Chapter Eight Flashcards
What is metabolism?
all of an organisms chemicall reactions
What is anabolic metabolism?
small molecules build into larger ones; energy requires
(e.g., photosynthesis)
What is catabolic metabolism?
large molecules broken into smaller ones; energy released
(e.g., cellular respiration)
What are the 3 main types of energy?
- light (radiation)
- kinetic
- thermal
- potential
- kinetic
What is kinetic energy?
energy assosciated with motion
What is thermal energy?
kinetic energy assosciated with the random movement of atoms of objects
Chemical energy is a type of _______ energy; what is it?
potential energy available for release in a chemical reaction
What is potential energy?
stored energy based on an objects location or structure
What is the 1st law of thermodynamics?
- total amount of energy in the universe is constant and conserved
- energy is not created or destroyed
- energy can be transferredd or change forms
What is the 2nd law of thermodynamics?
- every energy transfer increases entropy (disorder) of the universe; randomness of matter increases
- energy willl always be last from a system as heat in energy transfers or transforms
Spontaneous reactions…
- need initial nudge of energy
- proceeds without energy input
- not necessarily fast
Non-spontaneous reactions…
- need inital nudge of energy
- needs energy to continue
- slow reactions
Change in ____ ______ determines if a reaction is spontaneous or not
free energy
What change in free energy results in a spontaneous reaction?
negative ΔG
What change in free energy results in a non-spontaneous reaction?
0 or positive ΔG
What are exergonic reactions?
spontaneous reactions; energy outward, net release of energy
What are endergonic reactions?
- non-spontaneous reactions; energy inward, absorbs free energy from surroundings
- energy reequired
What happens to a cell if it has a net change in free energy of 0?
it has reached equilibrium; cell has died
What are the 3 kinds of work cells do?
- chemical
- transport
- mechanical
What is chemical work?
pushing endergonic reactions that would not occur spontaneously
What is transport work?
moving substances against gradients
What is mechanical work?
largely motion/ movement
What is energy coupling? What molecule is responsible?
using an exergonic reaction to drive an endergonic one; ATP
What are the main components of ATP?
- ribose (a sugar)
- nitrogenous base (adenine)
- chain of 3 phosphate groups
Why is ATP unstable?
the phosphate groups are easily broken
What happens with ATP for cells to do work?
the unstable bond between phosphate groups is broken via hydrolysis to release energy
How is ATP regenerated?
with the free energy of other exergonic (catabolic) reactions
What is activation energy?
energy required to initiate a reaction
What do catalysts do to reactions?
lower activation energy
_______ are catalysts
enzymes
How do enzymes lower activation energy?
- change orientation of substance
- substrate stretched to make breaking bondds easier
- active site may provide a local micro environment that favors the reaction
- amino acids in the active site participate in the reactions, but they are not changed
What are cofactors?
helper molecules that assist with the catalytic activity
What do inhibitors do?
inhibit or slow enzyme activity
What are the 2 types of inhibitors?
- competitive inhibitors: bond with the enzyme and block substrate from reaching the active site (positive)
- non-competitive inhibitors: don’t compete w/ substrate for active site; bound to other areas of the enzyme and change its shape (negative)
We often use negative inhibitors as a means of…?
poisoning other organisms
What happens in feedback inhibition?
What sfinal product shuts down the pathway temporarily; prevent wasting resources by making more than is needed
What is allosteric activation and inhibition?
- polypeptite subunit each with an active site
- complex has an active site and inactive shape
- activating molecule binds to the complex stabilizing the active form
- inhibitors bind to the complex stabilizing the inactive form
What is cooperactivity?
substrate bound to one active site stabilizes other active sites in their active form
