glycolysis and kreb's cycle

I NEED TO STUDYYYYY

What is glycolysis?

The process of breaking down glucose into Pyruvate, NADH, and ATP

glycolysis step 1

1. glucose enters the cell through GLUT4 transporters

2. HexoKinase enzyme adds a -PO4 group (phosphorylation) to the glucose to “lock it in”

3. now glucose is committed to glycolysis

   (costs 1 ATP)

(committing glucose to glycolysis)

(Also known as phosphorylation)

glycolysis step 2

converting the aldose sugar into a ketose sugar.

Glucose-6-Phosphate is converted to fructose-6-phosphate by phosphoglucose isomerase

(Convert G6P to F6P) (Isomerization)

glycolysis step 3

1. F6P gains a phosphate (becomes more unstable)

2. Produces F-1, and 6-BP

3. Enzyme PFK is a major regulator of the process (phosphofructokinase)

   costs 1 ATP

(Adding another -PO4) (second phosphorylation)

glycolysis step 4

1. F-1, 6-BP is broken in half by aldolase

2. 6C → two 3Cs

3. Produces G3P($) and DHAP(Pounds, euros? idk, foreign currency so what is practically is)

(Cleaving)

Glycolysis step 5

(Conversion of DHAP into G6P by triose phosphate isomerase)

(Isomerization)

glycolysis step 6

1. G3P is oxidized

2. Electrons go to NAD+ to become NADH

3. Nicotinamide Adenine Dinucleotide (reduced form)

4. NAD+ is reduce (leo ger)

5. G3P gains a phosphate to become 1, 3-BP

   (Produces NADH per molecule)

(Oxidize G3P)

Glycolysis step 7

1. 1, 3-BPG has a PO4 removed

2. ADP → ATP

3. PO4 moved directly by the enzymes

4. produces3-PG

   (2 ATP gained)

(substrate level phosphorylation)

Glycolysis step 8-9

1. move PO4 group around

2. make it more accessible

3. 3-PG → 2-PG → PEP

(Moving PO4 group around)

Glycolysis step 10

1. PEP has phosphate removed

2. ADP → ATP

3. PO4 directly moved via enzymes

4. produces Pyruvate (or pyruvate acid)

   (gained 2 ATP)

(Substrate level phosphorylation)

what are the net results of glycolysis? And is O2 required?

• 4 ATP created

• net gain of 2 ATP

• and 2 NADHs carrying electrons

• 2 pyruvates obtained

• No O2 required

Kreb’s cycle (citric acid cycle)

Series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-Coa.

Oxidation of pyruvate (step 0)

• Pyruvate is oxidized

• NAD+ → NADH

• CO2 removed (COO-) and Co-A added

(3C → 2C)

Krebs cycle step 1

Acetyl-CoA adds its 2C to Oxaloacetate (4C) to produce Citrate (6C)

Krebs cycle step 2 & 3

• Citrate converted to IsoCitrate

• removal & addition of H20

• Aconitate intermediate (step 2)

Krebs cycle step 4

• Isocitrate is oxidized: NAD+ reduced to

  NADH

• Carboxyl group -COO - is removed and exits as CO2

• 6C --> 5C α-Ketoglutarate

  
  

(Oxidation and De-carboxylation)

Krebs cycle step 5

• α-Ketoglutarate is oxidized & NAD+ is

  reduced to NADH

• Again -COO- is removed as CO2

• Co-enzyme A is attached again

• 5C --> 4C Succinyl-CoA

(Oxidation and De-carboxylation)

Krebs cycle step 6

• CoA is replaced by a phosphate group

• Succinyl-CoA (4C) -> Succinate (4C)

  • GTP is then transformed into ATP

  • prokaryotes & plants ATP is made directly

    
    

Krebs cycle step 7

• Succinate is oxidized & electrons are transferred to FAD+ to form FADH2

  (FADH2 is similar to NADH and goes to the ETC)

• Succinate (4C) --> Fumarate (4C)

  
  

(oxidation)

Krebs cycle step 8

• addition of H20 to form 4C Malate

Krebs cycle step 9

• Malate is oxidized to form

  Oxaloacetate which can regenerate

  the Krebs Cycle

• NAD+ is reduced to NADH

(oxidation)

Is Kreb’s cycle anaerobic or aerobic?

Aerobic, even if no O2 is used during the process, you need it for the ETC. if non is left, then you go to fermentation