Metabolism Flashcards by Tyler Turner

What is metabolism

A linked series of chemical reactions that begins with a particular molecule and converts it into some other molecule in a carefully defined fashion

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The pathways of metabolism are _______, and their activity is coordinated by sensitive means of communication in which _______ are predominant

interdependent, allosteric enzymes

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Reactions that convert energy form fuels into biologically useful forms

Catabolic

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Reactions that require inputs of energy to proceed

Anabolic

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Reactions that form complex molecules

Anabolic

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what is the universal currency of free energy in biological systems

ATP

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The release of more phosphate groups allows for a

greater free energy release

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What are three compounds that have a higher phosphoryl-transfer potential than ATP (to ADP) (list them in order form highest lowest)

Phosphoenolpyruvate (PEP) (-61.9), Creatine phosphate (-49.4) , 1.3- Biphosphoglycerate (1,3-BPG) (-43.1)

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What is the free energy when ATP is hydrolyzed to ADP

-30.5 kJ mol^-1

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What is the free energy when ATP is hydrolyzed to AMP

-45.6 kJ mol^-1

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ATP consists of

adenine, a ribose, and a triphosphate unit

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The active form of ATP is usually a complex of ATP with

Mg^2+ or Mn^2+

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Groups with higher phosphoryl-transfer potential can

transfer phosphates to groups with a lower potential

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Why is it important that ATP has a phosphoryl-transfer potential that is intermediate among the biologically important phosphorylated molecules

This intermediate position enables ATP to function efficiently as a carrier of phosphoryl groups

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The amount of ATP in the muscle suffices to sustain contractile activity for

less than a second

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what serves as a reservoir of high-potential phosphoryl groups that can be readily transferred to ADP

Creatine phosphate

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The reaction of creatine phosphate + ADP —-> ATP + creatine is catalyzed by

creatine phosphate

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What is the principal immediate donor of free energy

ATP

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ATP is consumed within a _____ of its formation

minute

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The _____ of carbon fuels is an important source of cellular engery

oxidation

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The total quantity of ATP in the body is limited to approximately

100 grams

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The turnover of the small quantity of ATP is

very high

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A resting human being consumes about ____ of ATP in 24 hours

40kg

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During strenuous exertion, the rate of utilization of ATP may be as high as

0.5 kg/minute

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Motion, Active transport, signal amplification, and biosynthesis can take place only if

ATP is continually regenerated from ADP

Generation of ____ is one of the primary roles of catabolism

ATP

carbon in fuel molecules--- such as glucose and fats---- is oxidized to _____. The resulting electrons are captured and used to regenerate ATP from ___ and __-

CO2, ADP, phosphate

In aerobic organisms, the ultimate electron acceptor in oxidation of carbon is _____-

Oxygen

What is the oxidation product of carbon fuels in aerobic organisms

Carbon Dioxide

in terms of oxidation- The more reduced a carbon is to begin with, the

more free energy is released by its oxidation

Which would release more free energy methane or methanol

methane

When a fuel is oxidized the oxidation takes place ____ carbon at a time

one

For a 2 hour run about how much ATP is utilized

about 60kg (132 pounds)

Which is more likely to be stored saturated or polyunsaturate fatty acids

Saturated

The carbon-oxidation energy is used in some cases to create a ______________ and in other cases to creat an ______. In either case, the end point is the formation of ____

Compound with high phosphoryl-transfer potential, ion gradient. ATP

what are some reasons that phosphates came to play a prominent role in biology

phosphate esters are thermodynamically unstable while being kinetically stable. thus energy release cn be manipulated by enzymes. Their kinetic stability makes them ideal regulatory molecules, added to proteins by kinases and removed only by phosphatases

What is the stability of phosphate esters due to

the negative charges that make them resistant to hydrolysis in the absence of enzymes

What account for the presence of phosphates in the backbone of DNA

Their negative charge makes them resistant to hydrolysis in the absence of enzymes

