Enzymes Flashcards

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1
Q

what are enzymes?

A

globular proteins
biological catalysts

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2
Q

what are reactions split into?

A

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

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3
Q

what is a co-enzyme?

A

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

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4
Q

what are the 2 type of enzymes?

A

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

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5
Q

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

A

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

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6
Q

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

A

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

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7
Q

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

A

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

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8
Q

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

A

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

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9
Q

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

A

extracellular
catabolic
breaks down lipids in small intestines

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10
Q

what is the lock and key model?

A

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

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11
Q

what is the induced fit model?

A

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)

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12
Q

what is metabolism?

A

the sum of all reactions in an organism

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13
Q

what is activation energy?

A

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

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14
Q

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

A

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

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15
Q

what are co-factors?

A

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

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16
Q

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

A

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

17
Q

what is the temperature co-efficient (Q10)?

A

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

18
Q

what is the effect of pH on enzymes?

A

-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

19
Q

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

A

-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

20
Q

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

A

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

21
Q

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

A

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

22
Q

what are the inhibitors?

A

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

23
Q

what is the end-product inhibitation?

A

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.