In: Anatomy and Physiology
AWAIS GMC, [01.02.19 07:39]
The ectoderm will form the outer components of the body, such as
skin, hair, and mammary glands, as well as part of the nervous
system.
AWAIS GMC, [01.02.19 08:27]
[In reply to AWAIS GMC]
Mitosis is divided into four phases with a preparing
interphase.
Interphase:-
-The DNA in the cell is copied in preparation for cell division,
this results in two identical full sets of chromosome.
-In the cytoplasm there are two centrosomes, each containing a pair
of centrioles, these structures are critical for the process of
cell division.
-During interphase, microtubules extend from these centrosomes.
1. Prophase:-
-The chromosomes condense into X-shaped structures that can be
easily seen under a microscope.
-Each chromosome is composed of two sister chromatids, containing
identical genetic information.
-The chromosomes forms pair so that both copies of chromosome 1 are
together, both copies of chromosome 2 are together, and so
on.
- At the end of prophase the membrane around the nucleus in the
cell dissolves away releasing the chromosomes.
-The mitotic spindle, consisting of the microtubules and other proteins, extends across the cell between the centrioles as they move to opposite poles of the cell.
2. Metaphase:-
-The chromosomes line up neatly end-to-end along the centre
(equator) of the cell.
-The centrioles are now at opposite poles of the cell with the
mitotic spindle fibres extending from them.
-The mitotic spindle fibres attach to each of the sister
chromatids.
3. Anaphase:-
-The sister chromatids are then pulled apart by the mitotic spindle
which pulls one chromatid to one pole and the other chromatid to
the opposite pole.
4. Telophase:-
At each pole of the cell a full set of chromosomes gather
together.
A membrane forms around each set of chromosomes to create two new
nuclei.
The single cell then pinches in the middle to form two separate daughter cells each containing a full set of chromosomes within a nucleus. This process is known as cytokinesis..
The mitotic spindle, consisting of the microtubules and other
proteins, extends across the cell between the centrioles as they
move to opposite poles of the cell.
The mitotic spindle fibres attach to each of the sister chromatids.
The mitotic spindle pulls one chromatid to one pole and the other
chromatid to the opposite pole.