L10-11: Bioenergetics + Enzymes

Question 1

Biological work: Synthetic

Answer 1

changes in chemical bonds

ex. formation of new chemical bonds/ synthesis of new molecules

Question 2

Biological work: mechanical

Answer 2

changes in the location/ orientation of a cell or subcellular structure

ex. physical change in position/orientation of cell
(movement of organelles/ vesicles along microtubules)

Question 3

Biological work: concentration

Answer 3

movement of molecules across a membrane against a concentration gradient (low->high)

ex. the accumulation of digestive enzymes into secretory vesicles to be released as food is digested

Question 4

biological work: Electrical

Answer 4

movement of ions across a membrane against electrochemical gradient

ex. ions are transported->a charged difference in the membrane
(the difference of H+ in mitochondria/chloroplast membrane for atp/ pumping Na+ & K+ in/out

Question 5

biological work: heat

Answer 5

a useful increase in temperature

ex. homeotherm (self-regulate heat)

Question 6

biological work: bioluminescence

Answer 6

production of light
-aka fluorescence: the production of light following absorption of light of a shorter wavelength

ex. using atp/ chemical oxidation
fireflies, jellyfish, mushrooms

Question 7

First Law of Thermodynamics

Answer 7

in every physical/ chemical change, energy in the universe is constant
*Although the form may change, but energy can never be replaced/ destroyed

Question 8

Second Law of Thermodynamics

Answer 8

the entropy of the universe increase= the capacity of a sys. to do work and will decrease

h= g+ ts

h: total energy
g: free energy (available to do work)
s: entropy (a measure of chaos, not available to do work)
t: temperature in degrees (K)

Question 9

activation energy

Answer 9

the energy required to break bonds and start a reaction
*biological systems are metastable because of this

Question 10

-G

Answer 10

energy available to do work

Question 11

+G

Answer 11

energy not available to do work

Question 12

exergonic

Answer 12

exergy is EXited/ released

reactants: more energy
products: less energy

G<0

example: ATP-> ADP+Pi (hydrolysis)

Question 13

endergonic

Answer 13

energy is ENtered/ consumed

reactants: less energy
products: more energy

G>0

example: ADP+Pi-> ATP (regeneration)

Question 14

what is the energy level in catalyzed reactions?

Answer 14

an uncatalyzed reaction requires a HIGHER activation energy than a catalyzed reaction
-no difference in free energy

Question 15

absolute energy

Answer 15

atp hydrolysis

start:
ATP
H=G(high) + TS (low)
-G

End:
ADP+Pi
H=G(low) + TS (high)
+G

Question 16

Keq

Answer 16

the ratio of product concentrations to reactant concentration of equilibrium

Question 17

Protein folding

Answer 17

folding: -G (spontaneously)
unfolding: +G (require energy to unfold as it is not spontaneous)

Question 18

Eduard Buchner

Answer 18

in 1897
discovered that yeast extracts could ferment sugar to alcohol
fermentation is promoted by molecules that continued to function when removed from cells

Question 19

James Summer

Answer 19

1926
isolated & crystalized protein-> crystals only contain proteins= all enzymes are proteins

Question 20

JBS Haldane

Answer 20

1930s
weak bonding interactions between an enzyme and its substrate might be used to catalyze a reaction

Question 21

enzymes

Answer 21

catalysts in biological systems
proteins

ex. ritonavir inhibits HIV protease where it stops viruses from replicating

Question 22

transition energy

Answer 22

reactant needs to reach this stage, where the reactants hs free energy higher than the products
=not stable because reactant molecules don’t stay there for long

Question 23

thermal activation

Answer 23

increases average energy of all molecules

Question 24

catalyst

Answer 24

an agent that enhances the rate of the reaction by lowering the activation energy

Question 25

characteristics of enzymes

Answer 25

group specific
substrate specific
remain unchanged unless denatured

Question 26

induced fit model

Answer 26

a substrate binds to an active site and both change shape slightly, creating an ideal fit for catalysis

ex. hexokinase & D glucose

Question 27

monkeys and peanuts

Answer 27

monkey: enzymes
substrate: peanuts
products: the shells & the inside

Question 28

reaction rates

Answer 28

The rate of an enzyme-catalyzed reaction increases with an increase in the concentration of an enzyme.

Question 29

maximum velocity

Answer 29

levels off because enzymes are limited where there is a higher substrate concentration

Question 30

types of enzymes regulations

Answer 30

1. feedback inhibition
2. allosteric regulation
3. covalent modifications

Question 31

feedback inhibition

Answer 31

an enzyme’s activity is inhibited by the enzyme’s end product.

Question 32

competitive inhibition

Answer 32

the inhibitor binds to the active site
=competes w/ substrate for binding= no products

Question 33

noncompetitive inhibition

Answer 33

the inhibitor binds to another site of the enzyme, but distort products
substrate is able to bind to the active site but does not produce products

Question 34

allosteric inhibition

Answer 34

enzyme is active
->inhibitor binds to the allosteric site, changes the shape of an enzyme
->substrate cannot bind=no products
enzyme is inactive

Question 35

allosteric activation

Answer 35

enzyme is inactive
->activator binds to the allosteric site, changes the shape of an enzymes
->substrate can bind= product formation
enzyme is active

Question 36

phosphorylation

Answer 36

adding a phosphate group

Question 37

dephosphorylation

Answer 37

removing a phosphate group

Question 38

proteolytic cleavage

Answer 38

some enzymes are precursors, where the cleavage is removed to become functional