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Cell Growth

Cell Growth. Cells cannot continue to grow indefinitely because: Too much volume, not enough surface area Not enough genetic material Cannot keep up with waste and nutrients. Chromosomes. sister chromatids. Chromosomes are made of DNA Chromatin?

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Cell Growth

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  1. Cell Growth • Cells cannot continue to grow indefinitely because: • Too much volume, not enough surface area • Not enough genetic material • Cannot keep up with waste and nutrients

  2. Chromosomes sister chromatids • Chromosomes are made of DNA • Chromatin? • Before cell division, each chromosome is replicated and consists of 2 identical “sister” chromatids • Where they attach is the centromere centromeres

  3. Cell Division in Eukaryotes • Eukaryotes divide by a process called MITOSIS. • A eukaryotic cell lives through a Cell Cycle with different phases: • Interphase = the time between cell divisions • G1 Phase • S Phase • G2 Phase • M Phase = • Mitosis • Cytokinesis

  4. The Cell Cycle —Draw this Diagram on your paper and label all parts Complete Cell Cycle = about 24 hours (in typical animal cells) 12 hr 0.5 hr Mitosis 6 hr 6 hr

  5. Interphase— Draw arrows to each phase of your drawing and write the following • Interphase is divided into 3 phases: • G1 – cell growth (organelles increase in number and size, many proteins are synthesized, and growth is fast) • S – DNA replication (synthesis of DNA) • G2 – preparation for Mitosis (more and more proteins, centrioles are replicated, more growth)

  6. Interphase • technically not part of mitosis, but it is included in the cell cycle • resting phase? • performing cell functions • DNA replicates (copies) • organelles double in number, to prepare for division

  7. Interphase(inter = between)

  8. MITOSIS • nuclear division • number of chromosomes remains the same

  9. Prophase: Draw the following on the back of your paper(pro=primary,first)

  10. ProphaseKey Events Write these notes out to the side of your drawing of prophase. • Chromatin coils to form visible chromosomes • In animals, centrioles begin to migrate to opposite poles • Spindles form at opposite ends of the cell • The nuclear envelope breaks down

  11. Metaphase: Again with the drawing…(meta is like middle) • In metaphase, the chromosomes are aligned at the middle of the cell. The spindles form the framework of the dividing cell.

  12. Anaphase: Draw some more…ana=upward,back The centromeres divide and the paired chromosomes (sister chromatids) move to opposite ends of the cell.

  13. Telophase/Cytokinesis: Should we draw?(telo=end) (cyto=cell, kinesis=movement) • In this last stage, two distinct daughter cells are formed after the chomatids have migrated to the opposite poles. Cytokinesis is also occurring at this time.

  14. What about Prokaryotes? • Most Prokaryotic Cells divide through binary fission, during which 2 identical cells are created from 1 cell.

  15. Onion Root Tip Lab • Be careful with the slides!

  16. Checkpoints in Cell Cycle • Ras cyclin—protein that checks to see if the cell is big enough to continue (occurs during G1) • p53—protein that checks for DNA damage during G1 (most common cause of cancer)

  17. Cancer- Why the checkpoints are important • Occasionally, cells lose control of the cell cycle • This results from: • failure to produce certain enzymes, • the overproduction of enzymes • Or the production of enzymes at the wrong time.

  18. Cancer • Cancer is a malignant growth resulting from uncontrolled cell division • Malignant =dangerous to health; marked by uncontrolled growth

  19. Tumors • Tumors are abnormal growth of cells • Benign tumors are non cancerous and only grow locally • Malignant tumors are cancerous and spread to other areas of the body

  20. Abnormal Cell Growth

  21. Abnormal Cell Growth

  22. A Large Abdominal Tumor

  23. Surgical Removal of Tumor

  24. Body without Tumor

  25. Cancer • Cancer is the second leading cause of death in the U.S. • Lung, colon, breast, and prostate cancers are the most prevalent types

  26. Causes of cancer Genetics Environmental Factors • Cigarette smoke • Air and water pollution • Exposure to UV radiation However, there are still unknown causes and researchers are working to discover these factors.

  27. Cancer prevention • Healthy Lifestyle • Low fat, high fiber diet • Exercise • Not smoking • Taking daily vitamins and minerals • Carotenoids, Vitamins A, C, E, and calcium

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