How Cells Maintain Homeostasis. Objective 2.03: Importance of Water, How cells maintain homeostasis, Movement of materials into and out of cells

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1 How Cells Maintain Homeostasis Objective 2.03: Importance of, How cells maintain homeostasis, Movement of materials into and out of cells

2 ? Homeostasis? Maintaining a stable, BALANCED, internal environment Example: Cell

3 Homeostasis! Maintaining a stable, BALANCED, internal environment Example: Cell

4 FYI Universal solvent = ability to dissolve many things Transports materials in organisms = blood is mostly water Makes up 70-95% of most organisms

5 is Polar Polar Molecule - Has a positive and negative end - Attracts other water molecules = surface tension - Allows water to move up through thin tubes inside of plants = capillary action

6 Plasma Membrane: Structure & Function

7 Plasma/Cell Membrane In an Animal Cell, it is the boundary between the inside and outside of the cell. In a Plant Cell, it is between the cell wall and the inside of the cell It is crucial in maintaining the cell s homeostasis!!

8 It is selectively permeable (or semi-permeable) It is choosy about what enters and leaves the cell. It keeps nutrients in, and harmful substances out

9 The Cell Membrane is referred to as the Fluid Mosaic Model Fluid: because the parts inside the cell membrane are always moving around. Mosaic: because it is made of many different parts and molecules (lipids, cholesterol, proteins, carbohydrates, etc.)

10 Structure of the Plasma Membrane The plasma membrane is a Phospholipid Bilayer Phosphate + Fat 2 Layers Other Components: Proteins, Cholesterol, Carbohydrates

11 Phospholipids The heads : Hydrophilic Polar Attracted to H 2 O inside and outside cell The tails : Hydrophobic Non-polar do NOT like water Point to the middle of the plasma membrane.

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13 Can things move through the cell membrane? Of course! If they are small, they can go through without energy needed Ex:, Oxygen If they are large, they have to go through a protein and it uses energy Ex: Sugar

14 What do you think A cell in your body does not maintain homeostasis, and too much water is allowed in. What might happen!?

15 The Movement of Materials into and out of Cells

16 Two Types of Cell Transport Passive Transport No energy required Movement of materials is from high to low Materials move DOWN a concentration gradient Examples are diffusion, osmosis, and facilitated diffusion Active Transport Energy is required Movement of materials is from low to high Materials move UP a concentration gradient Requires the use of proteins

17 Concentration Gradient!? When the concentrations of solutions are different Inside a Cell LOW concentration of solute (ex: salt) Outside a Cell HIGH concentration of solute (ex: salt)

18 Diffusion Movement of particles from an area of high concentration to an area of low concentration Goal is to reach dynamic equilibrium = inside and outside the cell are at equal concentrations

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20 Facilitated Diffusion Same as diffusion BUT uses a protein in cell membrane Used when particles are too big to squeeze through cell membrane

21 Transport Proteins for Facilitated Diffusion Channel Protein = does not change shape (a) Carrier Protein = can change shape (b)

22 Osmosis Osmosis: The diffusion of water across a semi permeable membrane. Hypertonic Isotonic Hypotonic (Cell Shrinks) ( Dynamic Equilibrium) (Cell Swells) 90% H2O In cell 10% In beaker 50% H2O In cell 50% In beaker 10% H2O In cell 90% In beaker

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24 Cells in Solutions Bursts Shrivels Plasmolysis- cell membrane pulling away from cell wall Turgor Pressure cell membrane pushes on cell wall

25 Where will the water go? 40% water outside cell, 60% water inside cell 40% sugar outside cell, 60% sugar inside cell

26 Passive Transport No energy required Movement of materials is from high to low Materials move DOWN a concentration gradient Examples are diffusion, osmosis, and facilitated diffusion Active Transport Energy is required Movement of materials is from low to high Materials move UP a concentration gradient

27 Active Transport Requires ENERGY! Movement is from LOW to HIGH Uses transport proteins (carrier or channel) Ex: muscle contractions + electrolytes

28 Energy!!!