Ditzner Exam 3

These flashcards cover definitions and key concepts related to metabolism, metabolic pathways, and glycolysis as discussed in the lecture notes.

Digestion

The first stage of metabolism; the process of breaking down larger molecules into smaller units that may be absorbed and utilized.

Metabolism

A highly integrated network of chemical pathways that enable a cell to extract energy from the environment to sustain life.

Metabolism: a highly integrated network of chemical pathways that enable a cell to extract energy from the environment to sustain life

• ____ (movement)

• ____________

• _________________

• ___________

Work, Active transport, signal transduction, biosynthesis

Catabolism

Reaction pathways that break down fuel and provide energy.

Anabolism

Reaction pathways that use energy to synthesize biomolecules.

Glycolysis

The breakdown of one molecule of glucose to two molecules of pyruvate; occurs entirely in the cytoplasm.

Glycolysis: the breakdown of 1 molecule of glucose (annd other monosaccharides) to 2 molecules of pyruvate (catabolic), occurs entirely in the cytoplasm

• Net Reaction: ______ converted to 2 molecules of _______ via _______

• 2 ____ are reduced to 2 ____

• 2 ___→2 ___ (net)

• Net ________ where change of G=____ kcal/mole

glucose, pyruvate, oxidation, NAD+, NADH, ADP, ATP, exothermic, -23

Gluconeogenesis

The synthesis of glucose from non-carbohydrate precursors, mainly occurring in the liver.

Metabolism

• Knowledge of normal metabolism is essential to understanding abnormalities that underlie _______

• Normal metabolism includes adaptation to periods of _______, _________, and _______; pregnancy and lactation

• Abnormal metabolism may result from _________ or ______ deficiencies, abnormal secretion of ________, or the actions of _____ or ______

• ________ of metabolic fuels provides the energy needed to generate ___ from ___ and the building blocks needed for _____

disease, fasting, starvation, exercise, nutritional, enzyme, hormones, drugs, toxins, oxidation, ATP, ADP, growth

• Irreversible=catalyzed by different ________ in different ___________

  • ________ pathways, ___________ regulated by enzymes unique to each → don’t occur at the ____ time

enzymes, directions, reverse, reciprocally, same

Tissue/Organ Level of Metabolism: ________ entering and __________ leaving tissues and organs can be measured and regulated

• E.g. regulation of blood glucose level by the _____

• Between meals: liver breaks down ______ to liberate ______ to be used by _____ cells, ___, ____ cells, etc.

• After a meal: excess ________ is converted into _______ or ___ stored between

substrates, metabolites, liver, glycogen, glucose, muscle, RBCs, brain, glucose, glycogen, fat

Sub-Cellular Level of Metabolism: each ________ or ___________ has specific roles

• __________ plays a central role

• Permits __________ and __________ of metabolic pathways at the _________ level

organelle, compartment, mitochondria, integration, regulation, molecular

_________ of Carbohydrates, Proteins, and Fats

• All pathways lead to ________

• Acetyl-CoA is ________ cleaved in Citric Acid Cycle to give ___ and ___

• Electrons “_________” in the Citric Acid Cycle are used to generate more ___ in the ____

• Harvested in the form of _________ (ATP)

Catabolism, acetyl-CoA, oxidatively, CO2, ATP, harvested, ATP, ETC, electrons

Acetyl-CoA

A central compound in the metabolism of carbohydrates, fats, and amino acids.

Citric Acid Cycle

A cyclic pathway that oxidatively cleaves acetyl-CoA to produce CO2 and ATP.

____________ metabolism (aerobically):

• Major fuel=_______ from ____

• Metabolized to _______ via _______

• Pyruvate ________ converted to acety-CoA

• Acetyl CoA further metabolized via _____________ and ___ to ___, ___ with concomitant generation of ATP

• Other pathways involved:

  • ______________ Pathway (ribose phosphate→RNA/DNA OR Triose Phosphate→Pyruvate)

  • Gluconeogenesis (______)

  • Glycogenolysis (_______)

Carbohydrate, glucose, diet, pyruvate, glycolysis, aerobically, Citric Acid Cycle, ETC, CO2, H2O, Pentose Phosphate, anabolic, catabolic

