Bio CH.9

KNOW FIGURE 9.16 IN THE PPT

-------------------

What is substrate-level phosphorylation?

-A smaller amount of ATP is formed in glycolysis and the citric acid cycle by substrate-level phosphorylation -Substrate-level phosphorylation, which is a process of forming ATP by the physical addition of a phosphate group to ADP can take place in the cytoplasm during glycolysis or inside the mitochondrial matrix during the Krebs cycle.

What is the electron transport chain?

-The final stage of aerobic respiration is the electron transport chain. -The electron transport chain (aka ETC) is a process in which the NADH produced during glycolysis, β-oxidation, and other catabolic processes are oxidized thus releasing energy in the form of ATP. -O2 pulls electrons down the chain in an energy-yielding tumble The energy yielded is used to regenerate ATP -NADH passes the electrons to the electron transport chain Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction O2 pulls electrons down the chain in an energy-yielding tumble The energy yielded is used to regenerate ATP

• What is biosynthesis?

-the production of complex molecules within living organisms or cells. -The body uses small molecules to build other substances These small molecules may come directly from food, from glycolysis, or from the citric acid cycle

• How are aerobic respiration, anaerobic respiration, and fermentation similar?

All use glycolysis (to create 2 ATP) to oxidize glucose and harvest chemical energy of food In all three, NAD+ is the oxidizing agent that accepts electrons during glycolysis

• Without oxygen, what two processes can couple with glycolysis to produce ATP?

Anaerobic Respiration: uses an electron transport chain with a final electron acceptor other than O2, for example sulfate Fermentation: uses substrate-level phosphorylation instead of an electron transport chain to generate ATP

• What is anaerobic respiration?

Anaerobic respiration is similar to aerobic respiration but consumes compounds other than O2

• Which process produces the most ATP, aerobic respiration or fermentation?

Cellular respiration produces 32 ATP per glucose molecule; fermentation produces 2 ATP per glucose molecule

• What is chemiosmosis?

Chemiosmosis is the use of energy in a H+ gradient to drive cellular work H+ then moves down its concentration gradient back across the membrane, passing through the protein complex ATP synthase H+ moves into binding sites on the rotor of ATP synthase, causing it to spin in a way that catalyzes phosphorylation of ADP to ATP Chemiosmosis is the movement of ions across a semipermeable membrane, down their electrochemical gradient.

What is NAD+?

Electrons from organic compounds are usually first transferred to NAD+, a coenzyme As an electron acceptor, NAD+ functions as an oxidizing agent during cellular respiration Short for nicotinamide adenine dinucleotide. A coenzyme that occurs in many living cells and functions as an electron acceptor.

• Where does glycolysis occur?

Glycolysis occurs in the cytoplasm

• What are the two phases of glycolysis?

Glycolysis occurs in the cytoplasm and has two major phases Energy investment phase Energy payoff phase

• Energy leaves an ecosystem in what form?

Heat

• How does the electron transport chain differ from an uncontrolled reaction?

Unlike an uncontrolled reaction, the electron transport chain passes electrons in a series of steps instead of one explosive reaction

• What is the sequence of most energy flow during cellular respiration?

glucose ->NADH -> electron transport chain ->proton-motive force ->ATP

• Pyruvate must be converted to what substance before it can enter the citric acid cycle?

Before the citric acid cycle can begin, pyruvate must be converted to acetyl Coenzyme A (acetyl CoA)

• Glycolysis breaks down glucose into what?

Glycolysis ("splitting of sugar") breaks down glucose into two molecules of pyruvate

• What is the most common mechanism for control of cellular respiration?

Feedback inhibition is the most common mechanism for control of cellular respiration

• Most of the energy extracted from food at the end of glycolysis and the citric acid cycle are in what forms?

Following glycolysis and the citric acid cycle, NADH and FADH2 account for most of the energy extracted from food

Can the electron transport chain operate without oxygen?

Most cellular respiration depends on electronegative oxygen to pull electrons down the transport chain Without O2, the electron transport chain will cease to operate

What are the primary components of the electron transport chain?

Most of the chain's components are proteins, which exist in multiprotein complexes

• What is NADH?

NADH (the reduced form of NAD+) represents stored energy that is tapped to synthesize ATP

• What is the difference between obligate and facultative anaerobes?

Obligate anaerobes carry out fermentation or anaerobic respiration and cannot survive in the presence of O2 Yeast and many bacteria are facultative anaerobes, meaning that they can survive using either fermentation or cellular respiration

Does glycolysis require oxygen?

Occurs whether or not O2 is present

• What is the difference between oxidation and reduction?

Oxidation: In oxidation, a substance loses electrons, or is oxidized The electron donor is called the reducing agent Reduction: In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced) The electron receptor is called the oxidizing agent

What is fermentation?

Partial degradation of sugars that occurs without O2. Fermentation is a metabolic process that consumes sugar in the absence of oxygen

• Do fats, proteins, and carbohydrates enter cellular respiration in the same part of the process? If not, how does each contribute to cellular respiration?

Proteins must be digested to amino acids; amino groups can feed glycolysis or the citric acid cycle Fats are digested to glycerol (used in glycolysis) and fatty acids (used in generating acetyl CoA) Glycolysis accepts a wide range of carbohydrates including starch, glycogen, and several disaccharides

Do all redox reactions transfer electrons?

Some redox reactions do not transfer electrons but change the electron sharing in covalent bonds - An example is the reaction between methane and O2

• Energy flows into an ecosystem in what form?

Sunlight

• The citric acid cycle breaks down pyruvate into what substance?

The citric acid cycle, also called the Krebs cycle, completes the break down of pyruvate to CO2

• Which substance in a redox reaction is the reducing agent?

The electron donor is called the reducing agent

• Which substance in a redox reaction is the oxidizing agent?

The electron receptor is called the oxidizing agent

• Where is the electron transport chain?

The electron transport chain is in the inner membrane (cristae) of the mitochondrion

• How are aerobic respiration, anaerobic respiration, and fermentation different?

The processes have different mechanisms for oxidizing NADH: In fermentation, an organic molecule (such as pyruvate or acetaldehyde) acts as a final electron acceptor In cellular respiration electrons are transferred to the electron transport chain

What are Redox Reactions: Oxidation and Reduction

The transfer of electrons during chemical reactions releases energy stored in organic molecules This released energy is ultimately used to synthesize ATP OR -- Chemical reactions that transfer electrons between reactants are called oxidation-reduction reactions, or redox reactions

• ATP synthase uses the exergonic flow of H+ to drive what?

to drive the phosphorylation of ADP

• What is aerobic respiration?

• Aerobic respiration consumes organic molecules and O2 and yields ATP