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MEH > Energy Production - Carbs 1,2,3 > Flashcards

Energy Production - Carbs 1,2,3 Flashcards

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1
Q

What is metabolism?

A

The inter conversion of biological molecules in small chemical steps

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2
Q

Name + define the two types of metabolic pathways

A

Catabolic - oxidative (release H) + the breakdown of large molecules into smaller intermediates + releases large amounts of energy

Anabolic - reductive + the synthesis of larger molecules from smaller intermediates + uses the energy released from catabolism

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3
Q

What types of energy carriers are released in catabolism?

A
  • reducing power - NADH, NADPH, FADH2
  • energy - ATP
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4
Q

How is reducing power converted to ATP?

A

Oxidative phosphorylation

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5
Q

What is the purpose of stage 1 in catabolism?

A

To convert nutrients from a form that can be taken up into cells

e.g. carbs > monosaccharides
Lipids > glycerol + fatty acids
Proteins > amino acids

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6
Q

Where does stage 1 catabolism occur?

A

Extracellularly (GI tract)

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7
Q

Does stage 1 catabolism produce energy?

A

No

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8
Q

What is the purpose of stage 2 catabolism?

A

Degradation of building blocks to small number of organic precursors
Glycolysis occurs here&raquo_space; ATP made

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9
Q

Where does stage 2 catabolism occur?

A

Intracellularly - cytosolic + mitochondrial

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10
Q

Does stage 2 catabolism produce energy?

A

Glycolysis occurs here so yes
Some ATP

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11
Q

What occurs in stage 3 catabolism?

A

Tricarboxylic acid cycle - Kerb’s cycle

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12
Q

Does stage 3 catabolism produce energy?

A

GTP produced

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13
Q

What occurs in catabolism stage 4?

A

Oxidative phosphorylation - ETC + ATP synthesis

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14
Q

What is required for stage 4 catabolism?

A

Oxygen to act as the final electron acceptor

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15
Q

Does stage 4 catabolism produce energy?

A

Lots of ATP - oxidative phosphorylation

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16
Q

What is the general formula for carbs?

A

(CH2O)n

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17
Q

What are the stages of catabolism?

A

Stage 1 - breakdown to monomers
**Stage 2* - breakdown to metabolic intermediates - glycolysis
Stage 3 - tricarboxylic acid cycle
Stage 4 - oxidative phosphorylation

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18
Q

How many units are oligosacharides?

A

3-12

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19
Q

What is sucrose made up of?

A

Glucose-fructose

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20
Q

What is lactose made up of?

A

Galactose-glucose

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21
Q

What is maltose made up of?

A

Glucose-glucose

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22
Q

What is the glucose concentration in blood?

A

5mM

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23
Q

What cells have an absolute requirement for oxygen and why?

A

Red blood cells - no mitochondria
Lens of eye - no mitochondria
Neutrophils - low O2 environment
Innermost cells of kidney medulla - low O2 environment

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24
Q

What enzymes are in your saliva for metabolism of carbs?