______ Metabolism (Beta-Oxidation):

• Major fuel=________ from ____ (hydrolyzed from __________)

• FA converted to ______ via Beta-Oxidation which can:

  • Feed into the Citric Acid Cycle and ETC

  • Serve as a ________ for synthesis of other ______ (e.g. cholesterol, steroids)

  • Be converted to _________ in liver as fuel during ___________

Lipid, fatty acids, diet, triacylglycerols, acetyl-CoA, precursor, lipids, ketone bodies, fasting/starvation

_________ Metabolism (Transamination/transfer of ___________):

• Proteins are first broken down to __

• AA are required for ______________

  • Some (essential) AA must be supplied by diet

  • Others can be synthesized from other sources (____________)

• ____ is a byproduct of AA _________

Protein, amino groups, AA, protein synthesis, diet, carbohydrates, Urea, catabolism

ATP

The energy currency of the cell, powering reactions that require free energy.

All steps in the metabolic pathway are _____________

Most steps are _______ (activity is not ________) → _______________

Irreversible steps typically catalyzed by ____________, activity of which is ________ (either by another substrate within the pathway and/or other factors)

enzyme-catalyzed, reversible, regulated, michaelis menten, allosteric enzymes, regulated, 

Bioenergetics

Biochemical thermodynamics or the study of energy changes accompanying biochemical reactions.

Exergonic Reaction

A spontaneous reaction where the change of free energy (ΔG) is less than zero.

Endergonic Reaction

A non-spontaneous reaction where the change of free energy (ΔG) is greater than zero.

E of products<E of reactants is __________

favorable

Endergonic reactions are “_____” with exergonic reactions further down the path to make it net _______ or _________

coupled, exergonic, favorable

• The _____ and ______ the bioenergetic/change of G graph of reaction is, the more irreversible to reaction can be

• The ______ and _____ the bioenergetic/change of G of reaction is, the more reversible to reaction can be

taller, narrow, shorter, wider

• The energy released by exergonic reactions are used to ____ endergonic reactions

• The individual steps of a metabolic pathway are ______ 

• ___ is considered the energy “currency” of the cell

• ATP→ADP + Pi (change of G=__ kcal/mol)

• ATP→ADP is _________

• Exergonic, mainly because of increased _________ energy of the free vs bound _______ (Pi)

• Reactions that _______ free energy are powered by ATP→ADP

• Reactions that _______ free energy power ADP→ATP

fuel, linked, ATP, -7, favorable, resonance, phosphate, require, release

• Phosporyl Transfer Energy: estimated by change of G of _________ of the _____________ compound

  • Can be transferred from a compound with a _______ potential to a compound with ____ potential

  • Increased change of G = increased ___

hydrolysis, phosphorylated, greater, less, PTE

• Phosphoenolpyruvate (___) and 1,3-Biphosphoglycerate (______) can transfer a __ → ___ to generate ATP

• ______________ and ___ (to ADP) = “ATP is the cell’s energy currency”

• ATP can transfer a Pi (w/o the Pi group) to ______-phosphate, __________ (PPi), _________-phosphate, and __________-phosphate 

PEP, 1,3-BPG, Pi, ADP, creatine phosphate, ATP, Glucose 1, Pyrophosphate, Glucose 6, Glycerol 3

• _________ pathways are comprised of oxidation reactions

• _________ pathways are comprised of reduction reactions

• Oxidaiton and Reduction reactions are always ______: 

  • if a subtraction is oxidized, whatever it reacted with is _______

Catabolic, anabolic, coupled, reduced

• Electrons are typically transferred as ________ in redox reactions

• (_) change of G = gives energy

• (_) change of G = requires energy

• Oil RiG

• Oxidation: ________ # of C-X bonds, increased oxygens or double bonds

• Reduction: ________ # of C-X bonds, decreased oxygens or double bonds

hydride (H-), -, +, increases, decreases

Explain how catabolic oxidation reactions fuel ATP synthesis.

2NAD+ is the oxidizing agent and Oxygen is present

Identify common redox reagents/electron “carriers” of metabolic pathways:

• ________: nicrotinamide adenine dinucleotide

• ________: Flavin adenine dinucleotide

NAD+/NADH, FAD/FADH

Redox Reactions

Reactions that involve the transfer of electrons between two species; always coupled.

