Glycolysis Kreb’s Cycle ETC and Chemiosmosis Light Reactions Dark Reactions

QUESTION 1 Where does glycolysis occur in the cell?

ANSWER Glycolysis occurs in the cytoplasm

QUESTION Indicate how many ATP are needed? How many ATP are made in total? How many net ATP result?

ANSWER 2 ATP are needed drive the reaction. 4 ATP are made in total. 2 ATP are the net gain.

QUESTION In the first reaction ATP is used to convert glucose to glucose-6 phosphate. What type of enzyme catalyzes this reaction.

ANSWER The enzyme is a kinase.

QUESTION Some of the reactions in glycolysis and example of redox reactions. What is oxidized and what is reduced and how many reductions occur?

ANSWER 2 G3P are oxidized as they give up hydrogen to 2 coenzymes (specifically NADH + H + )

QUESTION The final product of glycolysis is pyruvate. What will happen to this molecule if there is no oxygen present in an animal cell? What does this re- generate so that glycolysis can continue and ATP can be made?

ANSWER The pyruvate is hydrogenated to become lactic acid. This regenerates the NAD + that is needed by glycolysis.

QUESTION What is the name of the molecule that is both the initial reactant and final product in this cycle?

ANSWER Oxaloacetate

QUESTION Where in the cell does this process occur? Be specific and indicate where in the organelle this occurs.

ANSWER The matrix of the mitochondria

QUESTION For each turn of the Kreb’s cycle how many CO 2 molecules are produced? How many times does the cycle have to turn for each glucose molecule broken down?

ANSWER 2 CO 2 molecules are produced for each turn of the cycle. The cycle must turn twice for each glucose molecule broken down. Note that the other two CO 2 were lost when pyruvate was oxidized.

QUESTION Summarize the number and type of co-enzymes produced and the number of ATP made for each glucose molecule that is broken down.

ANSWER 6 NADH + H + 2 FADH 2 2 ATP

QUESTION What molecule must feed into this cycle and indicate three sources from which this molecule can be generated.

ANSWER Acetyl CoA must enter the cycle. Acetyl CoA was formed from the oxidation of pyruvate (carbohydrate metabolism), or from lipid or protein metabolism.

QUESTION What is the final acceptor in the ETC. What does it form?

ANSWER Oxygen is the final electron acceptor and reacts with the H + to form water.

QUESTION Where is the ETC located? Be specific and indicate where in the organelle that this occurs.

ANSWER The ETC is found on the cristae of the inner mitochondrial membrane.

QUESTION What is the overall function of the ETC?

ANSWER It’s function is to use the free energy from the electrons to transport H + into the intermembranal space.

QUESTION What is chemiosmosis? Be sure to discuss the key protein involved.

ANSWER Chemiosmosis is the movement of H + back across the inner mitochondrial membrane through the ATP synthase to generate ATP.

QUESTION How many ATP can be generated from 1 NADH + H + ? From 1 FADH 2 ? Why is there a difference?

ANSWER 3 ATP from 1 NADH + H + 2 ATP from 1 FADH 2 The difference is because FADH 2 enters the ETC further down than NADH + H +.

QUESTION Where do these reactions occur? Be specific about the location in the organelle.

ANSWER On the thylakoid membrane.

QUESTION What is the overall goal of the light reactions?

ANSWER To use light energy to produce ATP and NADPH 2 to fuel the dark reactions.

QUESTION How does Photosystem II replenish the electrons that it loses into the ETC? How does photosystem I replenish its electron lost due to photoexcitation.

ANSWER Electrons from the photolysis of water replenish the electrons lost by Photosystem II. Photosystem I gets the electron passed from Photosystem II and the ETC.

QUESTION What builds up in the thylakoid lumen? Why is this necessary?

ANSWER A high [H + ] builds up in the thylakoid lumen. This is so that chemiosmosis can occur where H + pass through an ATP synthase to make ATP.

QUESTION Name all of the pigments found in a photosystem and indicate which one is the most important and why?

ANSWER Chlorophyll a (most important) Chlorophyll b Xanthophyll Carotenoids

QUESTION Where in the cell does this process occur? Be specific about the location in the organelle.

ANSWER The stroma of the chloroplast.

QUESTION How many CO 2 molecules must feed into this cycle to form one glucose molecule?

ANSWER 6CO 2 are used to make a 6-C glucose molecule.

QUESTION In reality the Calvin cycle creates a simpler molecule than glucose. How many carbons does this molecule contain and what is it called?

ANSWER G-3P or glyceraldehyde-3 phosphate. It contains 3 carbons.

QUESTION What are three potential uses for G- 3P generated by the Calvin cycle?

ANSWER To create glucose for cellular respiration, to create cellulose for cell walls, or to create sucrose that can be moved to other parts of the plant.

QUESTION When is the waste product oxygen created?

ANSWER During photolysis of water in the light reactions of photosynthesis.