M-phase consists of mitosis and cytokinesis. Mitosis is divided into prophase, metaphase, anaphase and telophase where the chromosomes condense and duplicate, align at the metaphase plate, separate into daughter chromosomes, and decondense. Cytokinesis then occurs, where in animal cells the cell membrane invaginates at the cleavage furrow to divide the cytoplasm, and in plant cells a cell plate forms between nuclei that fuses with the parent cell membrane to divide the cell.
Nucleus” is a Latin word meaning Kernel
It is the “CONTROL CENTER” of the cell
Average diameter of nucleus is 6um, which occupies around 10% of cell volume
Nuclear Envelope
Nuclear Pores and complex
Nuclear lamina
Chromosomes & Chromatin
Nucleolus
Nucleoplasm
The study of the cell cycle focuses on mechanisms that regulate the timing and frequency of DNA duplication and cell division. As a biological concept, the cell cycle is defined as the period between successive divisions of a cell. During this period, the contents of the cell must be accurately replicated.
The cell cycle is regulated by cyclins and cyclin-dependent kinases.
How long is one cell cycle?
Depends. Eg. Skin cells every 24 hours. Some bacteria every 2 hours. Some cells every 3 months. Cancer cells very short. Nerve cells never.
Programmed cell death:
Each cell type will only do so many cell cycles then die. (Apoptosis)
Nucleus” is a Latin word meaning Kernel
It is the “CONTROL CENTER” of the cell
Average diameter of nucleus is 6um, which occupies around 10% of cell volume
Nuclear Envelope
Nuclear Pores and complex
Nuclear lamina
Chromosomes & Chromatin
Nucleolus
Nucleoplasm
The study of the cell cycle focuses on mechanisms that regulate the timing and frequency of DNA duplication and cell division. As a biological concept, the cell cycle is defined as the period between successive divisions of a cell. During this period, the contents of the cell must be accurately replicated.
The cell cycle is regulated by cyclins and cyclin-dependent kinases.
How long is one cell cycle?
Depends. Eg. Skin cells every 24 hours. Some bacteria every 2 hours. Some cells every 3 months. Cancer cells very short. Nerve cells never.
Programmed cell death:
Each cell type will only do so many cell cycles then die. (Apoptosis)
3. M-phase or mitotic phase occurd after
interphase stage, the dividing cells
enter M phase
4. M-Phase
Has two major parts
Mitosis Cytokinesis
Can subdivided into 4 phase
Prophase
Metaphase
Anaphase
Telophase
5. Prophase
• The chormosomes in the nucleus condense
and become more tightly coiled
• Each chormosomes consists a pair of sister
chormatids joined together at the centromere.
• The spindle fibre in the cytoplasm begin to
form and extends between the centrioles.
• The nucleolus disappers and the nuclear
membrane diseintegrates at the end of
prophase
6.
7. Metaphase
• Begin when centromeres of all the
choromosomes are lined up on the metaphase
plate.
• Two sister chromatids are attached to one
another at the centrometer.
• Metaphase ends when the centromeres
divide.
8.
9. Anaphase
• Two sister chormatids of each chromosomes
separate at the centromere.
• The sister chromatids are pulled apart to the
opposite poles by shortening of the spindle
fibre .
• The separated chromatids are called daughter
chromosomes.
10. • The two sister
chromatids of each
chromosome separate
at the centromere
• Spindle fibres will
contract and pull apart
the sister chromatids to
the opposite poles
• Once separate, the
chromatids are referred
to as daughter
chromosomes
11. Telophase
• Begins when two set of chromosomes reach
the opposite poles of the cell.
• Chromosomes start to uncoil and revert to their
extended state.
• The spindle fibre disappear and a new nuclear
membrane form around each set of
chromosomes.
• The nucleolus re-form in each nucleas.
14. 1)Following mitosis, the cytoplasm of the cell will
divide through a process called cytokinesis to form
two daughter cells, each having one nucleus
2) Cytokinesis is the process of cytoplasmic division
3) It usually begins before nuclear division is complete
THAT IS CYTOKINESIS
15. Cytokinesis in animal cell
• Actin filaments in the cytoplasm started to
contracts to pull a ring of the plasma
membrane,forming a cleavge furrow.
• The cleavge furrow deepens progressively
until the cell is separated into two daughter
cell.
19. Cytokinesis in plant cell
• A clevage furrow does not form.
• Instead a membrane –enclosed vesicles gather at
the plant cell’s equator between the two nuclei.
• The vesicles fuse to form cell plate.
• The cell plate grow outward and fuse with plasma
membrane of the parent cell.
• New cell wall and plasma membrane are formed
from the content of the cell plate
• Cellulose fibre are produced at the end of
cytokinesis.