Chapter 15: Metabolism: Basic Concepts & Design

Question 1

Energy is needed for….

Answer 1

Movement, active transport and biosynthesis

Question 2

Phototrophs vs Chemotrophs

Answer 2

capture and transform sunlight energy vs get energy from oxidizing carbon fuel

Question 3

Metabolic pathways are

Answer 3

• Stepwise reactions breaking down or synthesizing molecules
• reaction types are limited and often have common intermediates
• are typically defined by a specific substrate getting converted to a specific end point

Question 4

intermediary metabolism

Answer 4

• pathways interact with other pathways
• traditionally studied as isolated pathways and are then linked by defining key interaction points

Question 5

Types of metabolic pathways

Answer 5

Catabolic: Convert energy from fuel to ATP - glycolysis
Anabolic: require energy for synthesis - gluconeogenesis

• will often share reaction
• are key, regulated, irreversible reactions for distinct pathways

Question 6

Amphibolic pathways

Answer 6

Pathways that can be catabolic or anabolic depending of situation
Ex. TCA covert Acetyl-CoA to energy or TCS cycle providing carbon backbones for synthesis

Question 7

ATP is used because…

Answer 7

• high energy phosphates
• the hydrolysis is exergonic
• triphosphate unit contains 2 phosphoanhydride bonds that are unstable
• energy release used to power a host of cellular functions

Question 8

Phospho-anhydrides energy is based on 4 factors….

Answer 8

1. Electrostatic repulsion: pH 7.4, phosphates have a negative charges and triphosphates carry 4 negative charges - negative charges repel each other
2. Resonance stabilization: more sharing = lower energy state, when phosphates have anhydride bonds - the electron sharing is reduces compared to individual phosphates
3. Increase in entropy: Hydrolysis generates 2 molecules instead of one molecule
4. Stabilization due to hydration: Ability of water to hydrogen bond to molecule - more H-bonds possible with ADP and Pi