9 Glycolysis/Fermentation

Which stage of glucose metabolism produces the most ATP? Fermentation of pyruvate to lactate Krebs cycle Glycolysis Electron transport and chemiosmosis

Electron transport and chemiosmosis --- Electron transport and chemiosmosis (oxidative phosphorylation) can yield around 26 molecules of ATP.

Which term describes the degree to which an element attracts electrons? Reduction. Electronegativity. Oxidation. Polarity.

Electronegativity

True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups. . True False

True --- The three phosphate groups in an ATP molecule carry negative charges that strongly repel each other and give ATP a large amount of potential energy.

True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.

True ---- Glycolysis takes place in the cytoplasm, whereas the Krebs cycle and the electron transport chain, which generate the largest amounts of ATP during cellular respiration, take place in the mitochondria.

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+ oxygen pyruvate NADH NAD+ lactate

pyruvate

In fermentation _____ is reduced and _____ is oxidized. pyruvate ... NADH NADH ... lactate NAD+ ... pyruvate lactate ... NADH lactate ... ethanol

pyruvate ... NADH ---- The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

1. When a compound donates (loses) electrons, that compound becomes_____________ . Such a compound is often referred to as an electron donor. 2. When a compound accepts (gains) electrons, that compound becomes _____________ . Such a compound is often referred to as an electron acceptor. 3. In glycolysis, the carbon-containing compound that functions as the electron donor is _____________ . 4. Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called _____________ . 5. _____________ is the compound that functions as the electron acceptor in glycolysis. 6. The reduced form of the electron acceptor in glycolysis is _____________ water oxygen NADH NAD+ glucose reduced oxidized pyruvate.

1. oxidized 2. reduced 3. glucose 4. pyruvate 5. NAD+ 6. NADH --- In the net reaction for glycolysis, glucose (the electron donor) is oxidized to pyruvate. The electrons removed from glucose are transferred to the electron acceptor, NAD+, creating NADH.

How many NADH are produced by glycolysis? 1 3 4 5 2

2

In glycolysis there is a net gain of _____ ATP. 5 1 2 3 4

2 Correct It takes 2 ATP to produce 4 ATP.

Which of the following statements is not true of most cellular redox reactions? The electron acceptor is reduced. Changes in potential energy can be released as heat. The reactant that is oxidized loses electrons. A hydrogen atom is transferred to the atom that loses an electron.

A hydrogen atom is transferred to the atom that loses an electron. A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron.

Match each product of pyruvate metabolism with the condition under which it is produced: fermentation in human muscle aerobic oxidation fermentation in yeast and bacteria match to: A) lactate B) ethanol C) acetyl CoA

A) fermentation in human muscle B) fermentation in yeast and bacteria C) aerobic oxidation

In glycolysis, what starts the process of glucose oxidation? ATP hexokinase NADPH FADH2 ADP

ATP -- Some ATP energy is used to start the process of glucose oxidation.

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? Polar and nonpolar. Ionic and covalent. Proton and electron. Anion and cation.

Anion and Cation Each atom will carry a charge from the transfer of electrons.

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? Water Carbon dioxide ATP NADH

Carbon Dioxide ---- All of the carbon atoms in glucose are incorporated into carbon dioxide: Two molecules are formed as pyruvate is converted to acetyl CoA, and four molecules are formed during the Krebs cycle.

What molecules belong in spaces E and F? glucose, water, carbon dioxide, and oxygen glucose and oxygen oxygen and water carbon dioxide and oxygen carbon dioxide and water

Carbon Dioxide and water Carbon dioxide and water are by-products of cellular respiration.

Sort between correct and incorrect statements: -One of the substrates is a molecule derived from the breakdown of glucose -The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions -The enzymes involved in ATP synthesis myst be attached to a membrane to produce ATP -An enzyme is required in order for the reaction to occur -A bond must be broken between an organic molecule and phosphate before ATP can form

Correct statements: -One of the substrates is a molecule derived from the breakdown of glucose -An enzyme is required in order for the reaction to occur -A bond must be broken between an organic molecule and phosphate before ATP can form --- In substrate-level phosphorylation, an enzyme transfers a phosphate group from one molecule (an intermediate in the breakdown of glucose to pyruvate) to ADP to form ATP. This is very different from the mechanism of ATP synthesis that takes place in oxidative phosphorylation.

