1 / 79

Chapter 8

Chapter 8 . Cell Growth. In most cases, a living thing grows because it produces more and more cells. Limits of Cell Growth. Number 1. Cell membrane- food oxygen and water enter and wastes leave. How fast things enter and leave depends on the surface area

cshaffer
Download Presentation

Chapter 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. Chapter 8 Cell Growth

  2. In most cases, a living thing grows because it produces more and more cells

  3. Limits of Cell Growth

  4. Number 1 Cell membrane- food oxygen and water enter and wastes leave

  5. How fast things enter and leave depends on the surface area How fast products are used up and waste is produced depends on the volume

  6. Fig 8-2 • Surface Area and volume do not increase at the same rate so this is a problem

  7. Number 2 • DNA’s ability to direct the function of the cell becomes limited

  8. The Solution: Cell Division • The process where by the cell divides into two daughter cells • Draw picture in notes

  9. Limits on Cell Size

  10. Controls on Cell Growth • Cell behavior – cell growth and cell division are carefully controlled • Heart and nervous system – cells rarely divide

  11. Skin and digestive tract – cells divide through life

  12. When cells come in contact with other cells they tend to stop growing

  13. Cell growth can be turned on • Example – a cut, broken bone • Cell growth stops when fixed

  14. Uncontrolled Cell Growth • Results are severe • Cancer – disorder where cells have lost the ability to control their own growth

  15. 8-2 Cell Division: Mitosis and Cytokinesis

  16. Eukaryotic Cells • Nucleus and membrane bound organelles • Eukaryotic cells divide in two steps

  17. 1. Mitosis – the process by which the nucleus of a cell is divided into 2 nuclei, each with the same number and kinds of chromosomes as the parent cell

  18. 2. Cytokinesis – process of the cytoplasm dividing to form 2 new cells

  19. The process is complex • Large amounts of DNA need to be separated. • Each cell needs one copy of a chromosome

  20. Chromosomes • Structures in the cell that contain the genetic information that is passed from one generation to the next

  21. The cells of different organisms contain different numbers of chromosomes • Humans – 46 • Goldfish – 94 • Dog – 78 • Cat – 32

  22. Chromosome Structure • Ready to divide • DNA replicated • Chromosomes become visible by condensing

  23. The chromosome has two identical parts – 2 Chromatids The chromosome has two identical parts – 2 Chromatids

  24. The two chromatids are often called sister chromatids • Centromere – holds sister chromatids together

  25. The Cell Cycle

  26. The period of time from one mitosis to the next • A cell grows, prepares for division, and divides to form two daughter cells • Includes mitosis

  27.                               ` Mitosis – M phase

  28. Interphase • G1 – growth and activity • S- DNA replication • G2 – growth and activity

  29. Some cells in the body go through the cell cycle every 6 hours • Some cells never do (nerve and muscle)

  30. Interphase • Long • Period between cell divisions • 3 phases – G1, S, G2 • G1 – (gap1) – growth and development

  31. S (DNA synthesis phase) – replication • Proteins associated with chromosomes are also made • G2- gap 2 – shortest phase • Synthesis of materials needed for cell division

  32. During interphase the cell is active • Proteins are made • DNA is copied • ATP is made and used • Cells that are specialized do their thing • Example - secretion

  33. Mitosis is divided into 4 stages.

  34. Prophase (Ready) • Metaphase (Middle) • Anaphase (away) • Telophase (two)

  35. Prophase • Longest phase • 50-60% of total mitosis time • Chromosomes become visible – coil tightly • Centrioles separate and move to opposite sides

  36. Chromosomes attach to the spindle • Nucleolus disappears • Nuclear envelope breaks down

  37. Spindle • Meshlike structure that develops from the centrioles • Helps chromosomes move

  38. Metaphase • Shortest – few minutes • Chromosomes line up at the center of the cell

  39. Anaphase • Centromeres that join sister chromatids split • Sister chromatids separates into individual chromosomes • Chromosomes separate into two groups near the poles

  40. Over when chromosomes separate

  41. Telophase • Chromosomes loosen up – go back to chromatin • Occurs in the area where the nucleus will form • Nuclear envelope reforms • Nucleolus becomes visible • Mitosis is over

More Related