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a level biology > enzymes > Flashcards

enzymes Flashcards

1
Q

what are enzymes important for

A

chemical reactions which are needed for necessary life processes

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2
Q

why can’t life processes be done without enzymes

A
  • they happen very fast
  • happen under high temperatures and pressures
  • so would damage cell components
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3
Q

what are enzymes

A

biological catalysts and globular proteins

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4
Q

what do enzymes do

A

interact with substrate molecules causing them to react at much faster rates

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5
Q

what are anabolic reactions

A
  • reactions needed for growth
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6
Q

give an example of anabolic reactions

A
  • cellulose forms walls of plant cells
  • long protein molecules form contractile filaments of muscles in animals
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7
Q

how are anabolic reactions catalyzed

A

by enzymes

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8
Q

catabolic reactions

A

breaking down molecules - energy is released

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9
Q

what is energy needed for

A

growth

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10
Q

how are catabolic reactions catalyzed

A

enzymes

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11
Q

give an example of a catabolic reaction

A

digestion

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12
Q

what is metabolism

A
  • sun of all the different reactions and reaction pathways happening in a cell or an organism
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13
Q

how is metabolism controlled

A

enzymes

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14
Q

what affects enzyme action

A

temperature
pH
pressure

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15
Q

what is the Vmax

A

enzyme can only increase the rates of reaction up to a certain point = Vmax

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16
Q

for a reaction to occur what must happen

A
  • they need to collide in the right orientation
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17
Q

how do we increase rate of reaction and what affect does this have

A
  • at high temperatures and pressure
  • speed of molecules increase
  • numbers of successful collisions increase

=ror increased

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18
Q

what is enzyme specificity

A
  • each enzyme catalyses one biochemical reaction of which there are thousands in any given cell
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19
Q

what is activation energy

A

the energy that needs to be supplied for most reactions to start

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20
Q

how do enzymes reduce activation energy

A

enzymes help the molecules collide successfully

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21
Q

what is the active site

A

an area within the tertiary structure of the enzyme that has a shape which is complementary to the shape of a specific substrate molecule

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22
Q

lock and key theory

A

the same way that only the right key will fit into a lock only a specific substrate will fit into the active site of the enzyme

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23
Q

how does an enzyme substrate complex form

A

when a substrate is bound to the enzymes active site

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24
Q

when a substrate reacts with an enzyme what is formed

A

enzyme product complex

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25
Q

what happens after an enzyme product complex is formed

A

products are released leaving the enzyme unchanged

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26
Q

how do the enzyme and substrate specifically react

A

substrate is held in such a way by the enzyme that the right atom groups are close enough to react

r groups within the active site of the enzyme will also interact with the substrate forming temporary bonds

these put a strain on the bonds within the substrate which helps the reaction along

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27
Q

what is the induced fit hypothesis

A

active site of the enzyme changes shape slightly as the substrate enters

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28
Q

why does the active side change shape slightly as sub rate enters

A

initial interaction between enzyme and substrate is weak

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29
Q

what do the weak interactions between enzyme and substrate cause

A
  • changes in enzymes tertiary structure
  • this strengthens the binding putting a strain on the substrate molecule
  • this weakens a bond or bonds in the substrate
  • lowers activation energy
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30
Q

intracellular enzymes

A

enzymes that act within cells

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31
Q

give an example of a reaction that requires intracellular enzymes

A

synthesis from polymers to monomers

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32
Q

example of a reaction which used intracellular enzymes

A
  • making polysaccharides from glucose
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33
Q

what does the enzyme catalase do

A

ensures hydrogen peroxide is broken down to oxygen and water quickly to prevent accumulation

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34
Q

what is hydrogen peroxide

A

a toxic product of many metabolic pathways

35
Q

where is catalase found

A

plant and animal tissues

36
Q

what kind of enzyme is catalase

A

intracellular

37
Q

what do nutrients supply

A

substrates that the organism needs to make products to keep cells up with the demand

38
Q

what are nutrients needed for

A

growth
survival

39
Q

what do nutrients come in the form of

A

proteins and polysaccharides which are large molecules

40
Q

what is the issue with nutrients being large molecules

A

they can’t enter cells through the cell membrane and need to be broken down first

41
Q

what are extracellular enzymes

A

enzymes which work outside of the cell that made them

42
Q

how do enzymes help nutrients

A

they are released from cells and break down larger nutrient molecules into smaller ones in digestion

43
Q

extracellular enzyme example

A

fungi

44
Q

give an example of a single called organisms which needs extracellular enzymes

A

bacteria and yeast release enzymes to break down larger molecules such as proteins and the smaller molecules produced are then reabsorbed by the cells

45
Q

give an example of when multicellular organisms need enzymes

A
  • large molecules need to be digested so smaller molecules can be absorbed into the blood stream
46
Q

give example of extracellular enzymes involved in digestion in humans

A

amylase
trypsin

47
Q

where does the digestion of starch begin

A

mouth and continues to small intestine

48
Q

what are starch molecules initially broken into and how ?

