Chapter 8 Flashcards
what does an organisms metabolism do?
an organisms metabolism transforms matter and energy
what is metabolism?
the totality of an organism’s chemical reactions, an emergent property of life that arises from orderly interactions between molecules
how does a metabolic pathway begin and end and what happens each step?
begins with a specific molecule and ends with a product, is catalyzed for every step by a specific enzyme
what are catabolic pathways?
catabolic pathways release energy by breaking down complex molecules into simple compounds
what is an example of catabolism?
cellular respiration: the breakdown of glucose in the presence of oxygen
what is an anabolic pathway?
anabolic pathways consume energy to build complex molecules from simpler ones
what is an example of an anabolic pathway?
synthesis of protein from amino acids
define energy
energy is the capacity to cause change and exists in various forms
what is thermal energy (heat)
kinetic energy associated with random movement of atoms or molecules
what is thermodynamics?
the study of energy transformations
what happens in an isolated system?
an isolated system is unable to exchange energy with surroundings
what happens in an open system?
energy and matter can be transferred between a system and its surroundings
first law of thermodynamics?
energy of the universe is constant, cannot be created or destroyed
second law of thermodynamics?
during every energy transfer, some energy is unusable and is lost as heat; it increases the entropy (disorder) of the universe
what are spontaneous processes?
spontaneous process dont require energy and can happen quick or slow, they increase entropy of the universe
what tells us whether a reaction is spontaneous or not?
free energy change
what is free energy change Change in G
a living systems free energy is energy that can do work when temperature and pressure are uniform
which processes have a negative G?
spontaneous processes have a negative G
what is free energy a measure of?
free energy is a measure of a systems instability, its tendency to change to a more stable state
free energy in a spontaneous change?
during a spontaneous change, free energy decreases and stability of a system increases
define exergonic reaction
an exergonic reaction proceeds with a net release of free energy and is spontaneous
define endergonic reaction
an endergonic reaction absorbs free energy from it surroundings and is nonspontaneous
group words together with spontaneous
a spontaneous reaction doesn’t require energy, it is catabolic because catabolic reactions lose energy, they are exergonic because they release free energy, a release of free energy means a -G
group words together with nonspontaneous
nonspontaneous reactions require energy, anabolic reactions need energy, they are endergonic because it takes in energy which results in a +G
are cells in equilibrium?
no because they are open systems and constantly experience a flow of materials
what types of work do cells do?
chemical, transport, mechanical
what is energy coupling?
cells managing energy resources by energy coupling, the use of an exergonic process to drive an endergonic one
what is ATP
ATP is the cell’s energy chuttle
what is ATP made of?
ATP is made of a ribose (a sugar), adenine (a nitrogenous base), and 3 phosphate groups
when is energy released from ATP?
energy is released from ATP when the terminal phosphate bond is broken
what does ATP hydrolysis lead to?
ATP hydrolysis leads to a change in protein shape and binding ability
How do enzymes speed up metabolic reactions?
enzymes speed up metabolic reactions by lowering energy barriers
what is a catalyst
a chemical agent that speeds up a reaction without being consumed by the reaction
what is an enzyme
an enzyme is a catalytic protein
What is activation energy?
The initial energy needed to start a chemical reaction is called the free energy of activation
what is activation energy often supplied in the form of?
activation energy is often supplied in the form of thermal energy that reactant molecules absorb from their surroundings
How do enzymes speed up reactions?
enzymes catalyze reactions by lowering the activation energy barrier
do enzymes affect the change in free energy?
no, they just hasten reactions that would have already occurred
What is a substrate?
a substrate is the reactant that an enzyme acts on
What is an enzyme-substrate complex
when the enzyme binds to its substrate
what is the active site?
the active site is the region on the enzyme where the substrate binds
what is induced fit?
induced fit of a substrate brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
how can the active site lower the activation energy barrier?
by orienting substrates correctly, straining substrate bonds, providing a favorable microenvironment, and covalently bonding to the substrate
What can affect an enzymes activity?
environmental factors such as temperature and pH
what do optimal conditions do?
optimal conditions favor the most active shape for the enzyme molecule
what are cofactors?
cofactors are nonprotein enzyme helpers
what are competitive inhibitors?
competitive inhibitors bind to the active site of an enzyme and compete with a substrate
what are noncompetitive inhibitors?
they bind to another part of the enzyme, causing the enzyme to change shape and making the active site less effective
what is allosteric regulation?
allosteric regulation may either inhibit or stimulate an enzyme’s activity
when does allosteric regulation occur?
it occurs when a regulatory molecule binds to a protein at one site and affects the proteins function at another site
what are allosterically regulated enzymes made from?
made from polypeptide subunits
what does binding an activator do?
stabilizes the active form of the enzyme
what does binding an inhibtor do?
binding an inhibitor stabilizes the inactive form of the enzyme
what is cooperativity?
a type of allosteric regulation that can amplify enzyme activity
