Week 3 -Pre2: Cellular Respiration and Fermentation P1

Does a gram of sugar or a gram of fat have more potential energy to be released through redox reactions?

Fat has more potential energy than sugar because:

• Fat: Has more C–H bonds → less oxidized → more energy to release.

• Sugar: Has more C–O bonds → more oxidized → less energy to release.

✅ Remember: The less oxidized a molecule is, the more energy it can release when it becomes oxidized.

How do photosynthesis and cellular respiration work together to cycle matter and transfer energy?

1. Photosynthesis (chloroplasts): Uses sunlight, CO₂, and H₂O to produce glucose (sugar) and O₂.

2. Cellular respiration (mitochondria): Breaks down glucose using O₂ to produce ATP, releasing CO₂ and H₂O.

3. ATP: Provides energy for cellular work.

4. Heat: Some energy is released as heat.

⭐ Remember:

• Matter cycles: CO₂, H₂O, glucose, and O₂ are reused.

• Energy flows: Sunlight → Glucose → ATP → Heat.

What process is this an overview of?

Cellular Respiration

What type of isomers are 3-phosphoglycerate and 2- phosphoglycerate?

structural isomers

Aerobic respiration:

consumes oxygen as a reactant 

Anerobic respiration:

replaces oxygen with another inorganic molecule. 

Oxidation vs. Reduction

LEO GER: loss of elections = ______; gain of elections = ______

Oxidation: loss of electrons

Reduction: gain of electrons

Oxidation; reduction

Explain what a reducing agent and an oxidizing agent is

• Reducing (electron donor) agent: Gives away electrons (becomes oxidized).

• Oxidizing agent (electron acceptor): Accepts electrons (becomes reduced).

Organic molecules with many C-H bonds are ______ sources of _____

good; energy

what is the Role of Electron Carriers in Cellular Respiration

Electron carriers are molecules that transport high-energy electrons to help produce ATP (energy) during cellular respiration.

The two main electron carriers are:

• NAD⁺ → NADH

• FAD → FADH₂

Electron carriers (NAD⁺ and FAD) collect high-energy electrons during glucose breakdown, becoming NADH and FADH₂. They deliver these electrons to the electron transport chain, where their energy helps produce ATP. They are then recycled to collect more electrons.

What are FADH2 and NADH

electron carriers

NAD+ (_______ Form)

oxidized

NADH (______ Form)

reduced

What is the goal of cellular respiration?

to fully oxidize glucose (take away all its electrons)

Dehydrogenases:

Dehydrogenases are enzymes that remove hydrogen atoms (and their electrons) from molecules during chemical reactions.

• Dehydrogenases remove hydrogen atoms and electrons from molecules like glucose as they are broken down.

• Electron carriers, such as NAD⁺ and FAD, accept the electrons and hydrogen.

Top: ______________ Bottom: _____________

becomes oxidized; becomes reduced

What is glycolysis?

breakdown of glucose into two molecules of pyruvate

Substrate-level phosphorylation:

direct way your cells make energy by the transferring a phosphate group from a molecule straight to ADP to make ATP.

What is the investment phase of glycolysis?

the investment phase of glycolysis is the initial stage where two ATP molecules are consumed to phosphorylate glucose.

what is the payoff phase in glycolysis

the stage in glycolysis where four ATP molecules are produced through substrate-level phosphorylation, resulting in a net gain of two ATP. (because two are needed to restart glycolysis) This phase ultimately converts into two molecules of pyruvate while also generating NADH.

This is the process of ?

Glucose + 2 NAD+ + 2 ADP + 2 phosphate → 2 ATP + 2 NADH + 2 H+ + 2 H2O + 2 pyruvate 

glycolysis, which breaks down glucose.

Explain Glycolysis

Final formula

Glycolysis: The process of breaking down 1 glucose molecule (6 carbons) into 2 pyruvate molecules (3 carbons each) to produce energy.

• Location: Cytoplasm (specifically, the cytosol).

• Produces: ATP, NADH, and pyruvate

Glycolysis Has TWO Main Phases:

Phase 1: Energy Investment Phase

1. Start with 1 glucose molecule (6 carbons).

2. Use 2 ATP to add phosphate groups to glucose.

3. Glucose is split into two 3-carbon molecules.

4. Both molecules become G3P, ready to produce energy.

Remember: Use 2 ATP → Split glucose → Form 2 G3P.

Phase 2: Energy Payoff Phase:

Pay off phase occurs twice for each glucose molecule – net yield of 2 ATP 

1. Start with 2 G3P molecules.

2. Electrons are transferred to NAD⁺, forming 2 NADH.

3. Phosphates are transferred to ADP, making 4 ATP.

4. The 2 G3P molecules become 2 pyruvate.

Remember: Payoff = 2 ATP, 2 NADH, 2 pyruvate

Glucose + 2 NAD+ + 2 ADP + 2 phosphate → 2 ATP + 2 NADH + 2 H+ + 2 H2O + 2 pyruvate