1 / 61

Chapter 10

Chapter 10. Cellular Growth and Division. CP BIO Ch. 10 Cell Division. Why are new cells needed? For growth and repair Replace damaged or old cells Regeneration – replace lost body part Growth For asexual reproduction Offspring are genetic copies of parent.

inez
Download Presentation

Chapter 10

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 10 Cellular Growth and Division

  2. CP BIO Ch. 10 Cell Division Why are new cells needed? • For growth and repair • Replace damaged or old cells • Regeneration – replace lost body part • Growth • For asexual reproduction • Offspring are genetic copies of parent

  3. Some organisms reproduce asexually • Offspring are genetic copies of the parent and of each other

  4. Regeneration – replace lost body part starfish can replace an arm flatworms can regrow a body Lizards can replace a tail

  5. Prokaryotic cells divide by binary fission

  6. Colorized TEM 32,500 LM 340 One-celled protists also do fission, but must do mitosis first to divide chromosomes evenly Prokaryotic chromosomes

  7. Sexual Reproduction – two parents • Genetic mix in offspring, each is different p. 274

  8. Eukaryotic nuclei contain many chromosomes Each chromosome contains thousands of genes - must be organized before cell can dividing

  9. Chromatin (loose form of chromosome) packs and condenses before a cell can divide • DNA is ALREADY COPIED (“replicated”) -coils, condenses • forms tightly packed, dense “CHROMOSOMES” • keeps copies organized and intact until cell splits

  10. DNA Groups of histones form nucleosomes chromatin DNA wraps around histones These group to form chromatin This coils and wraps until it all fits into the nucleus. One chromosome (copied and packed for cell division)

  11. SEM of human chromosomes Sister chromatids identical copies Centromere holds chromatids together Prokaryotes have a single, circular chromosome, no histones; no nucleus Double-stranded (replicated) chromosome

  12. Cell Cycle - has two phases Mitotic Phase -dividing cell Interphase – most of cell life - non-dividing cell Figure 10.7

  13. INTERPHASE G1 S(DNA synthesis) G2 Cytokinesis Mitosis MITOTICPHASE (M) G1 growth, normal life functions S “synthesis” – DNA replicates G2 final growth; prepares to divide INTERPHASE

  14. INTERPHASE G1 S(DNA synthesis) G2 Cytokinesis Mitosis MITOTICPHASE (M) Mitotic Phase A) Mitosis – chromosomes condense, organize and divide - each new cell gets one copy of every chromosome B) Cytokinesis – cytoplasm divides

  15. DNA replicates during S of interphase 1. Molecule “unzips” 2. Free nucleotides match up with open partner 3. A-T and C-G 4. Two identical molecules

  16. PHASES OF MITOSIS • PROPHASE – cell organizes & prepares • Chromatin • nuclear membrane, nucleolus disappear • spindle and asters form • Centrioles move to middle of cell • METAPHASE – chromosomes in middle • Centromeres attached to spindle fibers

  17. ANAPHASE -chromosomes separate • spindle fibers pull • chromatids to opposite poles of cell • TELOPHASE – return to normal • chromosomes relax/uncoil into chromatin • nuclear membranes form; nucleoli appear • spindle fibers disappear

  18. Cleavagefurrow SEM 140 Cleavage furrow Contracting ring ofmicrofilaments Daughter cells • CYTOKINESIS– cytoplasm divides •  2 identical daughter cells Animal cytokinesis • Cell membranes pulls in • Cytoplasm pinches in two

  19. Daughternucleus Cell plateforming Wall ofparent cell TEM 7,500 Cell wall New cell wall Vesicles containingcell wall material Cell plate Daughter cells • Plant cell cytokinesis • - cell wall is rigid • - cell plate forms • new cell wall grows • NO centriolesorasters

  20. Plant cell mitosis Same stages NO CENTRIOLES OR ASTERS

  21. Control of Cell Division Chemical signals tell a cell when to divide Normal rate: growth, repair - asexual reproduction in some organisms Slow rate: some cell types divide rarely (liver) - aging  slow healing, lose some cells Rarely or not at all: nerve, muscle, cartilage Fast rate: some cell types (skin, digestive lining) Uncontrolled cancer

  22. After forming asingle layer,cells havestopped dividing. Providing anadditional supply ofgrowth factorsstimulatesfurther cell division. Growth factors & cyclins • Chemicals secreted by cells • Can start or stop cell division

  23. Cell Growth and Healing • Injury – damaged cells secrete growth factors • Cells at edge of injury start dividing rapidly • New cells that form heal the break • As the bone heals, cell division slows