What do phosphatases do

they remove phosphates from proteins

What do kinases do

They add phosphates to proteins

The binding of phosphates to metabolites can have what effect in terms of the cell membrane

it causes them to no longer diffuse through the membrane

what are the three stages of extracting energy from foodstuffs

digestion (no energy captured)- protein are hydrolyzed to their 20 different amino acids, polysaccharides are hydrolyzed to simple sugars such as glucose, and lipids are hydrolyzed to glycerol and fatty acids. stage 2- numerous small molecules are degraded to a few simple units that play a central role in metabolism. most are converted to acetyl unit of acetyl CoA. (some ATP generation) Stage 3- ATP is produced form the complete oxidation of the acetyl unit of acetyl CoA. ( krebs/TAC cycle/citric acid cycle

For each acetyl group that is oxidized in the citric acid cycle how many pairs of electrons are transferred

4 pairs (three to NAD+ and one to FAD)

in aerobic organisms what is used to transfer electrons to oxygen and why

electrons are not directly transferred to oxygen and special electron carriers must be used, which are either pyridine nucleotides or flavins. The reduced forms of these carriers then transfer their high-potential electrons to oxygen

What is the reactive part of NAD+

its nicotinamide ring, a pyridine derivative synthesized form the vitamin niacin.

NAD+ accepts

a hydrogen ion and two electrons, which is the equivalent to a hydride ion

In NAD+ has a positive charge at the

Nitrogen

NAD+ is the ___ form

oxidized form

many activated carriers function as

coenzymes

FAD is the ___ form

oxidized form

The reactive pare of FAD is its

isoalloxazine ring, a derivative of the vitamin riboflavin

FAD accepts

two electrons and two protons

How is FMN (flavin monnucleotide) different form FAD

it lacks adenine

High-potential electrons are required in most biosyntheses because

the precursors are more oxidized than the products. So, reducing power is needed in addition to ATP

What is the electron donor in most reductive biosyntheses

NADPH

NADPH is the ____ form of NADP+

reduced form

NADPH differs from NADH in that the

2'- hydroxyl group of its adenosine moiety is esterified with phosphate.

NADH is primarily used for the generation of

ATP

The extra phosphoryl group on NADPH is a tag that enables enzymes

to distinguish between high-potential electrons to be used in anabolism and those to be used in catabolism

Coenzyme A is derived from

Vitamin pantothenate

Acyl groups are important in both

anabolism and catabolism

Acyl groups function in the oxidation of

fatty acids

Acyl groups function in anabolism

synthesis of membrane lipids

What is the reactive site of CoA

Terminal sulfhydryl group

Acyl groups are linked to CoA by

thioester bonds

what is the free energy for the hydrolysis of acetyl CoA

-31.4 kJ mol^-1

Why is a thioster bond more thermodynamically unsable than an oxygen ester

because the electrons of the C=O bond cannot form resonance structures with the C-S bond that are stable as those they can form with the C-O bond.

Acetyl CoA carries an ____ acyl group

Activated

The kinetic stability of activated carriers in the absence of specific catalysts is essential for their biological function because

it enables enzymes to control the flow of free energy and reducing power

most interchanges of activated groups in metabolism are accomplished by a rather

small set of carriers

almost all the activated carriers that act as coenzymes are derived from

vitamins

Vitamins are

organic molecules that are needed in small amounts in the diets of some higher animals

Is it biologically more efficient to ingest vitamins than to synthesize the enzymes required to construct them form simple molecules

Yes

Vitamin A (retinol) is a precursor of

retinal, the light-sensitive group in rhodopsin and other visual pigments, and retinoic acid, an important signaling molecules.

Function of Vitamin A

roles in vision, growth, and reproduction

Function of Vitamin C (Ascorbic acid)

Antioxidant

Functions of Vitamin D

Regulation of calcium and phosphate metabolism

Functions of Vitamin E

Antioxidant

Functions of Vitamin K

Blood Coagulation

Metabolism is regulated through what 3 ways

1. ) the amounts of enzymes 2. ) their catalytic activities 3. ) The accessibility of substrates

How are enzymes controlled for

The rate of transcription for genes coding them. | they depend on the rate of synthesis and rate of degradation

How do we control catalytic activity

Allosteric control - feedback inhibition hormones coordinate metabolic relations

How do we control the accessibility of substrates

Compartmentalization segregates opposed reactions

Metabolism Flashcards

(83 cards)