A

into maltose
by enzyme amylase

49
Q

where is amylase produced

A

salivary glands and pancreas

50
Q

what from does amylase take in digestion

A

saliva - salivary glands
pancreatic juice - small intestine

51
Q

after starch is broken down into maltose what is it then broken down into and how

A

glucose
by enzyme maltase

52
Q

where is maltase produced

A

small intestine

53
Q

what enzyme catalyses the digestion of proteins

A

trypsin

54
Q

what are proteins broken down into

A

smaller peptides

55
Q

where is trypsin produced and released

A

produced pancreas
released with pancreatic juice in small intestine

56
Q

what happens to the amino acids produced by the action of proteases

A

absorbed into bloodstream by cells lining in digestive system

57
Q

what kind of enzyme is trypsin

A

a protease

58
Q

what is a protease

A

an enzyme which catalyses the digestion of proteins into smaller peptides

59
Q

what it’s important about the structure of enzymes for a reaction to occur

A
  • it needs to be the right shape so it’s complementary to the substrate
60
Q

what affects enzyme activity

A

temperature
ph
vmax
substrate concentration
enzyme concentration

61
Q

what happens when we increase the temperature of a enzyme reaction

A
  • increases kinetic energy of particles
  • particles move faster
  • collide more
  • more successful collisions
  • increased rate of reaction
62
Q

what is temperature coefficient

A

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

63
Q

what happens to enzyme controlled reactions at very high temperatures

A
  • bonds holding the protein together vibrate more
  • vibrations increase
  • until bonds strain and break
  • tertiary structure changes

DENATURED

64
Q

what happens when the enzyme has denatured

A
  • active site changes shape
  • no longer complementary to substrate
  • substrate can’t fit into active sites
  • enzyme can’t function as a catalyst
65
Q

what is optimum temperature

A
  • temperature at which the enzyme has the highest rate of activity
66
Q

what is generally the optimum temperature for enzyme reactions in humans

A

40 degrees

67
Q

what are the optimum temperature for thermophilic organisms (bacteria found in hot springs) generally

A

70 degrees

68
Q

what is the general optimum temp for psychrophilic organisms (live in cold)

A

below 5 degrees

69
Q

what happens once enzymes have denatured above optimum temperature

A

decrease in rate of reaction is fast

70
Q

after an enzyme has denatured what doesn’t apply

A

temperature coefficient

71
Q

what happens if an enzyme controlled reaction is below optimum temperature

A

enzymes don’t denature they are just less active and rate of reaction slows down

72
Q

give an example of extremely cold environments

A

deep oceans
high altitudes
polar regions

73
Q

how are enzymes working in the cold structured

A
  • more flexible particularly at active site
  • less stable
  • smaller temperature changes will denature them
74
Q

what are thermophiles

A

organisms adapted to living in very hot environments

75
Q

give examples of very hot environments

A

hot springs
deep sea vents

76
Q

explain the structures of enzymes adapted to hot environments

A
  • more stable
  • more bonds (H and sulfur bridges ) in tertiary structure
  • more resistant to change as temp rises
77
Q

give an example of how enzymes show they are affected by temperature

A
  • tyrosinase produces melanin - pigment responsible for dark coloured fur
  • siamese cats produce a form of this that is denatured and inactive at normal body temperature so they are usually white/cream
  • at tail ears and limbs at a lower temperature the mutated tyrosinase denatures
  • causing discoloration (black) as melanin is produced
78
Q

what hold proteins and enzymes in their precise shape

A

hydrogen bonds
ionic bonds
between amino acid R groups

79
Q

how do the bonds holding proteins and enzymes together form

A

from interactions between polar and charged R groups present on amino acids forming primary structures

80
Q

what does a change in pH refer to

A

change in hydrogen ion concentration

81
Q

at a low pH how many hydrogen ions are present

A

lots

82
Q

at a low pH how many hydrogen ions are present

A

lots

83
Q

at a higher pH how many hydrogen ions are present

A

fewer

a level biology (6 decks)

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