A

Amylase

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25
What enzymes are in the pancreas for metabolism of carbs?
Amylase
26
What enzymes are in your small intestine for carb metabolism?
Lactase Sucrose Pancreatic amylase - a 1-4 bonds Isomaltase - a 1-6 bonds
27
What is primary lactase deficiency?
Absence of lactase persistence allele - mainly in northwest Europe Only occurs in adults
28
What is secondary lactase deficiency?
Caused by **injury to small intestine**: - gastroenteritis - coeliac disease - Crohn’s disease - ulcerative colitis In both infants + adults
29
What is Congential lactase deficiency?
Autosomal recessive defect in lactase gene Cannot digest breast milk
30
Symptoms of lactose intolerance
Bloatin/cramps Flatulence - accumulation of gas Diarrhoea Vomiting Rumbling stomach
31
How are monosaccharides absorbed?
1- active transport into intestinal epithelial cells by sodium dependent glucose transporter 1 SGLT1 2- passive transport via GLUT2 into blood 3- transported in blood to target cells 4- glucose uptake via facilitated diffusion using GLUT1-5 Na+/K+ ATPase needed to maintain conc. gradient for SGLT1
32
What role does Na+/K+ ATPase have in the absorption of monosaccharides?
Maintains the conc gradient for the SGLT1
33
Where is GLUT1 present?
All cells
34
Where is GLUT 2 present?
Main abdominal organs: - kidney - liver - pancreatic B cells - small intestine
35
Where is GLUT3 found?
Neurones Placenta
36
Where is GLUT4 found?
Adipose tissue Striated muscle
37
What regulates GLUT4?
Insulin
38
Where is GLUT 5 found?
Spermatozoa Large intestine
39
What GLUT is in abdominal organs?
GLUT2
40
Functions of glycolysis
Oxidation of glucose NADH production ATP synthesis Provides biosynthesis precursors for fatty acids
41
Features of glycolysis
Central pathway of CHO catabolism Occurs in all tissues - cytosolic Exergonic - produces energy Oxidative Irreversible
42
What are the key enzymes in glycolysis?
- hexokinase (glucokinase in liver) - phosphofructokianse-1 - pyrivate kinase
43
What is phosphofructokinase-1 regulated by?
**allosteric** 1- inhibited by high ATP + citrate 2- stimulated by high AMP + F2,6,BP **hormonal** 1- inhibited by glucagon 2- stimulated by insulin
44
Why are there so many steps in glycosides?
- Easier in smaller steps - Efficient energy conservation - Gives versatility - intermediates can be used in other pathways - Fine control - easier to slowdown/speed up specific parts
45
What is allosteric binding?
Binding at another site
46
Why is phosphofructokinase reaction irreversible?
Very negative delta G
47
What is the most important enzyme in glycolysis regulation?
Phosphofructokinase
48
What activates pyruvate kinase?
High insulin:glucagon ratio (High insulin, low glucagon)
49
How is NAD+ regenerated?
Oxidative phosphorylation Lactate dehydrogenase
50
What is lactate dehydrogenase important for?
Regenerating NAD+ when oxygen is low
51
What is plasma lactate concentration determined by?
Relative rates of: - production - utilisation - liver, heart, muscle - disposal - kidney
52
What is the normal concentration of plasma lactate?
<1mM
53
What is the plasma lactate concentration in hyperlactaemia?
2-5mM Below renal threshold No change in blood pH
54
What is the plasma lactate concentration in lactic acidosis?
>5mM Above renal threshold Blood pH lowered
55
Where is fructose metabolism?
Liver
56
Outline fructose metabolism
*fructokinase* *aldolase* Fructose > fructose-1P >glyceralaldehyde-3-P
57
Diseases related to fructose metabolism
**Essential fructosuria** - fructokinase missing **Fructose intolerance** - aldolase missing
58
What is essential fructosuira?
**Fructokinase missing** Fructose in urine
59
What is fructose intolerance?
**Aldolase missing** Fructose-1P accumulates in liver >> liver damage Managed by removing fructose + sucrose in diet
60
A deficiency in fructokinase causes what?
Essential fructosuria
61
How is essential fructosuria detected?
No clinical signs Fructose in urine
62
What does a deficiency in aldolase cause?
Fructose intolerance
63
Management of fructose intolerance
Remove fructose + sucrose from diet
64
Deficiencies in what enzymes cause galactosaemia?
