In order to proliferate, both normal and cancerous cells must undergo the process of cell division. This process is the end result of the cell cycle. The cell cycle has 2 major phases:

Mitosis
Interphase
Mitosis is the process by which a parent cell produces a pair of genetically identical daughter cells. It is part of the normal cell cycle. The cell cycle is divided into 2 distinct periods:

Interphase (cell growth)
Mitotic phase (cell division)
Interphase is the period of a cell’s life when it carries out its normal growth and metabolic activities. It is also the time during which a cell undergoes a closely ordered sequence of activities in preparation for cell division.

Interphase is made up of 3 sub-phases. During the G1 phase, the cell produces the proteins needed to copy the cellular DNA, which occurs during the second S phase of the cell cycle. There must be 2 identical copies of the DNA so that one copy is passed to each of the daughter cells. During the final G2 phase, which lies between the replication of the DNA and the beginning of mitosis (when the cell actually divides), the cell produces proteins needed for cell division.