Mol Lecture #28

Question 1

Carbon Cycle and energy

Answer 1

• Convert sun energy into a form that stores ATP, and ultimately release CO2 and H2O.

Question 2

Oxidation reactions:

Answer 2

• reactions in which atoms fully or partially lose one or more electrons.
  –> OIL: oxidation is lost

Question 3

Reduction rxns

Answer 3

• rxns in which one or more atoms fully or partially gain one or more electrons.
  –> RIG: reduction is gain

Question 4

Redox reactions and changes in free energy

Answer 4

• Couples because when one entity loses an electron, another one is gaining electrons.
• Movement of electrons to lower energy states in a series of redox reactions will release small units of free energy that can be harnessed to make ATP.
• Often we will talk about the transfer of whole hydrogens (1 electron 1 proton)- but we only really care about the transferred electrons.

Question 5

Series of Redox reactions

Answer 5

• Series of steps where the energy of electrons is slowly siphoned off.

Question 6

NAD+/NADH as an electron shuttle

Answer 6

• NAD is an electron shuttle that can be reduced and oxidized
  –> Nicotinamide with two sugars and an adenine
  –>Generic electron

Question 7

Oxygen as the final electron acceptor

Answer 7

• Highly electronegative (really willing to accept electrons even if they don’t have that much energy)
• Electrons will be moved to lower energy states as they are passed through redox reactions
• Oxygen is the final electron acceptor in cellular respiration because it is so electronegative

Question 8

Overview of Cellular Respiration

Answer 8

• Breakdown of energy-rich carbon molecules to release energy that can be stored as ATP
  –> Start w/ glucose
  –> C6H12O6 + 6O2 + 32ADP + 32 Pi= 6 H2O + 6CO2 + 32ATP (basic inputs as outputs)

Question 9

Cellular Respiration: Glycoylsis

Answer 9

• occurs in the cytosol, results in the breakdown of glucose to 2 molecules of pyruvate. Some ATP and NADH (and related FADH2) are produced (Not really important ATP)

Question 10

Cellular Respiration: Pyruvate oxidation/ Citric Acid Cycle

Answer 10

• occurs in the mitochondrial matrix, 1st results in the oxidation of pyruvate which is converted to CO2 by CAC. Some ATP and NADH are produced. (Not really important ATP)

Question 11

Stages of Cellular Respiration: Oxidative phosphorylation

Answer 11

• occurs in mitochondrial matrix and across the inner membrane. Electron transfer system delivers electrons from electron shuttles to oxygen. The Energy gained from electron transferring is used to create an H+ gradient that is converted to ATP. (H+ gradient → ATP) (important ATP)

Question 12

Glycolysis Summary

Answer 12

• Glucose is partially oxidized and broken down into smaller molecules.
• Summary: 1 glucose (6 carbons) goes to 2 pyruvates (each has 3 carbons), and obtain 2 net ATP production (Generate 4 ATP, but use 2). Also generated 2 NADH (reduced from NAD+). 10 reactions, catabolic overall (delta G is negative throughout), and have 5 energy requiring steps followed by 5 energy releasing steps.

Question 13

Major enzyme types in glycolysis

Answer 13

• Dehydrogenases
• Isomerases
• Kinases

Question 14

Dehydrogenases:

Answer 14

enzymes that transfer electrons during redox reactions by moving hydrogens.

Question 15

Isomerases:

Answer 15

• enzymes that convert molecules to different isomers.

Question 16

Kinases:

Answer 16

• enzymes that phosphorylate substrates.

Question 17

Energy Requiring Steps (Don’t really need to know the specifics) * watch video

Answer 17

• Making glucose 6 phosphate, rearranging the molecules (isomerase) to make fructo 6 phosphate…
• isomerase converts the two products back and forth.

Question 18

Energy-Releasing steps (Don’t really need to know the specifics) * watch video

Answer 18

• Substrate level phosphorylation: one way to get ATP out of this process (transferring the phosphate to ADP to make ATP)