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mitosis.What is the purpose of Mitosis? to make more cells
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mitosis.
Background:
What is CANCER?
Cell Theory (review)
1. All organisms are made up of one or more cells.
2. All cells carry on their own life activities.
3. New cells can arise only from other living cells by the process of cell division.2 Basic Types of Reproduction
1. Asexual reproduction- one parent; offspring is identical to parent
2. Sexual reproduction- two parents; offspring is not identical to parents
I. Overview of Cellular Division- (MITOSIS)
A. Two processes take place
1. division of the nucleus
2. division of the cytoplasmB. Review of the STRUCTURE of the NUCLEUS
1. nucleus is the control center of the cell
2. contains DNA (which is the hereditary material needed for the synthesis of all components of each cell)
3. DNA is found in chromatin which are long thin thread like material
4. Humans have 46 (23 pairs) of chromosomes
5. Structure of DNA
i. double stranded, twisted molecule
ii. each strand is connected by a hydrogen bond b/w base pairs
II. Interphase- "RESTING PHASE"
* Not a part of mitosis; this phase occurs BEFORE mitosis starts
* nuclear of genetic material (chromatin) are replicated
* cells grow in size
* more organelles, nucleic acid, & proteins are produced
* centrioles also replicate during this phase
III. Mitosis (in animals)
* a continuous process broken down into stages for convenience of studying*
A. Prophase- begins mitosis
1. chromatin condenses into chromosomes = sister chromatids
2. centrioles move to opposite sides (poles) of the cell
3. spindle fibers radiate out from centrioles to form asters
4. spindles attach to the centromere of chromosome
5. nuclear membrane & nucleolus disappearB. Metaphase- meta = middle
1. chromosomes lined up on equatorial plane
C. Anaphase -
1. daughter chromosomes move to opposite poles probably by shortening of spindle fibers
2. beginning of cytokinesis (cytoplasmic division) cell membrane 'pinches'.
3. centromeres divide, forming separate sister chromatidsD. Telophase- last phase of mitosis
1. chromosomes reach poles
2. chromosomes uncoil to form chromatin
3. spindles & asters disappear
4. nuclear membrane & nucleolus
5. cytokinesis is completed producing two daughter cells
6. basically the opposite of prophase
IV. Mitosis (in plants)
A. plant cell division differs from animal cell division in 2 ways
1. plants do NOT have centrioles therefore no asters (still have spindles)
2. rigid cell wall prevents cell membrane from pinching; instead, a cell plate forms which divides the cell in half.
V. ASEXUAL REPRODUCTION
* offspring genetically identical to parent & each other
*generally rapid
* high # of offspringA. Types of Asexual Reproduction
1. BINARY FISSION - parent divides into 2 equal parts
ex) bacteria, protozoa, some algae
2. BUDDING- offspring buds off the parent, identical division of nuclear material but unequal division of cytoplasm
ex) yeast, hydra
3. Spore Formation- single specialized cells produced by certain organisms that when released, germinate and grow and form new individuals (can be formed sexually or asexually)
ex) bread mold
4. Regeneration- ability of an organism to regrow lost body part
a. relatively simple animals- starfish, hydra, earthworm, planaria
5. Vegetative Reproduction- growing new plants from parts of other plants
a. bulb- short underground stem surrounded by thick fleshy leaves that contain stored food; tulips, onions, lilies
b. corm- resemble bulbs but do not contain fleshy leaves; gladioli, crocuses, water chestnuts
c. tuber- enlarged portion of an underground stem that contains food; whit potatoes
d. runner (stolon)- horizontal stem with buds along the surface of the ground; grasses, strawberry
e. rhizome- a horizontal stem that grows underground; ferns, irises, water lilies6. Artificial Vegetative Reproduction
a. cutting- stem, leaves, roots used to produce new individuals
b. layering- a stem is bent over & covered with soil and new individuals grow
c. grafting- 2 parts of plants are cut & joined together; roses, nectarinesStock- part that contains the roots
Scion- added piece on topd. advantages
*production of new entirely different plants
*development takes less time
*seedless fruit can be grown
*higher yields of fruits or nuts
VI. What happens when mitosis (cell division) does not work properly and too many cells are made to quickly?
Cancer is a variety of diseases in which cells of the body multiply without control. Cancer can occur in any of the several types of cells that make up the body. Malignancy has been linked with changes in the genetic material of the cells based on three lines of evidence. The daughter cells of a cancerous cell are always malignant, indicating cancer is an inherited property. Chromosome mutations, such as deletions and translocations, are often observed in cancer cells. Oncogenes are genes that cause some kinds of cancer. When oncogenes are turned off they will not cause cancer, but when they are switched on, this leads to uncontrolled growth of cells that we call cancer.