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BIOLOGY -MODULE 2 > enzymes > Flashcards

enzymes Flashcards

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1
Q

what are enzymes

A

biological catalysts
globular proteins
Interact with substrate molecules causing them to interact

Without the need of harsh conditions

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2
Q

What are metabolic reactions

A

All the reactions that take place in an organism

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3
Q

What is a catalyst

A

A substrate rhat increases the rate of reaction bht doesn’t take part

Can be reused

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4
Q

What is the turnover

A

The number of substrate molecules that an enzyme molecule can catalyse per second

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5
Q

How do catalysts lower the activation energy

A

Provide an alternative pathway

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6
Q

Vmax

A

Enzymes can only increase the rate of the reaction up to a certain point

Max initial velocity rate of the enzyme Catalyzed reaction

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7
Q

3 types of enzymes

A

Catabolic
Anabolic
Modifying
GISELLE

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8
Q

Catabolic acid

A

Break substrates down into smaller products

Releases energy

Eg energy released from glucose release

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9
Q

Anabolic enezymss

A

Build up reactions

USE energy e.g. synthesis of polymer based components

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10
Q

Modifying

A

Changing the substrate slightly

Eg from alpha to beta glucose

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11
Q

Specificity of an enzyme

A

Many enzymes produced by living organisms

Each enzyme catalysed ONE biological reaction , of which there are 1000’s in any given cell

Active site shape is determined by the tertiary structure and is UNIQUE to each enzyme

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12
Q

Lock and key

A

When substrate is bound to the active site - enzyme substrate complex is formed

Substrates react and the product is formed = enzymes product complex

Products released and enzyme reused

Substrate held by the enzyme - atom groups are close enough to react , RA GROJPS WITBIN THE ACTIVE SITE of the enzyme will ALSO interact with the substrate, forming temporary bonds - these bonds put strain on bonds within substrate helping the reaction along t

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13
Q

Induced fit hypothesis

A

Enzyme changes shape slightly as the substrate enters

Initial interaction between the enzyme and substrate is weak - but these weak interactions rapidly induce changes in the enzymes tertiary structure that help strengthen binding - putting strain in substrate molecules

WEAKEN A PARTiCULAR bond in substrate - lowering the activation energy

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14
Q

Mechanism of enzyme action?

A

Molecule needs to collide in the right orientation

Enzymes help molecules collide successfully

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15
Q

INTRA acellular enzymes

A

Enzyme action takes place Ainsjfe Cells

Catalase ensures hydrogen peroxide is broke down into 02 and H2O quickly

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16
Q

EXTRA cellular organisms

A

Work outside th cell that makes them
For some organisms like fungi - work outside the body
Single celled organisms release enzymes into immediate environment

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17
Q

why are extracellular enzymes needed

A

Nutrients needed to supply subtrates to cells for product making for organisms , but these nutrients are often in te form of polymers and are too large so have to be broken down

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18
Q

How is starch digested

A

Broken down into maltose using amylase
Amylase produced by salivary glands and pancreas
Maltose broken down in small intestien into glucose by maltase
GLUCOSE - Absorbed by cells lining digestive system = blood stream

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19
Q

Digestion of protein ?

A

Trypsin breaks down proteins into smaller peptides , then brooken down into aminoacids
Trypsin produced in PANCREAS and released within pancreatic juices into small intestine - amino acids absorbed by cell lining digestive system

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20
Q

What factors affect enzyme activity ?

A

Temperature
pH
Enzyme and substrate concentration

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21
Q

how does increasing temperature affect enzyme activity

A

Increasing the temperature of a reaction environment increases KE of the particles

As temperature increases, particles move faster and collide more frequently e.g. enzyme and substrate

Higher reaction rate

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22
Q

What is temperature coefficient

A

Q10

Measure of how much the rate of reaction increases with a 10 degree rise in temp

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23
Q

Denaturarion w

A

After optimum temp is reached
Bonds holding protein vibrate - STRAIN AND BREAK

CHANGE IN tertiary structure , active site changes - irreversible and q10 no longer applies

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24
Q

Temperature extremes - hot

A

Thermophiles
Enzymes present in these .organisms are more stable than other enzymes

Higher number of bonds ( H bonds and sulphur bridges) in tertiary structure

Shape of thee enzymes and active sites are more resistant to change as temp rises

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25
Q

Cold temp

Extreme

A

More flexible structures

Less stable

Smaller temp changes denature them

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26
Q

How is the enzyme held

A

H bonds and ionic bonds between amino acid r grojps hold protein in precise 3D shape
BONDS RESULT from interaction polar and charged R groups present on AA forming primary structure

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27
Q

PH

A

Change in h+ concentration

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28
Q

How does pH affect enzymes

A

H+ interact with polar and charged R groups

Changing H+ ion concentration changes degree of interaction

Interaction of R groups with H+ also affects interaction of R groups with each other

