Exam 3 (chapters 6,7 & 8)

Physicists often consider energy in two forms. What are they and how do they differ? What is the beginning source of energy on earth and how do organisms on earth utilize this energy?
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Physicists often consider energy in two forms. What are they and how do they differ? What is the beginning source of energy on earth and how do organisms on earth utilize this energy?
Potential and kinetic energy. potential energy is the energy stored in an object as a result of its position (this typically means something in a high place about to roll or fall off). Kinetic energy is a form of energy that an object or a particle has by reason of its motion.
The beginning source of energy on earth is the sun. We can easily trace the food chain to producers which are typically plants who get their energy from the sun.
What are the two laws that govern energy interconversions and what does each say?
First law: energy cannot be created or distroyed just transferred or transformed
Second law: every energy transferal/transformation increases the entropy (randomness) of the universe
Distinguish between endergonic and exergonic reactions and what would be the free energy change in each (∆G).
Exergonic- net release of energy (negative deltaG value)
Endergonic-net gain of energy (positive deltaG value)
What is activation energy and how does a catalyst work?
Activation energy is the energy that reactants must absorb before the reaction can start. Catalysts lower the amount of activation energy needed.
What is an enzyme and how does it work? What are 5 things that effect enzyme activity (both positively and negatively) and how do they do it?
Enzymes are proteins in specific chemical reactions that aids in lowering the amount of activation energy required.
Temperature- as temperature increases so do enzyme activity, after reaching the optimal temperature if the temperature continues to rise the enzyme will be denatured
pH- same as temperature optimal pH is normally about 6.3
Enzyme concentration-the more enzymes there are the more substrate can be bound to an enzyme at one time increasing the rate of reactions for a short period of time
Substrate concentration- a lot of substrates means it is more likely for a substrate to bump into an enzyme thereby increasing the rate of reaction for a short period of time
Inhibitors/activators- modifies the shape of the enzyme which means the substrate can no longer bind to that enzyme making the reaction slower or sometimes even stop.
Define feedback inhibition. Explain how enzymes are regulated by feedback inhibition (Worth 4 points).
The final product in an enzyme chain reacts with the inital enzyme in the chain to keep it from doing its function. After enough of this occurs it prevents the reaction from occuring.
What is metabolism and discuss the two types of reactions seen in metabolic pathways. Why is the term pathway used and what does it indicate? How are metabolic pathways controlled or regulated?. (Worth 5 points)
Metabolism- the chemical processes that occur within a living organism in order to maintain life
Catabolic pathways- break down
anabolic pathways- build up
the term pathways suggest that it is a series of steps taken to do that action not just one
Enzyme inhibitors control these pathways by preventing them from continuing after certain amount of reactions
What are Redox reactions and why are they so named? (Worth 4 points)
Redox reactions are electron transfer reactions they were originally named that because they dealt with reactions with O2 (oxygen). the oxidative reaction involves the lose of electrons and the reduces reaction is the gain of electrons.
What is the energy currency of the cell and how does it do its job? (Worth 3 points)
ATP by breaking off the phosphates energy (that is typically held in easy to break bonds) is released. The loss of that phosphate turns ATP into ADP which then needs to be recharged.
What is the overall chemical equation for the complete breakdown of glucose to CO2 and H2O? Explain how this is an oxidation-reduction reaction (4 Pts.).
C6H12O6 + 6O2 -> 6CO2 + 6H2O this is a redox reaction because as the glucose is oxidized (loses electrons) the oxygen is reduced (gains electrons).
How do cells make ATP and what is its role? (3 Pts.)synthesized from ADP. role: when the phosphate groups are broken off it releases energy that can then power reactionsList the four phases of complete glucose breakdown. Tell which ones' release CO2 and which produces H2O and ATP (4 Pts.).Briefly describe the four phases of cellular respiration (6 Pts.).Glycolysis-splits glucose into pyruvate pyruvate oxydation- pyruvate is oxydized and turns into acetyl- CoA Krebs cycle (AKA citric acid cycle)- continues oxidation of glucose oxydative phosphoralation- electrons lost in glycolysis and krebs cycle are put into electron transport chain to power more ATP and at the end creates waterContrast the energy-investment step of glycolysis with the energy-harvesting steps (2 Pts.).The energy needed to split glucose is provided by two molecules of ATP; this is called the energy investment phase. As glycolysis proceeds, energy is released, and the energy is used to make four molecules of ATP; this is the energy harvesting phase.What are the products of the Krebs cycle per glucose breakdown? Remember the breakdown of one glucose molecule yields 2 Acetyl CoA molecules, which will turn the Krebs cycle twice (5 Pts.).3 NADH 2CO2 1 ATP 1 FADH2What are the two distinct events of the Electron Transport Chain (4 Pts.)?exergonic reaction fallowed by a endergonic reaction and repeated multiple timesCompare the function of the mitochondrial inner molecule (ETC chain and ATP synthase) to a hydroelectric dam (2 Pts.).Both a hydroelectric dam and an ETC (electron transport chain) have potential energy before entering the ETC or when the water is being held behind the dam. Then as the water or electrons go through their different processes kinetic energy is released and can be harnessed and used elsewhere.What are NAD+ and FAD? What are their functions (2 Pts.)