chapter 8- metabolism Flashcards
how does the cell get energy and how does it use it
it extracts the energy stored in sugars and other energy containing molecules and applies energy to perform work
what is metabolism
totality of an organisms chemical reactions/interactions between molecules within the cell
how do metabolic pathways work
they begin with a specific molecule called substrate/reactant and end with product
each step is catalyzed by a specific enzyme
what is a catabolic pathway and example
it releases energy by breaking down complex molecules into simpler compounds
cellular respiration
what is an anabolic pathways
consumes energy to build complex molecules from simpler ones
synthesis of proteins
what is bioenergetics
the study of how organisms manage their energy resources
what is energy
capacity to cause change
types of energy
kinetic (motion)
heat (movement)
potential (location)
chemical (available to release)
what is thermodynamics
study of energy transformation
difference between isolated and open system
isolated cant exchange energy or matter with environment
open can exchange with environment
are organisms open or closed systems
open
what is the first law of thermodynamics
energy cant be created or destroyed
what is the second law of thermodynamics
energy transfer/transformation increases entropy of universe
do spontaneous processes occur with or without energy
without energy
if a process occurs without energy input what does it increase
entropy of universe
what does the cell do when it has less ordered materials
creates ordered structures
requires energy input
what does an organism do with ordered forms of matter and energy
replaces them with less ordered forms
what is free energy
delta G
energy that can do work when the temperature and pressure are uniform (cell env.)
what is the formula for free energy
delta G = delta H - (T)(delta S)
delta H: enthalpy
delta S: entropy
T is in kelvins
what happens during a spontaneous process regarding free energy and stability
delta G must be negative
stability of system increases (moving towards eq)
how is free energy related to stability
free energy is a measure of a system’s instability and its tendency to change to a more stable state
what is the state of maximum stability
equilibrium
what is an exergonic reaction
reaction with a net release of free energy
spontaneous
what is an endergonic reaction
reaction that absorbs free energy from surrounding
nonspontaneous
does metabolism ever reach equilibrium
no, open systems have a constant flow of energy and matter
what are the three kinds of cellular work
chemical
transport
mechanical
how do cells manage energy resources
energy coupling
what is energy coupling
using an exergonic process to drive an endergonic one
when atp is broken down what causes the release of energy
comes from the chemical change to a state of lower energy
what kind of reaction is atp hydrolysis
exergonic and can be used to drive an endergonic reaction
how does atp drive endergonic reactions
by phosphorylation
what is the molecule receiving a phosphate now called
phosphorylated intermediate
how is atp regenerated
using adp and energy released from catabolic/exergonic reactions
what is a catalyst and example
chemical agent that speeds up reaction and is not consumed
enzymes are catalysts
what is the activation energy/free energy of activation
energy required to start a chemical reaction
how do catalytic enzymes affect reactions
lower EA barrier
dont affect change in free energy, only speed up reactions that would eventually occur
when the enzyme binds to the substrate what is formed
enzyme-substrate complex
what is an active site
region on enzyme where substrate binds
what is the induced fit of a substrate
enzyme changing shape to better fit around substrate
what does the induced fit do
brings chemical groups of active site into positions that enhance their ability to catalyze the reaction
how does the active site lower the EA barrier
orients substrates correctly
strains bonds in substrate
provides favourable microenvironment
covalently bonds to substrate
enzyme activity is affected by
environmental factors (temp, pH)
chemicals that affect that specific enzyme
in which conditions does the enzyme work best
conditions that favour the most active shape
specific pH
what are cofactors
nonprotein enzyme helpers
inorganic or organic (coenzyme)
can be vitamins
what is a competitive inhibitor
binds to active site
competes with substrate
what is a noncompetitive inhibitor
doesnt bind to active site but causes a change in shape making active site less effective
inhibitors example
toxins
poisons
pesticides
antibiotics
what does a cell do to regulate metabolism
switches genes that code for specific enzymes on/off
regulating enzyme activity
what is allosteric regulation
either inhibiting or stimulating an enzyme’s activity
when does allosteric regulation happen
what a regulatory molecule binds to a protein at one site but affects the proteins functions at a different site
how does the binding of an activator vs inhibitor affect the enzyme
the activator stabilizes the active form of the enzyme
the inhibitor stabilizes the inactive form of the enzyme
what is cooperativity
form of allosteric regulation that can amplify the enzymes activity
what happens in feedback inhibition
the end product of a metabolic pathway shuts down the pathway
are enzymes located in specific areas of cell
yes
enzymes that act as structural components are in membranes
enzymes for cellular respiration are in the mitochondria
