Citric Acid Cycle - Lec 31

Aerobic metabolism

What do anaerobic organisms used to extract energy?

Aerobic organisms use oxygen to extract energy from nutrient molecules

Aerobic Metabolism

Does respiration or fermentation generate more energy?

Respiration generates significantly more energy than fermentation and was a. critical turning point in the evolution of life.

Aerobic Metabolism

Why oxygen?

Oxygen is an excellent electron receptor for two reasons

1. Availability-abundant

2. Power- highly electronegative

Aerobic etabolism

What released oxygen?

Oxygen was released by cyanobacteria 2.3 billion years ago but did not accumulate in the atmosphere for several hundred million years.

What are modern organisms classified based on?

What are the different classifications?

Modern organism are classified based on how they cope with ROS or how they use oxygen in energy generation.

Obligate anaerobes, aerotolerant anaerobes, facultative anaerobes, and obligate aerobes.

What is a obligate anaerobe?

Obligate anaerobes only grow in the absence of oxygen and use fermentation for energy production

What are aerotolerant anaerobes?

Aerotolerant anaerobes depend on federation but used detoxifying enzymes and antioxidant molecules to handle ROS.

What are facultative anaerobes?

Facultative anaerobes have not only biochemical reactions to detoxify ROS, but can use oxygen as an electron receptor when available.

What are obligate aerobes?

Obligate aerobes are highly dependent on oxygen for energy production, ROS protection from elaborate detoxifying mechanisms composed of enzymes and many antioxidant molecules.

What processes does Aerobic Metabolism consists of?

1. Citric Acid Cycle

2. Electron Transport Pathway

3. Oxidative Phosphorylation

Where does Aerobic Metabolism (and its processes) Occur?

What is most of the free energy captured by?

Aerobic Metabolism occurs within the mitochondria.

Most of the free energy is captured by the ETC

in Aerobic Metabolism Electrons are transferred from a ____ to …

Electrons are transferred from a redox pairs with a more negative reduction potential to those with more positive reduction potential.

REDOX COENZYMES FOR AEROBIC METABOLISM

What are redox coenzymes for aerobic metabolism (there are 2 redox coenzymes)?

What do both structures contain?

These are 2 coenzyme forms on nicotinic acid: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADPH)

What do NAD and NADPH both contain? (what do the two coenzyme structures both contain?)

Both structures contain adenosine and the N-ribosyl derivative of nicotinamide inks together through a pyrophosphate group.

REDOX COENZYMES FOR AEROBIC METABOLISM

What is riboflavin?

Riboflavin (B2) is a component of two coenzymes: Flavin mono nucleotides (FMN) and flavin adenine dinucleotide (FAD).

What do the coenzymes of Riboflavin (B2) function as)

FAD and FMN both function as tightly bound prosthetic groups of flavoproteins and can act as a donor or acceptor of two hydrogen atoms.

What can FMN do?

FMN can transfer one hydrogen atom at a time, which means it plays a key role in the link between the reactions in the mitochondrial matrix and the ETC.

What is the Citric Acid Cycle?

A series of sections that release chemical energy stored int he two-carbon acetyl group of acetyl-CoA

Citric Acid Cycle?

What is Acetyl-CoA synthesized from?

Acetyl-CoA is synthesized from pyruvate, the product of fatty aid catabolism, and from certain reactions in amnio acid metabolism

How many reactions is the Citric Acid Cycle composed of and in how many stages?

The citric acid cycles is composed of 8 reactions occurring in 2 stages:

1. two-carbon acetyl group of acetyl-CoA reaction with oxaloacetate and 2 CO2 released

2. oxaloacetate is rergenrated