Lecture 1 and 2: Intro & Glycolysis

Question 1

Definition of metabolism:

Answer 1

a series of linked reactions converting substrate into product

Question 2

Definition of Catabolism:

Answer 2

• Breakdown of larger molecules into smaller molecules.
• Oxidative process that releases energy.
• Makes ATP and reducing equivalents (i.e. NADH, NADPH, FADH2)

Question 3

Definition of Anabolism:

Answer 3

• Synthesis of larger molecules from smaller ones.
• Reductive process that requires energy.
• uses ATP and reductive power.

Question 4

What are the four major pathways of glucose?

Answer 4

1. Storage:
   
   • stored in the presence of excess energy as starch (plants) or glycogen (humans)
2. Synthesis of structural polysaccharides:
   
   • cell walls of plants, bacteria, and fungi.
3. Glycolysis:
   
   • oxidation yields energy, short term needs
4. Pentose Phosphate Pathway:
   
   • Oxidation yields NADPH and ribose 5-phosphate.
   • Detoxification
   • Biosynthesis of lipids and nucleotides.

Question 5

What is the importance of glucose? (x3)

Answer 5

1. Glucose is an excellent fuel:
   
   • oxidation yields lots of energy and is efficiently stored as glycogen.
2. Glucose is a biochemical precursor:
   
   • Provides carbon skeleton for all amino acids, membrane lipids, and metabolic cofactors.
3. Glucose is the most stable hexose:
   
   • has a low tendency to nonenzymatically glycosylate proteins.

Question 6

Two main phases of glycolysis:

Answer 6

1. Preparatory phase:
   
   • Activate glucose by phosphorylation.
   • Trap glucose in cell, use 2 ATP to modify cleavage into 3-carbon molecules.
2. Payoff phase:
   
   • Generate 4 ATP, 2 NADH, and 2 pyruvate

Question 7

What carbohydrate feed into glycolysis?

Answer 7

-Polysaccharides (glycogen and starch):
~glycogen phosphorylase cleaves off glucose as glucose 1-phosphate.

-Disaccharides:
     ~Lactose: glucose + galactose
     ~Sucrose: glucose + fructose
-Monosaccharides: 
     ~enter at different points.

Question 8

Bypass #1:

Answer 8

• Requires ATP
• Requires Biotin
• Requires CO2 (as HCO3-)
• Requires mitochondrial transport
• G = 0; so ratio of [PEP]/[PYRUVATE] dictates direction.

Question 9

Bypass #2:

Answer 9

• FBPase-1
  -Allosteric control
  ~activated by ATP
  ~inhibited by AMP

Question 10

Bypass #3:

Answer 10

-Liver only (G6Pase)
~must be able to export glucose to blood.
-Found in the endoplasmic reticulum.