Glossary of Biology Chapter 12 2
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- What are the key roles of cell division?
- The continuity of life based upon the reproduction of cells or cell division
the creation of duplicate offspring that provides for growth, development and repair
- Unicellular Organisms
- 1 mother cell divides and ends up with 2 identical daughter cells
- Multicellular Organisms
- development from a fertilized cell
- A cell's complete complement of DNA/genetic information and are packaged into chromosomes
- Eukaryotic Chromosomes
- Consist of chromatin, a complex of DNA and protein that condenses during cell division.
- Gemete Cells
- one set of chromosomes
- Somatic Cells
- 2 sets of chromosomes
- Cell cycle phase
- G1 phase - growth (protein synthesis)
S phase - DNA Synthesis - each chromosome duplicates into 2 sister chromatids, connected at the centromere
G2 phase - growth (protein synthesis)
M phase - mitosis or meiosis - division of nucleus, Cytokenesis - division of cytoplasm and other organelles the cell physcially divides
If cell stops dividing and leaves cell cycle, the cell enters G0 phase and is not duplicatiing
- Divides nucleus into identical copies
Consists of 5 distinct phases PPMAT
Prophase - chromosomes condense
Prometaphase - mitotic spindle attaches
Metaphase: chromosomes line up in the center mitotic spindle pulls apart the chromosomes to create daugher chromosomes
Anaphase - sister chromatids separate and move to different poles
Telophase - nuclear envelopes form
- (animals) The physical division of cells producing 2 separate, genetically equivalent daughters
Forms cleavage furrow involving the cytoskeleton
(plants) the cell wall builds cell plates to separate the sisters
- produce microtubles and mitotic spindle
Acts as the poles of the spindle
- Organelle made out of microtubles found in animal not plant cells.
At the poles of the cells pulling the sisters apart
- Central point that connect the sister chromosomes
- motor proteins at centromeres that moves chromosomes - like a winch in a car
- How do prokaryotes reproduce?
- by a process known as binary fission
- the process that separates the two daughter cells in animals.
- Cleavage furrow
- forms on the cell surface as a ring of actin microfilaments interacting with myosin proteins begins to contract on the cytoplasmic side of the membrane.
Cleavage furrows deepen wuntil the divising cell is pinched in two.
- Cell Plate
- forms from the fusion of membrane vesicles derived from the Golgi apparatus. The membrane of the enlarging cell plate joins with the plasma membrane, separating the two daughter cells. A new cell wall developes between the cells from the contents of the cell plate.
- Cell cycle is regulated
- the frequency of cell division varies with the type of cell
These cell cycle differences result from regulation at the molecular level
- Cell Cycle Control System
- consists of a set of molecules that function cyclically, coordinating the events of the cell cycle
Important internal and external signals monitor to determine whether the cell cycle should proceed past the 3 main chckpoints in g1, g2 and M phases
If no proceedure takes place the cell goes to G0 phase.
- Protein Kinases
- enzymes that activate or inactivate other proteins by phophrylating them.
- Stop and Go checkpoint signals
- both internal and external signals
MPF (maturation or (M phase) - promoting factor) activates a protein breakdown process that destroys its cyclin and MPF activity during anaphase
(stop signal) Density-dependent inhibition - crowded cells stop dividing
anchorge dependence - cells must be attached to a surface to divide.
- Cancer Cells
- exhibit neither density-dependent inhibition or anchorage dependence
do not respond normally to the body's control mechanisms
Benign tumor remains at site of orgin
malignant tumors invade surrounding tissues and can metastasize exporting cancer cells to other parts of the body where they may form secondary tumors
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