BICH 411 Exam 1

metabolism

sum of all chemical reactions that allow the body to obtain and use energy occurring in the cell

glycogenin

enzyme that functions as a primer for glycogenesis

why do we need metabolism?

need continuous influx of energy to battle entropy

metabolic pathway

series of connected, sequential enzymatic reactions that produce a specific product

what does an enzyme do?

lower activation energy to increase rate of reaction

what does an enzyme decidedly NOT do

impact spontaneity

why do metabolic pathways need intermediates

they couple unfavorable reactions with favorable ones and allow buildup of metabolite concentration to drive an otherwise unfavorable reaction forward

why are metabolic pathways irreversible

all steps together in a pathway create a favorable energy production that cannot be overcome by that same pathway in the reverse direction

first committed step

highly favorable reaction that easily occurs to start a pathway, often a point of regulation for the pathway

how are pathways controlled?

regulation of enzymes in committed steps, compartmentalization of pathways in different physical locations

catabolism

break down molecules to make energy, oxidation (in regards to the carbon), exergonic

anabolism

reductive biosynthesis of necessary molecules for body function, endergonic

draw inorganic phosphate

done (IP)

draw ATP

done (ATP)

draw ADP

done (ADP)

draw AMP

done (AMP)

draw PPi

done (PPi)

why is ATP hydrolysis so favorable

repulsion of negatively charged O- groups on the Pi groups, increased resonance stabilization, increased energy of solvation (more disorder)

tautomerization

conversion between 2 constitutional isomers using an investment of a proton

what are the main 3 high energy phosphate compounds

Posphoenol pyruvate (PEP), 1,3-Bisphosphoglycerate, and Phosphocreatine

what is the function of phosphocreatine

basically like fat storage but for ATP

what is the function of 1,3 BPG and PEP

substrate level phosphorylation in glycolysis

where do electrons from NADH and FADH2 go

ETC

where do electrons for anabolism come from

NADPH

what is another term for end products

waste products

what is the delta G for all ATP related reactions

-30.5

draw NADH

done (NADH)

draw NADPH

done (NADPH)

what is the part of NADH used for catabolism

the 2’ OH grouop which is the electron source for oxidative phosphorylation

what is NADH used for

catabolism

what structure is this

NAD+

what structure is this

NADH

Draw the conversion of NAD+ to NADH that you need for the exam

done (NAD+ to NADH)

what type of metabolic process is the conversion of NAD+ to NADH?

catabolic

what is the purpose of NAD+

accepts electrons from catabolism

what type of process is the conversion of NADH to NAD+

anabolic

draw the conversion of NADH to NAD+ that you need for the exam

done (NADH to NAD+)

what is the purpose of NADPH

provides the reducing power for anabolism

biosynthetic enzymes

operate in anabolic pathways

degradative enzymes

operate in catabolic pathways

vitamins

organic molecules that assist metabolic reactions

metabolic flux

rate at which molecules turn through enzymes in a metabolic pathway

how is metabolic flux controlled

allosteric effectors, covalent modifications, substrate cycles, genetic control

what are substrate cycles

enhancing rate of reaction through one pathway while limiting rate of reaction through the opposing pathway

draw the conversion of 1,3 BPG to PPG

done (13BPG to PPG)

draw conversion of PEP to pyruvae

done (PEP to pyr)

why is PEP such a high energy intermediate

hydrolysis of a phosphate group, tautomerization

how does glycolysis differ between organisms?

points of regulation and fates of pyruvate

cellular respiration

process where energy in metabolites is harnessed for ATP production

three parts of cellular respiration

glycolysis, pyruvate, oxidative phosphorylation

what conditions can glycolysis occur under?

aerobic and anaerobic

what are the big picture, net products of glycolysis

2 NADH, 2 ATP, 2 Pyruvate

what is the big picture of the investment phase of glycolysis?

2 ATP used to convert 6C glucose to 2 3C GA3P molecules

what is the big picture of the payoff phase of glycolysis

2 3C GA3P to 2 pyruvate, 4 ATP, 2 NADH

what are the two steps that produce ATP

PPG kinase and pyruvate kinase

what is the delta G for the glycolysis pathway

-85 kJ/mol

what is the first step of glycolysis

hexokinase

what does the hexokinase step do

transfer the y phsphate of ATP to the C6 hydroxyl of glucose

why is the hexokinase step neccesary?

the addition of the Pi group to glucose keeps it inside the cell so it can be used

draw the hexokinase step mechanism

done (hexokinase)

what is the difference between hexokinase and glucokinase

glucokinase can only digest glucose, found in the liver, lower affinity but higher capacity

why does glucokinase have a lower affinity for glucose?

so liver cells can pass needed glucose on to more functional cells when energy is scarce

how is hexokinase regulated

feedback inhibition

how is glucokinase regulated

hormones! insulin (activation) and glucagon (inhibition)

what is the second step of glycolysis

phosphoglucoisomerase

what does the phosphoglucoisomerase step do

isomerize the 6C glucose to a 5C fructose ring

why is the PGI step neccesary?

so that aldolytic clevage can happen in step 4

draw the PGI step reaction mechanism

done (PGI)

what is the third step of glycolysis

Phosphofructokinase 1

what is the first committed step of glycolysis?

PFK1

what does the PFK1 step do?

add a second Pi group to C1 to form F1,6BP

why is the PFK1 step neccesary?

so that 2 identical sugars can be created via aldolytic clevage

how is PFK1 regulated

allosteric control from -ATP and +AMP, as well as concentration of +fructose 2,6 bisphosphate

what regulates PFK2/FBPase2 activity?

insulin (activate) glucagon (inhibit)

what is the fourth step of glycolysis

aldolase

draw the aldolase reaction mechanism

done (aldolase)

what does the aldolase step do?

cleave the 5C fructose into 2 3C sugars

what is the fifth step in glycolysis

triose phosphate isomerase

what does the TPI step do?

isomerize the DHAP product from step 4 to be G3P so it can continue down glycolysis

draw the TPI step of glycolysis

done (TPI)

what is the sixth step of glycolysis

glyceraldehyde 3 phosphate dehydrogenase

what does the G3PD step do?

oxidize G3P to be 1,3 BPG

draw G3PD step of glycolysis

done (G3PD)

what is the 7th step of glycolysis

phosphoglycerate kinase

what does the PPG kinase step do?

transfer a phosphate group from 1,3 BPG to ADP to produce ATP

draw the PPG kinase step

done (PPG kinase)

what is the 8th step of glycolysis?

phosphoglycerate mutase

what does the phosphoglycerate mutase step do?

move the phosphate group from 3PG to the center to create 2 PG

why does the PPG mutase step have to occur?

to set up the formation of the high energy phosphate compound in the next step

draw PPG mutase step

done (PPG mutase)

what is the 9 step of glycolysis

enolase

what does the enolase step do

catalyze dehydration of 2PG to PEP

what does enolase need to function?

Mg2+

how is enolase regulated?

inhibition by fluoride that will complex with the Mg2+ that enolase needs to function

draw the enolase reaction

done (enolase)

what is the 10 step of glycolysis

pyruvate kinase

what does the pyruvate kinase step do

catalyze substrate level phosphorylation of ADP from PEP

is the pyruvate kinase step reversible

no

draw the pyruvate kinase step

done (pyruvate kinase)

how is the pyruvate kinase step regulated?

activated by AMP and F1,6BP and inhibited by ATP, acetyl coA, alanine, and glucagon