Unit 16 - Basic Concepts of Metabolism

start to use and play with the metabolic map on blackboard

got it

what is a requirement of living organisms?

living organisms require an input of free energy

why do living organisms need an input of free energy?

1. to be able to do mechanical work (muscle contraction; cellular movements)

2. for active transport of ions and molecules

3. for synthesis of macromolecules from simple precursors

free energy comes from the ___________

environment

where do phototrophs obtain their energy from?

sunlight

where do chemotrophs obtain their energy from?

through oxidation of carbon fuels

what type of structures build living organisms?

complex structures

building complex structures that are _____ in entropy is only possible when ____ is spent in the process

low, energy

ultimate source of energy for all life on earth is…

sunlight

identify the process that is represented by the blue circle

citric acid cycle

metabolism is composed of…

many interconnected reactions

Glucose → pyruvate is called…

pyruvate → lactate + acetyl CoA is called…

glycolysis, pyruvate oxidation + lactic acid fermentation

fuels are ________ and large molecules are ________ in a series of linked reactions called _________ ____________

degraded, constructed, metabolic pathways

glucose is ______ to pyruvate in ____ linked reactions, this whole process can be described as __________

metabolized, 10, glycolysis

pyruvate can then be metabolized into what two things?

acetyl CoA and lactate

different metabolic pathways have many common ________ used in multiple reactions that occur at the same _______

intermediates, time

metabolism consists of ______-_________ and ______-___________ reactions

energy-yielding, energy-requiring

what is catabolism?

the breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy

catabolic processes are _____ in nature while anabolic processes are ______ in nature

oxidative, reductive

this makes sense!! catabolic processes break down molecules, and as a result, energy sources like ATP are released, therefore, catabolic processes must LOSE these electrons so that they can be USED to create energy sources like ATP

catabolism produces energy in the forms of…

ATP and ion gradients

what is occurring in the two circles?

proton transfer

what is anabolism?

the set of metabolic pathways that construct bigger molecules from smaller units

_______ processes power ________ processes

catabolic, anabolic

what do anabolic reactions require?

an input of energy

reductive processes require electron ________ while oxidative processes require electron ________

sources, carriers

give examples of electron sources

NADPH, NADH, FADH2

give examples of electron carriers

NAD+, NADP+, FAD

give examples of catabolism

glycolysis, citric acid cycle, fatty acid oxidation

give examples of anabolism

synthesis of fatty acids from acetyl-CoA, proteins from amino acids, complex carbs from simple sugars

which molecules are energy rich and which are energy poor?

reduced molecules are energy rich and oxidized molecules are energy poor (reduction = gain of electrons → they have all that energy!!!!)

the more reduced carbon is to begin with…

the more free energy is released by oxidation

why is fatty acid a more efficient fuel compared to glucose?

the carbons in fats are more reduced than the carbons in glucose

what is the primary mechanism that occurs to obtain energy by non-photosynthetic organisms?

OXIDATION (catabolic processes are oxidative in nature)

describe the first stage of catabolism

fuels → broken down into smaller bits → no useful energy captured

describe the second stage of catabolism

• small molecules degraded into simple units → these simple units play a key role in metabolism

• most molecules are converted into acetyl CoA

• a small amount of ATP is generated

describe the third stage of catabolism

• ATP is produced due to complete oxidation of acetyl CoA → occurs during citric acid cycle and oxidative phosphorylation

what is a thermodynamically unfavorable reaction?

a non-spontaneous reaction that requires an input of energy

thermodynamically unfavorable reactions can be driven by…

thermodynamically favorable reactions

“thermodynamically unfavorable reactions can be driven by favorable reactions” describe this concept

• thermodynamically unfavorable reactions have a positive delta G and won’t proceed on their own

• however, cells need unfavorable reactions to build large molecules

• sooooo unfavorable reactions will couple with favorable reactions (that have a negative delta G) so that the overall reaction is favorable (look at the image)

give an example of a favorable reaction that often couples with unfavorable reactions

ATP hydrolysis

ATP is the _________ currency of free energy

universal

ATP hydrolysis drives metabolism by shifting…

the equilibrium constants of coupled reactions

what two criteria must be met to construct a metabolic pathway?

1. individual reactions must be specific

2. the pathway in total must be thermodynamically favorable

what is a specific reaction?

a reaction that yields only one particular product or set of products from its reactants

how can a thermodynamically unfavorable reaction in a pathway be made favorable?

if it is coupled with a more favorable reaction

identify the favorable reaction, the unfavorable one, and the intermediate

favorable: second one

unfavorable: first one

intermediate: B

energy derived from fuels for chemotrophs or light for phototrophs is converted into…

adenosine triphosphate (ATP)

why is ATP an energy rich molecule?

it’s triphosphate unit has two phosphoanhydride linkages

ADP stands for…

adenosine diphosphate

AMP stands for…

adenosine monophosphate

this is a fundamental mode of energy exchange in biological systems

ATP - ADP cycle

ATP hydrolysis products…

• ADP + P_i

• AMP + PP_i

list processes that require ATP

• motion

• active transport

• biosyntheses

• signal amplification

list processes that require ADP

• oxidation of fuel molecules

• photosynthesis

fill in the boxes

ATP is incredibly important, list some reasons why

• it is the immediate donor of free energy

• it is consumed within a minute of its formation (EVERYBODY WANTS IT)

• it must be constantly recycled to power the cell

• the generation of ATP is one of the primary roles of catabolism

phosphate can be transferred from compounds with ________ delta G to those with ________ delta G

higher, lower

what are the molecules that have higher energy phosphates than can be transferred to ATP?

• phosphoenolpyruvate (PEP)

• 1,3-Biphosphoglycerate (1,3-BPG)

• Creatine phosphate

PEP (Phosphoenolpyruvate) + ADP →

Pyruvate + ATP (phosphate from PEP is donated to ADP, ATP is created, PEP is left with pyruvate)

this reaction is ______ and can be used to synthesize _____

favorable, ATP

exercise depends on various means of generating ____

ATP

muscle contains only enough ATP to power muscle contraction for how long?

less than a second

what compound can regenerate ATP from ADP, allowing a short burst of activity during exercise?

creatine phosphate

what enzyme helps creatine phosphate regenerate ATP from ATP?

creatine kinase (kinases are transferases, the reaction transfers a phosphate molecule from creatine phosphate to ADP to create ATP)

after the creatine phosphate stores are depleted, how is ATP generated?

through metabolic pathways

what is an activated carrier?

a small molecule to which a chemical group or electrons have been added, which can then be donated to another molecule

ATP is an _________ ________ of ________ _______

activated carrier, phosphate groups

why is ATP an activated carrier of phosphate groups?

b/c phosphoryl transfer from ATP is an energetically favorable (exergonic) process

coenzyme A is also referred to as…

CoA

coenzyme A is a carrier of…

acyl groups

coenzyme A consists of…

two carbon fragments

NADH/NAD+

identify the oxidized form of the carrier and the reduced form

oxidized: NAD+ (lost an electron so it’s more positive)

reduced: NADH

which is often an electron acceptor: NAD+ or NADH?

NAD+

what are the major electron carriers in oxidation?

NAD+, FAD

identify the reduced and oxidized form: FADH₂ and FAD

reduced: FADH₂

oxidized: FAD

what is the activated carrier of electrons for the synthesis of biomolecules?

NADPH