Introduction to Metabolism Flashcards
Metabolism
Totality of an organisms chemical reactions.
Metabolism is an emergent property of life arising from interactions between molecules within cell.
Metabolic Pathways
Begin with a specific molecule (substrate/reactant) and end with a product.
Each step is catalyzed by a specific enzyme.
Types of metabolic pathways.
Catabolic Pathway
Anabolic Pathway
Catabolic Pathway
Release energy by breaking down complex molecules into simpler compounds.
Example of Catabolic Pathway
Cellular Respiration
Glucose
Anabolic Pathways
Consume energy to build complex molecules from simpler ones.
Example of Anabolic Pathways
Synthesis of protein
Bioenergetics
Study of how organisms manage their energy resources.
What is Energy?
The capacity to do/cause change.
What are the 4 forms of Energy?
Kinetic Energy
Thermal Energy
Potential Energy
Chemical Energy
Kinetic Energy
Energy associated with motion
Thermal Energy
Kinetic energy associated with random movement of atoms or molecules
thermal (aka heat)
Potential Energy
Energy that matter possesses because of its location/structure.
Chemical Energy
Potential energy avaliable for release in a chemical reaction.
First Law of Thermodynamics
The amount of energy in the universe is constant.
meaning
energy can not be created or destroyed; only transferred
Second Law of Thermodynamics
Every energy transfer or transformation increases entropy (disorder of universe).
Free Energy Change
A living systems free energy is energy that can do work when temperature and pressure are uniform, as in a living cell.
Change in free energy (delta G) is related to change in total energy (also called enthalpy delta H), change in entropy (delta s), and temperature in Kelvin (T)
Free-Energy Change Formula
delta G = delta H - (T*deltaS)
G = free energy H= total energy of a system T = temperature in Kelvin S = entropy
A cell reaction that decreases entropy of a system is ________
Anabolic
Free Energy
Measure of a system’s instability, its tendancy to change to a more stable state.
Equilibrium
State of maximum stability.
A process is only spontaneous and can perfom work when it is moving toward equilibrium.
Systems with high G (free energy)
complex/organized/non-random
Systems with low G (fre energy)
disordered/random
Exergonic Reaction
Proceeds with a net release fo free energy and is spontaneous.
In a graph reactants are higher and products are lower in energy.
Exo - release
Endergonic Reactions
Absorbs free energy from its surroundings and is non-spontaneous.
Products have higher energy than reactants.
Exergonic and Endergonic reactions
- take place together
Reactions in a closed system & equilibrium
Reactions in a closed system eventually reach equilibrium and then do no work
Open systems
cells not in equilibrium
Is metabolism at equilibrium
NEVERRRR
Equilibrium and Metabolism
Energy from exergonic reactions are coupled with endergonic reactions
Biological Systems - Equilibrium and Metabolism
- open
- not at equilibrium
- metabolism never at equilibrium
Three kinds of cellular work
Chemical
Transport
Mechanical
To do work, cells manage energy resources by energy
coupling.
Enery Coupling powered by ATP.
Ecergonic reaction -deltaG coupled to endergonic reaction deltaG
Energy Currency of Cell is
ATP
The Structure and Hydrolysis of ATP
Bonds between the phosphate groups of ATP can be broken by
hydrolysis
3rd bond is average high energy bond
Free energy for work
The Regeneration of ATP
ATP is a renewable resource
This molecule is recycled over and over
Catalyst
A catalyst is a chemical agent that speeds up a
reaction without being consumed
An enzyme is a ______
catalytic protein
example of an
enzyme-catalyzed reaction
Hydrolysis of sucrose by sucrase
Energy Profile of an Exergonic Reaction
Every chemical reaction between
molecules involves bond breaking and bond forming.
Initial energy needed to start a chemical reaction is called free energy of activation.
How Enzymes Lower the EA Barrier
Enzymes catalyze reactions
by lowering EA barrier.
Enzymes do not affect
change in free energy (∆G)
substrate
The reactant that an enzyme acts on.
Enzymes bind with substrates to form a complex.
The substrate than an enzyme binds to, and therefore the reaction catalyzed by each enzyme, is very specific
Enzymes have an affinity for a specific substrate.
active site
region on an enzyme where the substrate binds
Induced fit
Induced fit of a substrate brings
chemical groups of active site into
positions that enhance their ability to catalyze reaction
Catalysis in the Enzyme’s Active Site
In an enzymatic reaction, the substrate binds to the active
site of the enzyme
Active site can lower an EA barrier by
Orienting substrates correctly
Strain bonds of substrates
Provide favorable microenvironment
Covelently bond w/substrates
The Active Site and Catalytic Cycle of an Enzyme
- Substrates enter active site; enzyme changes shape such that its active site enfolds the substrates (induced fit)
- substrates are held in active sites by weak interactions, such as hydrogen bonds and ionic bonds
- The active site lowers EA and speeds up teh rxn
- Substrates are converted to products
- products are released
- Active site is avaliablefor 2 new substrate molecules
