M2: Enzymes Flashcards
2.1.4 Enzymes: Action of Enzymes
What’s an Enzyme?
Biological Catalyst
2.1.4 Enzymes: Action of Enzymes
What’s a Catalyst?
Something that speeds up a chemical reaction without being used up
2.1.4 Enzymes: Action of Enzymes
What can Enzymes do?
Affect structures in an organism & its function
2.1.4 Enzymes: Heterotrophs & Autotrophs
What are Heterotrophs?
Organisms that obtain nutrients by consuming other organisms
2.1.4 Enzymes: Heterotrophs & Autotrophs
What are Autotrophs?
Organisms that produce their own food
2.1.4 Enzymes: Heterotrophs & Autotrophs
What are Endotherms?
Regulate body temp
↳ enzymes can work near optimum temp
2.1.4 Enzymes: Heterotrophs & Autotrophs
Why do Endotherms Regulate their body temp?
Birds & Mammals
- Their enzymes function at near optimum temp
↳ helps them survive - Require greater food supply
2.1.4 Enzymes: Extracellular & Intercellular Enzymes
What’s an Extracellular Enzyme?
Released from outside the cell
2.1.4 Enzymes: Extracellular & Intercellular Enzymes
What’s an Example of an Extracellular Enzyme?
- Amylase
- Trypsin
2.1.4 Enzymes: Extracellular & Intercellular Enzymes
What’s the function of the Extracellular Enzymes Amylase & Trypsin?
Amylase: found in saliva & catalyses the hydrolosis of starch into maltose
↳ secreted in salivary glands
Trypsin: catalyses the hydrolosis of peptide bonds
↳ produced in pancrease & secreted in small intestine
2.1.4 Enzymes: Extracellular & Intercellular Enzymes
What’s an Intracellular Enzyme?
Found in cytoplasm
2.1.4 Enzymes: Extracellular & Intercellular Enzymes
What’s an Example of an Intracellular Enzyme?
- Catalase
2.1.4 Enzymes: Extracellular & Intercellular Enzymes
What’s the function of the Intercellular Enzyme Catalase?
Catalase catalyses the breakdown of hydrogen peroxide to harmless oxygen & water
2.1.4 Enzymes:
What type of proteins are Enzymes?
Globular proteins
2.1.4 Enzymes:
Why are Enzymes specific?
They have an active site which has a specific shape
↳ where substrate mol bind to
2.1.4 Enzymes: Lock & Key Model
What’s the Lock & Key Model?
- Only 1 Substrate (key) can fit into enzyme’s Active Site (lock)
- Both structures have unique shapes
2.1.4 Enzymes: Induced Fit Model
What’s the Induced Fit Model?
- Enzyme + Substrate = complex
↳ structural changes occur → Active Site fits precisely around substrate
↳ Substrate induces Active Site to change shape - Reaction takes place & product = different shape to substrate
↳ Active Site returns to its OG shape
2.1.4 Enzymes: Induced Fit Model
What are the Steps for an Induced Fit?
1) Shape of AS changes & moes to S closer to E
2) Amino acids = molded into precise form
3) Enzyme wraps around substrate → distorts it
↳ lowers AE
* Enzyme-substrate complex forms = fast reaction
E+S → ES→ P+E
Enzyme is not used up in reaction unlike substrate
2.1.4 Enzymes: Enzymes reduce Activation Energy
What is Activation Energy?
Energy required for particles to collide to cause a successful reaction
2.1.4 Enzymes: Enzymes reduce Activation Energy
More information on Activation Energy
Enzymes are catalysts → speed rate of reaction
- Reduce AE required to start reaction between molecules
- Substrate (reactants) are converted into products
- Reaction may not take place w enzyme in absence
↳ each enzyme has a specific catalytic action - Enzymes catalyse a reaction at max rate of an optimum state
2.1.4 Enzymes: Enzymes reduce Activation Energy
What’s formed when a substance binds to an enzyme’s active site?
An enzyme substrate complex is formed which lowers AE
2.1.4 Enzymes: Enzymes reduce Activation Energy
Why do Enzyme-Substrate Complex lower AE?
- If substrate mol need to be joined, attaching the enzyme holds them closer reducing repulsion between molecules
↳ they can bond more easily - If enzyme is catalysng a hydrolysis reaction, fitting into the active site puts more strain on bonds in substrate
↳ substrate mol breaks up more easily
2.1.4 Enzymes: Enzyme Functions
What are the Functions of an Enzyme?
1) Lowers AE
2) Speeds up reaction
3) Don’t take part in chemical reaction
4) Not used up
2.1.4 Enzymes: Factors affecting Enzyme Activity
What’s the affect of Increasing Temps on enzymes?
- Increasing temp, increses Ke of enzyme particles
- But too much heat/wrong pH, denatures enzyme
↳ alters bonding & loses shape
2.1.4 Enzymes: Factors affecting Enzyme Activity
What’s the affect of Decreasing Temps on enzymes?
- Decreasing temp, enzyme becomes less active
↳ reduction in Ke of enzyme particles - Enzyme = Inactivated
↳ regain function when returned to normal temp
2.1.4 Enzymes: Factors affecting Enzyme Activity
What’s Q10?
- Over a range of 0 – 40°C, Q10 for an enzyme-controlled reaction is 2.
- The rate of an enzyme-controlled reaction is doubled for every rise of
10°C. - Heat increases molecular motion, thus thereactants move more quickly and chances of their bumping into each other are increased.
- The temperature that promotes the maximum activity is referred to as the
optimum temperature.
