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Chapter 4 Cells Chapter 5 Cell Membrane and Signaling

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1 Chapter 4 Cells Chapter 5 Cell Membrane and Signaling
Unit 2 Review AP Biology Chapter 4 Cells Chapter 5 Cell Membrane and Signaling

2 1. Calculate surface area to volume ratio
3:5 3:10 3:50 Reduced 0.6 : 1 0.3 : 1 0.06 : 1 Surface Area = 6 X length squared Volume = length x length =x length

3 2. Which size cell would be the first to get a toxin in the middle?
The smallest cell would be first Why? The smallest cell has the greatest surface area relative to its volume. The toxin would have greater opportunity to enter the cell because of this ratio

4 3. Explain how prokaryotes carry out enzymatically catalyzed biochemical conversions without organelles? There are proteins in the cytoplasm moving around. This motion ensures that reactions are taking place at a rate sufficient for the cell to survive. There are also enzymes in the cytoplasm to catalyze reactions.

5 4. Explain whether ribosomes are present only in eukaryotes, only in prokaryotes, or in both.
Ribosomes make proteins and proteins are essential in all living things

6 5. Describe the structure and function of as many cellular organelles as you can in regard to the synthesis and secretion of protein signals. RER – proteins are synthesized on the ribosomes and then delivered to Golgi SER – stores Ca+ that trigger the secretion of proteins that are secreted by cells Golgi Body – concentrates, packages, sorts and modifies proteins to send them to their destination Ribosomes – make proteins from amino acids

7 6. Label the membrane.

8 7. Explain how the structure of the phospholipid is amphipathic and can form a bilayer that is nonpolar in middle and polar on the outsides Middle is hydrophobic due to the fatty acids Outside is hydrophilic due to the phosphate groups.

9 8. What are the 2 primary factors that influence membrane fluidity?
Lipid composition and temperature

10 9. Explain how the ink diffused through the gel even though there were no currents.
By diffusion  its random and it will go until equilibrium.

11 10. Describe 2 differences between passive and active transport
Moves materials from high to low No energy needed Moves materials from low to high Requires energy All require proteins

12 11. Define and provide a description
Isotonic Equal solute concentrations on each side of membrane No net movement of water in/out of cell Hypotonic Low solute concentration outside the cell Causes enlargement of cells Hypertonic High solute concentrations outside the cell Causes shrinking of cells

13 12. Is facilitated diffusion active or passive transport? Explain why.
No energy is required even though there are proteins involved.

14 13. Explain how cells are involved in the transition from wilted to normal.
Wilted  hypertonic resulting in a flaccid appearance When a wilted plant is watered, water moves in to the shrunken cells, expanding them. Cells become plump again and has turgor pressure.

15 19. Complete table. Simple Diffusion Osmosis Facilitated Diffusion
Active transport Cellular Energy required? No Yes Driving force? Concentration Gradient ATP hydrolysis Membrane protein required? Yes for some cells, No for others Directional? Specificity?

16 20. Explain the Na+K+ Pump 3 sodium ions get pumped OUT
2 potassium ions get pumped IN Requires 1 ATP – ATP gets broken down into ADP + inorganic phosphate

17 16. Explain how phagocytosis and pinocytosis are similar and different
Both forms of endocytosis Both involve the folding of the plasma membrane Both active transport Both bring materials into the cell Phagocytosis is bringing in large particles/cells Pinocytosis is bringing in fluids and dissolved substances

18 17. Describe each step of cell signaling
Signal arrives at target. Signal molecule may be a specific molecule or a physical stimulus. Receptor Signal molecule fits into the receptor protein and binding occurs Response Receptor changes its 3D shape and this initiates a cellular response

19 18. If a cell had no proteins, will it be able to respond to any environmentally stimuli? Explain
Cells must have specific receptors to any environmental stimuli and receptors are always made of protein

20 19. Why doesn’t caffeine enter the cell?
Caffeine is large Caffeine is polar (see nitrogens) It is unlikely to diffuse through the plasma membrane so it likely will bind to a receptor on the surfaces of nerve cells in the brain

21 20. All cells have Cytoplasm Plasma membrane ribosomes

22 21. Animals HAVE (and plants don’t)
Lysosomes Centrioles Flagella Cilia More rounder shape Smaller and more vacuoles

23 22. Plants HAVE & animals don’t
Cell wall Chloroplast Square shape Central vacuole

24 23. Prokaryote vs. Eukaryote
Older No nucleus (nucleiod) No organelles Simpler ribosomes Bacteria is an example Younger Nucleus and nuclear membrane Organelles Complex ribosomes Plants, animals, fungi and protists are examples

25 Exam: 20 multiple choice – cells (chapter 4) 9 chapter 5
3 cell signalling ch 4 Short Answer Labeling Chapter 4 Calculate % change in mass Calculate SA:V ratio Calculate solute potential Calculate standard deviation 10 point essay


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