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Week 10 > Energy and Metabolism > Flashcards

Energy and Metabolism Flashcards

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1
Q

what is the first law of thermodynamics

A

energy can neither be created nor destroyed but is transferred from one form to another or from one place or another

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2
Q

what is the second law of thermodynamics

A

energy doesn’t transform without entropy in the universe (usually lost as heat)

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3
Q

what is metabolism

A

the sum of all chemical reactions in which energy is made available and consumed in the body

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4
Q

examples of metabolism

A

oxidation of fuel to CO2 and water
- achieved by a series of biochemical reactions
production of energy (ATP) and loss of energy (heat)

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5
Q

what does the body need energy for

A

contraction of muscle
- skeletal, cardiac, smooth -> blood vessels and gut
accumulation of ions and other molecules against conc. gradients (nerve impulses)
biosynthesis -> building of tissues
waste disposal -> getting rid of the end products of bodily function
generation of heat -> maintenance of body temperature

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6
Q

reaction to create glucose 6 phosphate

A

glucose + PO4^2 –> glucose 6 phosphate
reaction cannot happen spontaneously because the energy of the products is higher than the sum of the energy of the reactants
in order for this equation to become spontaneous, we need to couple it with another equation
ATP -> ADP + PO4 2-

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7
Q

rules of gibbs free energy

A

if the product contains more energy than the substrate -> delta G is +ve
if the product contains less energy than the substrate -> delta G is -ve

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8
Q

is the catabolism of nutrients exergonic or endogonic?

A

exergonic
the cells can harness this energy as ATP

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9
Q

ATP basic info

A

energy currency of living organisms
- hydrolysis to give ADP and Pi liberates a large amount of energy

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10
Q

ATP equations

A

ATP (+ H2O) –> ADP + Pi
- delta G = -30kJ/mol
- in cells, delta G = -50kJ/mol
ADP + Pi –> ATP + H2O
- delta G = +30kJ/mol
- in cells +50 kJ/mol

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11
Q

endergonic definition

A

products of greater free energy than the reactants; non-spontaneous

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12
Q

free energy definition

A

the energy available in a system to do useful work

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13
Q

exergonic definition

A

reactants of greater free energy than the products; spontaneous

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14
Q

The tricarboxylic acid cycle (TCA)

A

also known as Krebs cycle
acetyl CoA (2 carbon) condenses with oxaloacetate (4 carbon) to produce citrate (6 carbon)
this occurs in 2 phases
- deoxycarbylation (citrate -> succinyl CoA (4 C )) -> 2 C molecules lost as CO2
- reductive (succinyl CoA to oxaloacetate)

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15
Q

what is the overall reaction for TCA

A

acetyl CoA + 3NAD+ + FAD + GDP + Pi + 2H2) –> CoA + 2CO2 + 3NADH + FADH2 + GTP (ATP) + 3H+

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16
Q

what are the products of 1 turn of TCA cycle

A

3 x NADH
1 x FADH2
^ molecules produce ATP in the ETC

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17
Q

what are the main components of the ETC

A

four protein complexes
ATP synthase
intermembrane space in mitochondria
FADH2
NADH
H+
co-enzyme Q
cytochrome C

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18
Q

progress of e- through the ETC

A

intermembrane has a higher conc. of protons because of pump
1- co-enzymes donate 2e- and H+ to the ETC
2- electrons passed through redox centre (in the complex)
- moved between redox centres
- each one has a higher affinity
- produces ATP (used to pump protons against conc. gradient)
3- co-enzyme Q passes the electrons to the next protein complex (1-> 2 -> 3)
4- cytochrome C -> complex 4
5- when e- reaches the end of complex 4
- 2H+ + 1/2O2 -> H2O
O2 is the terminal electron carrier

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19
Q

where does FADH2 enter the ETC

A

complex 2

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20
Q

what is oxidative phosphorylation

A

ATP synthase
- only way H+ can get back into matrix
- ADP + Pi -> ATP
- main generator of ATP

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21
Q

what is the ATP yield of the TCA (incl. ETC)

Study These Flashcards
A

produced by substrate level phosphorylation: 1 GTP (equal to ATP) + 3NADH + 1FADH
generally accepted that each___ oxidised by the ETC produces
- NADH = 2.5 ATP
- FADH2 = 1.5 ATP
- therefore, the total yield/ acetyl CoA is 1 + (3 x 2.5) + (1 x 1.5) = 10 ATP

22
Q

what is glycolysis

Study These Flashcards
A

glucose -> pyruvate (3 C)
occurs in the cytosol of cells
- can occur in all cells (e.g. RBCs and cells with shortage of O2)
exogonic reaction
2 phases
- endogonic (ATP investment)
- exogonic (generation)

23
Q

describe the process of ATP investment (stage 1 of glycolysis)

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A

glucose –> glucose 6 phosphate
- hexokinase, uses 1 ATP
glucose 6-phosphate –> fructose 6 phosphate
- phosphoglucose isomerase (reversable)
fructose 6 phosphate –> fructose 1,6 bisphosphate
- phosphofructokinase, uses 1 ATP
fructose 1,6 bisphosphate –> dihydroxyacetone phosphate
- triose phosphate isomerase
OR
fructose 1,6 phosphate –> glyceraldehyde 3 phosphate
- aldolase

24
Q

describe the process of generation (stage 2 of glycolysis)