Glycolysis Investment Phase

The first five steps of glycolysis that require an investment of ATP.

Investment Phase of Glycolysis: first 5 steps that uses 2 ATPs

• 1 molecule of ______ → 2 molecules of glyceraldyhyde 3-phosphate (________)

• Requires _ equivalents of ATP

• ________ (6-carbon ring) → 2 _______ (3-carbon chains)

• Produces 2 molecules of ___ proceed thru remaining 5 steps

• Catalyzed by ________ enzyme (irreversible steps)→ Steps , , and _

• Michaelis Menten = __________-

glucose, converted, 2, Pyranoses, trioses, GAP, allosteric, 1, 3, 10, irreversible

Glycolysis Pay-Off Phase

The remaining five steps of glycolysis that yield a net production of ATP.

Pay-Off Phase of Glycolysis: remaining 5 steps that yields 4 ATPs

• 2 molecules of ___ → 2 molecules of pyruvate (_______)

• _ equivalents of ATP produced thru “_____________________”

• 2 equivalents of ____ → ____ (_______)

• 1 molecule of glucose = ______ ATP (_ from substrate level/glycolysis)

  • Most come from ETC___

GAP, oxidized, 2, substrate-level phosphorylation, NAD+, NADH, reduced, 30-32, 2, ETC

Glycolysis Step 1:

Glucose → ________________ (______________)

1. _________ catalyzed by _______ 

   1. Phosphate transferred from ___ to ______

   2. Hexokinase has ___ affinity for glucose

   3. A key __________ enzyme

glucose-6-phosphate/glycogen, phosphorylated, Irreversibly, hexokinase, ATP, glucose, high, regulatory

Glycolysis Step 2:

Glucose-6-Phosphate/glycogen → _____________ (__________)

1. _________ reaction catalyzed by _________________

2. ___________ isomerization; 6-membered ring→5-membered ring thru ____ chain

3. _____ % is in the form with the structure on the bottom left

fructose 6-phosphate, isomerized, Reversible, phosphoglycose-isomerase, Aldose-to-ketone, open, small

Glycolysis Step 3:

Fructose-6-phosphate → ______________ (_________________)

1. Catalyzed by phosphofructo-kinase-1 (_______)

2. Consumes ___ equivalent of ATP

3. Irreversible, key regulatory step of glycolysis

4. Regulated by _________ enzyme

fructose-1,6-biphosphate, 2nd phosphorylation, PFK-1, 2nd, regulatory, allosteric

Glycolysis Step 4:

6-carbon furanose → ___________________ (______/breaks apart)

1. Cleaved into glyceraldehyde 3-phosphate (___) and dihydroxyacetone phosphate (____)

2. _________ reaction reversibly catalyzed by _______

2 3-carbon triose phosphates, cleaved, GAP, DHAP, Retro-aldol, aldolase

Glycolysis Step 5:

____ → ___ (_____________)

1. Catalyzed by _____________________

2. 2 ____ continues thru the glycolysis pathway

DHAP, GAP, reversible isomerization, triose phosphate isomerase, GAPs

Glycolysis Step 6:

GAP → ___________ (________ by NAD+, exergonic, electrons harvested, redox rxn)

1. 1st step of “_______” phase

2. __________; catalyzed by _______________________

3. NAD+ _______ to NADH; phosphorylation by _______ phosphate

4. _______ reduced 2NAD+ to NADH

1,3-bisophosphoglycerate, oxidized, payoff, reversible, glyceraldehyde 3-phosphate dehydrogenase, reduced, inorganic, Hydride (H-)

Glycolysis Step 7:

1,3-BPG → ______________ (phosphate __________)

1. 1,3-BPG is a ____ energy compound (high PTE)

2. Phosphate transferred from 1,3-BPG → ___ to generate ATP (2 total) and give 3-phosphoglycerate (______________________)

3. _________; catalyzed by ___________________

3-phosphoglycerate, transferring, high, PTE, ADP, substrate level phosphorylation, Reversible, phosphoglycerate kinase

Glycolysis Step 8:

3-phosphoglycerate → _______________ (____________ and phosphate ________)

