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Cells

Cells . Chapter 7. Cell Theory. 1665- Robert Hooke examines cork Named the little “boxes” cells 150 years later, several other scientists combined ideas to form Cell Theory: Living things have cells Cells are basic units of structure and function

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Cells

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  1. Cells Chapter 7

  2. Cell Theory • 1665- Robert Hooke examines cork • Named the little “boxes” cells • 150 years later, several other scientists combined ideas to form Cell Theory: • Living things have cells • Cells are basic units of structure and function • Cells come from reproduction of existing cells

  3. Check yourself! • Can cells appear spontaneously without genetic material from previous cells?

  4. Cell Types • Come up with a list of all the different cells that might be in your body. • What shape/size might they be? • Do they have anything in common? • How are they different?

  5. Cells • All cells have • A plasma (cell) membrane • Genetic material in some form • Break down molecules for energy • Can be one of two types: • Prokaryotic- cells with no nucleus, smaller • Eukaryotic- cells with a nucleus, larger, have organelles • Fig. 7.4

  6. Eukaryotic Cells • Have: • Membrane bound organelles (organelles are structures that carry out specific functions) • Nucleus- contains the cell’s genetic material in the form of DNA • Multi-cellular organism (plus algae and yeast)

  7. Prokaryotic Cells • Have: • Plasma membrane • No nucleus • No membrane-bound organelles • Very simple organisms • Could have been the first on Earth • Thought that eukaryotes evolved from prokaryotes • Been classified as bacteria, usually

  8. Prokaryote Examples Cocci Bacteria -Round -Streptococci

  9. Bacilli Bacilli -Rod Shaped

  10. Spirilli -Spiral shaped

  11. Video Lab • DVD • Time: 7.57 • Identify these four cells • 1. • 2. • 3. • 4.

  12. Plasma Membrane- Section 7.2 • What does it do? • Maintains homeostasis (the balance in an organism’s internal environment) • Controls what goes into and out of the cell • What does it look like? • Thin, flexible boundary around a cell • Where is it found? • In any organism- it separates the inside of the organism from the watery outside environment.

  13. Plasma Membrane • Unique- It has selective permeability • Membrane allows some substances to pass through cell without allowing others • The cell is surrounded by water on all sides • Like a fish net • Fig. 7.5, pg. 187 • Animation

  14. Plasma Membrane • Structure: • Mostly made of lipids • Lipids are usually made of glycerol and three fatty acids • However, in this case, a phosphate group replaces a fatty acid making a phospholipid • Therefore, these lipids are called Phospholipids: glycerol backbone, two fatty acid chains and a phosphate group • Has a bilayer of phospholipids- two layers of phospholipids are arranged tail to tail • Fig. 7.6

  15. Phospholipid Bilayer of P.M. • Each phos.lip. is diagramed as a head with two tails. • Heads are polar (the phosphate group makes it that way) and attracted to water- Hydrophilic • Fatty acid tails are nonpolar- Hydrophobic • So, the head loves water and the tails hate water. Water will not pass easily through the tails. • How does water get into the cell then?

  16. What else is in the Plasma Membrane? • Cholesterol, proteins, and carbs • Proteins help give transport materials (such as water) & give shape to the membrane • Cholesterol helps prevent fatty acid tails from sticking together • Carbs help recognize chemical signals from the outside environment Analyze this statement: High levels of cholesterol lead to reduced blood flow, making cholesterol bad for individuals.

  17. Fluid Mosaic Model • This bilayer of phospholipids create a sea that molecules can float in- like apples floating in a crate. • Fish Tank Demo • The F.M.M can move around like a blanket on a swimming pool • The collection of the proteins, cholesterol and carbs let some substances in and keep others out • Fig. 7.7 • Animation Reading Check- Why is it beneficial to have a 2 layer system than a 1 layer system?

  18. Structures and Organelles- Section 3 • Concepts in Motion • Plant Cells and Animal Cells • Eukaryotes contain organelles that allow for specialization within cells • Consider a boot manufacturing company. If every person who worked their made their own pair of boots, the factory wouldn’t be very efficient. So, an assembly line is formed. • Cells have assembly lines in them, too. Parts move from one place in the cell to another, collecting more parts to complete the manufacturing process.

