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Cell division is responsible for
- growth - increases size
- repair - repair damaged cells
- reproduction - two identical cells
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Skin cells or Somatic cells undergo
Mitosis
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Skin cells
cells make up skin
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Somatic cells
cells that reproduce by cell division
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Mitosis
the process that divides the nuclear material during cell division
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DNA (deoxyribonuleic acid)
a long molecule that provides instructions for making, running, and repairing a cell
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RNA (ribonucleic acid)
one strand of DNA
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Why is DNA important?
DNA is the GENETIC CODE that is a unque pattern of base pairings to for characteristics.
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Structure of DNA
- twisted ladder, nucleotides, nitrogenous base molecule
- sides: sugar and phosphate
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Base Pairings: (nitrogenous bases)
Adenine & Thymine, Guanine & Cytosine
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Cell Cycle- the sequence of events in the cell from one cell division to another
- Interphase
- Prophase
- Metaphase
- Anaphase
- Telophase, Cytokensis
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Interphase -
growing and working, 90%
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Prophase -
sister chromotids visible, join 'X' shape, nuclear membrane breaksdown chromosomes spread out
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Metaphase -
spindle formed, chromotids attach to spindle fibres, chromotids line up in centre
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Anaphase -
chromotids pulled apart from spindle goes toward opposite poles of cell, chromotids called chromosoes
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Telophase -
- new chromosomes reach opposite poles
- events of prophase happen in reverse
- two nuclear membranes form
- spindle disappears
- chromosomes lengthen and get thinner
- nucleoli reappears
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Cytokensis -
- divides cytoplasm in two daughter cells
- pinching of cell membrance and cytplasm
- between two new nuclei
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Mutation
a change in DNA (genetic code) of a cell
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What does a mutation do?
A harmful mutation in a gene's DNA causes change in the protein that is produced.
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What does a mutation affect?
The body's functions.
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Tumours
- benign - harmless
- malignant- harmful, spreads
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What does a malignant tumor's cell look like?
The nuclei is enlarged, the cell is bigger.
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