PowerPoint Presentation

Chapter 9Cellular Basis of InheritanceBell RingerWhat happens to your skin cells when you get a cut?Divide and multiply to begin healing.Your skin is actually dead!

When a starfish loses a limb, what can the starfish do?Regrow the lost limb.

Why do cells divide?Cells divide to grow and make new cells.Cells divide to replace dead cells.Cells die when they are too old and cannot function any longer.Cells may become damaged.Single cells organisms divide to reproduce. 9.1 All cells come from cellsAsexual reproduction:Single cell or group of cells copies its DNA and then splits into two new organisms that are genetically identicalEx. Most unicellular such as Paramecium, but plants as well.

Sexual Reproduction:DNA from two parents combine to produce a genetically different organism. Most multicellular organisms. Egg + sperm = zygote

9.2 The cell cycle multiplies cells Where in the cell are the genes located?Nucleus

Cell division:Process by which a cell divides into two new cells. ChromosomeChromosome:Structures that contain the DNA that is passed from one generation to the next.

Sister jointed chromatids:Two identical copies of DNA Centromere: Area where sister chromatids of a chromosome attach.

How many chromosomes?Humans 46 chromosomes 23 pairs

Mosquito6 chromosomes 3 pairs

Banana22 chromosomes 11 pairs

Cell CycleHow often the cell divides depends on the type. Cell cycle:Series of events that cells go through as they grow and divide.

Cell CycleInterphase: Prep phase Copying DNA! The stage during which a cell carries out its metabolic processes and performs its functions.Interphase consists of G1 phase, S phase and G2 phase. G gap

G1 phase:Phase of intense growth, cells spends most of their time in this phase.S phase (synthesis):DNA is replicated, cell now contains two copies of each chromosome. Forms sister chromatids and centromere.

G2 phase: Continued preparation for cell division. Other organelles are replicated.

Mitotic phase (M phase): Cell cycle when the cell is actually dividing. Includes mitosis and cytokinesis.

Mitosis:The nucleus and the duplicated chromosomes divide and are evenly distributed. Very accurate and unique to eukaryotes.

Cytokinesis:Process where cytoplasm is divided into two.9.3 Cells divide during mitotic phase Spindle fibers:Framework of microtubules that guide the movement of chromosomes.

MitosisFour main stages.ProphaseMetaphaseAnaphaseTelophase

PMAT!MITOSISProphaseChromatin condenses into chromosomesNuclear envelope breaks downCentrioles separate and spindle fibers begin to form

MITOSISMetaphaseChromosomes line up across the center middle of the cellEach chromosome is connected to a spindle fiber at its centromere

MITOSISAnaphaseSpindle fiber pulls on chromosomesSister chromatids separate into individual chromosomes at the centromere

MITOSISTelophaseChromosomes gather at opposite ends of the cellTwo new nuclear envelopes form around each new set of chromosomesChromosomes uncoilSpindle fibers disappear

CYTOKINESISCytokinesis process in which the cytoplasm divides after mitosis

RESULT Formation of two new daughter cells each with an identical set of chromosomes

CytokinesisAnimal Cell vs. Plant CellAnimal cellsForm a cleavage furrow, where cell pinches in halfPlant cells Form a cell plate, where a new cell wall and membrane form

Eukaryotic Cell DivisionPneumonic IPlayMusicAndText ConstantlyInterphase - G1, S, G2ProphaseMetaphaseAnaphaseTelophaseCytokinesisAnimal cells cleavage furrowPlant cells cell plate

MitosisCell Cycle

Mitosis Video

http://www.youtube.com/watch?v=C6hn3sA0ip0Cancer QuestionsWhat are some causes of cancer?SmokingBad dietChemicalsRadiation AlcoholInheritance

9.4 Cancer cells grow and divide out of controlWhat is a tumor?Abnormal mass of normal cells.Benign or malignantBenign: Usually not harmful Malignant:Problematic can cause severe problems.

What is cancer?Uncontrollable cell division. Disruption telling your cells to stop dividing. Metastasis:Spread of cancer beyond their original site. Tumors usually removed by surgery. Cancer = Radiation therapy or chemotherapy (drugs)

Cancer Cells9.5 Meiosis functions in sexual reproductionMeiosis: Type of cell division that produces four cells, each with half the number of chromosomes as the parent cell. Mitosis - process by which the nucleus divides to form two nuclei, each containing a complete set of the cells chromosomesMeiosis two-stage form of cellular division that reduces the number of chromosomes per cell by one-half

Karyotype: Display of persons chromosomesHomologous chromosomes: Matching pair of chromosomes from each parent. Sex chromosomes: Determine the persons sex. X Y

Almost all human cells are diploid (2n). They contain two homologous sets of chromosomes. Single set of chromosomes are called haploid (n). Gametes are sex cells (eggs and sperm) and are haploid. For humans n= 23.What is happening in this picture?

Sperm (n) is fusing with an egg (n). This is called fertilization. The fertilized egg is called a zygote (2n).

Stages of MeiosisMeiosis 1Prophase 1: Homologous chromosomes stick together. Form a tetrad. Paired chromosomes consist of four chromosomes. Chromosomes cross over.

Metaphase 1 Tetrads line up in the middle of the cell and line up across the spindle.

Anaphase 1 Homologous chromosomes begin to separate to opposite poles.

Telophase 1 and CytokinesisChromosomes arrive at pole. Each pole has haploid set of chromosomes. Nucleus reforms and cell divides.

Meiosis 2 Prophase 2:In each haploid daughter cell, spindle forms, attaches to centromere and more chromosomes.

Metaphase 2Chromosomes line up in middle of the cell. Spindles attach to each sister chromatid.

Anaphase 2Sister chromatids separate and move to opposite poles.

Telophase 2 and CytokinesisChromosomes arrive at poles. Cytokinesis splits the cells one more time. Produces four haploid daughter cells.

Meiosis I

Diploid cell2N = 42 Haploid cellsN = 2Why does crossing-over occur?Crossing-over changes the combination of the genes on chromosomes. allows for variation among organisms

Meiosis II2 haploid cellsN = 24 haploid cellsN = 2Meiosis

http://www.youtube.com/watch?v=-DLGfd-Wpr4

9.6 Meiosis increases genetic variation among offspringCrossing over:The exchange of genetic material between homologous chromosomes.

Genetic recombination:New combination of genetic information in a gamete resulting in crossing over during prophase 1 of meiosis.

Mitosis vs. MeiosisMITOSISMEIOSISWhy does it happen?Growth, repair, replaceMake sex cells (gametes) Where does it happen in your body?When does it happen during your lifetime?Number of cells formedNumber of chromosomesNumber of cell divisionsTypes of cells formedEntire body EXCEPT.Reproductive organsFertilization Death

MalesPuberty DeathFemalesPuberty Menopause

1 cell 4 cells1 cell 2 cells46 23 23 meiosis I meiosis II2N N N meiosis I meiosis II46 462N 2NOneTwoAll EXCEPTGametes (reproductive cells)Sperm cellsEgg cells