Cellular respiration

Question 1

Do these transporters conduct passive or active transport? GLUT and SGLT

Answer 1

GLUT - passive

SGLT - active

Question 2

Which of the GLUT (1,2,3,4) transporters is insulin sensitive?

Answer 2

GLUT-4

GLUT-2 is NOT insulin sensitive

Question 3

What is the net ‘energy’ gain of glycolysis?

Answer 3

2 x ATP

2 x NADH (equiv to 6 ATP)

Question 4

In glycolysis, what do you start with and end with?

Answer 4

glucose -> 2 x pyruvate

Question 5

Where does glycolysis occur?

Answer 5

cytosol/cytoplasm

Question 6

Where does oxidative phosphorylation occur?

Answer 6

Mitochondria

Question 7

Where does the krebs/citric cycle occur and where is the electron transport chain (ETC) located?

Answer 7

Krebs cycle - mitochondrial matrix

ETC - inner mitochondrial membrane

Question 8

What is the name of process which imports pyruvate (from glycolysis) into the mitochondria?

Answer 8

Oxidative Decarboxylation

Question 9

What does oxidative carboxylation result in?

Answer 9

Import of pyruvate from glycolysis into the mitochondria involves oxidative decarboxylation
This produces acetyl-CoA and NADH inside the mitochondria

Question 10

What is the net (energy) gain from oxidative decarboxylation (per glucose molecule)?

Answer 10

1 x glucose = 2 x pyruvate = 2 x NADH in oxidative decarboxylation

Question 11

What is the net (energy) gain from the krebs cycle (per glucose molecule)?

Answer 11

1 x glucose = 2 x pyruvate = 2 x acetyl coA:

• 6 x NADH
• 2 x FADH2
• 2 x GTP

Question 12

How is acetyl-coA formed?

Answer 12

By β-oxidation of Fatty Acids

Question 13

What is the net (energy) gain from β-oxidation of Fatty Acids to create acetyl-coA?

Answer 13

1 x NADH

1 X FADH2

Question 14

What are the NADH and FADH2 produced from glucose used for?

Answer 14

Used in the ETC (inner mt membrane) to make ATP

Question 15

Describe how the electron transport chain works.

Answer 15

Energy from oxidation (removing electrons) of NADH and FADH2 is used to pump H+ across the mitochondrial inner membrane against their concentration gradient (into the intermembrane space)
As H+ moves back across the membrane through ATP synthase (into the mt matrix), ATP is produced from ADP

Question 16

In the ETC, what is the ultimate electron acceptor?

Answer 16

Oxygen - accepts electrons (from NADH/FADH2 to make H2O)

Question 17

What is gluconeogenesis?

Answer 17

Making new glucose from non-carbohydrate sources
In liver
Process requires energy (more made at end)
Sources:
Glycerol (triglycerides), amino acids (proteins), lactate (anaerobic glycolysis)

Question 18

What is the Cori cycle?

Answer 18

During vigorous exercise, muscle metabolism switches to anaerobic glycolysis, generating lactate.
The lactate is transported to the liver, where it is converted to glucose by gluconeogenesis (requires energy)

Question 19

How are amino acids (aa) used in the urea cycle?

Answer 19

AA’s - deamination by series of trasamination reactions - urea produced in liver via urea cycle - released into blood stream.

Question 20

Which amino acid is used in the urea cycle to make urea?

Answer 20

Arginine

Question 21

Which organs use the following as energy sources?
Glucose
Fatty acids
ketones
Amino acids

Answer 21

Glucose - most tissues (brain/RBCs)
Fatty acids - most tissues (minimal in neurons)
Ketones - most tissues (not liver) BRAIN
Amino acids - fast dividing cells (particularly glutamine) e.g. enterocytes and cancer cells