What are biofilms and how did they potentially contribute to the evolution of cells?

1. Imagine a nerve cell that measures 125 µm x 1 µm x 1 µm. Predict how its surface area-to-volume ratio compare with those in the project yesterday. Then calculate the ratio and check out your prediction. • How does the endosymbiotic theory explains the evolution of eukaryotic cells? • Antibiotics usually only effective against bacteria and kill them by reacting with their cell wall. Explain how it is possible that antibiotics do not destroy other cells.

2. What are biofilms and how did they potentially contribute to the evolution of cells? • How do bacteria perform cellular respiration if they don’t have mitochondria and photosynthesis if they don’t have chloroplasts? • If bacteria only reproduce asexually, how can they have such a wide genetic diversity?

3. The following data were collected by observing subcellular structures of three different types of eukaryotic cells. Based on an analysis of the data, identify a likely primary function of each cell type and explain how the data support the identification

4. Males afflicted with Kartagener’s syndrome are sterile because of immotile sperm, and they tend to suffer from lung infections. This disorder has a genetic basis. Suggest what the underlying defect might be. • List organelles that you would expect to see in large numbers in the following cells: • Cells that specialize in water transport • Cells that specialize in motion • Cells that specialize in protein hormone production • Cells that specialize in steroid hormone production • Cells that specialize in detoxification

5. Do plants have mitochondria? Why or why not? • Describe structural and functional distinctions between rough and smooth ER. • Describe what the endomembrane system is and how it is an interconnected entity within the cell. • Describe how transport vesicles integrate the endomembrane system. • Describe the path of a protein from the nucleus where the genetic information is stored for its production to its final destination outside of the cell.

6. Explain how the structure of the Golgi apparatus fits to perform its function. • Explain how the structure of the smooth ER fits to perform its function. • Explain how the structure of microfilaments and microtubules fit to perform their functions. • Describe the location and the general structure of the extracellular layer of cells. How does this structure fit to perform its function? • How would an animal cell be impacted by the loss or depletion of an extracellular matrix? • What would happen if plant cells did not have any plasmodesmata?

7. And one more really evil question on cell structure: • The polypeptide chain that makes up a tight junction waves back and forth through the membrane four times, with two extracellular loops, and one loop plus short C-terminal and N-terminal tails in the cytoplasm. What would you predict about the types of amino acid side chains that make up the tight-junction protein?

8. Suggest a hypothesis to explain why the thylakoid membranes of chloroplasts resemble those of cyanobacteria. • Contrast the cellular and DNA structures of prokaryotes and eukaryotes. • Although mutations are rare, they can still provide considerable genetic variation in a short period of time into bacterial populations. Explain the reasons why. • Distinguish among the three mechanisms that are used to transfer DNA from one bacterial cell to the next.

9. In a rapidly changing environment, which bacterial population would likely be more successful, one that includes individuals capable of conjugation or one that does not? Explain. • If a nonpathogenic bacterium were to acquire resistance to antibiotics, could this strain pose a health risk to people? Explain. • In general, how does DNA transfer among bacteria affect the spread of resistance genes? • Explain how viruses introduce genetic variation in host bacteria.

10. How has metagenomics contributed to our understanding of prokaryotic diversity? • Explain how Gram-positive and Gram-negative bacteria differ and how this difference influence potential treatment of bacterial diseases. • Explain how quorum sensing can help bacteria sense the presence of bacteria of other species in their environment. How does it help with bacteria of the same species?

11. In a bag with a selectively permeable membrane you have a solution of 4 % salt and 2 % starch. The bag is permeable to salt but not to starch. You place this in a beaker with distilled water. Draw this system, determine the direction of the movement of various substances and determine the type(s) of transport used. • Describe what happens with a plant cell when it is placed in a hypotonic solution.

12. Has 4 M of sucrose and 2 M of glucose Has 2 M of sucrose and 4 M of glucose • What is the tonicity of this system above? • What is moving through the membrane in what direction if the pores are about the size of glucose, but glucose can still fit through them? • Describe the direction of water movement and final state of the cell if: • Plant cell is placed in a hypotonic solution • Animal cell is placed in a hypertonic solution • Plan cell is placed in a hypertonic solution • Animal cell is placed in an isotonic solution

13. A researcher discovered a new drug that treats lysosomal disorders. What kind of information would you collect to know if the drug is able to enter the cell membrane? • The molar concentration of a sugar solution has been determined to be 0.3 M. Calculate the solute potential at 27 °C. Round your answer to the nearest hundredth. What is the water potential for this sample? If a cell is placed into this solution that has a Ψc = -0.5 bar, what is the tonicity of the cell compared to this solution? Predict the direction of water movement.

14. Calculate the water potential of a solution of 0.15 M sodium chloride in a beaker at 20 °C. If a cell with a Ψ = -0.8 MPa is put into this solution, what is the tonicity of the cell compared to the solution? What is the direction of water movement. • At 20°C, a cell containing 0.6M glucose is in equilibrium with its surrounding solution containing 0.5M glucose in an open container. What is the cell’s ΨP?

15. In beaker B, what is the water potential of the distilled water in the beaker, and of the beet core? Which of the following statements is true for the diagrams above? A. the beet core in beaker A is at equilibrium with the surrounding water B. the beet core in beaker B will lose water to the surrounding environment C. The beet core in beaker B would be more turgid than the beet core in beaker A D. The beet core in beaker A is likely to gain so much water that its cells will rupture E. The cells in beet core B are likely to undergo plasmolysis.

16. Determine the type of transport required in the following cases: • Glucose moves into the cell from a higher concentration area • Oxygen gas moves into the cell • Water moves into the cell • Sucrose moves into the cell with the help of H+ ions. • Sodium ions move out of the cell into a more concentrated area • Large oil droplet moves into the cell. • Cholesterol molecules move into the cell by using receptors. • The cell releases a protein hormone.