cell bio exam 3

metabolic pathways

aka cell respiration, includes anabolic and catabolic pathways

anabolic pathways, entropy effects, energy requirement

build up pathways (often polymers like starch/glycogen), decrease entropy, endergonic

catabolic pathways, entropy effects, energy requirement

breaking down pathways (ex hydrolysis of glucose), increase entropy, exergonic

high chemical energy molecule examples that can convert to ATP

GTP (higher in energy), creatine phosphate, NADH (reduced coenzyme, chem potential energy)

energy rich properties of ATP

adenine base, 5c ribose (linked to P groups by phosphoester bond), chain of 3 phosphate groups linked to each other by phosphoanhdyride bonds

where is the missing H that balances the hydrolysis of ATP to ADP reaction?

it is donated to solution as a proton

when is energy released in atp

when phosphoanhydride bonds are hydrolyzed, because Pi is much more stable than reactant

why is atp hydrolysis exergonic (3)

charge repulsion between p groups, resonance stabilization of products, inc entropy/ solubility of products

why is amp less energy than adp and atp?

no charge repulsion btwn p groups

what is delta g prime standard based on

25 degrees C, adp and atp in equal concentration,

what does delta g standard prime actually end up being

-10 to -14 kca/mol in cell, atp concentration is 5x adp driving the hydrolysis

biological oxidation involves

loss of H (dehydrogenation)

what enzymes remove H atoms

dehydrogenases

where do the removed e go from oxidation reaction

to another molecule, which is considered reduced

reduction

addition of e, endergonic process

hydrogenation

reaction involved in reduction becuase transfered e- are accompanied by protons (overall will be neutral H)

typical e- and H acceptors during biological oxidations

conenzymes, carry energetic electrons

coenzyme involved in energy metabolism (oxidized form)

NAD+ , will becomes NADH + H+ when 2H are added

observe each molecule and how it changes in redox rxns

what produces energy from organic compounds (carbs, proteins, fats) and in what form?

oxidation of organic compounds, in form of ATP and reduced coenzymes

oxidation of glucose, what is roughly the delta g, end products, and final e- acceptor

highly exergonic, -686kcal/mol for complete conversion of glucose to CO2 and H2O; O2 is final electron acceptor

do cells obtain the full delta g of glucose oxidation

no, energy conversion is not 100% efficient (entropy)

are coenzymes consumed

no they are recycled

overall reaction of glucose

glucose→ 6 co2

glycolysis and its yield

glucose→ 2 pyruvates; 2 atp, 2nadh

pyruvate oxidation and its yield

each pyruvate → acetyl coA (2 total) ; 2NADH

krebs cycle and its yield

2 acetyl coA→ 4 CO2 ; 2atp and 2 fadh2

summary of reactions for phase 1 of glycolysis

1. glucose is phosphorylated

2. glucose→ fructose

3. another phosphorylation

4. split in half

5. 2 g3p isomers produced

summary of enzymes for phase 1 of glycolysis

1. kinase

2. isomerase

3. kinase

4. unimoprtant

5. isomerase

why can phase 2 of glycolysis be done twice

because phase 1 produces 2 g3p isomers

phase 2 of glycolysis reactions summary

6. redox phosphorylation (energy step)

7. remove Pi that was just added, add it to adp to make atp

enzymes for phase 2 of glycolysis

6. dehydrogenase

7. kinase

phase 3 of glycolysis summary of reactions

8. move P group to another carbon

9. removal of h2o

10. remove P group from C, add it to adp to make atp

enzymes for phase 3 of glycolysis

8. mutase (isomerase family)

10. kinase

what is substrate level phosphorylation and which steps of glycolysis use this

direct synthesis of atp by transfer of P from a high energy substrate to ADP; steps 7 and 10 of glycolysis (both involve kinases)

summarize atp input and output for glycolysis

input 2atp, produce 2 atp in phase 2, produce 2 atp phase 3 (net 2 atp)

does pyruvate formation require oxygen

NO

brief overview of 3 phases of glycolysis

1. preparation and cleavage

2. oxidation

3. pyruvate formation

what must fermentation regenerate in the oxidized form so glycolysis can continue?

Nad+

2 types of anaerobic metabolism of glucose

to lactate, and to ethanol + CO2

why isnt there nad+ nadh or h+ shown in reaction of glucose to lactate

no net change in amounts of those molecules

proprionate fermentation

pyruvate → reduced to proprionate

glycol fermentation

butylene glycol formation

fermentation pathway common theme

reoxidizing nadh to nad+ by transfer of e- to an organic acceptor

essential features of fermentation process (2)

1. no external e- acceptor

2. no net oxidation

what does it mean that cancer cells exhibit aerobic glycolysis

they ferment glucose to lactate even in the presence of oxygen, allows them to outgrow normal cells

what can detect these cancer cells

pet scans via flurodeoxyglucose which will accumulate in cancer cells

radiolabeled biochemical precursors serve what purpose

label different C in glucose with the isotope c14, allowing tracing of individual molecules