Chapter 9: The Continuity of LifePowerPoint PresentationCharacteristics of cell divisionSlide 4Slide 5Slide 6Slide 7>>>Cell division consists of nuclear division and cytoplasmic division.Slide 9During the cell cycle the chromosomes replicate. ---Chromosomes are threadlike structures composed of chromatin, which is DNA and proteins bound to it.GenomeSlide 12Slide 13DNA ReplicationSlide 15Slide 16Sister Chromatids-If the chromosomes are photographed, the pairs can be arranged by size, shape and staining pattern to produce a karyotypeSlide 19---Diploid is the condition where cells have pairs of homologous chromosomesIn the ordinary body cells (not sperm or eggs) of many organisms the chromosomes occur in pairs.Humans: Autosomes (22 pairs) + 1 pair of sex chromosomes ---Autosomes are the non-sex chromosomes.Some cells have only half of the set of chromosomes and are called haploid. ---Haploid is the condition in which cells contain one set of chromosomes. No pairs. -the haploid condition is found only in the gametes.Slide 24Slide 25Spindle ApparatusMitosis – Early Prophase -chromatin condenses -spindle apparatus formsKinetochoresSlide 29Slide 30Slide 31Slide 32Slide 33Slide 34By the end of telophase replication of the nucleus is complete and two genetically identical daughter nuclei are present.Slide 36Slide 37MeiosisSlide 39Slide 40Slide 41Meiosis IIWhy is this necessary?Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54NO FURTHER REPLICATION OF CHROMOSOMES.Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Chapter 9: The Continuity of LifeCellular Reproduction---Cell division is the process in which the genetic information of a cell is passed along to the next generation of cells.Involves the division of a parent cell into 2 daughter cells.Characteristics of cell division Replication of DNAEqual distribution of DNA to opposite ends of the dividing cellSeparation into two daughter cellsmitotic celldivisioninterphaseDuring the cell cycle interphase alternates with mitosis (a.k.a. M phase)interphase---Interphase is the period of the cell cycle when the cell is not dividing)interphase-Interphase makes up about 90% of the cell cycle-high metabolic activity-chromosomes and organelles are duplicatedG2: cellgrowthG1: cell growth and differentiationinterphaseS: synthesis of DNA; chromosomes are duplicated>>>Cell division consists of nuclear division and cytoplasmic division.---Mitosis is the division of the nucleus. -During this process the DNA is equally distributed into 2 daughter nuclei.-The division of the nucleus is usually followed quickly by cytokinesis---Cytokinesis is the division of the cytoplasm that forms 2 separate daughter cells, each containing a single nucleus.chromatin proteinsDNADuring the cell cycle the chromosomes replicate.---Chromosomes are threadlike structures composed of chromatin, which is DNAand proteins bound to it.GenomeChromosomesChromatinDNA + proteins>>>>>>The genome of a eukaryotic cell is organized into multiple chromosomeschromosomecentromerecoiled chromatinThe eukaryotic chromosome has two “arms” which extend from a structure called the centromeregenescentromerep. 190DNA Replication•After the DNA has replicated, there are now 2 chromosomes that are attached at the centromere. •These 2 chromosomes are called sister chromatids. •So, DNA replication produces a replicated chromosome with 2 identical sister chromatids.sisterchromatidsduplicatedchromosome(2 DNA double helices)centromeresister chromatidscentromereSister Chromatids•During mitosis (cell division), the 2 sister chromatids separate, and each chromatid forms an individual chromosome.•These 2 chromosomes get split between the 2 daughter cells resulting from a mitotic division.-If the chromosomes are photographed, the pairs can be arranged by size, shape and staining pattern to produce a karyotype The y chromosome makes it male---Homologous chromosomes (homologues) are a pair of chromosomes that contain the same genes. They have the same size, centromere position and staining pattern. These are not the same as replicated chromosomes. For each pair of homologous chromosomes, you received one chromosome from your mother and one from your father.---Diploid is the condition where cells have pairs of homologous chromosomesIn the ordinary body cells (not sperm or eggs) of many organisms the chromosomes occur in pairs. -Each species has a characteristic number of chromosomes and the individual chromosomes are distinguished by size, shape, and staining pattern-Human cells contain 46 chromosomes, 23 pairs of homologous chromosomes.Humans: Autosomes (22 pairs) + 1 pair of sex chromosomes---Autosomes are the non-sex chromosomes.Some cells have only half of the set of chromosomes and are called haploid.---Haploid is the condition in which cells contain one set of chromosomes.No pairs.-the haploid condition is found only in the gametes.---Gametes are haploid egg or sperm cells and contain half the number of chromosomes of ordinary cells.Two haploid gametes unite during fertilization to form a zygote (a fertilized egg). ---Zygote is a diploid cell that results from the union of two haploid gametes.MITOSIS (a.k.a. M-phase)- Nuclear DivisionThe duplicated chromosomes are organized on a network of microtubules - and separatedThe mitotic phase (M-phase) of the cell cycle is divided into five phasesEARLY PROPHASE, LATE PROPHASE, METAPHASE, ANAPHASE AND TELOPHASESpindle Apparatus•This is part of the cytoskeleton in eukaryotic cells. •It separates the chromosomes into the daughter cells during cell division.•Remember, during S-phase, prior to cell division, the chromosomes duplicate. So each duplicated chromosome consists of a pair of sister chromatids.Mitosis – Early Prophase-chromatin condenses-spindle apparatus formsMITOSISspindle formationcondensingchromosomesPROPHASEKinetochores•These are protein structures on chromosomes where spindle fibers attach during mitosis.•Think of these as handles on the chromosomes that the spindle fibers hold onto.LATE PROPHASEkinetochorepolepole-nuclear envelope disappears-Microtubules from spindle attach to the kinetochore of chromosomes-polar microtubules radiate toward the cell’s equator. Each microtubule attaches to a separate sister chromatid.METAPHASEspindlemicrotubulesMetaphase-chromosomes move to and align on the equator of the cell.ANAPHASEPolar microtubulesAnaphase-sister chromatids divide into separate
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