Lecture 16

Question 1

metabolic pathways

Answer 1

series of chemical rxns whereby the products of onercn are the substrates for the next rxn etc.. till the end product is generated

Question 2

catabolism vs anabolism

Answer 2

cata= breakdown, release of E
ana= build up, net input of E

Question 3

cata/ana steps

Answer 3

cata= complex–> simple (ADP+ Pi —> ATP)

ana = simple –> complex (ATP —>ADP+ Pi )

Question 4

catabolism order of steps

Answer 4

1- proteins, NA, polysac, complex lipid
2- Monomers- AA, Nuctides, Sugars, FA, glycerol
3- Metabolic intermediates- pyruvate, Acetyl-coa, CAC int
4- net output- energy+ small molecules- h2o, co2, nh3

Question 5

anabolism order of steps

Answer 5

1- net input- energy+ small molecules- h2o, co2, nh3
2- Metabolic intermediates- pyruvate, Acetyl-coa, CAC int
3- Monomers- AA, Nuctides, Sugars, FA, glycerol
4-proteins, NA, polysac, complex lipid

Question 6

Cellular respiration

Answer 6

is the liberation of energy through the oxidation of food.

Question 7

how many oxidation states of carbon?

Answer 7

9

Question 8

Formal charge #

Answer 8

the higher the ox # the more oxidizied

-1 for each bond to hydrogen
0 for each bond to carbon
+1 for each bond to O, N or S

Question 9

alkane ox #

Answer 9

-4 –> most reduced

Question 10

alcohol ox #

Answer 10

-2

Question 11

aldehyde ox #

Answer 11

0

Question 12

carboxylic acid ox #

Answer 12

+2

Question 13

CO2 ox #

Answer 13

+4 –> most oxidized

Question 14

molecules with more reduced carbons yield more energy upon oxidation

Answer 14

methane= most reduced= most energy

why CO2 can’t be burned–> end product

Question 15

Why is ATP
the most widely used energy
currency of the cell?

Answer 15

• Hydrolysis yields lots of energy:
– ATP + H2O ADP + Pi
– ∆G0’= -30.5 kJ/mol (-7.3 kcal/mol)
– Phosphoryl group has high transfer potential
– Hydrolysis of ATP is favored because
• Relief of charge repulsion
• Resonance stabilization
• Ionization and Solvation of ADP

Question 16

hydrolysis of ATP

Answer 16

ATP4- + H2O —> ADP3- + P2-i + H+

Question 17

NADH is the most widely

Answer 17

used electron carrier in cells

reducing power

Question 18

Importance of coupling reactions:

Answer 18

• Problem: Virtually all synthetic reactions are
endergonic and cannot proceed as written.
(endergonic– need E to go to the right)

• Solution: Couple an endergonic reaction to an
exergonic reaction such that the overall reaction is
exergonic.

Question 19

Coupling Reactions

Answer 19

The overall ∆G of a coupled series
of reactions = sum of the ∆G’s for the individual
reactions.

Question 20

∆G of Pi + glucose —> glucose-6-P + H2O

Answer 20

+13.8

endergonic

Question 21

∆G of ATP + H2O —> ADP + Pi

Answer 21

-30.5

exergonic

Question 22

Coupling reactions to synthesize Glucose-6-
Phosphate from glucose and ATP

overall = ATP + glucose —> ADP + glucose-6-P

Answer 22

+13.8 - 30.5 = -16.7

Question 23

What is Glycolysis?

Answer 23

• Uses Glucose:
– Corn syrup, sucrose, starch, glycogen
– Primary source of energy for the brain
– Fuels quick bursts of activity in muscle
• 10 reactions
• Takes place in the cytoplasm of a cell.
• The oxidation of glucose to pyruvate, NADH
and ATP.

Question 24

Source of energy during a sprint:

Answer 24

1. Pre-existing ATP
2. Phosphocreatine via creatine
   kinase
3. Glucose via glycolysis
4. Glucose via glycolysis and
   respiration

Question 25

Creatine Kinase

Answer 25

PCr + ADP Cr + ATP

Question 26

Glucose gets into cells via glucose transporters

Answer 26

Facilitated Diffusion

Question 27

GLUT 1

Answer 27

ubiquitous– high affinity for glucose

Question 28

GLUT 2

Answer 28

liver and pancreatic β-cells – low affinity, high

capacity for glucose, These organs need to “sense” glucose levels.

Question 29

GLUT4

Answer 29

skeletal muscle and fat, responsive to insulin

Question 30

Glucose + 2 Pi + 2 ADP + 2 NAD+ —–>

Answer 30

2 pyruvates + 2 ATP + 2 NADH + 2 H+ + 2 H2O

Question 31

Hexokinase

Answer 31

first step in Glycolysis— Hexokinase activates glucose and keeps it in the cell.

Question 32

Types of hexokinases

Answer 32

Types I and II: brain, skeletal muscle, fat. High affinity for glucose

Type IV: “Glucokinase” in liver and pancreas. Theses organs need to “sense” glucose levels. Low affinity for glucose

Question 33

“Induced Fit” mechanism

Answer 33

The binding of glucose to Hexokinase induces a conformational change that helps the glucose bind and facilitates phosphorylation of the glucose.

Question 34

glycolysis

Answer 34

1st step in the catabolism of carbs- glucose broken down -> 2 pyruvate

net prod of ATP and red of 2 NAD+ to NADH

Question 35

citric acid cycle

Answer 35

takes place in the mitochondrial matrix–

oxidation of acetyl units to CO2 w/ prod of red equiv and ATP