  24. Programmed Cell Deathapoptosis • Cells damaged too much to repair • – self-destruct • 2. Embryonic development – lose unneeded cells

  25. Cancer is uncontrolled cell division DNA damage Cells begin to divide abnormally Continue dividing, invade healthy tissue (malignant) Spread through blood or lymph stream, can start new tumors (metastatic)

  26. Lymphvessels Tumor Bloodvessel Glandulartissue Cancer cells invadeneighboring tissue. Cancer cells spread throughlymph and blood vessels toother parts of the body. A tumor grows from asingle cancer cell. Cancer cells do not respond to signals that regulate the cell cycle • If not treated early, cancer will spread • kills by destroying organ function

  27. What causes cancer? • Defects in genes • Cells do not make or do not respond to control signals • Environmental injury • smoking, pollution, asbestos, radiation • Genetic tendency • Some cancers run in families (colon, breast)

  28. BE CAREFUL when sunning • Wear sunscreen, sunglasses • Avoid brightest part of the day • Don’t use tanning beds

  29. The most common cancer - skin

  30. Melanoma Basal cell Squamous Cell

  31. Cancer treatment Radiation – high-energy, carefully aimed at tumor Chemotherapy – drugs specific for tumor types • interfere with cell division • some normal cells destroyed, too • Skin (lose hair); digestive lining (nausea) Surgery– remove tumor and nearby cells Boost immune system – healthydiet, reduce stress

  32. Stem cells and differentiation Differentiate – cells specialize as embryo develops Stem cell – unspecialized cell - can differentiate to form many kinds of cells - depends on chemical signals from nearby cells

  33. Kinds of Stem Cells Totipotent - can form an entire organism from one cell - fertilized egg  embryo  full organism Pluripotent - specialize to form different kinds of cells - embryo cells  all cells in an organism Multipotent – can develop into most, but not all, cell types - adult stem cells  many kinds of cells

  34. Multipotent stem cells can form tissues

  35. Ch. 11.4 MeiosisCell Division for Sexual Reproduction Sexual Reproduction - two parents a. Offspring have NEW combination of genes b. genetic mix of both parents Advantage – genetic variation a. Some may have traits that favor survival b. Variation in individuals allows a species to evolve

  36. a. CONJUGATIONb. Recipient cell gets new genes Sexual Reproduction in bacteria and protists

  37. Complex organisms – make special cells a. gametes – sperm and egg b. Gametes combine in fertilization - make a zygote  new organism

  38. Chromosome Number: Diploid and Haploid Homologous chromosomes a. matched chromosome pairs b. one member of pair from each parent c. carry genes for the same traits d. 22 pairs autosomes; one pair sex chromosomes X, Y Gene for one trait

  39. Cells with paired chromosomes are diploid a. Somatic (body) cells are diploid b. 2n (n = number) Humans: 2n = 46 2 sets of chromosomes - 2 of every gene one chromosome pair Locus – location of gene on a chromosome Fruit fly 2n = 8

  40. Humans: 2n = 46 23 pairs of chromosomes One set of 23 came from each parent Chromosomes photographed during mitosis

  41. Haploid cells have ONE set of chromosomes (n) = ONE MEMBER from EACH homologous PAIR human: n = 23 gametes - sperm or egg

  42. Meiosis is “Reduction Division” • Reduces chromosome number • from diploid to haploid • Cell DIVIDES TWICE

  43. Meiosis - two cell divisions 2n parent cell DNA replicates in interphase First division – pairs separate Second division – sister chromatids separate  4 haploid daughter cells

  44. Homologous pairs separate in MEIOSIS TWO cell divisions - Daughter cells have ½ parent chromosome number Diploid cell - Has pairs (2n=2) Meiosis I - Pairs separate (n = 1) Meiosis II - copies separate (n = 1) Haploid cells -(n = 1)

  45. Crossing over – only in meiosis a. during Prophase I b. Homologous chromatids trade pieces c. Increases genetic variation

  46. Meiosis I Prophase I Metaphase I Interphase Anaphase I Telophase I Cytokinesis

  47. Meiosis II Haploid (n) cells Doubled chromosomes Prophase II Metaphase II Telophase II Anaphase II Haploid cells Single chromosomes

  48. Compare mitosis and meiosis

  49. Making sperm and egg Sperm: 2n parent cell  4 haploid sperm Ovum: 2n parent cell  1 haploid egg + haploid polar bodies

  50. Ovum needs all the cytoplasm Sperm needs only nucleus(DNA) - flagellum - mitochondria for energy Ovum and polar body

More Related