Presentation on theme: "Chapter 13:The Cell Cycle"— Presentation transcript:
1 Chapter 13:The Cell Cycle Adapted from: Kim Foglia
2 How did you get from there to here? And now look at you…How did you get from there to here?
3 Getting from there to here… Cell divisioncontinuity of life = reproduction of cellsreproductionunicellular organismsgrowthrepair & renewCell cyclelife of a cell from origin to division into 2 new daughter cellsUnicellular organismsCell division = reproductionReproduces entire organism& increase populationMulticellular organismsCell division provides for growth & development in a multicellular organism that begins as a fertilized eggAlso use cell division to repair & renew cells that die from normal wear & tear or accidents
4 A bit about DNA DNA is organized in chromosomes double helix DNA moleculeassociated proteins = histone proteinsNucleosome = a segment of DNA wrapped around 8 histone proteinsDNA-protein complex = chromatinorganized into long thin fiber
6 Chromosome Duplicated chromosome consists of 2 sister chromatids meet at the centromerecontain identical copies of the chromosome’s DNATelomeres = repeated sequence at end of each armp= short arm; q= long armCentromeres are segments of DNA which have long series of tandem repeats = 100,000s of bases long. The sequence of the repeated bases is quite variable. It has proven difficult to sequence.
8 Prokaryotic Chromosome Structure Bacteria have a one single loop of DNA
9 Types of Cells & Ploidy Levels There are two types of human cells: somatic cells and gametes.Somatic Cells = body cells (brain, muscle, heart, liver, skin, etc)Contain 46 chromosomes in humansDiploid (2n)= cell that contains two sets of homologous chromosomes23 PAIRS of homologous chromosomes = 46 TOTAL chromosomesGametes = sex cells (sperm or egg)Contain 23 chromosomes in humansHaploid (n)= cell that contains one set of chromosomes
10 FertilizationWhen sperm meets egg a zygote is formed. A zygote is the first cell of the embryo. Which of the cells above are haploid (n)? Diploid (2n)?
11 Homologous Chromosomes Chromosomes containing the same type of genetic informationone comes from male parent, one comes from female parentDADMOM
13 The chromosomes diagrammed below are arranged in a karyotype, the 46 chromosomes have been arranged in homologous pairs.
14 The first 22 pairs of homologous chromosomes are called autosomes or autosomal chromosomes. The 23rd pair of chromosomes determines the sex of the individual and are calledsex chromosomes.The sex chromosomes of a female are XX.The sex chromosomes of a male are XY.
16 Cell cycle Cell has a “life cycle” cell is formed from a mitotic divisioncell grows & maturesto divide againcell grows & matures to never divide againG1, S, G2, Mliver cellsG0epithelial cells, blood cells,stem cellsbrain nerve cells
17 Cell Division cycle Phases of a dividing cell’s life interphase cell growsreplicates chromosomesproduces new organelles & biomoleculesmitotic phasecell separates & divides chromosomesmitosiscell divides cytoplasm & organellescytokinesis
19 Interphase 90% of cell life cycle Characteristics cell doing its “everyday job”produce RNA, synthesize proteinsprepares for duplication if triggeredCharacteristicsnucleus well-definedDNA loosely packed in long chromatin fibers
20 Interphase Divided into 3 phases: G1 = 1st Gap S = DNA Synthesis G2 = 2nd Gap
21 Interphase G1 – First stage after division Cell recovers from previous divisionCell increases in sizeDoubles organellesAccumulates materials for DNA replicationCells do everyday jobsG0 – Some cells don’t complete the cycle (nerve and heart muscle)Continue normal cell operationsNo preparation for cell divisionCells will operate in this stage until organism dies9.1
22 Interphase S Stage – DNA synthesis occurs At the beginning it contains chromosomes containing one DNA strandAt the end each chromosome contains two identical strands of DNACopies chromosomesG2 – Growth & final preparations for divisionPrepares for divisionEnds with mitosisProteins that aid in mitosis are made in this stageMicrotubulesNucleus well-definedDNA loosely packed9.1
23 Interphase Nucleus well-defined Prepares for mitosis chromosome duplication completeDNA loosely packed in long chromatin fibersPrepares for mitosisproduces proteins & organelles
24 Mitosis copying cell’s DNA & dividing it between 2 daughter nuclei Mitosis – division of the nucleusis divided into 5 phasesProphasePrometaphasemetaphaseanaphasetelophase
26 Prophase Chromatin (DNA) condenses visible as chromosomes chromatidsfibers extend from the centromeresCentrioles move to opposite poles of cellFibers (microtubules) cross cell to form mitotic spindleactin, myosinNucleolus disappearsNuclear membrane breaks down
27 Prometaphase Proteins attach to centromeres creating kinetochoresMicrotubules attach at kinetochoresconnect centromeres to centriolesChromosomes begin moving
28 Kinetochore Each chromatid has own kinetochore proteins microtubules attach to kinetochore proteins
29 Metaphase Spindle fibers align chromosomes along the middle of cell meta = middlemetaphase platehelps to ensure chromosomes separate properlyso each new nucleus receives only 1 copy of each chromosome
31 Anaphase Sister chromatids separate at kinetochores move to opposite polespulled at centromerespulled by motor proteins “walking”along microtubulesincreased production of ATP by mitochondriaPoles move farther apartpolar microtubules lengthen
32 Separation of chromatids In anaphase, proteins holding together sister chromatids are inactivatedseparate to become individual chromosomes1 chromosome2 chromatids2 chromosomes
33 Chromosome movementKinetochores use motor proteins that “walk” chromosome along attached microtubulemicrotubule shortens by dismantling at kinetochore (chromosome) endMicrotubules are NOT reeled in to centrioles like line on a fishing rod.The motor proteins walk along the microtubule like little hanging robots on a clothes line.In dividing animal cells, non-kinetochore microtubules are responsible for elongating the whole cell during anaphase, readying fro cytokinesis
34 Telophase Chromosomes arrive at opposite poles Spindle fibers disperse daughter nuclei formnucleoli fromchromosomes disperseno longer visible under light microscopeSpindle fibers disperseCytokinesis beginscell division
35 Cytokinesis Animals cleavage furrow forms ring of actin microfilaments forms around equator of cellmyosin proteinstightens to form a cleavage furrow, which splits the cell in twolike tightening a draw stringDivision of cytoplasm happens quickly.
36 Cytokinesis in Animals (play Cells Alive movie here)
39 Cytokinesis in Plants Plants vesicles move to equator line up & fuse to form 2 membranes = cell platederived from Golginew cell wall is laid down between membranesnew cell wall fuses with existing cell wall