1 / 28

Chapter 8: Cell Reproduction

Chapter 8: Cell Reproduction. Review. Organelles Centrioles Made of microtubules Acts as anchors in cell division Mitotic Spindle fibers Two Main types Kinetochore Fibers- Attach from centriole to centromere of chromosomes and assists in movement of chromosomes

brasen
Download Presentation

Chapter 8: Cell Reproduction

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 8: Cell Reproduction

  2. Review • Organelles • Centrioles • Made of microtubules • Acts as anchors in cell division • Mitotic Spindle fibers • Two Main types • Kinetochore Fibers- Attach from centriole to centromere of chromosomes and assists in movement of chromosomes • Polar Fibers – Extend from pole to pole and keep the shape of the cell during cell division • Nuclear envelope • Double Phospholipid bilayer surrounding nucleus • Allows selective passage of RNA and other material • Nucleolus • Dense area where DNA is concentrated in the nucleus

  3. Section 8.1 • Chromosomes • Chromosome Structure • Rod-shaped and made of DNA and proteins called histones • Two full copies of DNA • Form it takes before cell division • Has two identical halves called chromatid • Chromatid • Half of the chromosome • One full copy of DNA • Attached in the center • Centromere • Center where chromatids are held together • Chromatin • Less tightly coiled DNA-protein complex • Tin = thin *Think spaghetti • Form taken during transcription

  4. Section 8.1 • Sex Chromosomes • Determine gender of the organism • May carry genes for other characteristics • Either X or Y • Female = XX Male = XY • One pair (or two chromosomes) • Autosomes • Remaining chromosomes • Contain genes for many traits • 22 pairs (or 44 chromosomes)

  5. Section 8.1 • Homologous Chromosomes • Two copies of each autosome • One copy from each parent • Same size and shape • Carry genes for the same trait • Karyotype • Photomicrograph of chromosomes • Notice there are 22 pairs of autosomes and 1 pair of sex chromosomes • What is the gender of this organism?

  6. Section 8.1 • Diploid • Cells that are diploid contain two autosomes from each homologous pair and two sex chromosomes • Abbreviated as 2n • Memory key * di = two • Occurs in all cells except sperm and egg cells • Haploid • Cells contain only one set of chromosomes • Therefore, half the number of chromosomes of a diploid cell • Abbreviated as 1n • Memory key * hap = half • Sperm cell (1n) and egg cell (1n) create a diploid cell (2n)

  7. Section 8.1 Notice high number of chromosomes in fern compared to humans!

  8. Section 8.1 • Activity • Create a karyotype! • Arrange in pairs according to length, centromere position, and banding pattern • Questions • How many autosomes are there? How many sex chromosomes? • Is the organism a male or female? • Why are karyotypes important tools for geneticists? • Homework • Review questions on p. 153 #1-5

  9. Section 8.1 Review Answers • Name the proteins that DNA wraps around to form a chromosome in eukaryotic cells. • Histones. • How do the structure and location of a prokaryotic chromosome differ from that of a eukaryotic chromosome? • A prokaryotic chromosome consists of a circular DNA molecule. Eukaryotic chromosomes are rod-shaped, associated with histone and nonhistone proteins, and found within the cell’s nucleus. • Does chromosome number indicate whether an organism is a plant or animal? Explain. • No. For example, chimpanzees have the same number of chromosomes as potatoes or plums.

  10. Section 8.1 Review Answers 4. Contrast sex chromosomes with autosomes. • Sex chromosomes determine the gender of an organism. Autosomes are all of the other chromosomes in an organism. 5. Using Table 8-1, list the haploid and diploid number of chromosomes for each organism.

  11. Section 8.1 Review Answers

  12. Section 8.2 • Cell Cycle • Repeating set of events in the life of a cell • Interphase • Time between cell divisions • Three phases • G1 – Cell growth • S – DNA is copied • G2 – Growth and prep for cell division • Cell division • Two phases • Mitosis – Nucleus of the cell divides • Cytokinesis – Division of the cell’s cytoplasm

  13. Section 8.2 • Cell Division • Prokaryotes • Remember: Has cell wall, no nuclei, no membrane-bound organelles • Binary fission • Division of prokaryotic cell into two offspring cells

  14. Section 8.2 • Cell Division (cont’d) • Eukaryotes • Mitosis • Division of the nucleus • Four stages (Prophase, Metaphase, Anaphase, Telophase) • Cytokinesis • In animal cells, pinching of cell membrane occurs • Cleavage furrow • In plants, cell plate formation

  15. Section 8.2 • Control of Cell Division • Checkpoints = traffic signal • Three main checkpoints • G1 checkpoint • G2 checkpoint • Mitosis checkpoint

  16. Section 8.2 • Activity • Venn diagram: Cell division in Prokaryotes vs Eukaryotes • Karyotype Part 2 • Homework • Create the cell cycle

  17. Section 8.2 (cont’d) • Mitosis • Prophase • Tight coiling of DNA into chromosomes • Nucleolus and nuclear membrane break down • Centrosomes appear and move to opposite ends of the cell • Kinetochore fibers extend from kinetochore from each chromatid to centrosome • Metaphase = Middle • Kinetochore fibers move chromosomes to center of cell • All chromosomes line up in a single file line

  18. Section 8.2 • Anaphase • Chromosomes separate at the centromere and chromatids move to opposite poles • Chromatids are now considered individual chromosomes • Telophase • Spindle fibers disassemble • Chromosomes return to less tightly coiled chromatin state • Nuclear envelope forms around each set of chromosomes • Nucleolus forms in each of the newly forming cells • Animation

  19. Mitosis vs Meiosis • Where do they occur? • Mitosis – in the body cells • Meiosis – in the germ cells • Why does it occur? • Mitosis • Asexual reproduction • Growth and development • To replace old cells • Meiosis • Formation of gametes (egg and sperm cells) that will be used in sexual reproduction

  20. Mitosis vs Meiosis • End result? 46 46 23 23 46 46 23 23 23 23 MEIOSIS MITOSIS

  21. Meiosis • Also known as reduction division • Occurs in germ cells found in the ovaries and testes • Produces sex cells which are haploid • Occurs in two phases • Meiosis I • Reduces the number of chromosomes from diploid to haploid • Meiosis II • Produces four haploid daughter cells

  22. Meiosis I

  23. Meiosis I • Prophase I • DNA coils tightly into chromosomes • Spindle fibers appear • Nucleolus and nuclear envelope disassemble • Synapsis =Pairing of homologous chromosomes • Tetrad =Pair of homologous chromosomes twisted around each other • Crossing over may occur • Genetic recombination

  24. Meiosis I • Metaphase I • Spindle fibers attach to centromere of tetrads • Tetrads line up along midline • Anaphase I • Homologous chromosome pairs are separated and move to opposite poles • Independent assortment occurs • Telophase I • Chromosomes reach opposite ends of cell • Spindle Fibers disappear • Cytokinesis begins

  25. Meiosis II

  26. Meiosis II • Prophase II • Spindle fibers form and attach to the centromeres of the double stranded chromosomes • Metaphase II • Chromosomes are moved to the midline of the dividing cell • Anaphase II • Chromatids separate and move toward opposite poles • Telophase II • Nuclear membrane forms in each of the four new cells • Cytokinesis II occurs resulting in four new cells, each with half the original cell’s number of chromosomes

  27. Section 8.3 • Results of mitosis vs. meiosis

  28. Section 8.3 • Development of Gametes • Spermatogenesis • Oogenesis • Polar bodies • Sexual reproduction

More Related