BIO 1305 Chapter 9: Cellular Respiration and Fermentation

C6H12O6 + 6O2

Photosynthesis starts with 6CO2 + 6H2O + light energy , and produces:

6CO2 + 6H2O + ATP

Cellular respiration starts with C6H12O6 + 6O2 , and produces:

Fermentation

The partial degradation of sugars that occurs without oxygen.

Aerobic respiration

Consumes organic molecules and oxygen and yields ATP.

Anaerobic respiration

Similar to aerobic respiration but consumes compounds other than oxygen.

Cellular respiration

Includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration.

ADP and phosphate

Cells must constantly regenerate their supply of ATP from _____________ and ________________.

transfer of electrons

The _____________________ during chemical reactions releases energy stored in organic molecules.

Redox reactions

Chemical reactions that transfer electrons between reactants; also known as oxidation-reduction reactions.

Oxidation

The loss of electrons from a substance in redox reactions.

Reduction

The addition of electrons to a substance in redox reactions, as the positive charge diminishes.

reducing agent

In redox reactions, the electron donor is called the __________________.

oxidizing agent

In redox reactions, the electron acceptor is called the __________________.

release energy

Redox reactions that move electrons closer to the electronegative O atoms _____________________.

oxidized, reduced

During cellular respiration, fuel molecules, such as glucose are _________________ and O2 is ________________.

hydrogen

Organic molecules with an abundance of __________________ are excellent sources of high-energy electrons.

redox process

Cellular respiration is a ___________________; energy is released as hydrogen and electrons are transferred to O atoms.

ATP

The oxidation of glucose transfers electrons from a higher energy state to a lower energy state with O atoms. This releases energy that is to be used to synsthesize __________.

proton (hydrogen atom)

In cellular respiration, each electron travels with a __________________.

electron carriers

Hydrogen atoms are first passed to ____________________, rather than directly to O2.

Nicotinamide adenine dinucleotide (NAD+)

An electron acceptor that becomes NADH when reduced (after accepting 2 electrons and 1 proton).

NADH

Represents stored energy that will be used to make ATP.

Electron Transport Chain

NADH delivers electrons to the _______________________________, where it is oxidized back to NAD+.

Oxidative phosphorylation

The process powered by redox reactions that generates almost 90% of the ATP.

Substrate-level phophorylation

The process by which some ATP is formed in glycolysis and the citric acid cycle.

Glycolysis

Process that occurs in the cytoplasm that harvests chemical energy by oxidizing glucose to pyruvate.

Energy investment phase

First phase of glycolysis where 2 ATP are used to split glucose into 2 three-carbon sugar molecules.

Energy payoff phase

Second phase of glycolysis where 4 ATP are synthesized, 2 NAD+ are reduced to NADH, sugars are oxidized to form 2 pyruvate and 2 H2O molecules.

2 ATP

A net of __________ are produced by substrate-level phosphorylation during glycolysis.

pyruvate

In glycolysis, all of the carbon present in glucose is accounted for in the two molecules of ________________.

Pyruvate oxidation

Converts into Acetyl CoA before entering the citric acid cycle.

CO2

Pyruvate dehydrogenase catalyzes the oxidation of pyruvate's carboxyl group, releasing the first _____________ of cellular respiration.

reduction

Pyruvate dehydrogenase catalyzes the ________________ of NAD+ to NADH.

Acetyl COA

Pyruvate dehydrogenase catalyzes the joining of the remaining two-carbon fragment with coenzyme A to form ___________________.

Citric acid cycle (Krebs cycle)

Oxidizes organic fuel from pyruvate, generating *1 ATP, 3 NADH, and 1 FADH2 per turn. 2 CO2 are produced as waste.

twice

Because 2 pyruvate are produced per glucose, the citric acid cycle runs __________ per glucose molecule consumed.

citrate

In the first step of the citric acid cycle, the acetyl group of acetyl CoA joins the cycle by combing with oxaloacetate, forming ____________.

oxaloacetate

The next seven steps of the citric acid cycle decompose the citrate back to ____________________, making the process a cycle.

NADH and FADH2

Produced from the citric acid cycle and carry electrons to the electron transport chain.

inner mitrochondrial membrane

Molecules of the electron transport chain are embedded in the ____________________ in eukaryotic cells.

proteins

Most of the molecules in the electron transport chain are ___________________.

Cytochromes

Electrons are passed through a number of carrier molecule including several _________________ (proteins with heme groups containing an iron atom).

Electron carriers

____________________ alternate between reduced and oxidized states as they accept and donate electrons.

O2, H2O

Electrons drop in free energy as they are transferred down the chain, finally to ________ to form _________.

Oxygen

The final electron acceptor.

ATP

No ___________ is produced directly by the electron transport chain.

ATP synthase

Protons (H+) move down concentration gradient across the membrane passing through _____________________.

Chemiosmosis

An energy-coupling mechanism where energy is used in a proton gradient to drive cellular work, eventually leading to the phosphorylation of ADP to ATP.

electronegative oxygen

Most cellular respiration depends on _______________________ to pull electrons down the transport chain.

Fermentation

Provides alternate mechanisms to regenerate NAD+ and allows ATP production to continue by glycolysis.

extention of glycolysis

Fermentation is an ___________________ that oxidizes NADH by transferring electrons to pyruvate or its dervatives.

Alcohol fermentation

Process in which pyruvate is converted to ethanol by removing CO2 from pyruvate, and producing NAD+ and ethanol.

Lactic Acid Fermentation

Process in which pyruvate is reduced directly by NADH to form lactate and NAD+. No CO2 is produced or released.

glycolysis

Fermentation and anaerobic and aerobic respiration use _____________________ (net ATP = 2) to oxidize glucose and harvest the chemical energy of food.

organic molecule

A major difference between fermentation and cellular respiration is that fermentation uses an __________________ (pyruvate or acetaldehyde) that acts as a final electron acceptor to oxidize NADH to NAD+.

2 ATP

Fermentation produces ________________ by substrate-level phosphorylation per glucose molecule.

32 ATP

Cellular respiration produces up to __________________ in aerobic respiration with substrate level phosphorylation and ATP by oxidative phosphorylation.

Obligate anaerobes

Carry out fermentation or anaerobic respiration and cannot survive in the presence of CO2.

facultative anaerobes

Yeast and many bacteria are __________________________, meaning that they can survive using either fermentation or cellular respiration.

carbohydrates

Glycolysis can use many _____________________, including starch, glycogen, and several disaccharides.

deamination

Proteins used for fuel must be digested into amino acids and their amino groups must removed in a process called _________________.

glycerol

Fats are digested to _________________ to produce compounds needed for glycolysis.

beta oxidation

Fatty acids are broken down by ________________ and yield acetyl-CoA, NADH, and FADH2.