Biochem unit 4

Metabolism involves what?

Multi-enzyme pathways that cooperate to capture energy and build biomolecules.

Do metabolic pathways cooperate?

Yes

Catabolism

nutrients and cell constituents broken down for energy and raw materials

anabolism

production of biological molecules from simpler components, requires input of energy

what is formed from catabolic pathways?

CO2, H2O, NH3, ATP, reduced coenzymes

what is used for anabolism

simple sugars, amino acids, fartty acids, nucleotides

T or F, biomolecules and primary metabolites are not shared

F

what are the six main metabolic intermediates?

amino acids, nucleotides, glucose, fatty acids, pyruvate, acetyl-CoA

synthesis and degradation pathways

nitrogen fixation and assimilation, urea cycle, glycogen degradation and synthesis, pentose phosphate pathways, gluconeogenesis, fatty acid degradation and synthesis

central metabolic pathways

oxidative phosphorylation, glycolysis, citrate cycle, photosynthesis and carbon fixation

what is it called when an exergonic reaction is paired with an endergonic reaction?

energetic coupling

what exergonic reaction are endergonic reactions usually paired with?

ATP hydrolysis (ATP + H2O → ADP + Pi)

delta G ATP hydrolysis

-7.3kcal/mol

what does coupling change for the system?

overall equilibrium

why does ATP act as a free energy donor?

It has high free energy during hydrolysis, a phosphate group is removed which removes one negative phosphate, making ADP more stable and lower energy

why does phosphoryl transfer occur?

a favorable energy transformation

order of phosphoryl transfer high to low free energy (delta G’)

phosphoenolpyruvate (-70), bisphosphoglycerate (-60), phosphocreatine (-40), ATP (-30.5), glucose 6-P (-15), glycerol-P (-10)

why is ATP the universal eneregy

It is the middle-man energy-wise

what does metabolic flux depend on?

products/substrates and levels of enzyme activity

metabolic flux

rate at which substrates/metabolites and products are interconverted

What do glucose pathways look like before breakfast

-high degradation of glycogen, low synthesis of glycogen, high glyconeogenesis of pyruvate, low glycolysis of glucose to pyruvate

-low influx of glucose, high efflux of glucose to the blood

What do glucose pathways look like after breakfast?

-Low degradation of glycogen, high synthesis of glycogen, low gluconeogenesis of pyruvate to glucose, high glycolysis of glucose to pyruvate.

-high influx of glucose, low efflux of glucose (it is stored)

what is the delta G’ of reversible steps?

close to 0

what is an irreversible step called?

committed step

The energy released by the hydrolysis of ATP to ADP and P_i is equal to what?

the energy needed by the reverse reaction of ADP + P_i → ATP.

Hydrolysis of what compounds could be involved in a reaction coupled to the synthesis of ATP from ADP + Pi

phosphoenolpyruvate, 1¸3-bisphosphoglycerate,

phosphocreatine

Synthesis of what compounds could be achieved by coupling to ATP hydrolysis to ADP + Pi?

glucose-1-phosphate, pyrophosphate, glucose-6-phosphate, glycerol-3-phosphate

glucose oxidation is ___

exergonic

glucose oxidation reaction

C6H12O6 + 6O2 → 6CO2 + 6H2O + free energy

delta G glucose oxidation

-686 kcal/mol

Are redox reactions coupled or uncoupled

coupled

reduced molecule is ___ agent, oxidized molecule is ___ agent

oxidizing agent, reducing agent

what does carbon lose when it is oxidized?

electrons and hydrogen

why does carbon lose electrons when it loses H?

the oxygen it is now bound to will pull electron density away from it because it is electronegative/

order of least to most oxidized carbon structures

methane, methanol, formaldehyde, formic acid, CO2

do reduced or oxidized molecules have higher free energy?

reduced

electron donor and acceptor in glucose oxidation

glucose (higher energy, going to be oxidized, more H), O2 respectively (lower energy, going to be reduced, more O)

what is the form of energy released when glucose is oxidized to CO2?

heat

why do cells use a stepwise oxidation of glucose?

there is too high of an EA, an enzyme would not allow the reaction to happen fast enough, and all energy released as heat without it.

electron carriers do what to glucose?

oxidize it

____ deficiency causes pellagra

niacin

what is NAD derived from?

Niacin (from vitamin B3)

example of niacin defiency

no soaking corn in CaO (lime) means the protein-bound niacin is not released

FAD is reduced to ___ which is reduced to ___

FADH (semiquinone), FADH2

where is FAD derived from?

vitamin B2

FADH is a what

radical

FADH is more flexible than NAD because what?

it can take 1 electron

electron carriers pass electrons from glucose to O2, which does what?

releases energy in small packets