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Biology Hope > Enzymes > Flashcards

Enzymes Flashcards

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1
Q

What are enzymes ?

A
  • biological catalysts
  • globular proteins
  • speed up chemical reactions without being used up
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2
Q

What are anabolic reactions ?

A

building of molecules

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3
Q

What are catabolic reactions ?

A

breaking of molecules

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4
Q

What is the lock and key hypothesis ?

A
  • only a specific substrate will fit into the active site
  • forms an enzyme-substrate complex
  • substrate reacts and products are formed
  • enzyme- product complex
  • products are released
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5
Q

What is the induced fit hypothesis ?

A
  • active site slightly changes to fit the substrate
  • weaken the bonds in the substrate and lowers the activation energy
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6
Q

What is activation energy ?

A

the amount of energy that needs to be supplied to chemicals before the reaction will start

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7
Q

How does the formation of the enzyme substrate complex lower the activation energy ?

A
  • ## when catalysing a breakdown reaction the substrate fitting into the active site puts a strain on the bonds and the substrate can break more easily
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8
Q

What are intracellular enzymes ?

A
  • enzymes that act within cells
  • catalase breaks down harmful hydrogen peroxide into water and oxygen
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9
Q

What are extracellular enzymes ?

A
  • secreted by cells and catalyse reactions outside of cells
  • digestion of proteins and starch
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10
Q

How is starch digested ?

A
  • starch is broken down into maltose by amylase
  • maltose is broken down into glucose by maltase
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11
Q

How are proteins digested ?

A

-trypsin catalyses the digestion of proteins into smaller peptides
- trypsin is produced in the pancreas and released with pancreatic juice

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12
Q

what is the effect of temperature on enzymes

A
  • increasing temperature increases kinetic energy and the particles move faster and collide frequently
  • more frequent collisions between the substrate and enzyme
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13
Q

Enzyme denaturation from temperature

A
  • increasing temperature increases vibrations until the bonds strain and break
  • breaking of the bonds changes the tertiary structure
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14
Q

Enzymes and optimum temperature

A
  • temperature at which the enzyme has the highest rate of activity
  • once denaturation occurs the decrease in the rate of reaction is rapid
  • decrease in the rate of reaction below the optimum is less rapid as the enzyme is less active
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15
Q

what is temperature coefficient

A
  • measure of hoe much the rate of reaction increase with 10 degrees
  • rate of reaction doubles with a 10 degree increase
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16
Q

what is the effect of pH on enzymes

A
  • when pH changes from the optimum causes denaturation and a change in shape
  • renaturation - pH returns to the optimum
  • more hydrogen bonds (low pH) the R-groups interact less and bonds break and changes shape
  • shape of the enzyme changes as pH changes
  • only functions within a narrow pH range
17
Q

what is the effect of enzyme concentration

A
  • higher the concentration the greater number of active sites available and greater likelihood of an enzyme substrate complex formation
  • sufficient amount of substrate available the initial rate of reaction increases linearly
  • limited amount of substrate any further increase in enzyme concentration won’t increase the reaction rate
18
Q

what is the effect of enzyme concentration

A
  • greater substrate concentration the high the rate of reaction
  • no. substrate molecules increase likelihood of enzyme substrate complex formation
  • all active sites become saturated and any increase in substrate concentration won’t increase the rate of reaction
19
Q

What are enzyme inhibitors

A
  • molecules that prevent enzymes from carrying out their normal function as catalysts
20
Q

what are competitive inhibitors

A
  • molecule has a similar shape to substrate
  • blocks substrate from entering active site
  • cannot carry out its function
  • reduces the number of substrate molecules binding to active sites and slows rate of reaction
  • reversible
21
Q

what is the effect of competitive inhibitors on the rate of reaction

A
  • high concentration of inhibitor reduces rate of reaction
  • high concentration of substrate increases the rate of reaction
22
Q

what are non competitive inhibitors

A
  • inhibitor binds to allosteric site
  • causes tertiary structure of the enzyme to change and the active site
  • active site no longer has a complementary shape
23
Q

what is the effect of non competitive inhibitors on the rate of reaction

A
  • increasing the concentration of enzyme / substrate won’t overcome the effect
  • increasing concentration of the inhibitor decreases the rate of reaction
24
Q

what is end - product inhibition

A
  • enzyme inhibition that occurs when the product of a reaction acts as an inhibitor to the enzyme that it produces
  • regulates metabolic pathways
25
Q

What is an example of a metabolic pathway

A
  • glucose is broken down by the addition of two phosphate groups
  • addition of the second phosphate group is catalysed by phosphofructokinase
  • high ATP levels more ATP binds to the allosteric site on PFK preventing the addition of the second phosphate to glucose
  • As ATP is used up less binds to the PFK and the enzyme catalyses the second addition
26
Q

what are co factors

A
  • inorganic non-protein substances
  • help the enzyme function properly
  • help enzyme and substrate to bind together
  • aren’t used up or changed
  • can be permanent or temporary
27
Q

what are co enzymes

A
  • organic non-protein cofactors
  • changed by the reaction
  • move chemical groups between enzymes aiding in catalysis
28
Q

what are prosthetic groups

A
  • cofactors that are a permanent structure of the enzyme they assist
  • essential to the enzyme functioning properly
  • form the final 3D shape of the enzyme

Biology Hope (26 decks)

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