cell cycle b chapter 12~ the cell cycle. cell division: key roles b genome: cell’s genetic...
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Cell Division: Key RolesCell Division: Key Roles Genome: cell’s genetic informationGenome: cell’s genetic information Somatic (body cells) cellsSomatic (body cells) cells Gametes (reproductive cells): Gametes (reproductive cells):
sperm and egg cellssperm and egg cells Chromosomes: DNA moleculesChromosomes: DNA molecules Diploid (2n): 2 sets of chromosomes Diploid (2n): 2 sets of chromosomes Haploid (1n): 1 set of chromosomesHaploid (1n): 1 set of chromosomes Chromatin: DNA-protein complexChromatin: DNA-protein complex Chromatids: replicated strands of a Chromatids: replicated strands of a
chromosomechromosome Centromere: narrowing “waist” of Centromere: narrowing “waist” of
sister chromatidssister chromatids Mitosis: nuclear divisionMitosis: nuclear division Cytokinesis: cytoplasm divisionCytokinesis: cytoplasm division Meiosis: gamete cell divisionMeiosis: gamete cell division
The Cell CycleThe Cell Cycle
Interphase Interphase (90% of cycle)(90% of cycle) • G1 phase~ growth • G1 phase~ growth
• S phase~ • S phase~ synthesis of DNA • G2 synthesis of DNA • G2 phase~ preparation for phase~ preparation for
cell divisioncell division Mitotic phaseMitotic phase
• Mitosis~ nuclear • Mitosis~ nuclear division • Cytokinesis~ division • Cytokinesis~ cytoplasm cytoplasm divisiondivision
MitosisMitosis
ProphaseProphase PrometaphasePrometaphase MetaphaseMetaphase AnaphaseAnaphase TelophaseTelophase
ProphaseProphase
Chromosomes Chromosomes visiblevisible
Nucleoli Nucleoli disappeardisappear
Sister chromatidsSister chromatids Mitotic spindle Mitotic spindle
formsforms Centrosomes Centrosomes
movemove
MetaphaseMetaphase
Centrosomes at Centrosomes at opposite polesopposite poles
Centromeres are Centromeres are alignedaligned
Kinetochores of Kinetochores of sister chromatids sister chromatids attached to attached to microtubules microtubules (spindle)(spindle)
AnaphaseAnaphase
Paired centromeres Paired centromeres separate; sister separate; sister chromatids chromatids liberatedliberated
Chromosomes move Chromosomes move to opposite polesto opposite poles
Each pole now has a Each pole now has a complete set of complete set of chromosomeschromosomes
TelophaseTelophase
Daughter nuclei Daughter nuclei formform
Nuclear Nuclear envelopes ariseenvelopes arise
Chromatin Chromatin becomes less becomes less coiledcoiled
Two new nuclei Two new nuclei complete mitosiscomplete mitosis
CytokinesisCytokinesis
Cytoplasmic Cytoplasmic divisiondivision
Animals: Animals: cleavage cleavage
furrowfurrow Plants: Plants:
cell platecell plate
The reasons that cells divide.The reasons that cells divide.• The larger the cell the more demands The larger the cell the more demands
the cell places on its DNA. the cell places on its DNA. • The second reason is it has a harder The second reason is it has a harder
time moving enough nutrients and time moving enough nutrients and wastes across the membrane.wastes across the membrane.
DNA doesn’t copy itself except for DNA doesn’t copy itself except for during cell divisionduring cell division
Why Division
Cell Cycle regulationCell Cycle regulation
Growth factors- Growth factors- protein that helps protein that helps stimulate divisionstimulate division
Density-dependent Density-dependent inhibition-crowded inhibition-crowded cells stop dividingcells stop dividing
Anchorage Anchorage dependence- must dependence- must be attached to be attached to somethingsomething
RegulatorsRegulators
These help tell cells when to divide and These help tell cells when to divide and when to stop or to not divide at all.when to stop or to not divide at all.
These are proteins that regulate cell These are proteins that regulate cell division. They are called Cyclins.division. They are called Cyclins.
There are 2 types of regulators internal There are 2 types of regulators internal and external growth factors.and external growth factors.
Cancer is uncontrolled cell growth. Cancer is uncontrolled cell growth. Because it doesn’t respond to internal Because it doesn’t respond to internal growth factors or external growth growth factors or external growth factorsfactors
InternalInternal growth factors- are proteins that growth factors- are proteins that respond to events inside the cell. respond to events inside the cell. • They don’t let it divide till all the They don’t let it divide till all the
chromosomes have been copiedchromosomes have been copied• Don’t let it go into anaphase until the Don’t let it go into anaphase until the
spindle fibers are attached spindle fibers are attached External growth factors- proteins that External growth factors- proteins that
respond to events outside the cell.respond to events outside the cell.• Tell it to speed up or slow down the cell Tell it to speed up or slow down the cell
cyclecycle• Growth factors stimulate cell growth and Growth factors stimulate cell growth and
division of cells.division of cells.• Another are molecules found on the Another are molecules found on the
surface of neighboring cells that tell the surface of neighboring cells that tell the cell to slow down or stop dividingcell to slow down or stop dividing
• These prevent excessive cell growthThese prevent excessive cell growth
CancerCancer
Transformation- change from a Transformation- change from a normal cell to cancernormal cell to cancer
Tumor: benign or malignantTumor: benign or malignant Metastasis- moveMetastasis- move