Biology

Bio 101
Week 1 Homework

You may either write the answers out by hand on separate sheets of paper or complete them electronically. On some question it may be easier to draw diagrams are structures that is perfectly fine.

1. What are the noncovalent interactions that are important in biological system? Place them in order of strength from the weakest to strongest. How are this interaction mediated by interactions with water?

2. What is the difference between a saturated fatty acid and unsaturated saturated one? How might unsaturation affect the fluidity of a membrane?

3. Amino acids have the generic structure seen below, where R represents different carbon-based side chains.

Looking at the structure above describe how amino acids link together and form a polypeptide or protein.

4. Based on the properties of the R-groups describe what might happen if even one amino acid is substituted for another in a polypeptide chain. Provide a specific example.

5. Aquaporins are proteins embedded in the plasma membrane that allow water molecules to move between the extracellular matrix and the intracellular space. Based on its function and location, describe the key features of the protein’s shape and the chemical characteristics of its amino acids.

6. What are the structural differences between RNA and DNA?

7. What are the structural and functional similarities and differences between mitochondria and chloroplasts?

8. Why do phospholipids tend to spontaneously orient themselves into something resembling a membrane? What properties of a these subsequent lipid bilayers make them idea for a cell membrane?

9. Discuss why the following affect the rate of diffusion: molecular size, temperature, solution density, and the distance that must be traveled.

10. How do cells move water move through the membrane?

11. Why do ions have a difficult time getting through plasma membranes despite their small size? How are ions transported through biological membranes?

12. Where does the cell get energy for active transport processes?

13. Describe the position of the transition state on a vertical energy scale, from low to high, relative to the position of the reactants and products, for both endergonic and exergonic reactions. How do enzymes affect the energy of the reactants, product, and transition state.

14. Do you think that the EA for ATP hydrolysis is relatively low or high? Explain your reasoning.

15. Explain in your own words the difference between a spontaneous reaction and one that occurs instantaneously, and what causes this difference.

16. Nearly all organisms on Earth carry out some form of glycolysis. How does this fact support or not support the assertion that glycolysis is one of the oldest metabolic pathways?

17. What is the primary goal of glycolysis and the citric acid cycle (think about what is being produced and what it is used for)?

18. Why is it important to have regulatory control over metabolic pathways like glycolysis?