Galactokinase Uridyl transferase UDP-galactose epimerise
65
What is galactosaemia?
Inability to utilise galactose
66
What is the most common cause of galactosaemia?
Galactose-1P uridyl transferase deficiency Galactose + galactose1-P accumulate
67
Complications of galactosaemia
Galactose enters other pathways *aldose reductase* Galactose > galactitol Accumulation of galactose + galactitol cause swelling + protein precipitation Increased aldose reductase activity uses excess NADPH - Crystallin protein denatures >> **Cataract**
68
What does build up of galactose 1P cause?
Damage to liver, kidney + brain
69
What do Heinz Bodies suggest?
G6PDH deficiency
70
What molecule plays an important role in regulating the affinity of haemoglobin for O2?
2,3-bisphosphoglycerate
71
What are Heinz bodies caused by?
Precipitated haemoglobin aggregates + binds to cell membrane
72
What are Heinz bodies removed by?
Spleen
73
What can a deficiency in pyruvate dehydrogenase cause?
**Lactic acidosis** - Pyruvate cant be converted to acetyl CoA - anaerobic respiration occurs to regenerate NAD+ - lactate build up
74
What is pyruvate dehydrogenase sensitive to and why?
Vitamin B1 Requires coenzymes which are provided by vit B
75
What is pyruvate dehydrogenase activated by?
Pyruvate NAD+ ADP Insulin
76
What is pyruvate dehydrogenase inhibited by?
Acetyl CoA NADH ATP Citrate
77
Outline the intermediates in the TCA cycle?
Citrate Isocitrate a-ketogluarate Syccinyl-coA Succiante Fumarate Maleate Oxaloacetate
78
Net gain from TCA cycle
6 NADH 2FADH2 2GTP
79
How is the TCA cycle regulated?
Energy availability Isocitrate dehydrogenase - rate limiting enzyme a-ketoglutarate dehydrogenase
80
Key features of oxidative phosphorylation
- ETC + ATP synthesis - NADH + FADH2 reoxidation - lots of ATP produced - O2 acts as final electron acceptors
81
Outline oxidative phosphorylation
1- NADH + FADH2 get reoxidised 2- energy from this powers proton translocating complexes 3- H+ ions move from matrix to intermembrane space which creates a proton motive force 4- H+ attach to ATP synthase 5- ADP >> ATP
82
How does high ATP conc regulate oxidative phosphorylation?
Low [ADP] - no substrate for ATP synthase Inwards H+ flow stops Increase in H+ in inter membrane space ETC + ATP synthesis stops
83
Two processes of using reducing power in ATP synthesis
1- **electron transport** - e- from NADH + FADH2 transferred through ETC 2- **oxidative phosphorylation** - free energy released used to drive ATP synthesis
84
How many molecules of ATP is produced from 1 NADH?
2.5ATP
85
How many molecules of ATP are produced from 1FADH2?
1.5
86
What proof translocatioing complexes does NADH + FADH2 use?
NADH - Complexes I, III, IV FADH2 - complexes III + IV
87
What effect to inhibitors have on oxidative phosphorylation?
Block ETC by blocking O2 acting as FEA
88
Examples of inhibitors
Cyanide Carbon monoxide
89
What effect do uncouplers have on oxidative phosphorylation?
- Increases membrane permeability to H+ - stops PMF - H+ cross membrane without passing through ATP synthase so no ATP synthesis - no inhibition of ETC
90
Examples of uncouplers
Fatty acids Dinitrocresol Dinitrophenol
91
Compare oxidative phosphorylation + substrate level phosphorylation (4 points)
**Oxidative phosphorylation** - requires membrane-associated complexes - cannot occur without O2 - major process for ATP synthesis - energy cooling occurs indirectly through generating + using PMF **Substrate level phosphorylation** - requires soluble enzymes - can occur to an extent without O2 - minor process for ATP synthesis - energy coupling occurs directly through formation of high energy of hydrolysis bond
92
How does energy coupling occur in oxidative phosphorylation?
Indirectly through generating and using PMF
93
How does energy coupling occur in substrate level phosphorylation?
Directly through formation of high energy of hydrolysis bond
94
Symptoms of galactosaemia
Cataracts Hypoglycaemia Hepatomegaly + cirrhosis Renal failure Vomiting Seizure + brain damage
95
Function of the outer and inner membrane of mitochondria
Allows a proton gradient to be formed

MEH (23 decks)

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