3. Krebs Cycle

Question 1

What is Acetyl-CoA

Answer 1

Centrel Molecule in energy metabolism, can produce ATP or lipids

Question 2

What are the two pathways acetyl-coA can go on

Answer 2

1: If you need energy: Acetyl-CoA enters the kreb cycle to produce ATP
2: If you dont need energy: Acetyl-CoA is used to produce fat for energy storage

Question 3

Does cellular respiration ever slow down?

Answer 3

Yes - regulatory enzymes slow down the Krebs cycle when energy is not needed (ie. when sleeping), to presevre energy

Question 4

Whats the first step of the Krebs Cycle

Answer 4

Acetyl-CoA mixes with oxoloacetate (found in the matrix), producing a 6C molec called citrite
Acetyl-CoA has 2C, oxoloacetate has 4C = 6C

Question 5

Where does the Krebs cycle take place

Answer 5

In the mitochondrial matrix

Question 6

What is step two if the Krebs Cycle

Answer 6

Citrate changes a form into another isomer

Question 7

What is an isomer

Answer 7

Compounds with the same formula but a different arrnagment of atoms

Question 8

What are intermediate steps

Answer 8

When substances are formed in the middle of chemical reactions between the reactants and desired products

Question 9

What is step 3 of the Krebs Cycle

Answer 9

Electrons are added to NAD+ making an NADH molecule (this is reduction), a single CO2 is produced. The loss of f 1C does not change the form of citric acid

Question 10

What is step 4 of the Krebs Cycle

Answer 10

A second NADH is produced in the same fashion, and another CO2 molecule is produced. This process leaves 4C in the molecule convertes it back to oxoloacate, there are then no more glucose carbons as everything from glucose has been released as CO2

Question 11

What is step 5 of the Krebs Cycle

Answer 11

GTP is made from a phosphate bonding to GDP. This is later converted to ATP

Question 12

What is step 6 of the Kreb Cycle

Answer 12

FAD removes two hydrogens form the molecule, beocming FADH2. FAD is used instead of NAD+ as it is a much stronger oxidizer. No carbons are lost

Question 13

What is step 7 of the Krebs Cycle

Answer 13

Water is added, breaking down bonds within the molecule

Question 14

What is step 7 of the Krebs Cycle

Answer 14

Water is added, breaking down bonds within the molecule

Question 15

What is step 8 of the Krebs Cycle

Answer 15

NAD+ comes to oxidize the molecule, producing another NADH, the process is reduction because it is gaining electrons.

Question 16

How many steps are there in the Kreb Cycle

Answer 16

8

Question 17

Name the products from the Kreb Cycle

Answer 17

• 2 carbons (step 3 and 4)
• Thee NADH (step 3, 4, and 8)
• 1 FADH2 (Step 6)
• 1 Molec GTP (Step 5)

Question 18

What are the names of all the intermediates in order

Answer 18

Acetyl-CoA, Citrate, Isocitrate, alpha ketoglutarate, succinyl-CoA, succinate, Fumarate, Malate, Oxoloacetate