Which of these is NOT a product of glycolysis? pyruvate ATP NADH FADH2

FADH2 ---- Correct FADH2 is a product of the citric acid cycle.

Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? Krebs cycle Electron transport chain Glycolysis Fermentation

Fermentation ---- Fermentation is an alternate pathway used when oxygen levels are low.

Which molecule is metabolized in a cell to produce energy for performing work? ATP Phosphate Glucose ADP

Glucose --- Correct Glucose is used to produce high-energy ATP in a cell.

What molecules belong in space A and B? glucose and oxygen carbon dioxide and water carbon dioxide and oxygen oxygen and water glucose and carbon dioxide

Glucose and Oxygen Photosynthesis produces glucose and releases oxygen into the atmosphere.

Which step of the cellular respiration pathway can take place in the absence of oxygen? Krebs cycle Electron transport chain Glycolysis Fermentation

Glycolysis --- Glycolysis can take place in the absence of oxygen; its product, pyruvate, enters the cellular respiration pathway or undergoes fermentation depending on the availability of oxygen.

Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed? Oxygen, nonpolar. Hydrogen, polar. Oxygen, polar. Hydrogen, nonpolar.

Hydrogen, Polar --- Hydrogen loses electrons to oxygen, which is more electronegative and thus pulls the electrons closer to itself in the water molecule.

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? Redox. Ionic. Polar covalent. Nonpolar covalent.

Ionic ---- The complete transfer of an electron from lithium to fluorine results in a stable compound in which both atoms have full outermost shells.

What organelle is indicated by the letter C? chloroplast peroxisome lysosome mitochondrion Golgi apparatus

Mitochondria Mitochondria are the sites of cellular respiration.

Which of the following statements about the electron transport chain is true? Water is the last electron acceptor. NADH and FADH2 donate their electrons to the chain. Electrons gain energy as they move down the chain. The electron transport chain is the first step in cellular respiration.

NADH and FADH2 donate their electrons to the chain. --- The electrons lose energy as they move down the chain, and this energy is used to create a proton gradient that drives the synthesis of ATP.

Which of the following statements is true of the bonds in a water molecule? The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1. Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. Oxygen acts as the electron acceptor and is oxidized. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero.

Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. ---- The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero.

What process occurs in structure H? intracellular digestion photosynthesis ribosome synthesis protein synthesis cellular respiration

Photosynthesis

Sort the following items according to whether they are reactants or products in the anaerobic reduction of pyruvate during lactic acid fermentation. pyruvate lactate NAD+ NADH

REACTANTS pyruvate NADH PRODUCTS lactate NAD+

Identify all correct statements about the basic function of fermentation. Select all that apply. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. The basic function of fermentation is the production of ethyl alcohol or lactic acid. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis.

The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. Fermentation occurs in the absence of oxygen and does not yeild as much ATP. Read about fermentation.

In muscle cells, fermentation produces _____. carbon dioxide, ethanol, NADH, and ATP lactate and NAD+ lactate, NADH, and ATP pyruvate carbon dioxide, ethanol, and NAD+

lactate, NAD+

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions? NADH only ATP only pyruvate, ATP, and NADH pyruvate and ATP only CO2 only O2 only ATP and NADH only

pyruvate, ATP, and NADH --- ATP is the main product of cellular respiration that contains energy that can be used by other cellular processes. Some ATP is made in glycolysis. In addition, the NADH and pyruvate produced in glycolysis are used in subsequent steps of cellular respiration to make even more ATP.

In glycolysis, ATP molecules are produced by _____. cellular respiration oxidative phosphorylation substrate-level phosphorylation photophosphorylation photosynthesis

substrate-level phosphorylation --- A phosphate group is transferred from glyceraldehyde phosphate to ADP.