More H+ ions = less R grojps are able to interact = bonds break REVERSE FOR LESS

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29
Q

PH buffer

A

Resists a change in pH

Mops up excess h+ ions

Eg haemoglobin in blood

30
Q

Substrate and enzyme concentration

A

When the conc of substrate is increased the number of substrate molecules , atoms or ions in a particular area or volume increases

The increased number of substrate particles leads to a higher collision rate between susbraye and active site

More enzyme substrate complexes and EPCS formed

31
Q

Renatursrion - pH

A

When pH changes from optimum

Enzyme and active site shape altered

HOWVEER if it returns to optimum protein will resume orgnila shape

32
Q

Why do we need inhibitors

A

So reactions don’t happen too fast

Leads to build up of excess products

Ensure nto wastig products and substrates

33
Q

What is an inhibitor

A

A molecule that prevents enzymes calaysing reactions

34
Q

How do NON competitive inhibitions work

A

Inhibitor binds the enzyme at a location other than the active site ( allosteric)

The binding of the inhibitor causes the tertiary structure of the enzyme to change meaning the active site changes shape

ACITVE SITE AND SUBSTRATE NO LONGER COMPLEMENTARY

Some bind reversibly, others irreversible

35
Q

how does increasing temperature affect enzyme activity

A

Increasing the temperature of a reaction environment increases KE of the particles

As temperature increases, particles move faster and collide more frequently e.g. enzyme and substrate

Higher reaction rate

36
Q

What is temperature coefficient

A

Q10

Measure of how much the rate of reaction increases with a 10 degree rise in temp

37
Q

Denaturarion w

A

After optimum temp is reached
Bonds holding protein vibrate - STRAIN AND BREAK

CHANGE IN tertiary structure , active site changes - irreversible and q10 no longer applies

38
Q

Temperature extremes - hot

A

Thermophiles
Enzymes present in these .organisms are more stable than other enzymes

Higher number of bonds ( H bonds and sulphur bridges) in tertiary structure

Shape of thee enzymes and active sites are more resistant to change as temp rises

39
Q

Cold temp

Extreme

A

More flexible structures

Less stable

Smaller temp changes denature them

40
Q

How is the enzyme held

A

H bonds and ionic bonds between amino acid r grojps hold protein in precise 3D shape
BONDS RESULT from interaction polar and charged R groups present on AA forming primary structure

41
Q

PH

A

Change in h+ concentration

42
Q

How does pH affect enzymes

A

H+ interact with polar and charged R groups

Changing H+ ion concentration changes degree of interaction

Interaction of R groups with H+ also affects interaction of R groups with each other

More H+ ions = less R grojps are able to interact = bonds break REVERSE FOR LESS

43
Q

PH buffer

A

Resists a change in pH

Mops up excess h+ ions

Eg haemoglobin in blood

44
Q

Substrate and enzyme concentration

A

When the conc of substrate is increased the number of substrate molecules , atoms or ions in a particular area or volume increases

The increased number of substrate particles leads to a higher collision rate between susbraye and active site

More enzyme substrate complexes and EPCS formed

45
Q

Renatursrion - pH

A

When pH changes from optimum

Enzyme and active site shape altered

HOWVEER if it returns to optimum protein will resume orgnila shape

46
Q

Why do we need inhibitors

A

So reactions don’t happen too fast

Leads to build up of excess products

Ensure nto wastig products and substrates

47
Q

What is an inhibitor

A

A molecule that prevents enzymes calaysing reactions

48
Q

How do NON competitive inhibitions work

A

Inhibitor binds the enzyme at a location other than the active site ( allosteric)

The binding of the inhibitor causes the tertiary structure of the enzyme to change meaning the active site changes shape

ACITVE SITE AND SUBSTRATE NO LONGER COMPLEMENTARY

Some bind reversibly, others irreversible

49
Q

examples of irreversible non competitive inhibitors

A

often very toxic
Organophosphate used as insecticides and herbicides inhibit the enzyme acetyl cholinestease - an enzyme necessary for nerve impulse transmission and can lead to muscle cramps and paralysis

50
Q

non competitive inhibition - indegestion

A

protein pump inhibitors
long term indegestion

Irreversibly block an enzyme system responsible for secreting hydrogen ions into the stomach

This makes PPI’s effective in reducing the production of excess acid which if left untreated can lead to stomach ulcer formation