1. ________; catalyzed by ___________________

2-phosphoglycerate, isomerization, transferring, Reversible, phosphoglycerate mutase

Glycolysis Step 9:

2-phosphoglycerate → ______________ (PEP) (__________)

1. _________; catalyzed by ______

2. ___ is another high-energy phosphate (high phosphoryl transfer potential=transfer Pi group to _________)

2-phosphoenolpyruvate, dehydration, Reversible, enolase, PEP, anything

Glycolysis Step 10:

2-phosphoenolpyruvate → __________________ (_____________________)

1. ___ transfers a phosphate to ___ to generate ___; _____________________

2. _________; catalyzed by ______________

pyruvate/pyruvic acids, enol-to-keto tautomerization PEP, ADP, ATP, substrate level phosphorylation, Irreversible, pyruvate kinase

Aerobic Conditions:

• _______ is further oxidized in ____________ via _______________ and ___

• This _______ NAD+ which is in _____ supply in cells

• Glycolysis can continue to breakdown more glucose

• NADH _______ to NAD+ (_____________) and O2 _________ to H2O (__________) in ETC

Pyruvate, mitochondria, Citric Acid Cycle, ETC, replenishes, short, oxidized, mitochondria, reduced, cytoplasm

Anaerobic Conditions:

• Not enough __ in the mitochondria to ________ NAD+

• Another source of ____necessary for glycolysis to continue

• Mainly occurs in ______________ cells

O2, replenish, NAD+, actively respiring muscle

Step “__” of Glycolysis

• Pyruvate → ______ (reduced by ____)

• NADH ________ to NAD+ and glycolysis continues

11, lactate, NADH, oxidized,

Cori Cycle

The process where lactate produced in muscles is transported to the liver and converted back to pyruvate.

Gluconeogenesis

• ______ of glycolysis, but only in the synthesis of _ molecule of glucose from _ molecules of pyruvate

• Occurs in _____ (starvation); glucose required by ______ and ____

• Key Differences:

  • Starts with pyruvate in mitochondra; several additional prep steps needed

    • ______________ FOR PYRUVATE in mitochondrial membrane

    • Pyruvate → _________ → _______ (transported) → _________ → ___

    • Eats up 2 ____ and 2 ____

    • ________ oxidized to malate in ________

    • ______ reduced to Oxaloacetate in ________

  • Requires _ ATP equivalents

  • Key regulatory steps are catalyzed by enzymes that are different than for glycolysis (Steps _, _, and _)

  • It’s also net exothermic (has to be) but by much ____ (change of G=__ kcal/mol)

Reverse, 1, 2, liver, brain, RBCs, no transporter, oxaloacetate, malate, oxaloacetate, PEP, ATPs, GTPs, Oxaloactetae, mitochondria, Malate, cytoplasm, 6, 1, 3, 10, less, -9

• For the regulation of glycolysis and gluconeogenesis, 2 pathways are not active at the same time

  • When 1 pathway is activated, the other is _______

  • Regulated by the ________ enzymes distinct to each pathway

    • _____ (glycolysis) or _________ (gluconeogenesis)

    • ___________ (glycolysis) or ______ (gluconeogenesis)

  • In most tissues, gluconeogenesis stops with formation of ____________, which is converted to glycogen and stores

  • Last step of gluconeogenesis occurs primarily in _____ cells; maintains ___________ levels

  • Activated or inactivated by various _________ or _________ (glucagon, insulin)

inhibited, allosteric, PFK-1, F-1,6-BP, Hexokinase, G-6P, glucose 6-phosphate, liver, blood glucose, metabolites, hormones

Reciprocal Regulation

The regulation where one pathway is activated while the other is inhibited, balancing metabolic needs.

When energy stores are high

• Glycolysis ________

• Gluconeogenesis ________

inactivated, activated

When energy stores are low

• Glycolysis ________

• Gluconeogenesis ________

activated, inactivated

• Allosteric activators/inactivators include:

  • ___, ____ (activators)

  • ___, ___, ___ (inactivators)

F-2, 6-BP, ATP, ADP, AMP

NAD+/NADH and FAD/FADH

Common electron carriers in metabolic pathways involved in redox reactions.