Ch. 03 Cell


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Also includes DNA, RNA and mitosis

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Ch. 03 Cell

  1. 1. Chapters 3 & 4 Cells, DNA, Mitosis & RNA
  2. 2. Cells <ul><li>vary in size </li></ul><ul><li>vary in shape </li></ul><ul><li>measured in micrometers </li></ul>
  3. 3. A Composite Cell <ul><li>hypothetical cell </li></ul><ul><li>major parts </li></ul><ul><ul><li>nucleus </li></ul></ul><ul><ul><li>cytoplasm </li></ul></ul><ul><ul><li>cell membrane </li></ul></ul>
  4. 4. Cell Membrane <ul><li>outer limit of cell </li></ul><ul><li>selectively permeable – controls what moves in and out of the cell </li></ul><ul><li>phospholipid bilayer </li></ul><ul><ul><li>hydrophilic  water-soluble “heads” form surfaces </li></ul></ul><ul><ul><li>hydrophobic  water-insoluble “tails” form interior </li></ul></ul>
  5. 5. Cell Membrane
  6. 6. Cytoplasmic Organelles <ul><li>Endoplasmic Reticulum </li></ul><ul><ul><li>transportation system </li></ul></ul><ul><ul><li>Rough ER </li></ul></ul><ul><ul><ul><li>studded with ribosomes </li></ul></ul></ul><ul><ul><ul><li>protein and lipid synthesis </li></ul></ul></ul><ul><ul><li>Smooth ER </li></ul></ul><ul><ul><ul><li>lipid synthesis </li></ul></ul></ul><ul><ul><ul><li>break down of drugs </li></ul></ul></ul><ul><li>Ribosomes </li></ul><ul><ul><li>free floating or connected to ER </li></ul></ul><ul><ul><li>site of protein synthesis </li></ul></ul>
  7. 7. Cytoplasmic Organelles <ul><li>Golgi apparatus </li></ul><ul><ul><li>group of flattened, membranous sacs (pancakes) </li></ul></ul><ul><ul><li>packages and modifies proteins then ships </li></ul></ul><ul><ul><li>“ Fed Ex” </li></ul></ul><ul><li>Mitochondria </li></ul><ul><ul><li>powerhouse of the cell (energy)  ATP </li></ul></ul><ul><ul><li>looks like a jellybean with squiggles </li></ul></ul>
  8. 8. Cytoplasmic Organelles <ul><li>Lysosomes </li></ul><ul><ul><li>digest worn out cell parts or unwanted substances via enzymes </li></ul></ul><ul><ul><li>Like “Lysol” they kill unwanted things  </li></ul></ul><ul><li>Peroxisomes </li></ul><ul><ul><li>break down organic molecules </li></ul></ul><ul><li>Centrosome </li></ul><ul><ul><li>two rod-like centrioles </li></ul></ul><ul><ul><li>distributes chromosomes during cell division </li></ul></ul>
  9. 9. Cytoplasmic Organelles <ul><li>Cilia </li></ul><ul><ul><li>short hair-like projections </li></ul></ul><ul><ul><li>propel substances on cell surface </li></ul></ul><ul><li>Flagellum </li></ul><ul><ul><li>long tail-like whip </li></ul></ul><ul><ul><li>provides motility to sperm </li></ul></ul>
  10. 10. Cytoplasmic Organelles <ul><li>Vesicles </li></ul><ul><ul><li>membranous sacs </li></ul></ul><ul><ul><li>store substances </li></ul></ul><ul><ul><li>GA and ER packs things into vesicles! </li></ul></ul><ul><li>Microfilaments and microtubules </li></ul><ul><ul><li>thin rods and tubules </li></ul></ul><ul><ul><li>give cytoplasm strength </li></ul></ul><ul><ul><li>allows for movement of organelles </li></ul></ul>
  11. 11. Cell Nucleus <ul><li>control center of cell </li></ul><ul><li>nuclear envelope </li></ul><ul><ul><li>porous double membrane </li></ul></ul><ul><ul><li>separates nucleoplasm from cytoplasm </li></ul></ul><ul><li>nucleolus </li></ul><ul><ul><li>dense collection of RNA and proteins </li></ul></ul><ul><ul><li>site of ribosome production </li></ul></ul><ul><li>chromatin </li></ul><ul><ul><li>fibers of DNA and proteins </li></ul></ul><ul><ul><li>stores information for synthesis of proteins </li></ul></ul>
