BIOL 1105: Lesson 08: Energy from Organic Molecules I

How do autotrophs obtain energy?

Produce their own ATP and organic molecules through photosynthesis

How do heterotrophs gain energy?

They live on organic molecules produced by autotrophs

How do cells extract energy?

Through oxidizing organic molecules

All organisms use ________ ____________ to extract energy from chemical bonds of organic molecules.

cellular respiration

Cellular Respiration involves a series of _________ _________ reactions.

enzyme catalyzed

Oxidation involves the gain of electrons (true or false)?

False; oxidation = loss of electrons

Dehydrogenation

loss of protons

Harvested electron undergo a series of __________ reactions.

redox

Electrons _________ (lose/gain) energy with each transfer.

lose energy

What do redox reactions transfer?

electrons and associated energy

What happens to released energy from a reaction?

It can be lost as heat or converted to ATP

Electrons posses energy when they are….

harvested from organic molecules

When are energy-depleted electrons transferred to the final electron acceptor protein?

After multiple redox reactions

Cofactor

small chemicals that assist enzymes

(True or False) Electron carriers cannot be reversed once oxidized or reduced.

False; they can be easily reversible

What are the Four Stages of Glucose Oxidation?

(1) Glycolysis, (2) Pyruvate oxidation, (3) Krebs Cycle, (4) Electron transport chain and chemiosmosis

Glycolysis converts ______ Glucose(s) into ______ pyruvate(s)

(1) One, (2) Two

What are the two phases of glycolysis?

(1) Energy input, (2) Energy production (ATP)

What is Glucose first converted into?

Two G3P Molecules

What does the generation of G3P require?

Energy input

Glucose involves the ________ of 2 ______ molecules

(1) Hydrolysis, (2) ATP

What is each G3P molecule converted into?

Pyruvate

NAD+ => NADH

G3P is oxidized

After Pi is added to G3P, each Pi (4 total) will be….

transferred to ADP

What are the products of glycolysis?

2  ATP (net) + 2 NADH 

How does ATP synthesis occur during glycolysis?

Substrate-level phosphorylation

ATP Synthesis in glycolysis is _________ ___________.

enzyme catalyzed

Oxidative phosphorylation

allows eukaryotes to synthesize much more ATP in the presence of oxygen 

Where does pyruvate oxidation occur during aerobic respiration?

• the mitochondrial matrix in eukaryotes

• Plasma membrane of prokaryotes

• catalyzed by pyruvate dehydrogenase

What is a coenzyme?

small organic molecule that functions as a cofactor

Each pyruvate molecule is used to generate…

• 1 CO2

• 1 NADH

• 1 acetyl-CoA => then fed into krebs cycle

In the Krebs cycle, oxidation of the acetyl group is generated by ___________ _______________.

pyruvate oxidation

Where does the Krebs cycle occur?

In the matrix of the mitochondria

What are the three parts of the nine steps in Krebs cycle?

• Acetyl-CoA + oxaloacetate -> citrate 

• Citrate rearrangement and decarboxylation (2 CO2 released) 

• Regenerations of oxaloacetate 

What is decarboxylation?

process by which a carbon atom in the form of CO2 breaks off from a larger organic molecule. Catalyzed by pyruvate dehydrogenase ( a multienzyme complex)

NAD+ Accepts _________ to Form________.

(1) Electrons, (2) NADH 

The Krebs cyclic pathway starts and ends with ______________.

oxaloacetate

Per Glucose, what does the Krebs Cycle produce?

• 2 ATP

• 6 NADH

• 2 FADH2