Cell Life, Division, and Reproduction

Specialized Cells Cells are specialized – have particular function/role Ex: nerve, blood, muscle, sperm, etc Ex: nerve, blood, muscle, sperm, etc

Specialized Cells Nerve cell – Transmits electrical signals throughout body

Specialized Cells Blood Cell Blood Cell - Carries Oxygen throughout our bodies to our organs

Specialized Cells Muscle Cell – contracts to assist the movement of organisms

Specialized Cells Sperm Cells – sexual reproductive cell for animals

Specialized Cells Xylem – transports water in vascular plants (plants on land)

Specialized Cells Phloem – carries sugars and other organic tissues for plants

Cell Life Organisms begin as masses of undifferentiated cells DNA expression determines what each cell be

Cell Life Have same chromosomes and DNA Differentiation – only PARTS of DNA activated  determines function/structure of cell All cells have potential to be any cell Differentiation occurs, it is irreversible

Cell Life Different genetic instructions used in different types of cells Cells environment and history Cells environment and history Chemical signals released by other cells Chemical signals released by other cells

Cell Life Stem Cells – unspecialized cells that reproduce and have ability to specialize into many types of cells Embryonic – found in embryos Embryonic – found in embryos Adult – found in organisms Adult – found in organisms /watch?v=8JTw2RpDo9 o ?v=tPulEAryPO0&feature=relat ed tch?v=slh88WmR8QA&feat ure=related

Cell Cycle Interphase (cell growth) Interphase (cell growth) Mitosis (nuclear division) Mitosis (nuclear division) Cytokinesis (cell division) Cytokinesis (cell division)

Interphase Most life of cell in interphase Prepares for division by duplicating chromosomes Centrioles replicate

Interphase G1- Cell Grows S (synthesis)- Replication of DNA G2- cell prepares to divide

Mitosis Cell (somatic) copies it’s DNA and divides to create two new daughter cells - identical to parent Create new cells Create new cells Replace damaged or old cells Replace damaged or old cells Cell growth Cell growth When cell approaches max size When cell approaches max size Stages: (phase) pro-, meta-, ana-, telo- pro-, meta-, ana-, telo-

Organization of DNA Before replication, DNA is organized from Chromatin to Chromosomes. Chromatin – long strands of DNA around histones Pg 244

Organization of DNA 1.Chromatid - one of the two identical parts of the chromosome, or “sisters” 2.Centromere - Point of attachment. Pg 244

Prophase -Chromosomes get small, centrioles move to the poles of the cell, and spindle fibers develop Pair of Centrioles Spindle Fibers Chromosomes consisting of 2 Sister Chromatids

Prophase - Nuclear Envelope disintegrates, spindle fibers move chromosomes toward the center of cell. Spindle Fibers Chromosomes

Metaphase - Chromosomes line up across center of the cell Spindle Fibers Chromosomes Center of Cell

Anaphase - Chromatids move apart and travel to opposite ends of cellular spindle Chromatids Chromosome Chromatid

Telophase - envelope surrounds each set of Chromatids to form new Nucleus and the Cytoplasm starts to divide Cleavage Furrow

Cytokinesis - Cytoplasm divides and two cells with identical genetic material are formed Daughter Cells

Cytokinesis In plants Cell plate laid down across middle Cell plate laid down across middle Membrane forms around each cell Membrane forms around each cell Cell walls form on each side Cell walls form on each side In animals Plasma membrane pinches in Plasma membrane pinches in

Mitosis

Cell Size Limitations Diffusion- diffusion is slow DNA – has to be enough to support protein needs Surface area-to-volume ratio too large, cell cannot function properly

Control of Cell Cycle Controlled by cyclin proteins and enzymes Controlled by cyclin proteins and enzymes Cells lose control – over/under/failure of production or certain enzymes Cells lose control – over/under/failure of production or certain enzymes Loss of control = malignant growth “Cancer” Loss of control = malignant growth “Cancer”

Cancer Masses, or tumors, deprive cells from nutrients Masses, or tumors, deprive cells from nutrients Second leading C.O.D. in U.S. Causes- Environmental factors Environmental factors Some more prone than others Some more prone than others

Cancer Prevention Healthy Lifestyle Low fat high fiber Low fat high fiber Fruits, vegetables, grains Fruits, vegetables, grains Vitamins and minerals Vitamins and minerals Exercise and tobacco free!! Exercise and tobacco free!!

Meiosis Why We Are Who We Are Pg 276

Why Meiosis? Mitosis- cells are clones (asexual) Parent cell – n# of chromosomes; Daughter cells – n# of chromosomes Parent cell – n# of chromosomes; Daughter cells – n# of chromosomes Offspring would have 2x chromosomes Offspring would have 2x chromosomes Meiosis – division of sex cells Offspring has same number of chromosomes after fertilization Offspring has same number of chromosomes after fertilization Diploid – Haploid (sex cells) Diploid – Haploid (sex cells)

Diploid Di= two Contains both sets of homologous chromosomes Number of chrms in diploid cell represented by 2N

Haploid Haploid Means “one set” Only one set of chromosomes Gametes (sex cells) Sperm and egg Sperm and egg Represented by N Zygote- fertilized egg; sexual reproduction Turns into multicellular by mitosis Turns into multicellular by mitosis

Meiosis Number of chromosomes is cut in half through the separation of homologous chromosomes in a diploid cell

Chromosome Number Homologous chromosomes Chromosome that has a corresponding chromosome, one from each parent Chromosome that has a corresponding chromosome, one from each parent Sister chromatid Tetrad

Meiosis Meiosis I A diploid cell enters here PMAT 1 Meiosis II The diploid cell that entered meiosis has become 4 haploid cells PMAT 2

Phases Prophase 1 Each chromosome pairs with its homologous chromosome Each chromosome pairs with its homologous chromosome Exchange portions of chromatids in the process …. CROSSING OVER Exchange portions of chromatids in the process …. CROSSING OVER

Crossing Over

Metaphase 1 Spindle fibers attach to chromosomes and line them up side by side Anaphase 1 The spindles pull homologous chromosomes apart to opposite poles/ends Telophase 1 Nuclear membranes form and cell separates into two new cells

Meiosis II Simply mitotic division of products Only difference is chromosomes do not replicate before they divide

Genetic Variation Genetic recombination Reassortment of chromosomes by crossing over or segregation of homol. chromosomes Reassortment of chromosomes by crossing over or segregation of homol. chromosomesPolyploidy More than two sets; often in plants More than two sets; often in plants

Nondisjunction Trisomy – has an extra chromosome Gamete with extra fuses with gamete with one Gamete with extra fuses with gamete with one Monosomy- missing chromosome (fatal) Homologous chrms. do not separate, can cause tri and tetrasomy Homologous chrms. do not separate, can cause tri and tetrasomy

Nondisjunction Types XO – Turner’s syndrome XO – Turner’s syndrome XXX – Trisomy X (metafemales) XXX – Trisomy X (metafemales) XXY – Klinefelter’s syndrome XXY – Klinefelter’s syndrome XYY- Jacob’s Syndrome XYY- Jacob’s Syndrome OY – males (lethal) OY – males (lethal)

Gene Linkage and Maps Linked – genes close on same chromosome inherited together Linked – genes close on same chromosome inherited together Can separate via crossing over Gene combinations to make chromosome map w/ relative locations Gene combinations to make chromosome map w/ relative locations