  12. 12. Structure of DNA <ul><ul><li>Pages 115-117 </li></ul></ul><ul><ul><li>Double helix </li></ul></ul><ul><ul><li>Sugar and phosphates on the sides </li></ul></ul><ul><ul><li>Bases pairs as the rungs </li></ul></ul><ul><ul><ul><li>Adenine and Thymine (2) </li></ul></ul></ul><ul><ul><ul><li>Cytosine and Guanine (3) </li></ul></ul></ul><ul><ul><li>DNA wrapped about histones forms chromosomes </li></ul></ul>
  13. 13. DNA Replication <ul><li>Unwind </li></ul><ul><li>Unzip </li></ul><ul><li>Complementary base pairs (A  T, C  G) </li></ul><ul><ul><li>In order </li></ul></ul><ul><ul><li>Okazaki fragments </li></ul></ul><ul><li>Proofreading enzyme </li></ul><ul><li>Winds back up again </li></ul>
  14. 14. Simple Diffusion <ul><li>movement of substances from regions of higher concentration to regions of lower concentration </li></ul><ul><li>requires no energy, happens naturally </li></ul>
  15. 15. Facilitated Diffusion <ul><li>diffusion across a membrane with the help of a channel or carrier molecule </li></ul><ul><li>Still requires </li></ul><ul><li>no energy </li></ul>
  16. 16. Osmosis <ul><li>movement of water through a selectively permeable membrane from regions of higher concentration to regions of lower concentration </li></ul><ul><li>Diffusion of water </li></ul><ul><li>Still no energy needed </li></ul>
  17. 17. How osmosis affects the body, especially RBCs <ul><li>Isotonic solution- same inside and out, no net change </li></ul><ul><li>Hypertonic solution- solution outside is stronger so water leaves the cell to dilute the outside; cell shrivels </li></ul><ul><li>Hypotonic solution- solution outside is weaker so water goes into the cell to dilute the cell; cell swells and may burst </li></ul>
  18. 18. Filtration <ul><li>smaller molecules are forced through porous membranes </li></ul><ul><li>Ex: molecules leaving blood capillaries </li></ul><ul><li>Still requires no energy </li></ul>
  19. 19. Movements Into and Out of the Cell <ul><li>Passive Transport </li></ul><ul><ul><li>NO cellular energy </li></ul></ul><ul><ul><li>simple diffusion </li></ul></ul><ul><ul><li>facilitated diffusion </li></ul></ul><ul><ul><li>osmosis </li></ul></ul><ul><ul><li>filtration </li></ul></ul>
  20. 20. Active Transport <ul><li>carrier molecules transport substances across a membrane from regions of lower concentration to regions of higher concentration </li></ul><ul><li>“ going against the flow” </li></ul><ul><li>REQUIRES ENERGY </li></ul>
  21. 21. Endocytosis <ul><li>cell engulfs a substance by forming a vesicle around the substance </li></ul><ul><li>REQUIRES ENERGY </li></ul>Pinocytosis - cell drinking Phagocytosis - cell eating
  22. 22. Exocytosis <ul><li>reverse of endocytosis </li></ul><ul><li>substances in a vesicle fuse with cell membrane </li></ul><ul><li>contents released outside the cell </li></ul><ul><li>REQUIRES ENERGY </li></ul>
  23. 23. Transcytosis <ul><li>endocytosis followed by exocytosis </li></ul><ul><li>transports a substance rapidly through a cell </li></ul><ul><li>Ex: HIV crossing a cell layer </li></ul>
  24. 24. Movements Into and Out of the Cell <ul><li>Passive (Physical) Processes </li></ul><ul><ul><li>NO cellular energy </li></ul></ul><ul><ul><li>simple diffusion </li></ul></ul><ul><ul><li>facilitated diffusion </li></ul></ul><ul><ul><li>osmosis </li></ul></ul><ul><ul><li>filtration </li></ul></ul><ul><li>Active (Physiological) Processes </li></ul><ul><ul><li>REQUIRE cellular energy </li></ul></ul><ul><ul><li>active transport </li></ul></ul><ul><ul><li>endocytosis </li></ul></ul><ul><ul><li>exocytosis </li></ul></ul><ul><ul><li>transcytosis </li></ul></ul>