2.1.4 Enzymes: Factors affecting Enzyme Activity
Enzyme-Substrate Complex
Increasing temp = Increasing Enzyme-substrate complex
* Increasing temp, increanses Ke of enzyme particles
↳ more frequence & successful collisions
* But too much heat energy/wrong pH alternates bonding within enzyme
↳ denatures → loses shape
* Lack of heat energy/pH
↳ disabled → can’t carry function anymore (slowly)
↳ enzyme can’t fit into substrate & lock into substrate
2.1.4 Enzymes: Factors affectng Enzyme Activity
What’s the affect of pH on Enzymes?
Above or below optimum pH, the H+ & OH- ions found can mess up the ionic & hydrogen bonds that hold the enzyme’s tertiary structure in place
↳ changes active site shape : enzyme = denatured
2.1.4 Enzymes: Factors affecting Enzyme Activity
What’s the affect of Concentration on enzymes?
- Higher conc, higher speed
↳ more particles that are able to collide w each other → more frequent reactions - But if there’s a higher conc of substrate than AS, enzyme can’t work any faster
↳ working at its optimum or reached saturation point
2.1.4 Enzymes:
Condensation Reaction w Enzymes
2.1.4 Enzymes:
Hydrolysis Reaction w Enzymes
2.1.4 Enzymes: Competitive Inhibitor
What’s meant by ‘Competitive Inhibitor’?
(Reversible)
Competes w SUBSTRATE to bind to AS but no reaction takes place
↳ block AS so no substrate can fit in it
2.1.4 Enzymes: Competitive Inhibitor
Why are Competitive Inhibitors Irreversible?
They’re strong, covalent bonds
↳ inhibitor can’t be removed
2.1.4 Enzymes: Competitive Inhibitor
What’s the shape of a Competitive Inhibitor?
Molecules have similar shape to that of the substrate mol
2.1.4 Enzymes: Competitive Inhibitor
What factor affects how much the Enzyme is Inhibited?
Relative conc of the inhibitor & the substrate
2.1.4 Enzymes: Competitive Inhibitor
How does High conc of Inhibitor affect how much enzyme is inhibited?
It’ll take up nearly all the AS & hardly any of the substrate will get to the enzyme
2.1.4 Enzymes: Competitive Inhibitor
How do Higher conc of Substrate affect how much enzyme is inhibited?
Substrate’s chances of getting to AS before inhibitor increases
↳ increases RoR
2.1.4 Enzymes: Non-Competitive Inhibitor
What’s meant by ‘Non-Competitive Inhibitor’?
(Reversible)
Binds enzyme away from AS
↳ binds to enzyme’s allosteric site
↳ AS changes shape : substrate mol can no longer bind to it
2.1.4 Enzymes: Non-Competitive Inhibitor
Why are Non-Competitive Inhibitors Reversible?
They’re weaker Hydrogen or Ionic bonds
↳ inhibitor can be removed
2.1.4 Enzymes: Non-Competitive Inhibitor
Why don’t they compete w substrate?
They are a different shape to the substrate mol
2.1.4 Enzymes: Non-Competitive Inhibitor
How does increasing conc of Substrate affect RoR?
Doesn’t affect RoR
↳ enzyme activity will still be inhibited
2.1.4 Enzymes: Non-Competitive Inhibitor
What’s the Allosteric Site?
Anywhere in an enzyme except the active site
2.1.4 Enzymes:
What are Irreversible Inhibitators?
- Binds to enzyme
↳ form covalent bonds at AS
↳ enzyme denaturs : there’s no enzyme substrate complex
2.1.4 Enzymes:
(5 marks)
A: As temp increases, enzyme & substrate gain more energy, increases AE causing more frequent & successful collision
B: Enzyme rate of reaction reached its optimum
C: Lots of heat energy, causing enzyme to denature decreasing the rate of reaction → AS changes shape
2.1.4 Enzymes:
What are Cofactors?
Molecule/ion that helps enzyme work
- Inorganic (minerals)
- Temporarily Bound
i.e Cl- in amylase
2.1.4 Enzymes:
What are Coenzymes?
Organic non-protein mol. binds temporarily w substrate to enzyme AS
- Organic (vitamins)
- Temporarily Bound
i.e NAD (respiration), NADP (photosynthesis)
2.1.4 Enzymes:
What are Prosthetic Groups?
Non-protein organic mol. that forms permanent part of protein mol.
- Permanently Bound
i.e Fe2+ in haem group (haemoglobin)
Zn2+ in Carbonic Amhydrase
2.1.4 Enzymes:
What’s a Colorimeter?
Equipment that gives us a quantitative reading of colour
Measures light absorbance when it passes through a cuvette of a coloured liquid
2.1.4 Enzymes:
What’s the affect of Deadly Poisons on Enzymes?
100-200 mg Cyanide kills adult in 2 hrs
- Inhibit or Over-activate enzymes
- Cyanide = Non-Competitive Inhibitator
↳ for respiratory enzyme
2.1.4 Enzymes:
What’s Ethylene Glycol Poisoning?
Found in Anti-freeze
- Broken down by liver (alcohol dehydrogenase)
↳ producing oxalic acid (very toxic) - Alchohol = Competitive Inhibitor
Treatment
* Large dose of ethanol
↳ reduced RoR → allows ethylene to be excreted harmlessly
2.1.4 Enzymes:
What’s the affect of Snake Venom on enzymes?
Contains Phosphodiesterases
- Interferes w workings of prey’s heart
↳ fall in blood pressure - Contains Inhibitator for Acetylcholineesterase
↳ enzyme involved in nerve transmission - Contains Hyaluronidase
↳ digestive enzyme that breaks down connective tissue
↳ helps toxins penetrate tissue quickly
2.1.4 Enzymes:
What’s the function of Antibiotics?
Kill / Inhibit growth of micro-organisms
- Penicillin = Inhibitor of Bacterial Enzyme
↳ forms cross bridges in cell wall - Cell walls = not made
↳ bacterial reproduction = halted