An Introduction To Metabolism Flashcards
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What is metabolism?
The totality if an organism’s chemical reactions
Definition of matabolic pathway
A series of connected chemical reactions that feed one another
Def of catabolic pathways
Involves the break down of complex molecules into simpler ones
Energy is released by breaking down complex molecules into simpler compounds
Cellular respiration definition
The breakdown of glucose in the presence of oxygen
This is an example of a pathway of Catabolism
What is kinetic energy?
Associated with motion
What is heat/thermal energy
Kinetic energy associated with random movement of atoms or molecules
Potential energy definition
Energy that matter possesses because of its location or structure
Chemical energy definition
Potential energy available for release in a chemical reaction
Additional
What is thermodynamics?
The study of energy transformations
What is the first law of thermodynamics?
Energy can be transferred and transformed but it cannot be created or destroyed
What does the 2nd law of thermodynamics state?
During every energy transfer or transformation some energy is unusable and is often lost as heat
What are spontaneous reactions?
They occur without energy input
Can occur quickly or slowly
For a process to occur without energy input, it must increase the entropy of the universe
Define the free energy of a living system
∆G
Energy that can do work when temperature and pressure are uniform( constant)
∆G=G (final state) - G (initial state)
What is another equation for ∆G?
∆G= ∆H - T×∆S
∆S= entropy
What is the change is free energy for spontaneous reactions?
Only processes with a negative ∆G are spontaneous
And/or
T∆S must be positive
Definition of Free Energy
A measure of a system’s instability
How does free energy change during a spontaneous change?
Free energy decreases and the stability of a system
When can a process perform work ?
When it moving toward equilibrium
What is an Exergonic Reaction in metabolism?
Proceeds with a net release of FREE ENERGY and is SPONTANEOUS.
What is an Endergonic reaction in metabolism?
Absorbs free energy from its surroundings and is non-spontaneous
What is a fact about reactions in a closed system?
Reactions in a closed system eventually reach equilibrium and the do not work
CELLS ARE NOT IN EQUILIBRIUM–THEY ARE OPEN SYSTEMS
Does metabolism ever reach Equilibrium?
No
What are the 3 kinds of work a cell does?
Chemical
Transport
Mechanical
How do cells do work?
They manage energy resources by energy coupling, the use of an exergonic process to drive an Endergonic one
What is ATP composed of?
A ribose
Adenine( nitrogenous base)
Three phosphate groups
What does hydrolysis do to ATP?
It breaks the bonds between the phosphate groups of ATP’s tail
Energy is the released from ATP when terminal phosphate bond is broken
(NB) this release of energy comes from the chemical energy to a state of lower free energy—not from the phosphate bonds themselves
How does ATP drive Endergonic reactions?
This is more like ‘how does it give off energy to reactions that require it to occur’
It drives Endergonic reactions by phosphorylation- by transferring a phosphate group to some other molecule
What is the recipient molecule called( during phosphorylation)?
Phosphorylated intermediate
How does ATP do transport work?
ATP phosphorylates transport proteins
How does ATP help cells do mechanical work?
ATP binds no covalently to motor proteins and then is hydrolysed
Is ATP a renewable source? If so, how is it renewed?
Yes
It is regenerated by the addition of a phosphate group to ADP (adenosine Diphosphate)
Where does the energy to phosphorylate ADP come from?
The energy to phosphorylate ADP comes from catabolic reactions in the cell
Is Catabolism exergonic or Endergonic?
EXERGONIC
Is anabolism Endergonic or exergonic?
Endergonic
Definition of an enzyme
Catalytic protein– acts as a catalyst
What is an example of an enzyme catalysed reaction
Hydrolysis of sucrose by the enzyme sucrase
What is ∆G in a common word you know?
∆H
Enthalpy
What is the reactant an enzyme works on?
Enzyme’s substrate
What is an enzyme substrate complex?
What is formed when an enzyme binds to its substrate
Definition of the ACTIVE SITE…
The region on the enzyme where the substrate binds
Common for Ea barrier
Activation energy
How can the active site lower an Ea barrier?
Orienting substrates correctly
Straining substrate bonds
Providing a favourable microenvironment
Covalently bonding to the substrate
Explain the whole process of how an enzyme catalyses a reaction
Substrates enter active site
Substrates are held in active site by weak interactions
Active site then lowers the Ea and speeds up the reaction
Substrates are converted to products
Products( not longer substrates) are released
What can influence an enzyme’s activity?
General environmental factors—- temperature and pH
Chemicals that specifically influence the enzyme.
2 facts of about ENZYME ACTIVITY
- Every enzyme has an optimal temperature in which it can function
- Each enzyme has an optimal pH in which it can function.
What are cofactors?
These are nonprotein enzyme helpers
May be inorganic or organic
What are the 2 types of ENZYME inhibitors
Competitive ENZYME inhibitors
Noncompetitive enzyme inhibitors
Explain the difference between a competitive and non-competitive enzyme inhibitors
A competitive enzyme inhibitor binds to the active site of the enzyme, competing with the substrate.
A non competitive enzyme binds to another part of the enzyme ( not the active site) to change shape and making the active site less affective.
What are examples of inhibitors?
Toxins
Poisons
Pesticides
Antibiotics
What can be noted under the evolution of ENZYMES?
Enzyme’s are protein encoded by genes
Mutation in genes lead to changes in amino acid composition of an enzyme
Altered amino acids may alter substrate specificity.
Under new environmental conditions, a novel form of an enzyme might be favoured
Chemical chaos would occur if a cell’s metabolic pathways were not tightly regulated
Explain how these metabolic pathways are regulated.
A cell regulated metabolic pathways by switching ON or OFF the genes that encode specific enzymes or by regulating the activity of the enzymes.
Allosteric regulation may either inhibit or stimulate an enzyme’s activity.
How does allosteric regulation occur?
Allosteric regulation occurs when a regulatory molecule binds a protein at one site and affects the the protein’s function at another site
Most allosterically regulated enzyme’s are made from polypeptide subunits
Each ENZYME has active and inactive sites
What does the binding of an activator/inhibitor do to active/inactive forms of enzymes respectively?
It stabilises
Cooperativity is a form ALLOSTERIC regulation that can amplify enzyme activity
★How does this regulation happen?
One substrate molecule primes(prepares) an enzyme to act on Additional substrate molecules more readily. . .
★‡Cooperativity is allosteric because binding by a substrate to one active site affects catalysis in a different active site.★
Cooperativity is a form ALLOSTERIC regulation that can amplify enzyme activity
★How does this regulation happen?
One substrate molecule primes(prepares) an enzyme to act on Additional substrate molecules more readily. . .
★‡Cooperativity is allosteric because binding by a substrate to one active site affects catalysis in a different active site.★
What is a proteolytic enzyme?
Also called a PROTEASE
Any group if enzymes that break the long chain-like molecules of proteins into smaller polypeptides or amino acids
What advantage can the inhibition of proteolytic enzymes be?
It may help with the management of inappropriate inflammatory response
What is the function of feedback inhibition?
This is the end product of a metabolic pathway which shuts the pathway.
Advantage of feedback inhibition
Prevents a cell from wasting chemical resources by synthesising more product than is needed
What are the 3 functions if metabolism????
Conversion of food to energy to run cellular processes
Conversion of food/fuel to building blocks for protein, lipids and nucleic acid
Elimination if metabolic wastes
Structures within the cell help bring order to metabolic pathways
Some enzymes are structural components of membranes
State an example of this and the enzyme location
In Eukaryotic cells, some enzymes reside in specific organelles
Eg. ENZYMES for respiration reside/are located in the mitochondria
