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Cell Theory

Understand the components and functions of the plasma membrane, its transport mechanisms, and how it contributes to homeostasis. Explore the roles of proteins, cholesterol, and more.

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Cell Theory

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  1. Cell Theory • Standards and Expectations! • Compare and contrast the functions and organization of prokaryotic and eukaryotic cells (Part 1) COMPLETE! • Describe the role of ribosomes, ER, and Golgi in the production and packaging of proteins (Part 2) COMPLETE! • Explain how materials move into and out of a cell (Part 3) • Describe how carbohydrates, proteins, lipids, and nucleic acids function in the cell. (Part 4)

  2. Cell Theory • Plasma Membrane and Transport • The PM is the barrier that surrounds the cell • Allows the cell's internal environment to remain the same separate from the outside. (homeostasis) • Selectively permeable – allows certain molecules in and keeps other molecules out. • Fluid mosaic model – it has many components and exhibits fluidity (moves like water) • The only way to get into the cell is to penetrate the plasma membrane.

  3. Cell Theory • Plasma Membrane and Transport

  4. Cell Theory • PM Components • Phospholipid bilayer – provides the main structure • Proteins – Integral and Peripheral – communication, transport, and anchors • Cholesterol – adds fluidity to membrane • Carbohydrates – cell to cell recognition bound to lipids and proteins.

  5. Cell Theory Phospholipid bilayer – phosphate heads interact with water. Hydrophobic tails hide from water providing the firm structure.

  6. Cell Theory • Cholesterol • Wedged between phospholipid molecules • At high temperatures, it stiffens up causing it to be less fluid. • Hinders the tight packing of the phospholipid lowering the temperature it would need to solidify. • It is called a “temperature buffer”

  7. Cell Theory • Plasma Membrane and Transport

  8. Cell Theory • Proteins • Integral – penetrate the hydrophobic core of the lipid bilayer • Peripheral – attached to membrane and integral proteins • Transport - integral • Enzyme activity - integral • Signal reception – integral + peripheral • Cell – Cell recognition - integral + carbohydrates • Intercellular joining (cells hook up) - integral • Attaches to the cytoskeleton and extra cellular matrix – integral + peripheral

  9. Cell Theory • Peripheral proteins usually attach to integral proteins in order to aid in communication and anchor cell components

  10. Cell Theory • Protein functions...

  11. Cell Theory • Viruses, hormones, bacteria, and toxins all can interact with carbohydrate chains allowing them to recognize cells.

  12. Cell Theory • Plasma membrane permeability • Nonpolar molecules can easily dissolve in the lipid bilayer and passes into the cell. • Polar molecules, ions, and large macro molecules do not pass through the hydrophobic core of the cell membrane. • Transport proteins are required for facilitated diffusion in order to regulate passage of polar molecules and ions.Carrier proteins are required for active transport • Aquaporins are transport proteins that allow the passage of water into the cell.

  13. Cell Theory • Quick review of the types of transport • Passive – no energy (high to low concentration) • Facilitated diffusion – movement of particles with a transport protein (high to low concentration) • Diffusion – movement of particles from high to low concentration • Active transport – requires ATP and moves from low to high concentration

  14. Cell Theory • Sodium-Potassium pump (Active transport) • Pumps ions against the concentration gradient • Pump transitions between 2 different shapes of the Na+ and K+ (electrolytes) • The charged ions aid in an electrochemical gradient. • This pump is used mostly in muscle and nerve cells allowing current (signal) from the brain to pass through each cell.

  15. Cell Theory

  16. Cell Theory • QUESTION! • Na+ and K+ are considered electrolytes that must be replenished when people become dehydrated. People who suffer eating disorders (bulimia in particular) and extreme dehydration run the risk of heart attack. Why is heart attack a risk for people who suffer these issues?

  17. Cell Theory • TASKS! • Discuss the types of proteins in the plasma membrane and the types of transport that are involved. • Discuss the role of cholesterol and how it contributes to the fluidity of the plasma membrane. • How do pathogens interact with a cell? How do they know which cell to attack? • Discuss the mechanisms behind the NA+/K+ pump. Why would this type of transport be found in nervous and muscle cells?

  18. Cell Theory • Standards and Expectations! • Compare and contrast the functions and organization of prokaryotic and eukaryotic cells (Part 1) COMPLETE! • Describe the role of ribosomes, ER, and Golgi in the production and packaging of proteins (Part 2) COMPLETE! • Explain how materials move into and out of a cell (Part 3) COMPLETE! • Describe how carbohydrates, proteins, lipids, and nucleic acids function in the cell. (Part 4)

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