Unit 5 Bio Flashcards
What is the structure of an enzyme?
Tertiary protein with a very specific 3D shape.
Includes an active site which is held together by peptide, hydrogen, ionic and disulphide bonds
Explain the lock and key theory
In order for there to be a successful collision the substrate has to fit exactly into the active site of the enzyme forming an enzyme-substrate complex
How are the substrate and active site describe ?
Substrate = specific
Active Site = complimentary
Explain the Induced fit theory
The active site and substrate are not fully complimentary in shape. As a result both areas change structure slightly, the bonds in the substrate weakens and the reaction occurs at lower activation energy
What is an Intracellular enzyme ?
Work inside the cells
What are extracellular cells ?
Secreted from cells for use outside of the cell
What factors affect enzymes ?
- Temperature
- Substrate Concentration
- pH
- Enzyme concentration
- Inhibitors
What is a competitive inhibitor?
They are complimentary in shape to the active site of the enzyme. They therefore prevent the formation of enzyme-substrate complexes by blocking the active site.
These can not bind permanently
What is a non-competitive inhibitor ?
Binds to the enzyme away from the active site at an allosteric site.
This alters the shape of the active site so no enzyme - substrate complexes can be formed. Some inhibitors bind reversible, while others bind irreversibly
What do enzymes do to the activation energy?
Enzymes are catalysts meaning they lower activation energy of reactions but remain unchanged in the reaction.
Explain the correlation between pH and enzymes
Most have an optimum pH
Small changes from optimum make small reversible changes in the enzyme molecule reducing its efficiency.
Large changes can disrupt ionic and hydrogen bonds causing permanent changes to the shape of the active site.
Substrate concentration effect on rate of reaction
Enzyme reaction relies on successful collisions between enzymes.
Any increase in the substrate conc will increase collisions and the rate of reaction.
At some point any further increase has no effect on the rate of reaction and is no longer the limiting factor
Effect of temperature on the rate of reaction
At low temps = low kinetic energy and so few successful collisions
As the temp increases, the kinetic energy increases therefore more collisions and enzyme-substrate complexed form per unit time.
Over the optimum vibrations in the enzyme molecule weaken some bonds and becomes denatured.
Effect of enzyme concentration on the rate of reaction
Assuming any excess in substrate, any increase in enzyme concentration increases the rate of reaction as more active sites are available for reaction
What is an autotrophic organism ?
Makes complex organic molecules from simple inorganic ones
Heterotrophic organisms
Consume complex organic food molecules
What is the difference between photoautotrophic and chemo autotrophic?
Photo = use light as a source of energy for synthesis of food
Chemo = Oxidise inorganic molecules to provide energy for synthesis of food
Saprophytic Organism
External digestion of food using secretion of enzymes followed by absorption of the products of digestion into the organism
Holozoic Organism
Internal digestion of food. Involves ingestion, absorption, assimilation and egestion
Adaptations for nutrition for a carnivore jaw
Canines - long and pointed to pierce flesh and seize pray
Incisors - on upper and lower jaw to grip and tear flesh
Premolars and Molars - Have sharp cusps that cut and crush. Jaw has strong muscles and moves in a vertical plan opening wide and strongly clamping down to hold prey.
Carnassial Teeth - Act like shears sliding past each other to rip muscle from bone
How would you describe the gut of a carnivore?
relatively short
Usually a large stomach for digestion of mostly protein diet
Small caecum
What is the job of endopeptidases ?
Hydrolyse peptide bonds between specific amino acids in the middle of the peptide chain to form shorter polypeptide chains
What do exopeptidases do?
Hydrolyse peptide bonds on the end of the peptides, from the free amino acids end or the free carboxyl end
Endoparasite and example
Lives inside another organism
Pork Tapeworm
Ectoparasite and example
Lives on the surface of another organism
Head louse
Define parasite
Live on or in another host organism, obtaining their nutrition from the host and harming the host
