Energy, Metabolism, Enzymes

Question 1

All living organisms…

Answer 1

require constant input of energy

Question 2

What laws control energy transformations?

Answer 2

the laws of thermodynamics

Question 3

first law of thermodynamics

Answer 3

energy cannot be created nor destroyed, only transformed

(law of conservation of energy)

Question 4

second law of thermodynamics

Answer 4

universe becomes more disordered during energy conversions

entropy increases

Question 5

Gibb’s free energy (G)

Answer 5

calculated to determine free energy available

Question 6

exergonic/exothermic reaction

Answer 6

term used when energy is released in a reaction

∆G is negative

Question 7

endergonic/endothermic

Answer 7

term used when energy is absorbed in a reaction

∆G is positive

exergonic reactions power endergonic reactions

Question 8

metabolism

Answer 8

sum of all chemical reactions in cells
metabolic reactions take place in multipstep pathways controlled by enzymes and help cells carry out chemical activities

Question 9

catabolism

Answer 9

when reactions break down molecules

Question 10

anabolism

Answer 10

when reactions build up molecules

Question 11

enzyme-controlled reactions

Answer 11

• enzymes do not provide energy for reaction, does not cause a reaction
• enzymes are catalytic proteins that speed up reactions by lowering energy of activation (Ea)

Question 12

transition state

Answer 12

reactive (unstable) condition of substrate after enough energy

Question 13

characteristics of enzymes

Answer 13

• gloublar proteins that exhibit tertiary structure
• are substrate specific (only specific substrates will bind)
• induced-fit model describes how enzymes work (as substrate enters active site, enzyme will alter its shape so substrate fits
• binds to substrate(s), forming enzyme-substrate complex
• are reused
• enzymes named after substrate with the suffix “ase”
• can catalyze reactions in both directions
• often require assistance from cofactors (inorganic) or coenzymes (vitamins)
• efficiency affected by temperature and pH

Question 14

inhibition of enzymatic reactions

Answer 14

metabolism regulated by controlling when and where enzymes are active

by controlling genes that code enzymes or by regulating existing enzymes

existing enzymes are regulated by competitive or noncompetitive inhibition

Question 15

competitive inhibition

Answer 15

otherw compounds resemble substrate molecules and compete for same active site on enzyme, can be overcome by increasing concentration of substrate

Question 16

noncompetitive inhibition

Answer 16

some enzymes allosteric (change in shape alters efficiency), molecules called noncompetitive inhibitors or allosteric regulators binds to another distinc site to change the shape of the enzyme

Question 17

feedback inhibition

Answer 17

form of allosteric regulator, it is when the end product is the regulator of the enzyme that catalyzes in an early stage of the pathway

Question 18

cooperativity

Answer 18

type of allosteric activation

substrate molecule binds to one active site of one subunit to cause change in the entire molecule and locks all subunits in active position