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Chapter 8: Cellular Respiration
Terms in this set (44)
organism that produces glucose
organism that consumes glucose
the process by which cells acquire energy by breaking down molecules produced by photosynthesizers
a redox coenzyme. can oxidize a metabolite by accepting electrons or reduce a metabolite by giving up electrons.
when a metabolite is oxidized, NAD+ accepts two electrons plus one H+ to form NADH. the high energy electrons received in this reaction are then carried to the electron transport chain.
a redox coenzyme, accepts two electrons and two H+ ions to become FADH2.
respiration that requires the presence of O2 (the preparatory reaction, the citric acid cycle, the electron transport chain)
respiration that does not require the presence of O2 (glycolysis)
anaerobic process that occurs when oxygen is not available to break down pyruvate. pyruvate is further metabolized (after glycolysis) in the cytoplasm for a net gain of only two ATP per glucose molecule.
the breakdown of glucose (6 carbon molecule) into two pyruvate (3 carbon) molecules. oxidation results in NADH and a net gain of two ATP. occurs outside of the mitochondria.
the preparatory reaction
pyruvate (3 carbon molecule) is broken down into a 2-carbon acetyl group, and a 1-carbon CO2 molecule is released. occurs twice per glucose molecule. takes place in the matrix of the mitochondrion.
citric acid cycle aka Krebs cycle
each 2-carbon acetyl CoA matches up with a 4-carbon molecule (oxyloacetate), forming two 6-carbon citrate molecules. as citrate bonds are broken and oxidation occurs, NADH and FADH2 are formed and two CO2 per citrate are released. one ATP is produced per turn of the cycle (two acetyl groups per glucose molecule = two turns of the cycle). occurs in the matrix of the mitochondrion.
electron transport chain
consists of a series of carriers on the cristae of the mitochondria. NADH and FADH2 give their high-energy electrons to the chain. energy is released and captured as the electrons move from a higher-energy to a lower-energy state during each redox reaction. this energy will later be used to produce ATP through chemiosmosis. after oxygen receives electrons at the end of the chain, it combines with hydrogen ions (H+) and becomes water.
What are the inputs and outputs of a glycolysis reaction?
Input: 1 Glucose, 2 NAD+, two ATP, 4 (ADP + P)
Output: 2 Pyruvate, 2 NADH, 2 H2O, 4 ATP, 2 ADP
an enzyme passes a high-energy phosphate to ADP to form ATP
production of ATP from ADP and P using the energy from H+ crossing the mitochondrial membrane through ATP synthase due to an electrochemical gradient. this process of forming ATP is called chemiosmosis.
ATP production due to an electrochemical gradient of H+
the complex of proteins in the cristae of mitochondria and thylakoid membrane of chloroplast that produces ATP from the diffusion of H+ across a membrane
three-carbon sugar that results from the breakdown of glucose during glycolysis
the product of the preparatory reaction. in the preparatory reaction, two pyruvate molecules are converted to acetyl-groups and CO2. the two-carbon acetyl-groups are then carried into the citric acid cycle in the mitochondrial matrix by a molecule called CoA.
in the preparatory reaction, pyruvate gives 1 H+ and two e- to NAD+
folds of the inner mitochondrial membrane that jut out into the matrix
the innermost compartment of the mitochondrion, filled with a gel-like fluid.
an enzyme that helps pyruvate to form acetyl-CoA
What are the inputs and outputs of the preparatory reaction?
Input: 2 Pyruvate, 2 CoA, 2 NAD+
Output: 2 Acetyl-CoA, 2 CO2, 2 NADH
What are the inputs and outputs of the citric acid cycle?
Input: 2 Acetyl-CoA, 6 NAD+, 2 FAD, 2 (ADP+P)
Output: 4 CO2, 6 NADH, 2 FADH2, 2 ATP
an enzyme that has four carbons and bonds to Acetyl-CoA to form a six carbon citrate at the beginning of the citric acid cycle
a difference in concentration of H+ ions between two sides of a membrane
theoretical energy yields
in cellular respiration, the breakdown of one glucose molecule could, potentially, create 36-38 molecules of ATP. however, the conditions necessary for this to occur are not generally realized.
actual energy yield
the amount of energy that comes from the breakdown of glucose in practice (about 28-30 molecules of ATP)
the product of the fermentation of carbohydrates by yeast
lactic acid fermentation
anaerobic respiration performed in animal cells, glucose is converted to lactate and ATP
What are the inputs and outputs of fermentation?
Input: 1 Glucose, 2 ADP + 2 P
Output: 2 Lactate and 2 ATP (animal cells) or: 2 Alcohol and 2 CO2 and 2 ATP (plant cells)
the removal of an amino group
a protein that has a tightly bound heme group with a central atom of iron, the same as hemoglobin does (compose many of the redox carriers)
the process by which fatty acid molecules are broken down in the mitochondria to generate Acetyl-CoA, NADH, and FADH2
Describe the value of ATP in biological metabolic reactions.
provides energy needed for other reactions by breaking phosphate bonds (hydrolysis of ATP)
Describe two ways in which cells generate ATP and indicate which is a more efficient process.
Substrate level phosphorylation: transferring a P directly to ADP from another molecule
Oxidative phosphorylation/chemiosmosis: use of ATP synthase and energy derived from a proton gradient to make ATP (is the more efficient of the two)
Describe the role of ATP, NAD+, and FADH in coupled reactions.
All of these molecules act as energy carriers.
Explain how cellular respiration is a series of coupled metabolic reactions.
Glycolysis: ATP hydrolysis is coupled with substrate-level phosphorylation. The reduction of NAD+ is coupled with the addition of a phosphate group.
Preparatory Reaction: the production of Acetyl-CoA is coupled with the reduction of NAD+ to NADH.
Krebs Cycle: synthesis of ATP is coupled with the reduction of NAD+ and FADH.
Electron Transport Chain: the oxidation of NADH and FADH2 is coupled with the transport of H+ into the inter membrane space against its concentration gradient.
What is the net equation for cellular respiration?
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy
Why is oxygen required for aerobic respiration?
Oxygen is the final electron acceptor.
How many ATP are made during oxidative phosphorylation each from NADH and FADH2 and why?
Each NADH molecule makes 3 ATP because it is present for all three parts of the ETC.
Each FADH2 makes 2 ATP because it enters the ETC on step later than NADH.
How many ATP are made from one glucose in eukaryotes and prokaryotes?
36 in eukaryotes and 38 in prokaryotes.
How can food molecules other than glucose be oxidized to make ATP?
Nucleotides enter the Krebs Cycle.
Amino Acids enter the Krebs Cycle.
Monosaccharides enter glycolysis.
Fatty acids convert to Acetyl-CoA, fats provide the most energy.
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