1 / 38

Cell Reproduction and Division Ch 8

Cell Reproduction and Division Ch 8. Chromosomes. Chromosome : DNA wrapped up w/ histones (proteins) = organized Chromatin : uncoiled chromosome= unorganized DNA. Chromosome #. All species have their own characteristic # of chromosomes in each cell. Chromosome Number.

milica
Download Presentation

Cell Reproduction and Division Ch 8

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. Cell Reproductionand DivisionCh 8

  2. Chromosomes • Chromosome: DNA wrapped up w/ histones (proteins) = organized • Chromatin: uncoiled chromosome= unorganized DNA

  3. Chromosome # • All species have their own characteristic # of chromosomes in each cell

  4. Chromosome Number • Diploid 2n: pairs of chromosomes (1 from each parent • Haploid 1n: unpaired chromosomes (sperm or egg)

  5. Chromosome Terminology Centromere 1 Chromosome With 2 chromatids (duplicated) 1 Chromosome Centromere 2 chromosomes (both duplicated) If these are homologous it is a tetrad 2 chromosomes (Unduplicated)

  6. Chromosome Types SEX CHROMOSOMES Determine Gender • Males: XY • Females: XX • Male determines gender of the baby AUTOSOMES • All non-sex chromosomes

  7. How many C’somes do you have? • Humans: 23 pair = 46 chromosomes • Karyotype: arrangement of an individuals chromosomes

  8. Homologous Chromosomes • Have the same type of information but with different details • #2 from mom has same kind of info as #2 from dad • Which ones aren’t homologous?

  9. Haploid/Diploid

  10. 25Cell Division

  11. Cell Division in Prokaryotes • Binary Fission-Bacterial Cells reproduce asexually

  12. Mitosis & Cell Division In Eukaryotes • When a cell gets too big, it divides or stops growing • Eukaryotes first divide nucleus =Mitosis, then divide the rest =cytokinesis

  13. Cell Cycle • A cells life is divided into a cycle • Interphase, Mitosis & Cytokinesis are steps in the cycle

  14. Stages of the cell cycle • INTERPHASE = most active & majority of time • G1 stage = "GAP 1” - intense growth • Sstage = "Synthesis” • DNA replication occurs-IT DOUBLES! • G2 stage = "GAP 2” - duplicate organelles • G0 stage = exit cycle & never divide again (CNS=nerve cells) • MITOSIS • M stage = mitosis - nucleus divides • Divided into PMAT • Cytokinesis= cell divides

  15. Interphase • The cell is metabolizing, growing and preparing for mitosis • Chromosomes are not clearly seen • Where a cell spends most of its life

  16. Controlling the Cell Cycle • Length varies • 3 checkpoints based on proteins • G1, G2 and Mitosis • Errors can lead to cancer. • In cancer, regulation of the cell cycle is lost • Normal cell growth & behavior is lost.

  17. What is Mitosis? • Nuclear division • Produces two identical daughter cells during prophase, metaphase, anaphase, and telophase (PMAT).

  18. Prophase= PREPARE for division, chromosome PRESENT • Chromatin begins to condense and c’some becomes visible. • Spindle fibers form

  19. Prophase (cont.) • Nuclear membrane dissolves • Microtubules form mitotic spindle • Kinetochore fibers and polar fibers attach to centromeres

  20. Metaphase-in MIDDLE • Spindle fibers align the chromosomes in the center or equator of the cell • Helps to ensure each new nucleus will receive one copy of each chromosome.

  21. Anaphase-Chromatids APART • Chromatids separate and move to opposite sides • Spindle fibers break down • Once separate they are called chromosomes

  22. Telophase-almost TWO cells • Chromosomes arrive at opposite poles • Nuclear envelope re-forms around daughter nuclei. • Chromosomes uncoil • Spindles disappear

  23. Cytokinesis in Animal Cells • Cytoplasm is pinched (cleavage furrow) into two daughter cells

  24. Plants • In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.

  25. Meiosis - formation of gametes

  26. Sexual Reproduction • Sex cells divide by meiosis to produce haploid gamete (half the number of chromosomes) • Gametes will join & fertilize • Meiosis produces 4 gametes that are slightly different in genetic makeup from each other • Two gametes join to form 1zygote

  27. Meiosis IReduces number of chromosomes by half (diploid to haploid) PMAT I’s – separate homologous pairs • Meiosis II: Separates the sister chromatids PMAT II’s

  28. Meiosis I

  29. Meiosis II

  30. Prophase I: • Synapsis (pairing of homologous c’somes) • When crossing-over happens (genetic recombination)

  31. Crossing over: during Meiosis I Homologous pairs form tetrads, cross over and separate into individual chromosomes • Homologous c’somes exchange genetic material • Important for genetic diversity

  32. Prophase I Each tetrad has two chromo- somes & four chromatids

  33. Meiosis • Spermatogenesis: production of sperm cells • Oogenesis: production of egg cells

  34. Comparing Meiosis & Mitosis Genetic identity of progeny • Meiosis • Daughter cells have new assortment of parental chromosomes • Chromatids not identical; crossing over • Diploid to haploid • 1 cell  4 • Mitosis • Identical daughter cells • diploid • 1 cell  2

  35. Sexual Reproduction • Formation of offspring through meiosis and the union of a sperm and an egg (zygote) • Offspring are genetically different from parents

  36. Independent Assortment • Anaphase I – homologous chromosomes separate from each other • Mendel figured this out

More Related