unit 3 (topics 1-4)

Question 1

metabolism

Answer 1

all of the chemical reactions in an organism

Question 1

metabolic pathways

Answer 1

series of chemical reactions that either build up (anabolic)/break down (catabolic) complex molecules

Question 2

catabolic pathway

Answer 2

pathways that release energy by breaking down complex molecules into simpler ones

Question 3

anabolic pathway

Answer 3

pathways that consume energy to build complicated molecules from simpler ones

Question 4

energy

Answer 4

ability to do work

Question 5

kinetic energy

Answer 5

energy associated with motion (thermal energy)

Question 6

potential energy

Answer 6

stored energy (chemical energy)

Question 7

law of thermodynamics

Answer 7

the study of energy transformations in matter; two laws

Question 8

1st law of thermodynamics

Answer 8

-energy cant be created or destroyed
-energy can be transferred or transformed

Question 9

2nd law of thermodynamics

Answer 9

-energy transformation increases the entropy (disorder) of the universe
-during energy transfers/transformations, some energy is unusable and often lost as heat

Question 10

free energy

Answer 10

used to determine the likelihood of reactions in an organism (if they’re spontaneous or not), or if the reactions are energetically favorable

change in free energy = change in total energy-change in entropy

🔺G = 🔺H - T🔺S

Question 11

exergonic reaction

Answer 11

• reactions that release energy (cellular respiration)
  -🔺G<0 (negative G)
• spontaneous
• drive endergonic reactions

Question 12

endergonic reaction

Answer 12

• reactions that absorb energy (photosynthesis)
• 🔺G>0 (positive G)
• not spontaneous

Question 13

ATP

Answer 13

• molecules use this as a source of energy to preform work
• couples exer/endergonic reactions to power cellular work
• organisms obtain energy by breaking the bond between the 2nd and 3rd phosphate in a hydrolysis reaction (phosphorylation: released phosphate moves to another molecule to give energy)

Question 14

cells three kinds of work

Answer 14

MECHANICAL: movement (contraction of muscle cell, beating cilia, etc.)
TRANSPORT: pumping substances across membranes against spontaneous movement
CHEMICAL: synthesis of molecules (building polymers from monomers)

Question 15

enzymes

Answer 15

• macromolecules (type of protein) that catalyze reactions by lowering the activation energy
• are not consumed by the reaction

Question 16

enzyme structure/function

active site
allosteric site
induced fit
enzyme catabolism
enzyme anabolism
cofactors
coenzymes
inhibitors (permanent and reversable)

Answer 16

ACTIVE SITE: where enzyme binds to substrate
ALLOSTERIC SITE: where non-competitive enzymes go
INDUCED FIT: enzymes will change shape of active site to make substrates bind better
ENZYME CATABOLISM: enzyme helps break down complex molecules
ENZYME ANABOLISM: enzyme helps build complex molecules
COFACTORS: non-protein molecules that assist enzyme function (holoenzyme)
COENZYMES: organic cofactors
INHIBITORS: reduce activity of specific enzymes
–>PERMANENT: inhibitor binds with covalent bonds
–> REVERSIBLE: inhibitor binds with weak interactions

Question 17

allosteric activator

Answer 17

substrate binds to the allosteric site and stabilizes the shape of the enzyme so that the active sites remain open

Question 18

allosteric inhibitor

Answer 18

substrate binds to allosteric site and stabilizes the enzyme shape so the active sites are closed (inactive form)

Question 19

cooperativity

Answer 19

substrate binds to one active site (on an enzyme with more than one active site) which stabilizes the active form

Question 20

feedback inhibition

Answer 20

sometimes, the end product of a metabolic pathway can act as an inhibitor to an early enzyme in the same pathway