Chapter 15: Metabolism Basic concept and design

What are the three stages of the generation of energy from food?

1. large molecules are broken down into smaller molecules (digestion)

2. small molecules processed into molecules of metabolism (acetyl CoA)

3. ATP produced from complete oxidation of acetyl CoA

What is energy required for?

power muscle contraction, cell movement, biosynthesis

What do phototrophs do?

obtain energy by capturing sunlight

What do chemotrophs do?

obtain energy through oxidation of carbon fuels

What are metabolic pathways?

the way molecules are synthesized or degraded stepwise in a series of reactions and are highly regulated into large complexes

What is the currency of life and how can it be formed?

ATP can be formed by oxidation of carbon fuels

what is metabolism?

a series of linked reaction that convert a specific reactant to a product (entire set is intermediary metabolism)

What is the pathway for glucose metabolism?

glucose → pyruvate (in 10 steps)→ anaerobic (lactate) or aerobic (acetyl CoA)

How do catabolic pathways work?

combust carbon fuels to synthesize ATP or ion gradients

How do anabolic pathways work?

Use ATP and reducing power to make large biomolecules

What are amiphibolic pathways?

Can function anabolically or catabolically (regulated irreversible reactions are distinct)

What is the criteria for metabolic pathways?

1. individual reaction must be specific

2. must be thermodynamically stable (unfavorable can be favorable with coupling)

Why is ATP hydrolysis exergonic?

The two phsphoanhydride bonds are unstable so when they break energy is released→ used to power cellular function (delta -G)

What is phosphoryl transfer potential?

the standard free energy of hydrolysis to allow molecules to transfer phosphoryl groups to acceptor molecules (ATP has high potential)

Why does ATP have high phosphoryl-transfer potential?

1. charge repulsion

2. resonance stability

3. increase in entropy

4. stabilization by hydration

what can generate ATP from ADP

creatine phosphate for a short burst of activity

Why are phosphate and its esters important?

1.Phosphate esters are thermodynamically unstable, yet they are kinetically stable.

2.Phosphate esters are stable because the inherent negative charges resist hydrolysis.

3.Because phosphate esters are kinetically stable, they are ideal regulatory molecules, added to molecules by kinases and removed by phosphatases.

what oxidizes and accepts to form H2O?

carbon atoms are oxidized to yield CO2 and electrons accepted by O2 to form H2O

• more reduced carbon=more free energy released

What are the two characteristics of activated carriers?

1. kinetically stable without catalysts

2. metabolism of activated is with small amount of carriers

What are common activators?

ATP for phosphoryl groups, NAD+ and FAD carry activated electrons from oxidation of fuels. NADP+ for reductive biosynthesis

What is coenzyme A?

CoA is activated carrier of acyl groups ad is exergonic bc thioester is unstable

What vitamin serves as a coenzyme?

Vitamin B

How are metabolic processes regulated?

1. amount of enzymes

2. catalytic activity (covalent modification)

3. accessibility of substrates (opposite reactions in diff compartments)

enzyme activity