Bio 100, ch 6 - Cellular respiration
Why is the citric acid cycle called a cycle?
Acetyl CoA binds to oxaloacetate that is restored at the end of the cycle.
Cellular Respiration
Aerobic harvesting of energy from food molecules by cells.
What is oxidation? What is reduction?
Oxidation is the loss of electrons. Reduction is the gain of electrons.
Cyanide differs from dinitrophenol in that
cyanide is an electron transport blocker, while dinitrophenol makes the membrane of the mitochondrion leaky to H+ ions.
In biological systems, an important enzyme involved in the regulation of redox reactions is
dehydrogenase.
During which of the following phases of cellular respiration does substrate-level phosphorylation take place?
glycolysis and the citric acid cycle
Sequence of steps as energy is extracted from glucose during cellular respiration
glycolysis → acetyl CoA → citric acid cycle → electron transport chain
Which of the following metabolic pathways is common in aerobic and anaerobic metabolism?
glycolysis.
Where does glycolysis occur in a eukaryotic cell?
in the cytoplasmic fluid
The mitochondrial cristae are an adaptation that
increases the space for more copies of the electron transport chain and ATP synthase complexes.
Glycolysis is the only stage of cellular respiration that _____.
requires ATP to make ATP. Glycolysis contains an "investment" phase and a "payoff" phase. Two ATP are required to make four ATP.
Where do the reactions of the citric acid cycle occur in eukaryotic cells?
the mitochondrion
A kilocalorie is defined as:
the quantity of heat needed to raise the temperature of 1 kg of water by 1°C.
Given the relatively modest number of calories burned by anything but the most vigorous activities, why can people consume over 2,000 kilocalories a day, yet maintain a healthy body weight?
Most of the energy consumed in food is spent maintaining the body's functions, so only a fraction of food energy needs to be burned in exercise.
At the end of the citric acid cycle, most of the energy remaining from the original glucose is stored in
NADH.
What molecule is required to move pyruvate to the citric acid cycle?
O2 Oxygen must be present for the pyruvate to enter the citric acid cycle. Although the citric acid cycle itself does not use oxygen, oxidative phosphorylation does.
Citric acid cycle
Produces some ATP and carbon dioxide in the mitochondrion. The citric acid cycle breaks down carbon molecules, releasing carbon dioxide and forming some ATP
What is the difference between respiration and cellular respiration?
Respiration is gas exchange. Cellular respiration produces ATP.
The processes of photosynthesis and cellular respiration are complementary. During these conversions, what happens to some of the energy?
Some energy is lost in the form of heat.
Stages of cellular respiration
Stage 1: Glycolysis Stage 2: citric acid cycle Stage 3: electron transport chain
How do cells capture the energy released by cellular respiration?
They produce ATP.
Electron transport chain
Uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration. In the electron transport chain, electrons move from one electron carrier to another, eventually reaching oxygen. The released energy is used to make ATPs.
A mutant protist is found in which some mitochondria lack an inner mitochondrial membrane. Which of the following pathways would be completely disrupted in these mitochondria?
oxidative phosphorylation
Some human cells are restricted to aerobic respiration to recycle NADH and FADH2. If these cells are deprived of oxygen, then _____.
oxidative phosphorylation would come to a halt because there wouldn't be any oxygen to "pull" the electrons down the transport chain
The ATP synthase in a human cell gets energy for making ATP directly from _____.
the flow of H+ through a membrane
Oxidative phosphorylation could not occur without glycolysis and the citric acid cycle, because _____.
these two stages supply the electrons needed for the electron transport chain The main function of glycolysis and the citric acid cycle is to supply oxidative phosphorylation with electrons carried by NADH and FADH2.
Rotenone is a poison commonly added to insecticides. Insects exposed to rotenone will die because
they will no longer be able to produce adequate amounts of ATP.
As a result of glycolysis there is a net gain of ________ ATPs.
2
How many molecules of NADH are produced during glycolysis?
2
Cellular Respiration formula
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + ATP energy
Products of cellular respiration:
Energy to make ATP and carbon dioxide
What process takes place in the cytosol of a eukaryotic cell?
Glycolysis, the breakdown of glucose into two molecules of pyruvic acid, takes place in the cytosol--outside the mitochondria
Which organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?
Mitochondrion. All of the steps of cellular respiration except for glycolysis takes place in the mitochondrion.
During cellular respiration, electrons move through a series of electron carrier molecules. Which of the following statements about this process is true?
Molecular oxygen is reduced when it accepts electrons and forms water.
The function of coenzyme A in the citric acid cycle is most like
a limousine driver dropping off a couple at the school prom.
Which of the following processes produces the most ATP per molecule of glucose oxidized?
aerobic respiration
In the electron transport chain, the final electron acceptor is
an oxygen atom.
In cellular respiration, glucose _____ electrons, whereas _______ electrons.
loses ........ oxygen gains (During cellular respiration, glucose loses electrons and oxygen gains electrons. Oxidation and reduction always go together, as electron transfer requires both a donor and an acceptor.)
A molecule that functions as the electron donor in a redox reaction ______________.
loses electrons and loses energy. (In cellular respiration, glucose is oxidized when it loses electrons in hydrogen atoms. Oxygen is reduced as it gains electrons in hydrogen atoms.)
In humans, oxygen and carbon dioxide are exchanged with the atmosphere via the _____.
lungs
The enzymes of the citric acid cycle are located in the
matrix and inner mitochondrial membrane.
The end products of the citric acid cycle include all of the following except
pyruvate
After glycolysis but before the citric acid cycle,
pyruvate is oxidized.
Glycolysis
Begins cellular respiration by splitting glucose in half and produces 2 ATPs for each glucose. In glycolysis, glucose is split into two molecules of pyruvic acid. The released energy is stored in ATP and the electron carrier NADH.
During cellular respiration, NADH
delivers its electron load to the first electron carrier molecule.
To obtain energy from starch and glycogen, the body must begin by
hydrolyzing both starch and glycogen to glucose.
