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Flashcards in Ketone Bodies Deck (17)
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1

Where are ketone bodies produced?

mitochondrial matrix of Liver cells( only when acetyl-CoA levels are higher than CTC capacity)

- allow for energy of peripheral tissues

2

Ketoacidosis

High concentration of ketone bodies in the blood stream

subsections are
- high in blood (ketonemia)
- high in urine (ketonuria)

3

3-KA-CoA thiolase

Enzyme that catalyzes the 1st step of ketogenesis

Takes 2 acetyl CoA and forms Acetoacetyl-CoA

4

HMG-CoA synthase

Enzyme that catalyzes the 2nd step of Ketogenesis.

Takes acetoacetyl-CoA and Acetyl-CoA and forms HMG-CoA

- HMG-CoA is a key intermediate in cholesterol biosynthesis

5

HMG-CoA lyase

Enzyme that catalyses the 3rd step of ketogenesis

Cleaves HMG CoA to form Acetoacetate and acetyl CoA

* conducted ONLY in liver*

6

(B) HDB dehydra

Enzyme that catalyses optional 4th reaction of Ketogenesis

Interchanges (b)-HDB and Acetoacetate

- going from acetoacetate -> (b)-HDB requires oxidation of NADH

- going from (b)-HDB -> acetoacetate requires reduction of NAD+

7

Ketone bodies are formed by what two molecules?

Acetoacetate and (b)-hydroxybutyrate


- acetoacetate can spontaneously form acetone

8

Advantage of ketone bodies over fatty acids

Ketone bodies are far more soluble and can move further in the body. (Fatty acid needs to use albumin as a transporter).

9

Ketolysis

Action of forming 2 acetyl CoA from ketone bodies

(Occurs in peripheral cell matrix)

10

BHB DHase

1st step of ketolysis
Converts (b) HDB into Acetoacetate and generates 1 NADH

* if ketone body arrives to peripheral cell as Acetoacetate already, this step is skipped*

11

Transferase

2nd step of ketolysis

Binds a succinyl group from succinyl-CoA to acetoacetate to form

AA-CoA and succinate

12

3-KA-CoA thiolase

4th step in ketolysis

Takes AA-CoA and generates 2 acetyl-CoA

13

How much ATP is formed from one (b)-HDB ketone body?

21.5 (transferase requires 1 ATP)

22.5-1 = 21.5

14

How much ATP is formed from 1 Acetoacetate ketone body?

19 (transferase requires 1 ATP)

20-1 = 19

15

Ketoacidosis is most common in what type of diabetes?

type 1 diabetes

16

What ketone body form is most favored under normal conditions?

b-HDB is more favored since NADH concentrations are favored over NAD+

17

What happens when more Than normal acetyl-CoA is prevalent?

Is converted to ketone bodies