Name: Quinn Thomas Section: 608151-3 Intro Bio Discussion Homework Week of February 14, 2022 1. Explain why raising the temperature in which a cell lives might slow one of the cell’s enzyme-catalyzed chemical reactions. At higher temperatures, the protein is denatured, and the rate of the reaction decreases. Enzymes work best at a specific temperature so when that tempertature is exceed the enzymes no longer function properly and the cell’s reactions decrease. 2. Most cells must maintain a relatively constant internal environment. To do this, they must be able to control the movement of materials into and out of the cell. What characteristics of the cell membrane determine what gets into the cell and what doesn’t? That is, what determines the permeability of a cell or organelle membrane? To answer these questions, first complete the answers to the following questions: a. If a cell membrane were composed of only a phospholipid bilayer, what barrier properties would it have?b. What different roles or functions do membrane proteins serve?c. Why are some cell types more permeable to a substance (for example, sodium ions) than others?“semi-permeable” the lipid bilayer is permeable to large and small non polar molecules largely impermeable to larger polar molecules and small and large ions help diffusion or transport molecules through membranes facilitated diffusion - carriers and channels active transport - pump membrane protein determines what is allowed to pass through the membrane the number and type of membrane protein on a cell determines its permeability to different substances the DNA in each cell determines what kinds of transporters each cell has! 1Name: Quinn Thomas Section: 6083. Consider the following diagrams for parts a, b and c. Assume the line is a biological membrane, and the X’s and O’s are unknown substances. For each pair of diagrams, assume that time has passed between the first and second diagram. For each pair, explain what could have happened to get that result. ! ! ! a. What could have happened to get the result above? How would your answer change if you knew X was a small non-polar molecule? How would it change if you knew X was glucose? The process depicts diffusion which involves the movement of molecules from an area of high concentration to an area of low concentration. The lipid bilayer is permeable to and allows for the diffusion of small non-polar molecules. Glucose cannot move across a cell membrane through simple diffusion, instead it is transferred through facilitated diffusion which involves molecules moving through the membrane by passing through channel proteins. if the molecule was small and nonpolar it could diffuse through the cell If the molecule was glucose it would need a carrier or channel protein ! 2Name: Quinn Thomas Section: 608! ! ! b. What could have happened to get the result above? How would your answer change if you knew X was a small non-polar molecule? How would it change if you knew X was glucose? The image depicts active transport in which the molecules move against the concentration gradient from an area of low concentration to an area of high concentration. If X was a small non-polar molecules or glucose it would still need active transport Glucose is transferred through co-transport (“secondary” transport”). The facilitated diffusion of one molecule drives active transport of a second. The “X” is going against the concentration gradient - active transport - needs a pump ! ! ! c. What could have happened to get the result above? X and O are going with the concentration gradient - secondary aative transport (co-transporter) symporter - both molecules moving into the cell anti-porter - one moving in, one moving out ! 3Name: Quinn Thomas Section: 6084. Substances can move across the membrane via simple diffusion, facilitated diffusion, or active transport. Please answer questions a, b, and c by filling in the chart below: 5. What is the theory of endosymbiosis? How is it hypothesized to have happened? The endosymbiotic theory is how scientists think mitochondria and chloroplasts evolved in eukaryotic organisms. Endosymbionts are organisms that form a symbiotic relationship with another cell or organism. a. Where does it occur in the membrane?b. Does it require transport protein? (yes/no)c. Does it require input of energy? If so, explain the types of energy that can be used and how.Simple diffusionphospholipid bilayernonoFacilitated diffusionmembrane proteins (pores or carrier proteins)yesnoActive transportmembrane proteins (pumps) and cell membrane yesyes energy can come from: 1. chemical reactions 2. high energy electrons from electron carriers 3. non-chemical energy from co-transport!