Cell cycleBody cells have a life cycle called the Cell Cycle that lasts, on average, 18-24 hoursConsists of two main parts:InterphaseLong period when cells are not dividing (95%)Mitotic PhaseShort period when cell divide (5%)Some cells divide indefinitely, but slow as we ageSome cells stop dividing and stay in Interphase, temporarily or permanentlyInterphaseSubdivided into three parts:G1 (gap 1)primary growth phase, cells do their normal functions (including protein production)S (synthesis)synthesis of DNA for next cell division (DNA Replication)G2 (gap 2)final growth phase before cell division, more normal activities, duplication of organellesMitotic phaseMitosisNuclear divisionDuplicated DNA is disturbed between two daughter nucleiCytokinesisDivision of cytoplasmTwo new daughter cells are formedSemi-conservationSemi=halfReplicationDuplication of all DNA in a cell:DNA strands uncoil and unzipEach single strand serves as a template for the creation of a new complementary strandDNA nucleotides are positioned and linked by DNA polymerasePrecise base pairing (A-T, C-G) assures that an exact copy is madeEach duplicated DNA molecule consists of one “new” strand and one “old” strand of DNA, called semi conservative.MutationsAlterations or “mistakes” in the DNA codeOccur most frequently during DNA replicationCausesChemical and physical forces ( UV light, X-rays)Some mutations are repaired by repair enzymesEffects of mutations“Silent” mutations have no effectMany mutations are harmful, may result in cell death or cancerSome mutations are beneficialSister ChromatidsChromosomes before Replication consist of one DNA moleculeChromosomes after Replication consist of two duplicated DNA moleculesThe duplicate daughter chromosomes are called sister chromatidsSister chromatids are held together by a centromereHomologous Chromosomes2 chromosomes in a pair in your body, one from moms egg, one from dads sperm. Chromosomes cannot be identical since they are from different places.Homologs are pairs of chromosomes that are the same size and shape (usually) and contain the same genesOne of each pair is inherited from your mom, the other from your dadHumans have 23 pairs or 46 total chromosomesCell 23 determines the sex of babyCell reproductionTwo types of cell reproduction processes:Mitosis:Makes 2 new, genetically identical body cellsFor growth and development, and repair of lost, dead or damaged cellsGenerates new diploid cells (cells with 2 copies of each chromosomes.)Meiosis:Makes 4 genetically different sex cells (gametes eggs or sperm)For reproductionGenerates haploid gametes (cell with 1 copy of each chromosome) (made with half amount)Made with only one chromosome rather than 2, so when the eggs match up with sperm, it fits up to make a babyOne chromosome in a pair, rather than 2MitosisNuclear division (mitosis) followed by cytoplasmic divisionSequence of phases: prophase, metaphase, anaphase, telophase(PMAT) order of phases.ProphaseChromatin condenses into visible chromosomesNuclear membrane dissolvesMitotic spindle formsCentrioles migrate to cell poles(picture)MetaphaseDuplicate chromosomes form single line at the equator between centriole polesSpindle is fully formed and attached to centromeresAnaphaseSister chromatids separateDaughter chromosomes are pulled toward poles by spindle microtubulesTelophaseReverse of prophaseMitotic spindle disintegratesNuclear membranes reformChromosomes uncoil and revert to chromatinCytokinesis (division of cytoplasm) is occurringMitosis VS. Meiosis.All cells in human body divide by mitosis, except cells that form sperm and eggsAll body cells other than sperm and eggs have 46 chromosomes (23 pairs and are diploid)Gametes (sperm, eggs) have 23 chromosomes (are haploid)Reduction in chromosome number from diploid to haploid is accomplished by meiosis, a special cell division process that occurs in ovaries and testesMeiosisMeiosis includes two successive cell division processes:Meiosis IProphase I, metaphase I, anaphase I, telophase I, and cytokinesisMeiosis IIProphase II, metaphase II, anaphase II, telophase II, and cytokinesisMeiosis 1Prophase IDuplicated homologous chromosomes pair up and swap segments (crossing over)Metaphase IHomologous pairs of chromosomes line up in a double lineAnaphase IHomologs separate, but Sister Chromatids stay togetherTelophase I and CytokinesisEnd of Meiosis I: two haploid daughter cells, but chromosomes are still in duplicated stateBIOL 1140 1st Edition Lecture 8Outline of Last Lecture I. Transcription, translationa. Process, convertingII. RNA, DNAa. 3 types of DNA III. Genetic Codea. Making a protein Outline of Current Lecture I. Homologues chromosomes a. Reproduction, chromosomesII. Meiosis III. Mitosis  Cell cycle- Body cells have a life cycle called the Cell Cycle that lasts, on average, 18-24 hours- Consists of two main parts:o Interphaseo Long period when cells are not dividing (95%)o Mitotic Phase- Short period when cell divide (5%)- Some cells divide indefinitely, but slow as we age- Some cells stop dividing and stay in Interphase, temporarily or permanentlyThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Interphase- Subdivided into three parts:o G1 (gap 1)- primary growth phase, cells do their normal functions (including protein production)- S (synthesis)o synthesis of DNA for next cell division (DNA Replication)- G2 (gap 2)o final growth phase before cell division, more normal activities, duplication of organelles Mitotic phase- Mitosiso Nuclear divisiono Duplicated DNA is disturbed between two daughter nuclei - Cytokinesis o Division of cytoplasmo Two new daughter cells are formed Semi-conservationSemi=half Replication- Duplication of all DNA in a cell: o DNA strands uncoil and unzipo Each single strand serves as a template for the creation of a new complementary strando DNA nucleotides are positioned and linked by DNA polymeraseo Precise base pairing (A-T, C-G) assures that an exact copy is made o Each duplicated DNA molecule consists of one “new” strand and one “old” strand of DNA, called semi conservative. - Mutationso Alterations or “mistakes” in the DNA codeo Occur most frequently during DNA replicationo Causes Chemical and physical forces ( UV light, X-rays)- Some mutations are repaired by repair enzymes- Effects of mutationso