Cellular Respiration Test

Flashcards for the CR test

Cellular Respiration Formula

C₆H₁₂O₆ + 6O₂ → 6CO_{2 +} 6H₂O + ATP

Aerobic Cellular Respiration

• Oxygen is present.

• Occurs in the mitochondria.

• Formula is OPPOSITE of photosynthesis.

• Produces 36/38 ATP for 1 glucose molecule

Steps of Aerobic Cellular Respiration

• Glycolysis

• Pyruvate Oxidation

• Krebs Cycle

• Electron Transport Chain

Anaerobic Cellular Respiration

• Oxygen is not present.

• Occurs in the cytoplasm.

• Formula is OPPOSITE of photosynthesis (without oxygen).

• Produces 2 ATP for 1 glucose molecule.

Glycolysis

• The splitting of glucose into 2 pyruvates

• Occurs in the cytoplasm

• First step in both aerobic and anaerobic cellular respiration

• Does NOT require oxygen (hence being part of anaerobic cellular respiration)

• 1 glucose molecule (6 carbon molecules) → 2 pyruvates (3 carbon molecules each)

The Steps of Glycolysis

Step 1: Investment Stage - ATP splits the glucose

• 2 ATP molecules are used (invested).

• The glucose molecule is split into two 3-carbon molecules (2 pyruvates).

• Prepares the molecules for the energy-releasing stage, where ATP is produced.

Step 2: Energy-releasing Stage

• Each 3-carbon sugar is oxidized, and energy is released.

• NADH is made (energy carrier).

• ATP is made (4ATP/Net 2ATP).

End products:

2 pyruvates (3 carbons each), 2NADH, 4ATP (Net 2ATP)

Acetyl-CoA/Pyruvate Oxidation

• Links glycolysis to the rest of aerobic cellular respiration.

• Pyruvates from glycolysis enter the mitochondria.

• Takes place in the mitochondrial matrix.

• Happens 2x (for each pyruvate produced in glycolysis).

Steps of Pyruvate Oxidation

1. Pyruvate (from glycolysis) enters the mitochondria.

2. 1 carbon is removed from pyruvate as CO₂

3. The remaining 2-carbon piece is oxidized, reducing NAD⁺ to NADH.

4. The 2-carbon piece attaches to Coenzyme A(CoA) to form Acetyl-CoA.

End Products (AFTER 2x):

2 Acetyl CoA, 2 CO₂ (waste product)_, 2 NADH

Acetyl-CoA

2-carbon group/molecules and Coenzyme A

Mitochondrial Matrix

The fluid inside the mitochondria.

Contains:

• Enzymes for energy production (especially for the Krebs Cycle).

• Mitochondrial DNA

• Ribosomes

• Gel-like fluid

Krebs cycle/Citric Acid Cycle

• Takes place in the Mitochondrial Matrix.

• Acetyl-CoA, produced from pyruvate oxidation, is the starting material.

• Occurs 2x for each Acetyl-CoA

Steps of Krebs Cycle

• Acetyl-CoA joins with a 4-carbon molecule to form citric acid

• Citric acid is broken down, releasing CO₂.

• NAD⁺ is reduced to NADH (energy carriers), and another CO₂ is released.

• FAD turns into/is reduced to FADH₂ (energy carrier).

• The cycle makes 1 GTP.

• The cycle repeats, regenerating the original 4-carbon molecule.

End Product (1 cycle):

3 NADH, 2 CO₂, 1 FADH₂, 1 GTP/ATP

End Product (1 glucose molecule/2 cycles):

6NADH, 4CO₂, 2FADH₂, 2 GTP/ATP

GTP

Energy carrying molecule equivalent to ATP

Mitochondrial Cristae

The folds inside the mitochondria.

• Give more space to make ATP.

• More folds = more energy.

Electron Transport Chain

• AKA oxidative phosphorylation/Chemiosmosis.

• Takes place in the mitochondrial cristae.

• Produces the most amount of ATP in aerobic cellular respiration.

Steps of the ETC

1. NADH + FADH₂ deposit their electrons in the ETC.

   • NADH → NAD⁺ / FADH₂ → FAD⁺

2. Electrons flow down the ETC.

3. Gives energy to pump electrons from the matrix to the intermembrane space, causing an electrochemical gradient.

4. Hydrogens flow down their electrochemical gradient back into the matrix through ATP synthase, producing 32 ATP

5. Oxygen is split in half, and hydrogens are added, producing water.

End Products:

ATP (32/34 per glucose), H₂O, NAD⁺ and FAD (recycled to be used again in glycolysis and the Krebs cycle)

Total amount of ATP produced in Aerobic Cellular Respiration

36/38 ATP

Lactic Acid Fermentation (Anaerobic C.R) + Steps

• Typically happens in animals (cells) and some bacteria.

• It occurs when you feel sore during exercise. That is lactic acid building up in your muscle cells (animal cells).

Steps:

1. Glycolysis breaks down glucose into 2 pyruvate molecules.

2. Pyruvate turns into lactic acid (lactate).

3. NADH turns back into NAD⁺, so glycolysis can keep making ATP.

End Product:

2 ATP, 2 Lactate, 2 NAD⁺

Alcoholic Fermentation

• Typically happens in yeast (cells) and some bacteria.

• It occurs when you bake bread or brew wine, or beer.

Steps:

1. Glucose is broken down into 2 pyruvates through glycolysis.

2. Each pyruvate is converted into 2 acetaldehyde (losing a carbon).

3. Acetaldehyde is then turned into 2 ethanol using NADH (which turns back into NAD⁺).

End Product:

Net 2ATP, CO₂, 2 Ethanol (alcohol), 2NAD⁺

Why regenerate NAD⁺?

NAD⁺ is regenerated so glycolysis can continue so there is a steady supply of ATP.

Where is the majority of usable energy produced from the Krebs cycle contained in?

NADH and FADH₂

Which is more efficient, Aerobic or Anaerobic C.R?

Aerobic cellular respiration is more efficient, because it produces more ATP (36/38) than anaerobic cellular respiration (2 ATP).

What type of cells does Cellular Respiration occur in?

Eukaryotic cells

Oxygen in the ETC

• Electronegative oxygen pulls electrons down the ETC and acts as the final electron acceptor.

• Combines with protons (H⁺) to create water.

Water in the ETC

• Water is made at the end of the ETC when oxygen combines with electrons and H⁺.

Hydrogens in the ETC

• Pumped into the Intermembrane space and creates a proton gradient.

• Flows through ATP synthase

NADH/FADH² in the ETC

• NADH and FADH₂ = electron carriers

• They start the ETC and help make ATP by giving up electrons.

• After, they turn back into NAD⁺ and FAD to be reused.

Intermembrane space in the in the ETC

• Holds the H⁺ ions that build up and help power ATP production.

ATP synthase in the ETC

• An enzyme that makes ATP

• Bonds ADP to P, forming ATP