LECTURE 7 - Enzymes and thermodynamics

Question 1

energy

Answer 1

capacity to do work

potential : stored in chemical bonds/interactioms

kinetic : energy expressed as movement such as heat/radiant energy

Question 2

bioenergetics

Answer 2

the transfer of potential to kinetic energy and back (in living systems)

Question 3

entropy

Answer 3

measure of disorder

Question 4

first law

Answer 4

energy can neither be created nor destroyed but it can be transformed

Question 5

second law

Answer 5

entropy of the universe is increasing
(things are always trying to get to the higher entropy state)

Question 6

thermodynamics

Answer 6

substrate(s) –> product(p)
if lower : exergonic, giving out energy
if higher : endergonic, absorbing energy
when S > P, exergonic
when S < p, endergonic

Question 7

diff between endergonic/exergonic and endothermic/exothermics

Answer 7

all gonics are thermics
gonics mean the change in energy
thermics mean the change in heat/enthalpy

Question 8

activation barriers

Answer 8

high activation barriers causes resistance, reaction will happen less quickly

low activation barrier means larger fraction of S moleclues to have enough energy to get over the barrier
vice versa (vv)

Question 9

catalysts

Answer 9

alternate pathway –> lower Ea for faster reaction rate.greater proportion of suubstrate molecules have sufficient energy to react and occur in successful collisions
enzymes : biological catalysts

Question 10

how do enzymes lower transition state energy

Answer 10

transition state energy (activation energy)
E + S –> ES –> ES –> E + P
ES : enzyme-substrate complex
ES : enzyme-transition state complex

Enzymes lower the transition state energy (activation energy) of a chemical reaction by stabilizing the transition state, which is the high-energy, unstable intermediate state between the substrate (S) and the product (P) in the reaction. By stabilizing the transition state and facilitating the reaction steps, enzymes effectively lower the energy barrier (activation energy) required for the reaction to proceed. This means that a larger fraction of substrate molecules will have enough energy to cross the transition state, resulting in a faster reaction rate.

Question 11

enzyme bidning models

Answer 11

lock and key model : fits directly, highly specific, rigid, pre-defined fit
induced-fit model : S induces a shape change –> substrate binding induces a shape change in the active site to accommodate the substrate –> both the enzyme and substrate undergo slightstructural adjustments during binding –> ideal fit for catalysis
selection model : enzyme exists in mulitple forms, and only one of them binds with Substrate A

Question 12

cofactor

Answer 12

e.g metal ions/organic substances etc that binds to enzymes for optimal activity

Question 13

inhibitor

Answer 13

competitive : binds to active site
allosteric : binds to allosteric site and stops enzyme

Question 14

enzyme pathways

Answer 14

are sequences of enzymatic reactions that work together to achieve specific cellular functions, such as metabolism, synthesis of cellular materials, and signaling between cells

Mutations can have various effects on enzyme pathways
e.g. reduce activity/ change specificty/ increase activity/cause disease

Question 15

enzyme location

Answer 15

enzymes in the wrong place can cause problmes

–> Cardiac enzymes suchas lactate dehydrogenase (LDH)(LDH) that are typically within the cells of the heart muscle (cardiomyocytes) in the blood stream

can indicate a recent heart attack

Question 16

rate of reaction

Answer 16

rate of reaction is change in product (dP) over change in time (dt)
–> dP/dt