1 / 33

The Cell Cycle

The Cell Cycle. Chromosomes. Chromosomes are condensed strands of DNA. Many, many genes fit on one chromosome. Chromosomes. The tips of the chromosomes are called telomeres. Chromosomes are bound in the middle with centromeres.

aviva
Download Presentation

The Cell Cycle

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. The Cell Cycle

  2. Chromosomes • Chromosomes are condensed strands of DNA. • Many, many genes fit on one chromosome.

  3. Chromosomes • The tips of the chromosomes are called telomeres. • Chromosomes are bound in the middle with centromeres. • The long arm of a chromosome is the q arm. • The short arm of a chromosomes is the p arm.

  4. Weight Height Eye Color Hair Color Genes • A gene is a section of a chromosome that codes for a specific protein (trait).

  5. Tall Medium Brown Eyes Blue Eyes Blonde Red Hair Homologous Pair Chromosomes • Each cell has two of each kind of chromosome. • They aren’t exactly alike, but they code for the same traits. • These are called HOMOLOGOUS PAIRS.

  6. Chromosomes • Usually chromosomes are all jumbled up. This is called chromatin. • Only just before division do they condense down into visible chromosomes.

  7. SIMILAR IDENTICAL Chromosomes • Before a cell duplicates, the chromosomes must duplicate as well. • The two halves of the duplicated chromosomes are called SISTER CHROMATIDS. They are exactly alike.

  8. Cell Division

  9. Periods of the Cell Cycle • G1 and G2 – Growth • S – Synthesis of DNA • M – Mitosis (Cell Division) Interphase

  10. Cell Division • Mitosis – Growth and repair • Meiosis – Creation of sex cells (gametes) • Binary Fission – Cell division in prokaryotes like bacteria

  11. Mitosis • Nuclear division • Duplicated chromosomes are evenly distributed into two daughter cells • Purposes: • Reproduction of single-cell organisms (i.e. amoebas) • Tissue repair • Cell replacement • Tissue growth (i.e. bone lengthening)

  12. Mitosis • All somatic cells (non-gametes) in an organism have the same number of chromosomes and undergo mitosis. • The chromosome number is characteristic of a given species (e.g.humans 46, goldfish 94). • Somatic cells have 2 sets of chromosomes – DIPLOID.

  13. Mitosis • Daughter cells are the GENETIC EQUIVALENT of the parent cell (they have the same number of chromosomes) • Parent cells are diploid, or 2n – this means they have 2 of each chromosome • After mitosis daughter cells will be 2n as well (if a cell is haploid or n, it did not go through mitosis – it went through meiosis) • If a cell grasshopper’s gland is 2n=24, it has 24 chromosomes • After mitosis the daughter cell will have 24 chromosomes.

  14. I Pee on the MAT

  15. Interphase • Prophase (Mitosis) • Metaphase (Mitosis) • Anaphase (Mitosis) • Telophase (Mitosis) Let's watch an animation!

  16. Interphase • G1 Phase - First growth phase • 2 pairs of centrioles begin forming • S Phase - DNA is “synthesized” (chromosomes are replicated) • Each chromosome now consists of 2 replicas called sister chromatids held together at the centromere • Proteins needed for replication produced

  17. Interphase • G2 Phase - second growth phase • Proteins made for division • Completion of replication of centriole pairs • Cell growth and metabolic activities • 90% of time

  18. Interphase

  19. Prophase • Chromatin condenses to form visible chromosomes • Nucleolus disappears • Nuclear envelope breaks down

  20. Spindle Apparatus • Forms during Prophase • Made of microtubules • Spindle fibers pull chromosomes where they need to go • Centrioles/centrosome at each pole (animals cells) • Centrosome: region of the cell that organizes the spindle. • Some cancer medications interfere with the formation of a cancer cell’s microtubules. So, the spindle can’t form and the cancer cell can’t go through mitosis.

  21. Spindles are like Fishing Poles for Chromosomes

  22. Prophase

  23. Prophase

  24. Metaphase • Spindle formation complete • Chromatids line up at cell's equatorial plane.

  25. Metaphase

  26. Anaphase • Centromeres split • Sister chromatids separate into separate chromosomes – twice as many chromosomes now! • Chromosomes are drawn to poles/centrosomes

  27. Anaphase

  28. Telophase • 2 new nuclei • Nuclear membrane re-forms • Nucleolus reappears • Spindle disassembles

  29. Telophase

  30. Cytokinesis • Division of cytoplasm into 2 daughter cells • Animal cells: Cleavage furrow forms and pinches cell in two • Plant cells: Cell plate forms at equator of cell

  31. Cell Plate in Plant Cell

  32. Mitosis Let's watch the whole process now. Source: http://highered.mcgraw-hill.com/olc/dl/120073/bio14.swf

  33. Chromosome Number Practice

More Related