?Both are electron transport carriers responsible for taking the "high energy" elctrons to the electron transport chain where they synthesize ATP moleculesWhat other organic molecules can be broken down and used in cellular respiration? Where do they enter into the cellular respiration pathway (4 Pts.)?Lipids, carbohydrates and proteins. Glycolysis- carbohydrates and some proteins pyruvate oxydation-proteins krebs cycle- lipids, proteinsWhy does your body store more energy as fat and than carbohydrate? Compare the amount of ATP produced from carbohydrates to that produced from fats to support your answer. Use the data provided. (The following information will help with your comparisons). Both fats and carbohydrates undergo catabolism to produce ATP energy. Fat (triglyceride) is hydrolyzed to form glycerol and three fatty acids. An 18-carbon fatty acid produces approximately 108 ATP molecules when broken down. Calculate the number of ATPs produced by a fat made of 3 fatty acids, each of 18 carbon. Compare to ATPs formed from one glucose.) (3 Pts.)3 x 108= 324 ATPs 38 ATPs from glucose more ATPs are gotten from fats than carbohydrates so its more benefical to store fats.What happens to organic molecules when oxygen is not available in a cell? What are the drawbacks and benefits of this metabolic pathway? What are some common products produced from this process (6 Pts.)?If O2 isnt available then the ETC would stop so to overcome this they use another highly electronegative substance. Downside is now no water is being created by these reactionsHow is Aerobic Respiration regulated? (3 Pts.)transport proteins regulate how much glucose can enter the cellThe electron transport chain is so named because electrons are transported from one component to another. Describe the purpose of the electron transport chain. (2 Pts.)the ETCs primary purpose is to harvest the last bit of energy out of the electrons from glucose most of the time 34 ATPs are chargedDuring fermentation, explain why it is important to oxidize NADH to NAD+. (4 Pts.)That energy is needed in this reaction and allows for NAD+ to be reduced during photosynthesisIs the functioning of the electron transport chain always needed to make ATP via ATP synthase? (2 Pts.)ETC creates the high concentration in the cytosol by pumping H+ across the membrane. In theory this could occur naturally but ETC makes it more efficentWhy is it proper to say that almost all living things are dependent on solar energy (4 Pts.)?We can easily trace the food chain to producers which are typically plants who get their energy from the sun.Show that the overall equation for photosynthesis as a redox reaction (4 Pts.).6CO2 + 6H2O → C6H12O6 + 6O2 as water is being oxidized the CO2 is being reduced to form glucoseWhat part of the electromagnetic spectrum is utilized for photosynthesis (2 Pts.) ?All visable light can be used for photosynthesis except for green light. This means the usable light is from 380-500, 600-750Explain the function of NADPH. (2 Pts.)electron carrier assists in powering photosynthesisWhat is the purpose of accessory pigments, such as carotenoids, in photosynthesis? (2 Pts.)Carotenoids are yellow-orange pigments that allow for the absorption of other wavelengths that chlorophyll cant absorb. This makes photosynthesis more efficient because less light is going to wasteExplain the role that water plays in the light-dependent reactions. (2 Pts.)It is an electron donor in light dependent reactions. Electron help to power the ADP and NADH+ which are used in the Calvin Cycle.What is the energy cycle? (4 Pts.)The way energy moves through an environment. Example: energy enters an ecosystem from external sources and moves through its componentName the two major components of chloroplasts, and associate each with one of two sets of reactions that occur during photosynthesis. How are the two sets of reactions related (6 Pts.)?Thylakoid and stroma. Thylakoid is were the light dependent reaction occurs whereas the stroma is where the Calvin Cycle happens.Which part of a chloroplast absorbs solar energy, and which part forms a carbohydrate (2 Pts.)?Te thylakoid is the part of the chloroplasts that absorbs energy and the stroma helps to create a carbohydrate (glucose).Explain what is meant by chemiosmosis, and relate this process to the electron transport chain present in the thylakoid membrane (4 Pts.).Chemiomosis of ions through a selective permeable membrane. It is through chemiosmosis that electron carriers (like FAD and NADPH) can transport through a selective permeable membrane like what happens during the electron transport chain.Describe the three stages of the Calvin cycle. Which stage uses the ATP and NADPH from the light reactions (6 Pts.)?Carbon fixation, reduction, the regeneration of the CO2 acceptor (RuBP aka substrate for Rubisco)Discuss some of the differences between C3 and C4 plants, contrasting the actions of RuBP carboxylase and PEPCase. (5 Pts.)Rubisco creates a six carbon sugar and is in both plants whereas PEP is in C4 and it creates four carbon sugarExplain CAM photosynthesis, contrasting it to C4 photosynthesis in terms of partitioning a pathway (4 Pts.).CAM photosynthesis is separated by opening and closing the stomata based on day/night whereas C4 is separated by different cells (mesophyll abs bundle sheath cells).What two molecules are produced as a result of the noncyclic electron pathway of the light reactions (2 Pts.)?*Oxygen and NADP+Can the Calvin cycle occur in the dark? (2 Pts.)Yes, until NADP+ and ATP runs outWhat is the advantage of having different pigment molecules? (2 Pts.)Different pignments allow to aboard different wavelengths which makes it more efficient.What are the two stages of photosynthesis? What are the key products of each stage? (5 Pts.)Light dependent reaction: (in; light and water out; O2, ATP, NADPH) and Calvin Cycle (in; CO2 and H2O, ATP, NADPH Out; glucose, oxygen, ADP, NADP+)