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16 Cards in this Set
- Front
- Back
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Cell Cycle in Prokaryotes/Binary fission/DNA?Enzyme? |
Begins: When cell is formed Ends: When the cell divides and forms 2 new cells 1)Cell elongates, DNA is replicated 2)Cell wall and plasma membrane begin to divide 3)Cross wall forms around divided DNA 4)Cells separate Binary fission: 1) Copy the Dna 2) Split the cell in two: - Produces 2 daughter cells - Exact copy of parent cell DNA A DNA K DAM-metylase |
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Cell cycle in eukaryotes? Phases? Interphase(G1,S,G2)? Mitotic phase(P,M,A,T,C)? Mitosis? Incomplete Cell cycle?Example? |
Interphase Mitotic phase Cytokinesis Interphase (G1,S,G2) G1-Gene expression -Protein synthesis occur -Duplication of organelles -Cell growth -6 hours S-DNA amount doubles - Proteins associate with DNA -7 hours G2-Cell growth continue -Tubulin and other proteins for cell division is produced -2 hours Mitotic phase Prophase,Metaphase,Anaphase,Telophase,Cytokinesis Mitosis - Process of dividing and separating chromosomes into two new cells Incomplete Cell Cycle Example: Embryonic cells These cells lack G1 and G2 only S and mitosis for fast duplication, approx: 30 min |
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Non-Dividing Cells! G0-cells? Examples G0-Phase T-cells? Examples |
G0 cells-No dividing cells, inactive cells outside the cell cycle in arrested in the G0 phase. Ex. Liver, kidney and lung cells in adults Lymphocytes (Cancer cells cannot enter G0) G0 Phase-An extended G1 phase where cell neither dividing nor preparing to divide T-cells-Never divide again, "Terminally differentiated (Matured cell preforming functions, when terminally differentiated they never divide again) Ex. Nerve cells Striated muscle cells |
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Scientists that discovered regulation of cell cycle |
Nobel prize 2001 awarded to: Leeland H. Hartwell Tim Hunt Sir Paul M. Nurse For discoveries in Key regulators of the cell cycle |
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Proteins in the cell cycle! CDK? Group of CDK´s? Group of cyclins(G1,Sphase,Mphase) Examples? |
CDK Cyclin Dependant Kinases are used by cells to regulate cell division. Cyclin Dependant Kinases are inactive unless bound to a cyclin molecule CDK + Cyclin becomes a MPF (Maturation Promotion Factor) Cyclins Cyclins concentration varies over the duration of the cell cycle Concentrations rise during G2 and fall during mitosis Late S-phase concentrations begin to accumulate During mitosis cyclins are de-graded Group of cyclins G1 Cyclins-Signals to cell to prepare for DNA replication S-phase Cyclins - Signals to cell to enter S-phase and duplicate DNA M-phase Cyclins - Initiate formation of mitotic apparatus Group of CDK´s? G 1 CDKs S phase CDKs M phase CDKs |
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Checkpoints! G1 Checkpoint? G2 Checkpoint? Mitosis Checkpoint? |
G1 Checkpoint Cell big enough? Environment suitable? No ->G1 complex stops the cell cycle G2 Checkpoint DNA replicated? No->G2/M complex stops cell cycle until DNA is fully replicated Mitosis checkpoint Chromosomes aligned? DNA not damaged? No->Repair the DNA if possible otherwise cell will undergo apoptosis. |
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Regulation at G1? |
CDK(4,6,2) and Cyclin (D,D,E)! 1) Activating the Rb protein by phosphorylating it. 2) Ph-Rb function is: -prevent excessive cell growth -Inhibiting cell cycle progression |
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Oncogenes |
Oncogenes (Gene that has potential to cause cancer) + Rate of mitosis + Growth factor secretion + Angiogenesis |
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Protooncogenes |
Normal gene that can become a oncogene due to mutations or increased expression Promotes cell division Turned on or off If permanently on - Promotes uncontrolled cell division |
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D-type cyclins |
Needed for cancer cell proliferation, might be good target for for treatment of human cancer D-type cyclins |
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Apoptosis Mechanism of apoptosis (draw) Proteins/Function apoptosis P53 Protein? |
Apoptosis -Cell suicide -Does not cause inflammation -Active process Proteins of apoptosis Bcl-2 - Anti apoptopic protein BAD - Promotes cell death Apaf-1 - Activates capsase Caspase - Executioner of apoptosis p53-Guardian of the genome In its anti-cancer role, p53 works through several mechanisms: It can repair DNA. It can arrest mitosis (cell cycle regulator) It can initiate apoptosis If the p53 gene is damaged, then tumor suppression is severely reduced. The critical role of p53 is evident by the fact that it is mutated in over 50% of all human cancers |
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Morphological changes during apoptosis |
1) Normal Cell Cell shrinks 2) Nuclear changes Degrading of nucleus 3) Fragmentation Breakdown of organelles and DNA 4) Apoptopic bodies Eaten by macrophages |
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Apoptosis/Pathology |
Cancer cells have systems blocking apoptosis. Ex. HPV causing cervical cancer, peptide E6 inactivates protein p53 which initiates apoptosis. Ex. EBV-Epstein Barr virus causes burkitts lymphoma, this protein has similar functions to BCl-2 Ex. AIDS/HIV virus targets CD4+ receptors, T lymphocytes are affected and they decrease in number by apoptosis to protect the organism from the virus ->Bad immune system |
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Apoptosis Vs. Necrosis |
Apoptosis: Cell suicide Cell chooses to die Does not cause inflammation Active process Necrosis: Cell murder Cell does not want to die Causes inflammation Cell is passive victim |
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Significance of apoptosis in the developmental processes? |
Many cells are removed by apoptosis during development: Ex. Skin cells between fingers 50% of neurons during embryonic life |
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Cell cycle? Blastomere? Cleavage? |
Cell cycle - Is the interval between the end of mitosis in the parental cell and the end of the next mitosis in a daughter cells Blastomere - is a type of cell produced by cleavage Cleavage - is the division of cells in the early embryo |
