31 terms

AP Biology Ch. 4

Cell respiration
the means by which cells extract energy stored in food and transfer that energy to molecules of ATP
Two types of cell respiration
anaerobic; aerobic
Anaerobic respiration
oxygen is not present; also called fermentation
Aerobic respiration
oxygen is present
Processes following anaerobic respiration
glycolysis; alcoholic fermentation or lactic acid fermentation
Processes following aerobic respiration
glycolysis; citric acid cycle (krebs cycle); electron transport chain; oxidative phosphorylation
consists of adenosine plus three phosphates
when one phosphate group is removed from ATP from hydrolysis this results
10 step process that breaks down 1 molecule of glucose into 2 three carbon molecules of pyruvate or pyruvic acid and releases 4 molecules of ATP; occurs in the cytoplasm and produces ATP anaerobically; end product is pyruvate; ATP is produced by substrate level phosphorylation
Energy of activation for glycolysis
Net gain of ATP in glycolysis
raw material for the Krebs cycle
Substrate level phosphorylation
direct enzymatic transfer of a phosphate to ADP
Two types of anaerobes
facultative; obligate
Facultative anaerobes
can tolerate the presence of oxygen but do not use it
Obligate anaerobes
cannot live in an environment containing oxygen
Alcohol fermentation
the process by which certain cells convert pyruvate from glycolysis into ethyl alcohol and carbon dioxide in the absence of oxygen; oxidize NADH back to NAD+
Lactic acid fermentation
pyruvate from glycolysis is reduced to form lactic acid or lactate; NADH gets oxidized back to NAD+
Citric acid cycle
a cyclical series of enzyme catalyzed reactions; takes place in the matrix of the mitochondria and requires pyruvate; completes the oxidation of glucose to CO2; turns twice for each glucose molecule; acetyl co-A combines with oxaloacetic acid to produce citric acid; each turn releases 3 NADH, 1 ATP, 1 FADH, and CO2
Two internal compartments in the mitochondria
outer compartment; matrix
Where does the electron transport chain take place?
cristae membrane
NAD+ and FAD
carry protons or electrons from glycolysis and the Krebs cycle to the electron transport chain; facilitates the transfer of hydrogen atoms from a substrate; vitamin derivatives
Electron transport chain
a proton pump in the mitochondria that couples two reactions; uses the energy released from the exergonic flow of electrons to pump protons against a gradient from the matrix to the outer compartment; establishes a proton gradient inside the mitochondrion; makes no ATP
proteins structurally similar to hemoglobin; present in all aerobes and are used to trace evolutionary relationships
Oxidative phosphorylation
the phosphorylation of ADP into ATP by the oxidation of the carrier molecules NADH and FADH2
All of the following processes produce ATP EXCEPT...
a. lactic acid formation
b. oxidative phosphorylation
c. glycolysis
d. the Krebs cycle
a. lactic acid formation
Which of the following is the most important thing that happens during aerobic respiration?
a. electrons move down the electron transport chain in a series of redox reactions
b. acetyl coA enters the Krebs cycle
c. NAD carries hydrogen to the electron transport chain
d. ATP is produced
d. ATP is produced
Which is an example of a feedback mechanism?
a. phosphofructokinase, an allosteric enzyme in glycolysis, is inhibited by ATP
b. lactic acid gets converted back to pyruvic acid in the human liver
c. ATP is produced in mitochondria as protons flow through the ATP synthase channel
d. energy is released from glucose as it decomposes into CO2 and H2O
a. Phosphofructokinase, an allosteric enzyme in glycolysis, is inhibited by ATP
Which process of cell respiration is most closely associated with intracellular membranes?
a. oxidative phosphorylation
b. the Krebs cycle
c. glycolysis
d. substrate level phosphorylation
a. oxidative phosphorylation
During cell respiration, most ATP is formed as a direct result of the net movement of...
a. electrons flowing against a gradient
b. electrons flowing through a channel
c. protons flowing through a channel
d. protons flowing against a gradient
c. protons flowing through a channel
Glycolysis is the first phase of aerobic cellular respiration. It is a complex, enzyme controlled set of reactions in which glucose molecules are broken down into pyruvate in the absence of oxygen. Although it does not produce much ATP, glycolysis is important because pyruvate is the raw material for the next phase of cellular respiration, which will ultimately produce large amounts of ATP by oxidative phosphorylation. One of the enzymes at the beginning of glycolysis is PFK, phosphofructokinase, an allosteric enzyme. When ATP binds to the allosteric site on PFK, the enzyme changes shape and no longer functions. Which of the following statements best explains the importance of the enzyme PFK in glycolysis?
a. PFK inhibits glycolysis when oxygen levels are high
b. PFK enables glycolysis to continue when no oxygen is present
c. PFK inhibits the production of ATP when ATP levels are high
d. PFK enhances the production of ATP when ATP levels are high
c. PFK inhibits the production of ATP when ATP levels are high