Enzymes

Question 1

what are enzymes?

Answer 1

globular proteins
biological catalysts

Question 2

what are reactions split into?

Answer 2

structure: enzymes form the biological molecule (anabolic reactions) that make up living tissue
e.g. production of collagen

function: enzymes break down biological molecules (catabolic reactions) that provide organisms with energy and building material
e.g. respiration

Question 3

what is a co-enzyme?

Answer 3

a non-protein substance that enhances the action of an enzyme.

-fits into the active site of the enzyme to active the whole enzyme and also allow the substate to fit into the new complementary active site

Question 4

what are the 2 type of enzymes?

Answer 4

Intracellular: enzymes that catalyse reactions within cells. e.g. catalyse
Extracellular: enzymes that catalyse reactions outside cells e.g.amylase and trypsin

All enzymes are proteins and so are made in the cells by protein synthesis

Question 5

type of enzyme: Helicase
-intra/ extracellular
-anabolic/catabolic
-what is does?

Answer 5

intracellular
catabolic
unzips gene - catalyses teh breaking of H+ bonds between nitrogeneous bases in DNA

Question 6

tyep of enzyme: Pepsin
intra/extracellular
anabolic/catabolic
what it does?

Answer 6

extracelular
catabolic
breaks down proteins- digests protein in the stomach of mammals

Question 7

type of enzyme: amylase
intra/extracellular
anabolic/catabolic
what it does?

Answer 7

extracellular
catabolic
converts starch (alpha glucose) to maltose (sugar)

Question 8

type of enzyme: ligase
intra/extracellular
anabolic/catabolic
what it does?

Answer 8

intracellular
anabolic
join together okazaki fragments of newly synthensized of DNA to form strand

Question 9

type of enzyme: lipase
intra/extracellular
anabolic/catabolic
what it does?

Answer 9

extracellular
catabolic
breaks down lipids in small intestines

Question 10

what is the lock and key model?

Answer 10

1) substrate binds to the enzyme’s active site, forming an enzyme-substrate complex (ES complex)
2) The enzyme converts the substrate into products, forming enzyme-product complex (EP complex)
3) The product is released from the enzyme’s active site. The enzyme retain its original shape

Question 11

what is the induced fit model?

Answer 11

1) the substrate enters the enzymes active site, forming an ES complex
2) the enzyme undergoes a conformational change which causes the conversion of substrate into product, forming an EP complex
3) The product is released from the enzymes active site. The enzyme retains its original shape (if pH or temp change), (if not saty same as product left it)

Question 12

what is metabolism?

Answer 12

the sum of all reactions in an organism

Question 13

what is activation energy?

Answer 13

For a reaction to occur, there must be a physical collision between the substrate and the active site- with suffient energy, this is called the activation energy
-enzymes lower the activation energy needed

Question 14

describe waht the graph of rate of reaction for pH, temp, substrate concentraion, enzyme concentration would look like?

Answer 14

pH - upside down U, optimum pH would be the peak of the U and the ends where it touches the x-axis is where it denatures
temp- gradually increases as there is more kinetic energy, reaches the optimum temp and then the line decreases rapidly (denatures)
Substrate concentration - gradual increase as more active site filled, then levels off as all active sites occupied
enzyme concentration - gradual increase as more active site available, then starts to level off as the substrate is limited

Question 15

what are co-factors?

Answer 15

co-factors are compounds which ehlp other molecules, e.g. co-enzymes and prosthetic group
-co enzymes= organic molecules and quite often bind loosely to the active site of an enzyme and aid in substrate recruitment
-Prosthetic groups= tightly bound amino acids which are permentantly attached to the enzyme aiding in enzyme activity

Question 16

enzyme factors:
how does temperature affect the rate of an enzyme controlled reaction?

Answer 16

As the temperature increases to the optimum, the substrate has more kinetic energy adn there would be more successful collisions with the enzyme, which would form an enzyme-substrate complex. This casues vibrations, from the increase in speed of the enzyme. If the temperature is above optimum (or below), the hydrogen bomnd in the teriary structure would be disrupted and then broken. Which casues the enzyme to denature: meaning the active site changes shape and is no longer complementary to it’s substrate

more collision=more bonds broken

Question 17

what is the temperature co-efficient (Q10)?

Answer 17

the co-efficient shows how much the rate changes whenever the temperature of the reaction increases by 10 degrees.
the enzyme becomes denatured above the optimal temperature
- too much vibrations - active site to change

equation:
Q10= rate at higher temperature / rate at lower temperature

Question 18

what is the effect of pH on enzymes?

Answer 18

-pH is the measure of potential of hydrogen ions (H+). The higher the concentration of hydrogen ions the lower the pH.
-Each enzyme has no optimum pH, because the tertiary structure is held in place by different bonds
-H+ ions interfere with the hydrogen bonds and ionic bonds holding the tertiary structure in place and therefore teh shape of the active site
-Both increasing and decreasing H+ concentration will alter the tertiary structure and therefore rate of reaction

Question 19

Remembering the Substrate concentration adn enzyme concentration graphs, what is happening in them?

Answer 19

-At soem point a ‘satuation’ point is reached where all of the enzyme’s active sites are occupied with substrate molecules
-At this point, the reaction is proceeding as fast as possible, which is referred to a Vmax
-This is the same for enzyme concentration

Question 20

what are the Pros and Cons of the lock and key model?

Answer 20

Pros = explains most enzymes display such high specificity to their substrate. simplistic in understanding
Cons = doesn’t show thta some enzymes bind to a variety of substances. can’t explain how to catalysis actually occurs

Question 21

what are the Pros and Cons for the induced fit model?

Answer 21

Pros = shows that an enzymes can bind to a variety of substances. can explain how catalysis actually occurs
Cons = doesn’t show how most enzymes have a high specificity to just one substrate. unproven model

Question 22

what are the inhibitors?

Answer 22

Competitive inhibitor = a substrate taht mimics the original substrate so they are structually and chemically similar
Non-competitive inhibitor = it binds to the allosteric site (outide of the enzyme) causing a conformational change to active site

Question 23

what is the end-product inhibitation?

Answer 23

End-product inhibitation (or feedback inhibitation) is a form of negative feedback by which metabolic pathways can be controlled.
The final product binds to an allosteric site (outside of an enymze site) of the first enzyme and temporarily inactivates the enzyme chain.