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Metabolism > Session 2-Energy,glycolysis,carbs and galactosaemia > Flashcards

Session 2-Energy,glycolysis,carbs and galactosaemia Flashcards

1
Q

Why are cell nutrients transported to body tissues?

A
  • Degraded to release energy
  • Used to synthesise cell components (NOT RBC)
  • Storage
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2
Q

What are the characteristics of catabolic pathways?

A
  • Oxidative-releases H+ ions for reducing power

- Release energy

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3
Q

What are the characteristics of anabolic reactions?

A
  • Reductive-use H+

- Use intermediate metabolites and energy produces by catabolism to drive the synthesis of cell components

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4
Q

Creatine is used for a quick release of energy in muscles, for example. What enzyme catalyses this?

A

Creatine kinase

Creatine + ATP —> Creatine phosphate + ADP

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5
Q

What 4 molecules are known as high energy signals and why?

A
  • ATP, NADH, NADPH, FAD2H

- signal that the cell has ADEQUATE energy levels and reducing power is available for anabolism

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6
Q

how are dietary polysaccharides hydrolysed?

A
  • Using glycosidase enzymes

- Releases glucose and maltose and leaves smaller polysaccharides (dextrins)

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7
Q

where does hydrolysing of polysaccharides begin and end?

A

Begins with salivary amylase

Continues in duodenum with pancreatic amylase

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8
Q

Where does digestion of disaccharides occur?

A

-Duodenum and jejunum

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9
Q

what are the 3 major enzymes involved in digesting disaccharides?

A

-lactase, glycoamylase, sucrase

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10
Q

What is the minimum glucose requirement for a healthy adult per day?

A

-180g/day

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11
Q

Which areas of the body require 40g and which 140g?

A

40g=tissues that only use glucose

140g=CNS that prefers glucose

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12
Q

Is glycolysis activated in ALL tissues?

A

Yes!

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13
Q

What does glycolysis generate?

A

-ATP (anaerobically)
-NADH from NAD+
-intermediates for cell functions
-NO LOSS of CO2
-

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14
Q

What is the difference between substrate level (SLP) and oxidative phosphorylation (OP)?

A
  • SLP- occurs if a reaction releases sufficient energy to allow the addition of phosphate onto ADP
  • OP- ATP generated from the oxidation of NADH and FADH2 (including the transfer of electrons and pumping of protons) Process generates electrochemical gradient which powers ATP synthase
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15
Q

what is the net production number of ATP in glycolysis?

A

2 ATP

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16
Q

Which 3 steps are irreversible?

A

1,3 and 10

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17
Q

What enzyme is used to catalyse step 1?

A

Hexokinase (glucokinase in liver)

glucose—>glucose-6-phosphate

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18
Q

What enzyme catalyses step 3?

A

PFK-1 (phosphofructokinase)

fructose 6-phosphate—>fructose 1,6-bisphosphate

19
Q

What enzyme catalyses step 10?

A

pyruvate kinase

phosphoenolpyruvate—>pyruvate

20
Q

what enzyme reduces pyruvate to lactate (lactic acid)?

A 
lactate dehydrogenase (LDH) 
NOTE: LDH increases NAD+ concn under anaerobic conditions for glycolysis to proceed
21
Q

what is the overall equation for the 11 steps of glycolysis, including the lactate step?

A

glucose+2Pi+2ADP –> 2lactate + 2ATP + 2H2O

22
Q

where do cell nutrients come from?

A
  • Diet
  • Synthesis in body tissues from precursors
  • release from storage in body tissues
23
Q

What concentration does lactate production have to exceed before it becomes a problem?

A

5mM-exceeds renal threshold and affects buffering capacity of plasma causing LACTIC ACIDOSIS

24
Q

What is glucose converted into at step 1 in glycolysis?

A

glucose 6-phosphate (ATP—>ADP)

25
Q

What is the reaction in step 3 of glycolysis?

A

fructose 6-phosphate—>fructose 1,6-bisphosphate

26
Q

what is the reaction in step 10 of glycolysis?

A

phosphoenolpyruvate—->pyruvate (ADP—>ATP)

27
Q

what is the overall reaction of galactose metabolism?

A

galactose + ATP—-> glucose-6-phosphate + ADP (continues to glycolysis)

28
Q

What 2 enzymes when lacked cause galactosaemia (inability to utilise galactose)?

A

galactokinase and galactose-1-P-Uridyl transferase (GUT)

29
Q

which enzyme deficiency in galactosaemia is more common?

A

uridyl-1-p-transferase

30
Q

why is the absense of the transferase enzyme more serious?

A

-causes build up of galactose and galactose-1-phosphate(toxic in liver)

31
Q

what happens when galactose accumulates in the blood?

A
  • Galactose—>galacticol (using ALDOSE REDUCTASE)

- NADPH—>NADP+ (less reducing power now available)

32
Q

how does cataracts form in the eye?

A
  • disulphide bond formation (s-s)

- Changes and alters protein and thus its function

33
Q

what else happens in the eye with increased galactose and galacticol levels?

A

-Raise in pressure (glaucoma) causing blindness

34
Q

why does galactose-1-phosphate damage liver?

A

-hides Pi making it unavailable for ATP synthesis

35
Q

what test can you do to see if someone is going to have an MI and why does this happen?

A

check blood creatine kinase levels-leak out of damaged cardiac myocytes (cells)

36
Q

what is the breakdown product of creatine called?

A

creatinine

37
Q

in which 3 ways is creatININE a useful clinical marker?

A
  • excreted via kidneys
  • creatinine excretion per 24 hours is proportional to muscle mass (provides measure of muscle mass)
  • creatinine in urine is marker of urine dilution
  • indicator of renal function
38
Q

Between glucose and pyruvate in glycolysis, name 6 important intermediates in between. Give roles for the 4th and 5th ones.

A
  1. Glucose 6 phosphate
  2. Fructose 6 phosphate
  3. Fructose 1,6 bisphosphate
  4. Glyceraldehyde 3 phosphate—>converts to dihydroxyacetone phosphate (DHAP) and then glycerol phosphate for TAG formation
  5. 1,3 BPG (bisphosphoglycerate)—>converts to 2,3 BPG for HB O2 affinity regulation
  6. Phosphoenolpyruvate
39
Q

How much NADH is produced during glycolysis?

A

2

40
Q

How much NADH is produced per pyruvate being oxidised to form acetyl CoA?

A

1

41
Q

Monosaccharides are absorbed into tissues by facilitated diffusion using transport proteins called….

A

GLUT1-5

42
Q

Why do RBCs go through the lactate pathway?

A

Cannot carry out TCA cycle or oxidative phosphorylation

Need to regenerate NAD+ by going through lactate pathway

43
Q

What are the roles of glut 1 and 4 and where is glut 4 found?

A

Move glucose into cells

Glut 4 found in muscle and adipose tissue

44
Q

Where is glut 2 found and what does it do?

A

Found in liver

Transfer glucose to blood from hepatocytes

Metabolism (14 decks)

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