Exam 2 - BIO13100

Endergonic reaction

results in increase of free energy; spontaneous

Exergonic reaction

results in decrease of free energy; non-spontaneous

Enzyme

a protein that acts as a catalyst

Active site

reactants encounter each other in the correct orientation, bonds are being broken & stabilized with specific r-groups (activation threshold goes down)

How do enzymes affect reactions?

speeds up

do enzymes affect the amount of free energy in reactants/products

no

If an amino acid near or in the active site changes…

an enzyme’s ability to catalyze a reaction will likely change

Activation energy

the amount of energy required to get a chemical reaction through its transition state

Herbivore

plant-eating animal

Pathogen

any agent that causes disease

Cell

membrane-bound structures that form the fundamental unit of life

Stomata

regulated openings in leaves where gas exchange occurs

Fitness trade-off

conflict between maximizing fitness and the fitness cost in aspects of one or more traits

Plasticity

the ability of the same genotype to produce different phenotypes (different environmental conditions)

Entropy

tendency of systems to reach a state of higher disorder or randomness

Concentration gradient

difference in a substance’s concentration across a cell membrane

Potential energy

energy of position

Electrical energy

energy in the movement of charged ions

Energy

the ability to do work

facilitated diffusion

diffusion of substances across cell membranes through integral membrane proteins

Diffusion

movement of ions/molecules from an area of higher concentration to an area of lower concentration

Passive transport

movement of ions/molecules that don’t require an input of energy

Active transport

movement of ions/molecules that requires an input of energy

Channel

an integral membrane protein that acts as a tunnel for a specific ion to cross membrane passively

Carrier

integral membrane protein that transports specific molecule across membrane passively (changes shape)

Pump

integral membrane protein that transports ion/molecule across membrane actively (against gradient)

Thermal energy

energy of motion in ions/molecules, measured as temp

Energetic coupling

phosphorylation reaction that makes a nonspontaneous reaction spontaneous (raises free energy of reactants)

Sink

the location where a substance is used or stored

Dormancy

a period without growth, conditions too bad to support photosynthesis

Proton pump

membrane transport protein that actively transfers protons against electrochemical gradient

Co-transport

transport of 2 substances across cell membrane by membrane protein (one down gradient, other against)

Mycorrhizal fungi

Fungi that live with plant roots and exchange nutrients for sugar

Xylem

water-conducting plant tissue

Phloem

sugar-conducting tissue

Bulk flow

movement of substances from areas of high pressure to low pressure