Fatty Acid and Glucose Oxidation

Question 1

H+/e- strippers and carriers

Answer 1

NAD loves to oxidised -CH2OH into -C=O to become NADH

FAD loves to oxidised CH2-CH2 –> CH=CH and becomes FADH2

Question 2

fatty acid oxidation from blood into cell

Answer 2

fat (in the form of triglyercides) from adipose tissue

while in the blood, the FA (essentially soapso not the best in our body eh?) are loosely associated with albumin to keep in solution and not just floating around (eeeee)

–> is hydrophobic so diffuses across membrane into the cytoplasm
loosely ssociated with FABP (fatty acid binding protein) again, similar function to albumin

–> CoA attaches = FA-CoA so it is trapped inside the cell

Question 3

fatty acid oxidation (activation of FA)

Answer 3

FA + CoA —(ATP –> AMP + PP) —> FA-CoA
* uses fatty acyl CoA synthetase –> synthetase requires ATP
* ATP removes two phosphate groups (PP = 2Pi) which can be hydrolyses for energy
* the SH group on the CoA is the reactive group and where the FA joins

Question 4

fatty acid oxidation from cytoplasm into matrix

Answer 4

carnitine moves FA into the matrix

CAT-1 (CPT I): Converts fatty acyl-CoA to fatty acyl-carnitine on the outer mitochondrial membrane.
Translocase: Transports fatty acyl-carnitine across the inner mitochondrial membrane.
CAT-2 (CPT II): Converts fatty acyl-carnitine back to fatty acyl-CoA inside the mitochondrial matrix, freeing carnitine to be reused.

CAT-1 AND 2 are Carnitine acyl transferases

Question 5

beta oxidation : H+/e- stripping of carbon chain into acetyl chain

Answer 5

starting with the FA-COA
1) oxidation : FAD –> double bond between beta carbon and alpha carbon; FAD into FADH2
2) hydration : H2O hydrates and forms an OH group on the beta carbon
3) oxidation : NAD+ –> the -CHOH on beta carbon into -HC=O; NAD+ into NADH
4) cleavage : CoA splits molecule into two products 1. a fatty acid CoA and 2. acetyl CoA

so FAD–> FADH2
NAD+ –> NAD
and Acetyl CoA

A C16 fatty acid carbon chain requires 7 rounds of beta oxidation to form 7 FADH2, 7NADH and 8 Acetyl CoA
[8 pieces you cut it 7 pieces?]

Question 6

Glycolysis comparison to beta oxidation

Answer 6

glucose is polar and requires TRANSPORTERS to bring into cytoplasm

adds a phosphate group instead of CoA to trap it in the cell = G6P

–> forms 2ATP/2NADH/2 x 3C (pyruvate)

sometimes pyruvate decarboxylates to lactate [pyruvate dehydrogenase] which oxidises NADH into NAD+ so NAD+ can be recycled for glycolysis

Question 7

glucose transporters

Answer 7

GLUT1: all cells/ all the time
GLUT4: muscle/adipose
GLUT2: only in liver/pancreas [blood glucose regulation] always present

Question 8

glycolysis investment phases

Answer 8

investment phase:
glucose –hexakinase–> G6P (glucose 6 phosphate)
* hexakinase is a kinase so it adds phosphate groups
–> uses 1 ATP molecule

G6P –> fructose 6 phosphate–phosphofructokinase–> fructose-1,6-bisphosphate –> 2x 3C
–> uses 1 ATP molecule to make bisphosphate

ATP used when phosphate added

Question 9

glycolysis return phases

Answer 9

fructose-1,6-bisphosphate –> 2x 3C
using aldolase

catalyzing the reversible cleavage of fructose-1,6-bisphosphate into two three-carbon products: glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP).

= dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P).

–>DHAP is isomerized into another molecule of G3P.

–> 2 G3P undergoes oxidation and phosphorylation = 2 NADH and 2x 1,3-bisphosphoglycerate.

2x 1,3-bisphosphoglycerate = 2x 3-phosphoglycerate + 2 ATP

2x 3-phosphoglycerate = 2x 2-phosphoglycerate

2-phosphoglycerate = phosphoenolpyruvate (PEP) + H2O

2x Phosphoenolpyruvate (PEP) = 2 x pyruvate + 2 ATP

4 molecules of ATP produced in total but net gain 2 ATP

Question 10

krebs cycle

Answer 10

• aims to make a lot of NADH and FADH2 to carry H+/e- to ETC

acetyl CoA (from glycolysis or beta oxidation)

citrate –> 6C
6C –> 5C = CO2 + NADH
5C –> 4C = CO2 + NADH
4C –> 4C = GTP (ATP)
4C –> 4C = FADH2
4C –> 4C
4C –> oxaloacetate = NADH

products : 3 NADH + 1 FADH2 + 1 GTP
1 GTP makes 10 ATP per acetyl CoA

Question 11

fatty acids nomeclature

Answer 11

chemist : starting as 1 from functional group, 2, 3, 4
dietician : complete other end as omega, omega-1 etc e.g. omega-3
biochemist : skipping the functional group, the next carbon as alpha, beta and gamma

Question 12

biochemical features of CoA to do its job

Answer 12

(-SH) at the end of its moleculefor the formation of thioester bonds during the activation of fatty acids
–> forming a compound called FA-CoA (acyl-CoA)
–> transported into the mitochondria for the beta oxidation process