Study These Flashcards
A

glyceraldehyde 3 phosphate –> 1,3 bisphosphoglyceral
- glyceraldehyde 3-phosphate dehydrogenase, catalyses PNAD+ conversion to NADH (reversible)
1,3 bisphosphoglyceral –> 3-phosphoglycerate
- phosphoglycerate kinase, catalyses ADP conversion to ATP (reversible)
3-phosphoglycerate –> 2-phosphoglycerate
- phosphoglycerate mutase (reversible)
2-phosphoglycerate –> phosphoenolpyruvate
- enolase, produces H2O (reversible)
phosphoenolpyruvate –> pyruvate
- pyruvate kinase, catalyses ADP -> ATP

25
outline the anaerobic conditions of glycolysis
pyruvate is converted to lactate - regenerated NAD+ (oxidised form) to keep glycolysis going - ATP is localised -> each cell needs to make it for itself
26
describe fermentation
glucose --> 2 pyruvate - glycolysis - 2ADP + 2Pi --> 2ATP - 2NAD+ + 2NADH +2H+ ] 2 pyruvate --> 2 lactate - 2NADH + 2H+ -> 2NAH+
27
overall equation for anaerobic glycolysis
C6H12O6 + 2ADP + 2Pi --> 2 lactate + 2ATP
28
describe process of the link reaction
pyruvate is transported into the mitochondrion and converted to acetyl CoA by the action of pyruvate dehydrogenase (1- pyruvate enters the mitochondrion through a transport protein 2- CO2 produced 3- NAD+ --> NADH + H+ 4- CoA reacts 5- acetyl CoA produced)
29
overall reaction of the link reaction
CH2-CO-CO2- (pyruvate) + NAD+ + CoASH -> CH3-CO-SCoA (acetyl CoA) + CO2 + NADH
30
describe fatty acid degradation
beta-oxidation 1- 16 C long chain (palmitic acid) 2- carbon backbone cleaved between the alpha and beta carbons (proximal to the carboxy terminus) 3- forms acetyl CoA 4- oxidation reaction happens 7 times produces 8 acetyl CoA molecules
31
overall products of one C16 molecule (palmitic acid)
b-oxid -> 7 x NADH + 7 x FADH2 + 8 x AcCoA TCA -> 8 x (3 x NADH) + (1 x FADH2) + (1 x ATP) total -> 31 NADH + 15 FADH2 + (8 x ATP) - 2 x ATP + (31 x 2.5 ATP) + (15 x 1.5 ATP) + 6 ATP = 106 ATP
32
simplified process of fatty acid metabolism
1- fatty acids are transported in the blood as a complex with albumin (most prolific plasma protein) (to make it hydrophilic) and are taken up by cells for oxidation 2- fatty acid modification (essential for entry into mitochondria) and entry into mitochondria 3- B-oxidation leading to energy (ATP) formation
33
detailed fatty acid metabolism
1- free fatty acid + CoA + 2ATP --> fatty acyl CoA (acyl-CoA synthase) 2- fatty acyl CoA --> fatty acyl carnitine (carnitine -> CoA) 3- fatty acyl carnitine enters mitochondrial matrix through transport protein 4- fatty acyl carnitine --> fatty acyl CoA (CoA --> carnitine) 5- fatty acid degradation
34
what are the two stages of protein metabolism
transamination and deamination
35
describe transamination
important because it releases the carbon backbone to be turned into intermediates of the Krebs cycle a-ketoglutarate most common to accept residue - produces glutamate (PROTEIN) and a-ketoacid - alanine -> pyruvate - aspartate -> oxaloacetate - all the intermediates of the Krebs cycle
36
describe deamination
in the liver production of ammonium cells have to be able to remove ammonium -> turns into urea glutamate -> a-ketoglutarate
37
what are glucogenic acids
glucose pyruvate oxaloacetate intermediate of TCA
38
what are ketogenic acids
fatty acids acetyl CoA acetoacetyl CoA *only lysine and leucine are totally ketogenic*
39
what happens to a-ketoacids
after they have been converted into intermediates they then - TCA cycle - recycled for fatty acid synthesis gluconeogenesis
40
metabolic adaptations to starvation
1- fat -> triglycerides in adipose tissue which is sufficient to prolong life for 3 months 2- protein -> provides approx. 14 days' worth of energy but is spared for as long as possible to permit mobility other sources: glycogen, glucose
41
what is the basal energy expenditure (BEE)
used to estimate the energy required to maintain basic functions - also known as basal metabolic rate (BMR) - when the person is lying down, relaxed (not asleep), in a normal ambient temperature
42
what is the equation for calculation BEE for males
BEE = 66.5 + 13.75W + 5.003H - 6.775A
43
what is the equation for calculation of BEE in females
BEE = 655.1 + 9.563W + 1.850H - 4.676A
44
BMI basic info
body mass index BMI = W/H2 - weight in Kg - height in M <20 = underweight 20-25 = ideal weight 25-30 = overweight >30 = obese
45
why is the BMI not always a good measure of an individual
doesn't account for muscle mass/ cardiovascular condition although helpful, should be used with some degree of caution
46
fatigue symptoms
tiredness lack of energy weakness exhaustion sleepiness some of the causes are metabolic in nature
47
what causes fatigue in short bursts of exercise
phosphocreatine depletion
48
what causes fatigue in middle bursts of exercise
phosphocreatine depletion and proton accumulation
49
what causes fatigue in long times of exercise
glycogen depletion
50
explanation of phosphocreatine depletion
entropy and loss of energy of heat - depletes energy stores in the body - phosphocreatine used when ATP is depleted (only for a short time) - stored ATP only lasts for about 2 seconds in sprinting
51
explanation of glycogen depletion
anaerobic glycolysis of stored glycogen starts to occur as the length of run increases - lactic acid - reduces the pH of the blood - only short time
52
what happens in intense sustained exercise
glycogen stores are depleted hitting the wall move to fat metabolism

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