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Biochemistry > 1.3 Biochemical Reactions > Flashcards

1.3 Biochemical Reactions Flashcards

1
Q

What is activation energy

A

energy needed to break existing bonds of reactants and to get reaction started so that new bonds can form

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2
Q

Exothermic reaction

A

Releases energy

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3
Q

Endothermic reaction

A

absorbs energy

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4
Q

How do chem reactions take place

A

reactant molecules must collide with enough force and in the correct geometric orientation so that bonds of reactant molecules break
- stable reactants require activation energy to reach the reactive state transition state in which old bonds begin to break and new bonds begin to form

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5
Q

If activation energy for a reaction is large, reaction will occur…

A

Slowly

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6
Q

The activation energy barrier prevents…

A

energy-rich molecules such as carbs, proteins, lipids, etc from undergoing SPONTANEOUS reactions and decompose to form less energy-rich simpler molecules

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7
Q

What are four ways to speed up chem reactions

A

heat, catalyst, increase concentration, increase SA by grinding

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8
Q

Which way do celle use to speed up chem reactions

A

catalysts (enzymes)

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9
Q

What are enzymes

A

biological catalysts that facilitate most chem reactions in cells
- protein molecules
- speed up chem reaction w/o being consumes

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10
Q

What are enzymes specific to:

A
  • substrate (reactants upon which enzymes will act)
  • type of reaction
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11
Q

What do enzymes do

A

lowers the activation energy barrier so that the transition state can be reached at moderate temperatures

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12
Q

How do enzymes speed up rate of reaction

A
  • bring substrates together in correct orientation
  • stretch and bend chem bonds of reactants that must be broken
  • destabalize the substrate by adding or removing H+ ions or electrons to or from the substrate
  • Provide the proper microenvironment (eg. correct pH)
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13
Q

Active Site

A
  • Made up of a segment of aa w/in polypeptide chain folded into 3D structure to form a small groove or pocket on protein surface
  • Very specific to the shape, size and charge of the substrate
  • Temp and pH sensitive
  • Where chem reactions take place!
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14
Q

Induced Fit Model

A
  1. Substrate enters active site
  2. Creates ENZYME-SUBSTRATE COMPLEX: weak bonds form between the enzyme and the substrate
  3. Enzyme changes shape to better accommodate substrate (induced fit)
  4. Reaction occurs
  5. Formation of products cause enzyme to alter back to original shape
  6. Products released
  7. Enzyme active site ready to receive next substrate
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15
Q

When enzyme-substrate complex has reached a maximum…

A

further increases in the concentration have no effect - all of the molecules are bound already

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16
Q

What is the optimal temp for typical human enzymes

A

37 deg celcius (body heat is 37)

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17
Q

What is the optimal temp for enzyme of thermophilic (heat-tolerant) bacteria

A

75 deg

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18
Q

What happens to enzymes if temp is raised

A

denaturation
- particles move faster, bump into each other, bonds are disrupted

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19
Q

What happens to enzymes if temp is lowered

A

reaction time is slower as particles move slower -> less chance of particles bumping into each other

20
Q

What is optimal pH for pepsin

A

2

21
Q

What is the optimal pH for tyrpsin (small intestine)

A

8

22
Q

What happens if enzymes are not at optimal pH

A

denaturation b/c of lose/gain ions

23
Q

What component is needed by some enzymes for catalytic activity

A

non protein components

24
Q

what are competitive enzyme inhibitors

A

binds to active site, preventing substrates from binding

25
Q

What are enzyme inhibito

A

chemicals that selectively inhibit the action of specific enzymes

26
Q

What are non competitive enzyme inhibitors

A

inhibitors bind to allosteric site & cause a change in the shape of the active site, preventing substrates from binding

27
Q

Which type of inhibition can be overcome by increasing amount of substrate

A

competetive inhibition

28
Q

What is the allosteric site

A

receptor site on enzyme, separate from active site
- when effectors (inhibitors of activators) bind, shape of enzyme changes, resulting in active or inactive enzyme

29
Q

Optimal pH for pepsin and trypsin

A

2 and 8

30
Q

Properties of Acids

A
  • produce H+ when dissolved in water
  • pH < 7
  • Sour
  • Can conduct electricity and cause skin burns
31
Q

Properties of bases

A

produce OH- when dissolved in water
- Accepts or reacts with H+ ions
- pH > 7
- bitter
- soapy or slippery
- can conduct electricity and cause skin burns

32
Q

How to calculate acidity

A

subtract pH level then multiple by 10^n

33
Q

What do acids do in water

A

ionize and produce H+ ions
- donate protons (H+)

Strong acids ionize completely
Weak acids ionize partially

34
Q

What do bases do in water

A

OH- dissociate to produce OH- ions, which accepts protons
- Strong bases dissociate completely
- Weak bases dissociate partially

35
Q

What type of reaction occurs during neutralization

A

double displacement

36
Q

What are the products of neutralization

A

H2O and ionic compound (salt)
acid + base -> salt + water

37
Q

What are buffers

A

solutions that minimizes the change in pH when a base or acid is added to the solution

38
Q

What are buffers made of

A

weak acid and a weak base

39
Q

What will weak acids do in the presence of a strong base

A

Release H+ ions

40
Q

What will weak bases do in the presence of a strong acid

A

Accept H+ ions

41
Q

How do buffers work in the presence of strong acid

A
  1. strong acid will ionize completely and release many H+ ions
  2. pH of solution will decrease
  3. Weak base in buffer will act
  4. Weak base accepts H+ to form weak acid
  5. pH change will be minimized
42
Q

How do buffers work in the presence of a strong base

A
  1. strong base will dissociate completly to release many OH- ions
  2. pH of solution will increase
  3. Weak acid in buffer will act
  4. H+ ions will be released to react with OH- to form water. upon release of H_, weak base will form
  5. pH change will be minimized
43
Q

What is the main buffer system in blood

A

carbonic acid - bicarbonate buffer

44
Q

Which organs help control blood pH

A

lungs, kidneys, heart
- remove CO2 helps increase pH
- remove HCO3- helps decrease pH

45
Q

What are redox reactions

A

chem reactions that involve the transfer of 1 or more electrons from one reactant to another
- Loss of electrons = oxidation
- Gain of electrons = Reduction

Electrons move from where they are weakly held to where they are more strongly held

46
Q

What is the substance that undergoes oxidation and loses and electron

A

Reducing agent

47
Q

What is the substance that causes another substance to be oxidized

A

oxidizing agent

Biochemistry (5 decks)

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