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Cell Membrane, Transport, Enzymes, & Energy Unit 4 Review.

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Presentation on theme: "Cell Membrane, Transport, Enzymes, & Energy Unit 4 Review."— Presentation transcript:

1 Cell Membrane, Transport, Enzymes, & Energy Unit 4 Review

2 The Cell Membrane helps maintain Homeostasis by regulating transport of materials in/out of the cell.

3 Function of the Cell Membrane The Cell Membrane is like the of the cell because it controls what can come in and out of the cell. Security Guard

4 PLASMA/CELL MEMBRANE The Cell Membrane is the barrier between the cytoplasm and the ExtraCellular Fluid (outside) of the Animal Cell. In Plant Cells (and other types), it separates the cytoplasm from the Cell Wall.

5 Cell Membrane Structure Cholesterol adds structure and stability to the cell membrane. It makes up about 20% of the cell membrane. Carbohydrate chains (glycolipids & glycoproteins) are always on the OUTSIDE of the membrane. Phospholipids make up the majority of both layers of the cell membrane.

6 Phospholipids Hydrophobic fatty acid tails = repel water Hydrophilic phosphate heads = love water

7 Phospholipid Bilayer

8 This process is called Diffusion. Solute Solvent The sugar molecules are spreading out.

9 Molecules always move from HIGH concentration to LOW concentration. It takes added ENERGY to move from low concentration to high concentration. Semipermeable means that it is selective about what can enter or leave, kind of like a picky eater.

10 Molecules that easily diffuse across the membrane are Hydrophobic (O 2 /CO 2 ) or SMALL & Uncharged/Polar (H 2 O). Sugars can NOT diffuse because of SIZE (too big). Ions can NOT diffuse because of CHARGE (charged & large molecules can not get across).

11 Does the cell have to use energy for this? NO This is called PASSIVE Transport. This is called moving WITH the concentration gradient (HIGH to LOW).

12 The diffusion of WATER is called OSMOSIS. This means that H 2 O is moving from where there is MORE H 2 O & LESS solutes TO where there is LESS H 2 O & MORE solutes. Does the cell have to use energy for this? NO This is called PASSIVE Transport.

13 Hypotonic Solution = Cell swells because H 2 O diffuses (osmosis) INTO the cell. Animal cells may burst. Plant cells have increased turgor pressure but are protected by their cell walls.

14 Isotonic solution = SAME concentration as the cytoplasm of the cell. H 2 O diffuses (osmosis) IN & OUT of the cell at the same rate. The cell stays the same size.

15 Hypertonic Solution = Cell shrinks because H 2 O diffuses (osmosis) OUT of the cell.

16 Facilitated Diffusion Large or polar molecules MUST diffuse through a Channel Protein LOW Concentration HIGH Concentration

17 Concentration Gradient

18 Does the cell have to use energy for this? NO This is called PASSIVE Transport.

19 HIGH Concentration LOW Concentration

20 Active Transport LOW Concentration HIGH Concentration MUST USE ENERGY to

21 ACTIVE TRANSPORT This is moving AGAINST the concentration gradient (LOW to HIGH) Does the cell have to use energy for this? NO That is why it is called ACTIVE Transport! (ATP is the energy molecule) ENERGY

22 The Na+/K+ Pump moves 3 Na+ ions out of the cell & 2 K+ ions into the cell for every molecule of ATP. This ION PUMP controls Neuron function. This is called the SODIUM (Na + )/POTASSIUM (K + ) Pump Active Transport!

23 Other Transport Mechanisms Into the cell Out of the cell ImportExport

24 Pinocytosis = takes in fluid Phagocytosis = takes in food/large particles Receptor Mediated = will only take in specific molecules Types of Endocytosis

25 Vesicle from Golgi Apparatus


27 Paramecia have a Contractile Vacuole that allows water to be pumped OUT of the cell because they live in a HYPOTONIC environment. This takes ENERGY but it allows them to maintain HOMEOSTASIS.

28 Contractile Vacuoles

29 ENZYMES ENZYMES are PROTEINS that are used in many chemicals reactions. They are necessary for living things because they SPEED UP (accelerate) important chemical reactions by lowering the amount of ACTIVATION ENERGY needed to start the reaction. Enzymes & Substrates have to fit together (complementary shapes) at the ACTIVE SITE so they are very specific Enzymes are reusable because they are not permanently changed in the reaction. Enzymes help weaken or form chemical bonds so that the reaction takes less energy to occur.

30 Activation energy is like the COST of the reaction & the enzyme is like a COUPON because it lowers the cost. Higher Cost (more energy required) LOWER Cost (less energy required)

31 Reactants = SUBSTRATES Substrates bind to the enzyme at the ACTIVE SITE to provide a place for the reaction. Enzyme-Substrate Complex The Enzyme is NOT permanently CHANGED in the reaction = Reusable

32 The Cell’s Energy Molecule = ATP Adenine Ribose 2 Phosphate groups 3 rd Phosphate group Adenosine triphosphate ATP = Adenosine Triphosphate Chemical bonds store ENERGY

33 ATP - P = ADP RELEASES energy This is called HYDROlysis

34 ADP  ATP ADP + P = ATP STORES energy Glucose gets broken down during Cellular Respiration so that energy can be stored in ATP. This is called PHOSPHOrylation

35 occurs in the produces Is broken down during The products go through the occurs in the produces 32 TOTAL 36 Cellular Respiration Equation C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + 36ATP

36 Take the Multiple Choice Quiz & Check Your Answers!

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