Lecture 1: Catabolism and Anabolism

the sum of all chemical and physical changes that occur in living organisms that allow for growth and survival of the organism

metabolism

metabolism is a balance of which two opposing forces?

catabolism and anabolism

breakdown of larger molecules into smaller ones, releases energy in the form of ATP and/or electrons = exothermic

catabolism

synthesis of complex molecules from simple precursors, requires energy = endothermic

anabolism

which phase is active depends on the tissue type and ______________ of the body

fed state

what are the energy yielding nutrients in catabolism?

carbohydrates, proteins, fats

what are the cell macromolecules produced in anabolism?

proteins, polysaccharides, lipids, nucleic acids

what the links between catabolism and anabolism?

1. ATP

2. electron carriers

3. Acetyl Coenzyme A

4. Pyruvate

the universal energy carrier used for immediate energy needs with a high turnover rate in the cell

ATP

3 places for the nucleophile to attack ATP:

phosphodiester bonds (alpha, beta, gamma)

why does ATP contain stored energy (aka a high energy bond)?

1. electrostatic repulsion

2. resonance stabilization

3. ionization

4. hydration

the phosphates carry four negative charges at pH 7 and these charges repel each other, so if they separate it is a favorable process

electrostatic repulsion

ADP and orthophosphate have more resonance _____________ than ATP

stabilization

upon hydrolysis of ATP, ADP immediately ________ releasing H+ to become ADP-3

ionizes

water can more easily interact with and surround ADP and Pi than it can interact with the phosphoanhydride bonds of ATP = more _____________________

H bonds = more energy gained AFTER cleavage

even though cleavage of ATP is favorable, it is relatively stable in the cell and does not _________________

spontaneously break down

ATP is thermodynamically ___________ and kinetically _____________

unstable, stable

what are the other triphosphates in the cell?

ATP, GTP, CTP, UTP

is there any chemical reason why ATP is the universal chosen carrier?

no, they are all energetically equivalent with the same 3 phosphates

ATP is a very favorable reaction and this is often used to ________________

drive unfavorable reactions

glutamate --> glutamine is made possible through what?

coupling the reaction with ATP cleavage

examples of compounds that have a higher (more negative) delta G of hydrolysis than ATP (-30.5 kJ/mol)

1. Phosphoenol Pyruvate (PEP) (-61.6 kJ/mol)

2. 1, 3 Bisphosphoglycerate (1,3 BPG) (-49.3 kJ/mol)

3. Phosphocreatinine

all three compounds with more negative delta G values can be used to make what?

ATP

what are the 2 major routes of ATP production?

1. substrate level phosphorylation

2. oxidative phosphorylation

occurs primarily in glycolysis, higher energy substrate with phosphate transfers its phosphate to ADP to make ATP

substrate level phosphorylation

occurs in mitochondria, electron transport chain

electron transfer in oxidation reactions (exothermic) is coupled to ATP production using NAD+/NADH shuttle and H+ gradient

oxidative phosphorylation

during oxidation/reduction reactions electrons are released and have to be housed on ______________ since electrons are too reactive to exist in free solution

electron carriers

what are the 2 main types of electron carriers?

1. pyridine nucleotides

2. flavin nucleotides

pyridine nucleotides are derived from the vitamin _________ which is found in tuna, chicken, and turkey and also found in bran but lost in the refining process so very little in white bread

niacin (nicotinic acid) (vitamin B3)

NAD+

nicotinamide adenine dinucleotide

NADP+

nicotinamide adenine dinucleotide phosphate

flavin nucleotides are derived from the vitamin __________ which is found in soybeans, spinach, and beet greens

riboflavin (Vitamin B2)

acetyl CoA is derived from the vitamin ______________ found in avocado, kale, broccoli, and eggs

Pantothenic acid (Pantothenate) (Vitamin B5)

CoA is an important carrier of acyl groups via _____________ bond

thioester

the thioester bond is a _________________ bond similar to phosphodiester bonds of ATP

high energy

acetyl CoA is an important metabolic __________ generated in a variety of oxidative pathways

intermediate

because CoA is a _______________________-, it cannot diffuse freely across cellular membranes and this must be transported via certain transport and shuttle mechanisms (very important and can result in disease states if faulty)

large hydrophilic molecule

Pathways that generate Acetyl CoA

1. glycogen--> glucose --> pyruvate --> acetyl coa

2. triglycerides --> free fatty acid --> acetyl coa

3. protein --> amino acids --> acetyl coa

pyruvate is what kind of structure?

acetyl group + carbon dioxide

pyruvate is a very important metabolic intermediate which can be sent out to the blood when blood glucose levels are low and is generated in a variety of pathways:

glycolysis, amino acid breakdown, and Cori cycle

pyruvate can be converted to a variety of molecules including:

certain amino acids, oxaloacetate, acetyl CoA, and lactate