enzymes Flashcards

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1
Q

what are enzymes?

A

biological catalysts that are commonly made of protein. They alter or speed up the rate of chemical reactions without themselves being chemically changed at the end of the reaction

  • is a protein (has specific 3D structure)
  • functions as biological catalyst
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2
Q

explain why enzymes lower activation energy?

A
  • activation energy is energy needed to start a chemical reaction
    glucose case study :
  • glucose is broken down during respiration to release energy
  • enzymes lower actication energy required for reaction to take place
  • cellular respiration can occur at normal body temperature (36.9 degrees celsius)
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3
Q

explain the fact that enzymes catalyse digestion?

A
  • some food molecules are large, complex and insoluble in water (e.g. starch, proteins, fats)
  • these molecules cannot diffuse across cell membrane
  • have to be digested into smaller, simpler and soluble molecules in order to be absorbed into the cell (e.g. glucose, amino acids)

digestive enzymes :

  • amylase (starch to maltose), in saliva
  • maltase (maltose to glucose), small intestine
  • pepsin (protein to polypeptides), stomach
  • lipase (fats to fatty acids and glycerol), small intestine
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4
Q

explain building up of complex substances?

A

anabolic reactions

  • condensation of amino acids to synthesize polypeptides
  • condensation of fatty acids and glycerol to synthesize fats
  • condensation of glucose to synthesize starch (plants)/ glycogen (animals)
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5
Q

explain breaking down of complex substances?

A

catabolic reactions

  • digestion of large, complex, insoluble food substances (starch –> glucose)
  • breaking down of glucose, during cellular respiration to release energy
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6
Q

describe enzyme names?

A
  • ends with ‘ase’

- shows substance on which enzymes acts on

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7
Q

describe classficiation?

A
  • according to chemical reactions they catalyse
  • hydrolases - hydrolytic reaction
  • proteases that digest proteins
  • lipases that digest lipids
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8
Q

describe enzyme and reaction?

A
  • digestion of carbohydrates : carbohydrase, catabolic reaction
  • digestion of cellulose: cellulase, catabolic reaction
  • synthesis of proteins : ribosome (ribozyme), anabolic reaction
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9
Q

explain the process when enzymes are effects by temperature?

A

Part A
- enzymes are inactive at low temperature
- kinetic energy is low at low temperature
- chances of substrate molecules colliding with enzymes are very low
Part B
- as temperature rises, enzyme activity increases
- increase in kinetic energy of molecules increases chance/frequency of effective collision between substrate and enzyme molecules
- this increases the rate of formation of enzyme-substrate complex to form products
Part C
- optimum temperature : rate of reaction is highest and enzymes are more active
- each enzyme has its own unique optimum temperature
- mostly 40-45 degrees celsius
Part D
- beyond optimum temperature, enzyme activity decreases rapidly until it reaches zero
- high temperature breaks weak hydrogen bonds within enzyme and changes 3D shape
- active sit loses original shape
- enzyme denatured

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10
Q

explain the process when enzymes are affected by pH

A
  • each enzyme has its own unique optimum pH at which it is most active
  • extreme changes in pH will cause the enzyme to denature and loses its function
  • however, some enzymes can function optimally under extreme pHs (pepsin in stomach, pH 2-3)
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