bio 109- CHAPTER 6- enzymes and energy

endothermic

energy of products > substrates (net energy input)

products have more energy than substrates

potential energy is higher disorder is lower

exothermic

energy of substrates > products (net energy output)

products have less energy than substrates

potential energy is lower disorder is higher

will happen on their own (may require activation energy)

anabolic

substrates built up into larger molecules

catabolic

substrates broken down into smaller molecules

activation energy

energy required to start an exothermic reaction

destabilize existing bonds (ex gas in a car)

reaction speed depends on energy in the system

lower activation energy = more kinetic energy left for reaction

enzyme

biological catalyst (usually a protein, some are RNA)

most are proteins (some are RNA)

shape of active site determine function

what do chemical reactions involve

forming or breaking chemical bonds

substrates (reactants)

molecules at start of reaction

products

molecules at end of the reaction

what is the first law of thermodynamics

energy cannot be created or destroyed

total amount of energy in the universe remains constant

only changes between kinetic and potential

during each conversion some energy given off as heat (kinetic energy)

what is the second law of thermodynamics

disorder (entropy) is continuously increasing

matter breaks to release energy

metabolism

total of all chemical reactions in an organism

anabolic reactions

use energy to build bigger molecules

catabolic reactions

release energy by breaking down molecules

what can exothermic reaction speed be increased by

1) increasing kinetic energy (heating)

2) decreasing activation energy (catalyst)

what are the three things speed of reaction is influenced by

1) temperature (more collisions between substrates)

2) concentration of substrates and products (mass action)

3) catalysts

catalysts

stress bonds or increase meeting of substrates

low activation energy = high kinetic energy = high speed of reaction

does not alter the amount of product

biochemical pathways

multiple reactions occur in a sequence

product of one reaction is substrate for the nect

promity = efficiency

reedback inhibition

products of pathway binds to an allosteric site on first enzyme

shuts down pathway so raw materials and energy are not wasted