  25. 25. The Cell Cycle <ul><li>4 major stages </li></ul><ul><ul><li>interphase </li></ul></ul><ul><ul><li>mitosis </li></ul></ul><ul><ul><li>cytokinesis </li></ul></ul><ul><ul><li>differentiation </li></ul></ul>
  26. 26. Interphase <ul><li>very active period </li></ul><ul><li>cell grows </li></ul><ul><li>cell maintains routine functions </li></ul><ul><li>Divided into 3 phases </li></ul><ul><ul><li>G 1 phase – cell grows and synthesizes organelles </li></ul></ul><ul><ul><li>S phase – DNA replication </li></ul></ul><ul><ul><li>G 2 phase - more cell growth until mitosis occurs </li></ul></ul>
  27. 27. Mitosis <ul><li>produces two daughter cells from an original cell </li></ul><ul><li>Stages (PMAT) </li></ul><ul><ul><li>P rophase – chromosomes become visible; nuclear envelope disappears; centrioles move to opposite sides </li></ul></ul><ul><ul><li>M etaphase – chromosomes line up down the m iddle </li></ul></ul><ul><ul><li>A naphase – chromosomes move a part to opposite sides </li></ul></ul><ul><ul><li>T elophase – chromosomes uncoil; nuclear envelope forms (opposite of prophase) </li></ul></ul>
  28. 28. Mitosis
  29. 29. Cytokinesis <ul><li>begins during anaphase </li></ul><ul><li>continues through telophase </li></ul><ul><li>contractile ring pinches cytoplasm in half </li></ul>
  30. 30. Differentiation
  31. 31. Control of Cell Division <ul><li>cell division capacities vary greatly among cell types </li></ul><ul><ul><li>skin and blood cells divide often </li></ul></ul><ul><ul><li>liver cells divide a specific number of times then cease </li></ul></ul><ul><li>chromosome tips ( telomeres ) that shorten with each mitosis provide a mitotic clock </li></ul><ul><li>cells divide to provide a more favorable surface area to volume relationship </li></ul><ul><li>growth factors and hormones stimulate cell division </li></ul><ul><ul><li>hormones stimulate mitosis of smooth muscle cells in uterus </li></ul></ul><ul><ul><li>epidermal growth factor stimulates growth of new skin </li></ul></ul><ul><li>tumors are the consequence of a loss of cell cycle control </li></ul><ul><li>contact inhibition </li></ul>
  32. 32. Tumors <ul><li>Two types of tumors </li></ul><ul><ul><li>benign – usually remains localized </li></ul></ul><ul><ul><li>malignant – invasive and can metastasize; cancerous </li></ul></ul><ul><li>Genes that cause cancer </li></ul><ul><ul><li>oncogenes – activate other genes that increase cell division </li></ul></ul><ul><ul><li>tumor suppressor gene – normally regulate mitosis; if inactivated they will not regulate mitosis </li></ul></ul>
  33. 33. RNA Molecules <ul><li>Messenger RNA (mRNA) - </li></ul><ul><ul><li>delivers genetic information from nucleus to the cytoplasm </li></ul></ul><ul><ul><li>single polynucleotide chain </li></ul></ul><ul><ul><li>formed beside a strand of DNA </li></ul></ul><ul><ul><li>RNA nucleotides are complementary to DNA nucleotides (exception – no thymine in RNA; replaced with uracil) </li></ul></ul><ul><ul><li>making of mRNA is transcription </li></ul></ul>
  34. 34. RNA Molecules <ul><li>Transfer RNA (tRNA) - </li></ul><ul><ul><li>carries amino acids to mRNA </li></ul></ul><ul><ul><li>carries anticodon to mRNA </li></ul></ul><ul><ul><li>translates a codon of mRNA into an amino acid </li></ul></ul><ul><li>Ribosomal RNA (rRNA) – </li></ul><ul><ul><li>provides structure and enzyme activity for ribosomes </li></ul></ul>
  35. 35. Protein Synthesis
  36. 36. Protein Synthesis