Cellular Respiration

What are the stages of cellular respiration?

What are the stages of cellular respiration?

Glycolysis

Pyruvate Oxidation

Krebs Cycle/ Citric Acid Cycle

Oxidative phosphorylation

Cellular Respiration is an ____ reaction

Exergonic (releases energy)

Catabolic (breaks down glucose)

LEO the lion goes GER

Losing electrons = oxidation

Gaining electrons = reduction

What is the equation of cellular respiration?

C6H12O6 + 6O2 —> 6CO2 + 6H2O + ATP

Much of the energy from glucose is…

Dissipated as heat

What happens as glucose is gradually broken down?

Some of the breakdown steps release energy that is directly captured as ATP

What happens during substrate-level phosphorylation?

A phosphate group is transferred from a substrate straight to ADP, forming ATP

When does substrate-level phosphorylation occur?

During glycolysis and citric acid cycle

Why is substrate-level phosphorylation significant?

It allows cells to generate ATP without the electron transport chain

What are electron carriers?

Small organic molecules that pick up electrons and drop them off to another site

What happens to glucose during glycolysis?

Glucose is broken down into two molecules of pyruvate

Glucose is oxidized (loses electrons)

How much ATP is generated

2 ATP

What happens to the electrons lost in glucose?

They are picked up by NAD+ to form NADH

What happens when electron carrier NAD+ picks up electrons and one proton (H+)

It becomes NADH

Where do the pyruvate molecules go after glycolysis?

Into the mitochondrial matrix

What is the mitochondrial matrix?

The inner most compartment of mitochondria

Where does pyruvate oxidation take place?

The mitochondrial matrix

What happens during pyruvate oxidation?

Each pyruvate from glycolysis loses electrons and is converted acetyl CoA

What is released during pryuvate oxidation?

Carbon dioxide

What is generated during pyruvate oxidation?

NADH

What is produced during the citric acid cycle?

ATP, NADH, FADH2

What is released during the citric acid cycle?

Carbon dioxide

Is any ATP made during pyruvate oxidation?

No

What is acetyl CoA?

A two-carbon molecule attached to Coenzyme A

What is the net gain of glycolysis?

2ATP + 2NADH

Is O2 required for glycolysis?

No

What are the two stages of glycolysis?

The energy investment stage and the energy payoff stage

What occurs during the energy investment stage of glycolysis?

Cell uses ATP to phosphorylate(add a phosphate group) compounds of glucose

Where does the Citric Acid cycle occur?

In the mitochondrial matrix

What happens to acetyl CoA during the Citric Acid cycle?

Combines with a four-carbon molecule to produce citric acid (citrate)

What is produced in the Citric Acid cycle?

ATP, NADH, FADH2

What is released during the citric acid cycle?

Carbon dioxide?

Where do the electron carriers (FADH2 and NADH) go after the Krebs cycle and glycolysis?

To the Electron Transport Chain

What happens to the electron carriers during Oxidative Phosphorylation?

NADH and FADH2 deposit their electrons in the ETC, turning back into NAD+ and FAD

In what direction do electrons move down the ETC (oxidative phosphorylation)

They move down the chain

What happens as electrons move down the ETC?

They move from a high to low energy level, releasing energy

They are used to pump protons (H+) out of the matrix, forming a gradient

During oxidative phosphorylation, protons (H+) flow back into the matrix through ____, making

ATP synthase; ATP

What happens at the end of the ETC?

Oxygen accepts electrons and takes up protons to form water

What is the electron transport chain?

A collection of protein and organic molecules found in the inner membrane of the mitochondria

What makes up oxidative phosphorylation?

The ETC and chemiosmosis

How is the ETC organized?

Into four large complexes

What are the two important functions of the ETC?

Regenerates electron carriers

Makes a proton gradient

Complexes I, III, and IV of the ETC are ____

Proton pumps

What is the process in which energy from a proton gradient is used to make ATP?

Chemiosmosis

Is chemiosmosis unique to cellular respiration?

No, it can occur in photosynthesis as well

Chemiosmosis accounts for…

Most (80%) of the ATP made during glucose breakdown in cellular respiration

what is anaerobic respiration?

The generation of ATP using other electron acceptors besides oxygen

What kinds of organisms use anaerobic cellular respiration?

Some prokaryotes such as bacteria and archaea that live in low oxygen environments

What is fermentation?

An anaerobic (non O2 requiring) pathway for breaking down glucose

What is the only extraction pathway in Fermentation?

Glycolysis

How is cellular respiration and fermentation similar?

They both begin w/ glycolysis

How is the glycolysis in fermentation different from cellular respiration?

The pyruvate made in glycolysis does not continue through oxidation and the Krebs cycle and the ETC does not run

What happens to the NADH made in glycolysis during fermentation

It cannot drop off its electrons and turn back into NAD+

What is the purpose of the extra reactions in Fermentation?

To regenerate NAD+ from NADH

What happens during Lactic Acid fermentation?

NADH transfers electrons directly to pyruvate, generating lactate as a byproduct

What is the byproduct of Lactic Acid Fermentation?

Lactate

What happens during Alcohol Fermentation?

NADH delivers electrons to a derivative of pyruvate, producing ethanol

What is the first step to produce ethanol in Alcohol Fermentation?

Step 1: A carboxyl (COOH) is removed from pyruvate and released as CO2

What is the second step to produce ethanol in alcohol fermentation

NADH passes its electrons to acetaldehyde, regenerating NAD+ and forming ethanol

Many archaea and bacteria are ____ meaning they can switch between aerobic and anaerobic pathways

Facultative anaerobes

Some bacteria and archaea are ____ meaning they can live and grow only in the absence of oxygen

Obligate anaerobes