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Macromolecules in Cells

Macromolecules in Cells. All cell parts are made up of macromolecules! Proteins Carbohydrates Lipids Nucleic Acids. What organelle allows molecules to pass from outside of the cell to inside of the cell?. Cell Wall Nucleus Cell Membrane Vacuole. Cell Membrane!.

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Macromolecules in Cells

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  1. Macromolecules in Cells • All cell parts are made up of macromolecules! • Proteins • Carbohydrates • Lipids • Nucleic Acids

  2. What organelle allows molecules to pass from outside of the cell to inside of the cell? • Cell Wall • Nucleus • Cell Membrane • Vacuole Cell Membrane!

  3. Which types of organisms are made of cells that contain cell walls? • Plants • Fungi • Bacteria • All of the above All of the above!

  4. Cell Walls • NOT THE SAME AS THE CELL MEMBRANE! • Located outside of the cell membrane! • Rigid & made of carbohydrates • Present in: • Plants • Fungi • Bacteria

  5. Cell Boundaries

  6. The Cell Membrane • All cells are bound by a cell membrane! • The cell membrane is made of: • Lipid Bilayer (Phospholipid Bilayer) • Proteins • Carbohydrates • Cholesterol

  7. The Phospholipid Bilayer The cell membrane is composed of 2 layers of phospholipids (lipid with a phosphate group). Remember! Lipids have a hydrophilic “head” (water loving) & a hydrophobic “tail” (water hating). The areas inside & outside of the cell are mostly water, so the hydrophobic tails turn in on themselves! So, the phospholipid heads face outwards (towards the inside & outside of the cell) & the tails form the middle!

  8. The Cell Membrane • The lipid bilayer is semi-permeable. • It allows some things across, but not others. • The structure of fits its function! • Flexible barrier • Semi-permeable • Sends & receives chemical messages from other cells

  9. Remember! • Phospholipids are water resistant & flexible. • Carbohydrates are like ID tags for the cell. • Proteins are for stability & act like passageways for substances to enter & leave the cell.

  10. Movement Across the Membrane We know things have to enter & leave the cell, but how? • There are 4 different types of movement across the cell membrane: • Diffusion • Osmosis • Passive Transport • Active Transport

  11. Diffusion • The movement of a molecule or atom from an area of high concentration to an area of low concentration until equilibrium is reached • Equilibrium means equal concentrations on both sides of the cell membrane! • Naturally occurs & normally no energy is required

  12. Remember! In a water/sugar solution, water is the solvent & sugar is the solute!

  13. If I add sugar to a glass of water, the sugar is initially very concentrated (the sugar molecules are close to each other). Eventually, the sugar molecules will spread through the water until they are evenly distributed!

  14. Diffusion Video Things like water, oxygen, & carbon dioxide can diffuse across the cell membrane.

  15. Osmosis • The movement of water across a semi-permeable membrane So what’s happening here?

  16. Remember! When a solute is dissolved in water, the solute breaks apart & chemically combines with the water molecules. In a salt/water solution, the water molecules are bound to the salt molecules. They are no longer FREE WATER MOLECULES!

  17. Semi-permeable Membrane Water-solute particle is too big to pass through the membrane! More free water molecules on this side of membrane… Free water molecules diffuse in this direction

  18. Let’s say you have a beaker with a semi-permeable membrane in the middle & you fill it up with water. Then, you add 5 tbsp. of sugar to the left side, but just 1 tbsp. of sugar to the right side. Will the water level stay even? There are more free water molecules on the right side, so they move to the left side of the beaker!

  19. Osmosis Video

  20. What happens (in terms of diffusion) when you add dye to water?

  21. Isotonic Solution • The same concentration of solute on both sides of the membrane • Water will continue to move into & out of the cell at an even rate!

  22. Hypotonic Solution • Outside solution has a lower concentration of solute than inside the cell (higher concentration of free water outside the cell) • Water will move into the cell! These red blood cells are in a hypotonic solution & have gained water!

  23. Hypertonic Solution • Outside solution has a higher concentration of solute than inside the cell (lower concentration of water outside the cell) • Water will move out of the cell! These red blood cells are in a hypertonic solution & have lost water!

  24. This cell is permeable to water, but not salt. What type of environment is this cell in? • Hypertonic • Hypotonic • Isotonic • IDK Hypertonic!

  25. This cell is permeable to water, but not salt. What type of environment is this cell in? • Hypertonic • Hypotonic • Isotonic • IDK Hypotonic!

  26. This cell is permeable to water, but not salt. What type of environment is this cell in? • Hypertonic • Hypotonic • Isotonic • IDK Isotonic!

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