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Bioenergetics > Week 7 - CHO & Indirect Calorimetry > Flashcards

Week 7 - CHO & Indirect Calorimetry Flashcards

1
Q

Storage of CHO

A

Blood glucose — Normal conc. 3-5mmol/L (euglycemia)

Liver glycogen — Approx 100g.

Muscle glycogen — 400-500g.

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2
Q

What are blood glucose levels regulated by?

A

Hormones + a primary cerebral fuel.

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3
Q

Define glycogenesis

A

Formation of glycogen from sugar mol.

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4
Q

Define gluconeogenesis

A

Formation of glycogen from aa, fats + other non-CHO

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5
Q

Define glycogenolysis

A

Breakdown of glycogen into glucose to use for energy transfer

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6
Q

What enzyme catalyses the breakdown of glycogen

A

Glycogen phosphorylase

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7
Q

What are the 3 stages in which energy is extracted from CHO

A

Glycolysis

TCA/Krebs cycle

Oxidative phosphorylation/ETC

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8
Q

Glycolysis

A

Oxidation of glucose/glycogen.

In cytoplasm

Produces lactate or pyruvate

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9
Q

General formula for CHO

A

Cn(H20)n

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10
Q

What is the primary regulator for the speed of glycolysis

A

Phosphofructokinase

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11
Q

Glycolysis

Step 1

A

Glucose + ATP – hexokinase –> Glucose-6-phosphate + ADP

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12
Q

Glycolysis

Step 2

A

Glucose-6-phosphate – phosphoglucose isomerase –> fructose-6-phosphate

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13
Q

Glycolysis

Step 3

A

Fructose-6-phosphate + ATP – (PFK) –> fructose 1,6-biphosphate + ADP

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14
Q

Glycolysis

Step 4

A

Fructose 1,6-biphosphate – aldolase –> dihydroxyacetone phosphate + glyceraldehyde 3-phosphate

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15
Q

Glycolysis

Step 5

A

Dihydroxyacetone P – triose P isomerase –> glyceraldehyde 3-P

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16
Q

Glycolysis

Step 6

A

Glyceraldehyde 3-phosphate + NAD+ + Pi — glyceraldehyde 3-phosphate dehydrogenase –> 1,3-biphosphoglycerate + NADH + H+

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17
Q

Glycolysis

Step 7

A

1,3 biphosphoglycerate + ADP – phosphoglycerate kinase – > 3-phosphoglycerate + ATP

18
Q

Which is the stage where ATP is first generated in glycolysis

A

Step 7

1,3 biphosphoglycerate + ADP – phosphoglycerate kinase – > 3-phosphoglycerate + ATP

19
Q

What might slow the rate of glycolysis in step 6?

A

‘Bottleneck’

If metabolic rate is very high, NAD+ can become saturated w/ H+, so that there’s not enough free NAD+ available.

20
Q

Glycolysis

Step 8

A

3-phosphoglycerate – phosphoglycerate mutase –> 2-phosphoglycerate

21
Q

Glycolysis

Step 9

A

2-phosphoglycerate – enolase –> phosphoenylpyruvate + H20

22
Q

Glycolysis

Step 10

A

Phosphoenylpryuvate + ADP + H+ – pyruvate kinase –> pyruvate + ATP

23
Q

What is the step that generates the 2nd ATP?

A

Step 10

Phosphoenylpryuvate + ADP + H+ – pyruvate kinase –> pyruvate + ATP

24
Q

What are the rate limiting steps in glycolysis

A

PFK in step 3

NAD+ in step 6

25
Q

Which are the ATP generating steps in glycolysis

A

7 + 10

26
Q

What is the principle of bomb calorimetry

A

To burn something in an O2 atmosphere placed inside a bucket of H20 so that temp changes of the H20 due to combustion can be measured.

– Can then determine how much energy was released.

27
Q

Steps to bomb calorimetry

A

Step 1 - Weigh sample ( use dextrose tablet )

Step 2 - Place sample in bomb. In a combustion cup sitting on electrodes.
Bomb is fired using fuse wires. — Make sure these touch the sample but NOT the cup.

Step 3 - Pressurise bomb w/ O2. - Aim for 30 atmospheres.

Step 4 - Place H20 in calorimeter after which infra-red will reflect back into H20.

Step 5 - Place H20 bucket on scale + press tare to get 0.
Step 6 - Weigh 2kg of H20.

Step 7 - Put everything together — Calorimeter in insulated bucket.

Step 8 - Leave device for about 5 mins, until steady temp is reached.

28
Q

How often should you record temp in bomb calorimetry

A

Every 30secs

29
Q

What is indirect calorimetry

A

When GE measurements are used to estimate the type + rate of substrate utilisation + energy metabolism.

30
Q

What is the role of NAD/NADH in the lead up to the TCA/Krebs/Cyclic cycle

A

To convert pyruvate (from step 10 of glycolysis) to lactate or Coenzyme A

31
Q

Pyruvate –> lactate in lead up to Krebs cycle

Which enzyme + what’s the result

A

LACTATE DEHYDROGENASE

NADH becomes NAD+

NAD+ travels to step 6 glycolysis

32
Q

Pyruvate –> acetyl CoA

Enzyme?
Result?

A

DEHYDROGENASE complex of CoA + pyruvate.

NAD+ accepts some H+ from pyruvate to prod. Acetyl-CoA —> NADH + H+

—— NADH is transported to mit. where H+ + e- can be used in the ETC.

Acetyl-CoA enters TCA cycle

33
Q

Why produce lactate?

What levels are NADH + NAD+ at a high metabolic rate?

A

Quick fix to keep a high glycolytic rate.

Rate of glycolysis is very fast.

But TCA + ETC are slower.

High metabolic rate = Availability of NADH is high vs. NAD+ is low. — Can be a problems for step 6 of glycolysis. So in order to maintain this step, the metabolic env. In the cell during high level of activity favours pyruvate —> lactate + NAD+ prod will help maintain glycolytic rate.

34
Q

When is pyruvate converted to Acetyl-CoA?

A

When metabolic rate is low + there’s LOTS of O2 + NAD+.

35
Q

Cytosol

A

Part of the mitochondria where glycolysis occurs

36
Q

Properties of co-enzymes

A

Less specific than enzymes

Act as co-binders

Temporary carriers

Reversible e- + H+ acceptors

i.e NAD+ & FAD

37
Q

How many steps are there in the TCA cycle

A

8

38
Q

What is the main purpose of the TCA cycle

A

Oxidise acetyl groups + strip off their e-.

39
Q

GTP

A

Guanosine triphosphate

Quickly converted to ATP by transferring the 3 P groups into adenosine sugar instead of guanosine.

40
Q

What is the energy transfer of the TCA cycle from 1 glucose mol.

A

6 NADH

2 FADH(2)

2 GTP

32 H

41
Q

List the TCA cycle intermediaries

A

Citrate

Isocitrate

alpha-ketoglutarate

Succinyl-CoA

Succinate

Fumarate

Malate

Oxaloacetate

42
Q

What are the key steps in the TCA cycle

A
  1. Oxaloacetate + Acetyl Co-A –> 6-C mol = citrate.

3+4. CO2 + NADH + H+ produced.

  1. 1 GTP prod.
  2. FADH(2) prod.
  3. NADH prod + oxaloacetate regenerated.

Bioenergetics (12 decks)

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