Lecture 30

Question 1

what is metabolism

Answer 1

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

Question 2

name some functions

Answer 2

protein synthesis
dna rep
fuse mitochondria
pump out sodium
produce atp

Question 3

is food transformation to energy 100% efficient

Answer 3

nooooo
some excreted out

Question 4

Describe glucose

Answer 4

C6H12O6+6O2→6CO2+6H2O
stored as glycogen
∆𝐺°′ = -2870kj/mol = tons, under standard conditions

Question 5

describe fatty acid

Answer 5

palmitate
C16H32O2 + 23 O2 → 16 CO2 + 16 H2O
∆𝐺°′ = -8781 kj/mol = completely oxidized, storing energy as triglycerides or fat = v efficient, since lots of energy, big molecule

Question 6

describe atp

Answer 6

ATP + H2O → ADP + Pi
∆𝐺°′ = -32.2kj/mol
drives unfavourable reactions
metabolism
Currency of cell
ratio of atp:adp matters

Question 7

what is unit of food labels

Answer 7

1kj=-.239kcal
1kcal = 1 large cal

Question 8

describe metabolism - 2 reactions

Answer 8

Catabolism = exergonic - complex to simple
anabolism = endergonic - synthesis of proteins - simple to complex
both coupled to produce atp

Question 9

describe stage 1 of metabolism

Answer 9

Interconversion of polymers and complex lipids with monomeric intermediates

Question 10

describe stage 2 of metabolism

Answer 10

Interconversion of monomeric sugars,
amino acids, & lipids with simpler organic compounds

Question 11

describe stage 3 of metabolism

Answer 11

Degradation or synthesis from inorganic Compounds including CO2, H2O, and NH3

Question 12

compare glycolysis and oxidative phosphorylation

Answer 12

glycolysis = have to deal with electrons, nad+ = dump electrons onto it, nadh reduced form with electrons, 2atp and 2nadh = products of glycolysis, lactate = electron receptor
op = final electron acceptor oxygen

Question 13

what is metabolism

Answer 13

integrated
high branched not linear

Question 14

what is a futile cycle

Answer 14

ex of how cells regulate many pathways
not a good thing for many cells in body

Question 15

describe futile cycle

Answer 15

atp –> fatty acids –> atp and acetyl coa
if happen simultaneously = bad for cell since all consumed at once - no more cycle - doesnt happen tho
allosteric reg helps - typically metabolite that activates one pathway inhibits other
also covalent reg or if in diff compartments

Question 16

give ex of futile cycle

Answer 16

if fatty acid synthesis and degragation occurred at same time = no useful work done
more ATP would be consumed in the endergonic reactions of fatty acid synthesis than produced in the oxidation reactions.

Question 17

what is glycolysis

Answer 17

fermentation
sweet splitting = split sugar
pathway that favours oxidation of glucose to put phosphates onto metabolites - lower delta g than atp, so have higher phosphorylation potiential than atp - high energy intermediate = can phosphorylate adp directly - SLP = substrate level phosphorylation
in mito = energy stored in gradient

Question 18

name tissues that synthesize glucose

Answer 18

liver
kidney cortex

Question 19

name tissues that use glucose as primary source of energy

Answer 19

kidney medulla
erythrocytes

Question 20

what is first step of glucose oxidation

Answer 20

glycolysis in cytosol

Question 21

how many steps in glycolysis

Answer 21

10
first 5 steps = energy investment
last 5 steps = energy generation

Question 22

describe theme of all fermentations

Answer 22

nadh produced earlier in pathway reoxidized to nad+ by transfer of electrons to som nad+ available for cell to continue to produce atp via glycolysis under anaerobic conditions

Question 23

describe lactate dehydrogenase reaction

Answer 23

gapdh step
e- acceptor gets reduced
nadh –> nad+
enzyme = lactate dehydrogenase puts e- from nadh on pyruvate
2 molecules of lactate made from 1 glucose
Makes lactate - regenerates nad - co factor for gapdh step to continue
∆𝐺°′ = -35.1kj/mol

Question 24

describe step 1 of glycolysis - hexokinase

Answer 24

glucose –> g6p
needs transporter that is selective to glucose to get into cells
if put phosphate = too large so glucose trapped in cell = committed now

Question 25

describe hexokinase

Answer 25

low km high affinity for glucose, small amount of glucose actiavtes hexokinase
hexokinase in liver = glucokinase = low affinity for glucose, needs lots of glucose to phosphorylated - bc liver produces glucose - not much need to trap it

Question 26

describe hexokinase delta g stuff

Answer 26

glucose + pi <–> gp6 + h2o
∆𝐺°′ = =13.8

atp + h2o <–> adp + pi
∆𝐺°′ = -32.2

so coupled togetehr
so now can form g6p
enzyme binds atp and transfers pi onto glucose

Question 27

describe g6p in 2 diff conditions

Answer 27

if exercising = g6p goes down path to make pyruvate
if eat meal = g6p shipped off to store glycogen

Question 28

describe step 3 of glycolysis - phosphofructokinase

Answer 28

f6p–> fbp
Fructose 6 phosphate –> fructose 1,6-biphosphate, 2 phosphates on carbons 1 and 6
pfk = 2 phosphorylations - doubly

Question 29

describe step 4 & 5 of glycolysis - aldolase and TIP

Answer 29

2 atp generating steps = provide energy
Cleavage by aldolase = fbp split
2gap and dhap - in eq
dimerization - triose phosphate isomerase

Question 30

describe step 6 of glycolysis - GAPDH

Answer 30

gap –> bpg (1,3 bisphosphoglycerate)
done by gapdh
∆𝐺°′ = +
makes nadh and bpg = first intermediate genrated with high phosphorylation transfer potiental - can generate atp

Question 31

describe step 7 of glycolysis - phosphoglycerate kinase

Answer 31

bpg –> 3pg + atp
happens 2x bc 2 trioses

Question 32

describe steps 6 and 7 of glycolysis

Answer 32

thermodynamically coupled
step 6 = endergonic
step 7 = exergonic
6.3+-17.2 = -10.9
net result neg
not in vivo = in cells acc, step 7 pulls step 6 forwards

Question 33

describe step 9 of glycolysis - enolase

Answer 33

2pg –> pep
lowest ∆𝐺°′
pep =phospho enol pyruvate, 2nd intermediate

Question 34

describe step 10 of glycolysis - pyruvate kinase

Answer 34

pep –> pyruvate
removes phosphate

Question 35

describe glycolysis pathway progress

Answer 35

3 enzymes catalyze reactions so highly exergonic = virtually irreversible
Hexokinase, phosphofructokinase and pyruvate kinase
cell must regulate the 3 intermediates

Question 36

describe glycolysis balance sheet

Answer 36

∆𝐺°′𝑜𝑓𝑔𝑙𝑢𝑐𝑜𝑠𝑒𝑜𝑥𝑖𝑑𝑎𝑡𝑖𝑜𝑛= −2,870𝑘𝐽/𝑚𝑜𝑙
∆𝐺°′𝑜𝑓𝐴𝑇𝑃h𝑦𝑑𝑟𝑜𝑙𝑦𝑠𝑖𝑠= −64.4𝑘𝐽/𝑚𝑜𝑙(−32.2x2)
64/2879 ~ 2% = generating atp = small portion in glycolysis