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44 Cards in this Set
- Front
- Back
Cell Cycle
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Key roles of cell division
The Cell Theory |
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The Cell Theory
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All organisms are composed of cells
Cells are the basic unit of structure and function All cells come from pre-existing cells. |
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Creation of cells in UNICELLULAR organisms
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1) Reproduction
(Mitosis) Two cells created just like the first cell. Creates whole organism |
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Creation of cells in MULTICELLULAR organisms
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1) Growth and Development
2) Tissue Renewal and Repair 3) Reproduction |
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Mitosis
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Concept 12.1
Most cell division results in genetically identical daughter cells Cell division part of the cell cycle |
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Cellular Organization of Genetic Material
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1) Genome
2) Prokaryotes 3) Eukaryotes |
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Genome
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Cell's or organism's genetic material
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Prokaryotes
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Single DNA molecule
Circular chromosome |
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Eukaryotes
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Multiple, Linear, DNA molecules
Linear chromosomes |
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Vast amount of human DNA
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"A typical human cell, for example, has about 2m of DNA -- a length about 250,000 times greater than the cell's diameter. Yet before the cell can divide, all of this DNA must be copied"
ACCURATELY |
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Cellular organization of Genetic Material
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Chromosome (100s-1,000s genes)
Somatic Cells (46 chromosomes) Gametes (23 chromosomes) -Egg cells and sperm cells |
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Chromatin
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In Eukaryotes
-Contains both DNA and associated proteins |
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Distribution of Chromosomes during Cell Division
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1) Before division
-Chromatin 2) After DNA duplicated -Chromosomes condense |
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Duplicated Chromosome
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SISTER CHROMATIDS attached at CENTROMERE
--Still only counts as one chromosome --> Separate during division --Now individual chromosomes |
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Mitosis definition
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Division of the nucleus
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Cytokinesis
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Division of the cytoplasm
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Meiosis definition
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Nonidentical daughter cells
Gamete formation (46 --> 23) |
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Cell cycle time
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Normal cell (hours)
Embryonic cell (minutes) |
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Cell Cycle
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Interphase
Prophase Prometaphase Metaphase Anaphase Telophase |
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Interphase
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Alternates with the mitotic phase
DNA DUPLICATION Subphases: (proteins and cytoplasmic organelles) G1 -- Growth S -- Replication G2 90% of time in interphase |
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G2 Interphase
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1) Nuclear envelope
2) Nucleoli 3) Centrosome 4) Uncondensed Chromosomes |
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G2 Interphase Image
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Prophase
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1) Nuclear Envelope
2) Condensed, discrete chromosomes (sister chromatids) 3) Nucleoli disappear 4) Mitotic Spindle begins to form 5) Centrosomes move away from each other |
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Mitotic Spindle
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Comes from centrosomes (microtubule organizing centers)
Microtubules assemble from centrosomes |
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Prophase Image
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Prometaphase
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1) Nuclear Envelope Fragments
2) Microtubules can invade nuclear area 3) Chromosomes more condensed 4) Chromatids have kinetochores 5) Kinetochore and Nonkinetochore microtubules |
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Kinetochore Stuff
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Kinetochore- PROTEINS associated with DNA
Kinetochore microtubules- (spindle microtubules) Chromosome walking (motor proteins) Tug of war, line chromosomes up at metaphase plate Depolymerization (kinetochore end) Pulls chromosomes from metaphase place to poles |
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Prometaphase Image
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Metaphase
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1) Centrosomes at opposite poles of cell
2) Metaphase Plate 3) Each kinetochore is attached to a kinetochore microtubule |
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Metaphase Image
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Anaphase
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SHORTEST STAGE OF MITOSIS
1) Cohesin Proteins cleaved (Sister chromatids part suddenly) 2) Daughter chromosomes move toward opposite ends (centromere first) 3) Kinetochore microtubules shorten 4) Nonkinetochore microtubules lengthen |
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Nonkinetochore Microtubules
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Overlap with those from other poles
Motor proteins walk them away from each other Polymerization at overlapping ends Elongate cell during Anaphase |
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Anaphase Image
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Telophase
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1) Daughter Nuclei Form
2) Nucleoli reappear 3) Chromosome less condensed Spindle depolymerized Ends Mitosis |
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Telophase Image
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Cytokinesis
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Division of cytoplasm
Cleavage furrow (animal cells) Actin microfilaments (like purse string) |
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Plant Cytokinesis
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Cell plate
Vesicles from Golgi--Membrane fuses with plasma membranes |
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Binary Fission
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Cell replication in Prokaryotes (bacteria)
Singular circular chromosome DNA duplication |
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Cell cycle control system
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Regulated at checkpoints (regulatory proteins survey cell)
G1 checkpoint 1) Go ahead (S, G2, M phases) 2) No go-ahead (G0) **Most cells G0 phase** |
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Stop and Go Signs at checkpoints
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1) Growth Factors
proteins 2) Density-dependent inhibition contact and nutrients 3) Anchorage Dependence attachment to substratum |
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Cancer
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Loss of cell cycle controls
NO density-dependent inhibition NO anchorage dependence |
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Tumor
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Mass of cells either:
1) Benign (cells remain in place) 2) Malignant (cells become invasive) 3) Metastasis Cells spread throughout body (blood and lymph) Secondary tumors |
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Regulatory proteins and genes
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Regulatory proteins normal: cell division regulated
Regulatory genes (DNA --> proteins) Proto-oncogenes ("go") Tumor suppressor genes ("stop") Transformation Gene mutations --> abnormal proteins Proto-oncogenes --> oncogenes "GOOOOOO" No tumor suppressor genes |
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Cancer: Multistep process
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Mutations in regulatory genes
Multiple mutations in a SINGLE cell Carcinogens 1) Smoking 2) UV light 3) Asbestos 4) Viruses --Can be predisposed (inherited mutations) |