Introduction to metabolism Flashcards
what is metabolism?
the total of all chemical reactions in the cell
describe Catabolism (6)
- bio degradation
- the breakdown of a larger molecule into smaller one(s)
- Breaks covalent bonds and releases energy, so they are exergonic
- Enzyme catalyzed
- Most are also oxidations (provides reducing power)
- Generates precursors for anabolism
describe anabolism (5)
- Biosynthesis
- The synthesis of a larger molecule from a smaller one or smaller ones
- Creates many new covalent bonds and requires energy input so they are endergonic (never endothermic)
- Enzyme catalyzed
- Mostly reductions
what is chemical work?
synthesis of complex molecules
what is transport work?
take up of nutrients; elimination of wastes, and maintenance of ion balances
what is mechanical work?
cell motility and movement of structures within cells
describe Free Energy and Reactions (3)
- ) G = H - TS
- ) Expresses the change in energy that can occur in chemical reactions and other processes
- ) Used to indicate if a reaction will proceed spontaneously
- if G is negative, reaction is spontaneous
- if G is positive, reaction is not spontaneous
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KNOW
what is an exergonic reaction?
chemical reactions with a negative Go′value that release free energy (if heat released it also exothermic)
what is an endergonic reaction?
chemical rReactions with a positive Go′ value require an energy input (it is never endothermic in biological systems)
slide 11-16
LOTS OF SHIT
what is a redox reaction?
what does it result in?
- Transfer of electrons from a donor to an acceptor
- results in energy release, which can be conserved and used to form ATP
what is oxidation?
the loss of an electron or electrons from an atom, or the loss of an electron, electrons or whole hydrogen atom (2 electrons and 1 proton) from a molecule
is oxidation exergonic or or endergonic?
explain
Removing electrons or a hydrogen atom removes energy so oxidations are exergonic
what is reduction?
the gain of an electron or electrons by an atom, or the gain of an electron, electrons or whole hydrogen atom (2 electrons and 1 proton) by a molecule
is reduction exergonic or endergonic?
explain
Adding electrons or a whole hydrogen atom (bonds) adds energy so reductions are endergonic
what is reduction potential(Eo′)?
tendency of a compound to donate electrons (to be oxidized) or to gain electrons (to be reduced)
(slide 23)
slides 24-26
take a look
SLIDE 27
look at (hard to make a flashcard for)
describe electron carriers (where they are located in bacteria and archaea and eukaryotic cells; also give examples)
- Located in cell membranes of chemoorganotrophs in bacteria and archaeal cells
- Located in internal mitochondrial membranes in eukaryotic cells
- Examples of electron carriers include NAD, NADP, and others
what does NAD stand for?
nicotinamide adenine dinucleotide
what does NADP stand for
nicotinamide adenine dinucleotide phosphate
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LOOK AT
what does FAD stand for?
flavin adenine dinucleotide
what does FMN stand for?
flavin mononucleotide
*riboflavin phosphate
what does coenzyme Q (CoQ) stand for
a quinone
also called ubiquinone
what do cytochromes do?
use iron to transfer electrons
iron is part of a heme group
what do Nonheme iron-sulfur proteins
use iron to transport electrons
(iron is not part of a heme group)
e.g., ferrodoxin
(slide 32)
what are enzymes? what do they allow?
- Organic molecules that act as catalysts and increase the rate of a chemical reaction
- Allow reactions to occur at physiological conditions so they proceed in a timely manner
Some enzymes are composed solely of one or more _______________-
Some enzymes are composed of one or more __________ and ________ components
polypeptides; polypeptides and nonprotein
what is the protein component of an enzyme?
Apoenzyme
what is a cofactor? describe
nonprotein component of an enzyme
prosthetic group – firmly attached
coenzyme – loosely attached, can act as carriers/shuttles
Holoenzyme = _________ + __________
+ ___________
apoenzyme + cofactor
+ coenzyme
what is activation energy?
- energy required to form transition-state complex
- Enzyme speeds up reaction by lowering Ea
how do enzymes lower Ea? (3)
- By increasing concentrations of substrates at active site of enzyme
- By orienting substrates properly with respect to each other in order to form the transition-state complex
- Induced fit model for enzyme-substrate interaction
enzyme activity is significantly impacted by what three things?
substrate concentration
pH
temperature
what is a competitive inhibiter?
directly competes with binding of substrate to active site
what is non-competitive inhibiter?
binds enzyme at site other than active site
changes enzyme’s shape so that it becomes less active
slide 42
meh :)
Regulation of Metabolism is Important for _____________________________________ and for Maintenance of ____________________
conservation of energy and materials; metabolic balance despite changes in environment
what are the three major mechanisms for metabolic regulation?
-metabolic channeling
-regulation of the synthesis of a particular enzyme (transcriptional and translational)
-regulation of enzyme activity
direct activation or inhibition of the activity of a critical enzyme
describe metabolic channeling (2)
- ) Differential localization of enzymes and metabolites
- ) Compartmentation
- differential distribution of enzymes and metabolites -among separate cell structures or organelles
- can generate marked variations in metabolite concentrations
for regulation of enzyme activity what are the Two important reversible control measures?
allosteric regulation
covalent modification
give 2 facts about allosteric regulation
Most regulatory enzymes
Activity altered by small molecule
describe allosteric effector (4)
- binds non-covalently at regulatory site
- changes shape of enzyme and alters activity of catalytic site
- positive effector increases enzyme activity
- negative effector inhibits the enzyme
give 2 facts about covalent modification
- Reversible on and off switch
- Addition or removal of a chemical group (phosphate, methyl, adenyl)
what are 2 advantages of covalent modification?
- respond to more stimuli in varied/sophisticated ways
- regulation of enzymes that catalyze covalent modification adds second level of control
describe feedback inhibition
-Also called end-product inhibition
-Inhibition of one or more critical enzymes in a pathway regulates entire pathway
(catalyzes the slowest or rate-limiting reaction in the pathway)
-Each end product regulates its own branch of the pathway
-Each end product regulates the initial pacemaker enzyme
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