51
Q

What is end product inhibition

A

Enzyme inhibition that occurs when the product of a reaction acts as an inhibitor go the enzyme that produces it

serves as NEGATIVE FEEBACK

Excess products are not made and resources not used

NON COMPETITIVE REVERSIBLE INHIBITION

52
Q

example of end product inhibition - respiration

A

GLUCOSE BROKEN DOWN

  1. Addition of 2 phosphates to the glucose molecule
  2. Addition of the 2nd phosphate group , which results in the initial breakdown of the glucose molecule is catalysed by the enzyme PFK and this enzyme is COMPLETELY inhibited by ATP

when ATP is HIGH - more ATP binds to all obstetric site of PSK, prevents 2nd addition of 2nd phosphate group to glucose, glucose NOT broken down adn ATP not produced at the same rate

As ATP is used up- less binds to PSK - enzyme can catalyse the addition of 2nd phosphate group for glucose respiration resumes and more production of ATP

53
Q

Competititive inhibition

A

Molecule of part of molecule has similar shape to the substrate of enzyme

Can fit into the active site of an enzyme

This blocks the substrate from entering the active site, preventing the enzyme from catalysing the reaction

The enzyme can’t carry out its function

Binds temporarily - effect is reversible ( FEW exception e.g. Aspirin)

54
Q

What is the effect of non competitive inhibition on reaction rate , as your add more enzyme/ substrate

A

Increasing the conc of substrate/ enzyme has NO effect

This is because the substrates don’t compete with inhibitor for active site - so the non competitive inhibitor binds and the active site can no longer be used

55
Q

Effect on reaction rate of competitive inhibitor

A

Substrate and inhibitor molecules present in solution will compete with each other to bind to active sites
This reduces number of substrate molecules binding to Clive sites in given time and reduce rate
Vmax can still be reached - when the eh substrate con centenarian is increases somuch that it overcomes inhibitor number by. A huge amount

56
Q

Examples of competitive inhibitors

A

Statins are competitive inhibitors of an enzyme used in the synthesis of cholesterol
Help pooeple reduce blood cholesterol concentration
High bloo cholesterol = heart disease

Aspirin irreversibly inhibits the active site of COX enzymes, preventing the synth is of prostaglandins and thromboxane , the chemicals responsible for producing pain and fever

57
Q

What are cofactors

A

Non protein helper

May form part of the active site or transfer atoms or routs from 1 reaction to another in multi steps pathways

58
Q

WHAT are coenzymes

A

Organic molecule cofactors

59
Q

Inorganic ion cofactors

A
  • Presence of an ion is required for a fast reaction
  • The ion makes the ESC form more readily
  • Temporarily binds to the substrate of the enzyme
  • Some cofactors act as cosubstrate , cofactors+ substrate = correct shape to bind to active site for the enzyme
  • Some cofactors change the charge distribution on the surface of the sub rate molecule/surface of enzymes active site, making the temporarily bonds in the ESC form more readily
60
Q

Example of inorganic ion cofactors

A

Making Amylase function properly (active site shape)

ONLY with CL- ions

61
Q

Where can you get inorganic ion cofactors from

A

Via diet as minerals including iron, calcium, chloride and zinc ions

62
Q

Prosthetic group cofactors

A

A COFACTOR that is permenantly bound - but by covalent bonds to an enzyme
PERMENANT

63
Q

Example of pros ethic group COFACTOR

A

E.g. Zinc based pros ethic group in carbonic anhydrase, an enzyme CRUCIAL in the transport of co2 in the blood

64
Q

Coenzyme

A

An organic non protein molecule that binds temporarily with substrate, to an enzyme active site - ESSENTIAL for enzyme acidity
Type of COFACTOR
Contain C

65
Q

How do coenzymes work? - changed?

A

Chemically changed
During the reaction and they need to be recycled to this original state
-this may sometimes be a different enzyme

66
Q

Coenzymes - examples

A

Vitamin b3 - used to synthesis and ( a coenzyme responsible for the transfer of H atom between molecules involved in reposition)

67
Q

How can you get coenzymes

A

Derived from vitamins, a class of organic molecule found in the diet

68
Q

Precursor activation ?

A

Many enzymes produced in an inactive form
Known as inactivate precursor enzymes, particularly enzymes that can cause damage within the cells producing them or to tissue where they are released , or enzymes whose action needs to be controlled and onlyactivated under certain conditions

69
Q

How do precursor enzymes get activated - what happened to them

A

Undergo a change in shape ( tertiary )
Particularly to the active site
Achieved by addition of a COFACTOR

70
Q

Precursor enzymes - before COFACTOR is added ?

A

APO enzyme

71
Q

After COFACTOR is affecting ? (Precursor enzymes )

A

Halo enzyme

72
Q

What are zymogens and pro enzymes

A

Precursor enzyme that are activated by….
- A change in tertiary structure by the action of another enzyme( e.g. Protease which cleaves certain bonds in the molecule)

  • A change in condition such as pH or temp results in a change in tertiary structure and activated in a precursor enzyme

BIOLOGY -MODULE 2 (24 decks)

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