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Mitosis is used for
Asexual reproduction
Growth
Tissue repair
Embryonic development
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Interphase: G1:
Cell growth, protein synthesis
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Interphase S
DNA Replication
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Interphase G2
Second growth phase, organelles multiply, preparation for mitosis
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M Phase
- Prophase
- Metaphase
- Anaphase
- Telophase
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Prophase
1.
Chromosomes condense
Nuclear envelope disintegrates
Nucleolus disappears
Mitotic spindle forms
Centrosomes move to poles and attach the spindle to the kinetochore
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Metaphase
2.
Chromosomes are moved to equator (metaphase plate) of the cell by spindle
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Anaphase
3.
Sister chromatids are split
Move to opposite poles (each single chromatid is now called a chromosome)
Microtubules shorten
There is now a complete set of chromosome at each pole
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Telophase
4.
Chromosomes at poles
Chromosomes uncoil into chromatin
Nucleolai reappear
Cell elongated
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Cytokinesis:
Division of cytoplasm to from two new cells
Happens after mitosis
Results in two equal daughter cells
Interphase follows
Is different in animal and plant cells
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Animal Cells Cytokinesis:
Plasma membrane pinches at the cleavage furrow
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Plant Cells Cytokinesis:
Firm cell wall forms a cell plate midway between poles, built from center to outside, vesicles fuse
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Cyclins:
A group of proteins called cyclins is used to ensure that tasks are performed at the correct time.
Unless the cyclins reach threshold concentration, the cell cycle does not proceed.
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Cyclins D E A B
Cyclin D: the move from G0 to G1 and G1 to S
Cyclin E: prepares for S and DNA Replication
Cyclin A: DNA replication inside the nucleus
Cyclin B: Assembly of mitotic spindle and preparation for mitosis
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Cancer:
A primary tumour is one that occurs at the original site of a cancer. A secondary tumour is a metastasis, a cancerous tumour that has spread from the original location to another part of the organism.
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... cause cancer
Carcinogens
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All mutagens are
are carcinogens
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oncogenes
Genes that cause cancer when they mutate
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Telomere:
end of a chromosome
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shortening of the telomere
aging
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for a cancer to develop
several mutations must occur in the cell
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using mitotic index in medicine
- 1. if tissues have a high mitotic index, it means lotsa uncontrolled cell division
- 2. used for diagnosis
- 3. to see if drugs are effective
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mutagen
- can be physical, chemical or organic
- virus
- cigarette smoke
- UV radiation
- x rays
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