LECTURE 0

Question 1

why study metabolism?

Answer 1

high level athletes
nutrition and diets
microbiology
cancer
metabolic diseases
pharmacology
neurology

Question 2

what is metabolism?

Answer 2

process through which living systems acquire and utilize the free energy they need to carry out their various functions
our bodies are open systems

Question 3

why is ATP the energy currency of the cell?

Answer 3

controlled amount of energy is released, more efficient
the breakdown of the molecules themselves releases too much energy and is not efficient

Question 4

what makes up metabolism?

Answer 4

catabolism (degradation) and anabolism (biosynthesis)

Question 5

what makes up energy expenditure?

Answer 5

SMR + activities + exercise

Question 6

what is standard metabolic rate?

Answer 6

metabolic rate of an organism not digesting food at thermoneutrality, under resting and stress free conditions
basic energy consumption at rest

Question 7

what is housekeeping ATP usage?

Answer 7

transcription
translation
protein folding
vesicular transport
membrane transport
regulated by ATP supply/demand
every cell does this

Question 8

what are the ATP usages in various cell types?

Answer 8

housekeeping, mitosis, specialised functions and contraction for the muscle cells

Question 9

what is a negative energy balance?

Answer 9

when there is more expenditure than there is intake
(anorexia, cachexia, death)

Question 10

what is a positive energy balance?

Answer 10

when there is more intake than there is expenditure
(weight gain, obesity, type 2 diabetes, death)

Question 11

what are metabolic pathways?

Answer 11

series of consecutive enzymatic reactions that produce specific products

Question 12

what are metabolites?

Answer 12

reactants, intermediates and products of metabolic pathways

Question 13

what are the 5 principles of metabolic pathways?

Answer 13

1. irreversible
2. have a first committed step
3. are regulated
4. catabolic and anabolic pathways must differ
5. occur in specific locations in eukaryotic cells

Question 14

what makes metabolic pathways irreversible?

Answer 14

a highly exergonic reaction is irreversible
it confers directionality when there is a multi step process (makes the entire pathway irreversible)

Question 15

why must metabolic pathways have an irreversible first step?

Answer 15

most reactions within a pathway function close to equilibrium
the first reaction commits the pathway to continue
regulates the pathway

Question 16

what regulates metabolic pathways?

Answer 16

by laws of supply and demand
to have control you have to regulate the rate limiting step

Question 17

what are some examples of regulation of metabolic pathways?

Answer 17

allosteric regulation
covalent modification by enzyme
substrate cycles
genetic control
hormones

Question 18

why must anabolic and catabolic pathways be different?

Answer 18

cannot reverse the pathways
if two metabolites are interconvertible, 1–>2 cannot be the same as 2–>1
regulation based on metabolic needs

Question 19

are metabolic pathways at equilibrium or not?

Answer 19

no, because a process at equilibrium cannot be directed
living organisms are open systems, input of energy is always required

Question 20

what does delta G 0 represent?

Answer 20

indicates the nature of the reaction
compare reactions when all substrates and products are at unit concentrations
indication of the likelihood of a reaction being reversible

Question 21

what do the signs of delta G 0 mean?

Answer 21

positive: endergonic, requires input of energy
negative: exergonic, produces energy

Question 22

what does delta G represent?

Answer 22

true indication of the direction of a reaction, likelihood of its reversibility in vivo

Question 23

what do the signs of delta G mean?

Answer 23

when =0 the reaction is at equilibrium, reversible in vivo
negative: irreversible in vivo

Question 24

what is coupling of reactions?

Answer 24

coupling an endergonic and exergonic reaction makes the overall reaction favorable in vivo