week 5 al

The breakdown of organic molecules is…

exergonic (gives off energy)

Fermentation is…

a partial breakdown of sugars without O2

Cellular respiration consumes…

organic molecules and O2 (or another terminal electron acceptor) and makes ATP using an ETC

Aerobic respiration terminal electron acceptor?

O2 at the end of the ETC

Anaerobic respiration terminal electron acceptor?

Something other than O2, like sulfate or nitrate

Aerobic vs anaerobic respiration?

Both use an ETC. Aerobic = O2 is the final acceptor. Anaerobic = sulfate, nitrate, etc.

2 ways ATP is formed?

Substrate-level phosphorylation and oxidative phosphorylation

Substrate-level phosphorylation is…

an enzyme transferring a phosphate directly from a substrate molecule to ADP

Where does substrate-level phosphorylation happen?

Glycolysis, the citric acid cycle, AND fermentation

Oxidative phosphorylation makes about ____% of the ATP from cellular respiration

90

Where does oxidative phosphorylation happen?

At the electron transport chain (inner mitochondrial membrane)

2 parts of oxidative phosphorylation?

The ETC and chemiosmosis

Cellular respiration usually refers to…

aerobic respiration (but technically includes both aerobic and anaerobic)

Which fuels can be used in cellular respiration?

Carbohydrates, fats, and proteins (glucose is traced as the example)

Redox reactions are…

reactions that transfer electrons between reactants

Oxidation = ____ electrons; Reduction = ____ electrons

lose; gain (OIL RIG)

The reducing agent is the electron ____

donor (gets oxidized)

The oxidizing agent is the electron ____

acceptor (gets reduced)

During cellular respiration, glucose is ____ and O2 is ____

oxidized; reduced

In the cellular respiration equation, which is the reducing agent?

Glucose (electron donor)

In the cellular respiration equation, which is the oxidizing agent?

O2 (electron acceptor)

How is the oxidizing agent changed in a redox reaction?

It gains electrons and loses potential energy

How is the reducing agent changed in a redox reaction?

It loses electrons and loses potential energy

Is NAD+ an oxidizing or reducing agent in respiration?

Oxidizing agent (it accepts electrons)

An "electron acceptor" is…

a molecule that takes electrons from another molecule (gets reduced)

3 stages of cellular respiration and locations?

Glycolysis (cytosol), pyruvate oxidation + citric acid cycle (mitochondrial matrix), oxidative phosphorylation (inner mitochondrial membrane)

Glycolysis breaks glucose into…

2 pyruvate (in the cytosol)

In glycolysis, where do the electrons come from?

Glucose

Why is glycolysis thought to be one of the first metabolic pathways to evolve?

It doesn't need organelles or O2, and it's found in most organisms

Alternate fuels for respiration?

Proteins (amino acids) and fats (glycerol + fatty acids)

Why funnel other fuels into the same pathways instead of new ones?

It's efficient: the cell reuses glycolysis and the citric acid cycle instead of building separate pathways

Modification needed before amino acids enter respiration?

Deamination (remove the amino group)

Modification needed before fatty acids enter respiration?

Beta oxidation (broken into 2-carbon pieces → acetyl CoA)

In eukaryotes, if O2 is present, pyruvate enters the…

mitochondrion

Pyruvate is converted to ____ before entering the citric acid cycle, releasing ____

acetyl CoA; CO2

Pyruvate oxidation makes ____ NADH per pyruvate (____ per glucose)

1; 2

The citric acid cycle is also called the…

Krebs cycle

How many times does the citric acid cycle turn per glucose?

Twice

Citric acid cycle yield per glucose?

2 ATP, 6 NADH, 2 FADH2

Which process makes the ATP in the citric acid cycle?

Substrate-level phosphorylation

Which pathways use substrate-level phosphorylation?

Glycolysis, citric acid cycle, fermentation

Which pathway uses oxidative phosphorylation?

The electron transport chain + chemiosmosis

Correct order of aerobic respiration?

Glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain

ATP yield per glucose at each stage?

Glycolysis 2, citric acid cycle 2, oxidative phosphorylation about 26–28 (about 30–32 total)

Where is the ETC in prokaryotes vs eukaryotes?

Prokaryotes = plasma membrane. Eukaryotes = inner mitochondrial membrane

Does ETC location support endosymbiotic theory?

Yes: the inner mitochondrial membrane matches the plasma membrane of the ancestral bacterium