  19. Organelles • Cytoplasm: • Area between the membrane and the nucleus • Gelatin-like fluid called cytosol • Salts, minerals and molecules are found here

  20. Cytoskeleton • Protein fibers in the cytosol • Help the cell maintain it’s shape. Fig. 7.8 • Made of • Microfilaments • Protein threads • Cell mvmt and shape • Microtubules • Strands of hollow tubes of protein • Help move things around in the cell

  21. Nucleus - Fig. 7.10 • Surrounded by the nuclear envelope • Similar to plasma membrane, except it allows larger sized substances to move through it • Stores heredity info • Chromatin is spread throughout • Complex DNA with proteins attached • Contains a nucleolus • Makes ribosomes

  22. Ribosome • Most numerous • No membrane • Made of proteins and RNA • Made in nucleus and transported to cytosol- May remain “free” in cytosol, or attach to the ER- “bound” • Protein synthesis (makes proteins) • Proteins can turn into ANYTHING, they are the play-dough of the cell

  23. Endoplasmic Reticulum • Tubes and sacs folded • Why folded? • Site of lipid and protein synthesis • Amount of ER depends on the cell function • Two types: • Rough- found in cells that make lg amts of proteins for other cells • Smooth- no ribosomes, but it still has functions – Fig. 7.11 • What types of cells would contain a large amount of rough endoplasmic reticulum?

  24. Golgi Apparatus- Fig. 7.12 • Processes, modifies and packages proteins into sacs called vesicles • The vesicles can then fuse with the plasma membrane to release proteins outside the cell • Membranes, like ER, looks like pita bread

  25. Writing Activity • Create a short biography of Camillo Golgi, who discovered the organelle. Chloroplast Nucleolus Vacuoles Nucleus Golgi Bodies

  26. Vacuoles- Fig. 7.13 • Fluid-filled • Stores food, enzymes and waste • Most animal cells do not contain vacuoles

  27. Vacuole Size in a Beet Cell Chloroplast Nucleolus Vacuoles Nucleus Golgi Bodies

  28. Lysosomes- Fig. 7.14 • Small, digest excess or worn-out organelles and food particles • Found only in animal cells • Digest bacteria and viruses • Has a membrane- keeps the potent enzymes inside from digesting the rest of the cell • Connection: Tay-Sachs disease is caused by a lack of a cell to clean out wastes • Concepts in Motion

  29. Centrioles- Fig. 7.15 • Made of groups of microtubules • Used in cell division • Found in cytoplasm of animal cells near the nucleus

  30. Mitochondria- Fig. 7.16 • Converts sugars into energy for cell • Site of reactions that transfer energy from compounds to ATP • More mitochondria in more energetic cells • Made of folded membrane that provides a large surface area for breaking sugar bonds • Energy produced from breaking bonds is stored • Kleenex box demo of surface area • Do plant cells have mitochondria? • Real-World Connections: Some diseases are due to problems with the energy (metabolism) carried out by the mitochondria • Some scientists believe the key to diseases such as Parkinson's and Alzheimer's is to increase the activity of the mitochondria in patients

  31. Chloroplasts- Fig. 7.17 • Capture light and energy and convert to chemical energy through photosynthesis • Contain thalakoids that trap energy from sun in chlorophyll (green pigment) • Belong to a group of plant organelles called plastids which are mostly used for storage • Mostly found in plant cells

  32. Cell Wall- Fig. 7.18 • Plant cells only • Surrounds the plasma membrane • Support and protects the cell • Contain cellulose (carbo) help add rigidness • How do plants benefit from the cell wall? • How is a cell wall different from the classroom wall?

  33. Cilia and Flagella- Fig. 7.19 • Found in both eukaryotic and prokaryotic cells • Made of microtubules • Assist in mvmt • If the cell is stationary, they move substances along the surface • Cilia propel eukaryotic organisms through water, line respiratory organs to help breath • Flagella- less numerous and longer • Where in the body would you find cillia? • Used for transportation • Esophagus • Stomach • Intestines • Female Reproductive organs • Sperm

  34. BrainPop • www.brainpop.com • If time- Cell Structure

  35. Developing Concepts- Review • Concepts in Motion- Visualizing Cells • Name the location of protein synthesis • Relate DNA to protein synthesis • Generalize how DNA in the nucleus can guide protein synthesis son the ribosome in the cytoplasm • Analyze why it would be an advantage to a protein-secreting cell to have ribosomes on the ER • What would happen to a cell if the number of ribosomes was reduced?

  36. Compare Cells • Complete a Venn Diagram showing which cell structures are found only in plant cells, only in animal cells, only in prokaryotes and found in all three • Table 7.1 will help! • Working Together- Read Pg. 200 together • Concepts In Motion • Cell Organization

  37. Charades! • Students: act out the part of an organelle while other groups try to guess your part

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