Enzymes - Intro and Models Flashcards
define enzymes
Biological catalysts, made of protein, with a specific active site. They speed up reactions whilst remaining unchanged.
define active site
indented area on the surface of an enzyme molecule with a shape that is complementary to the shape of the substrate molecule
define catalyst
chemical that speeds up the rate of reaction and remains unchanged and reusable as the end of the reaction
define metabolism
the chemical reactions that take place inside living cells or organisms
define product
molecule produced from substrate molecules, by an enzyme catalysed reaction
define substrate
molecule that is altered by an enzyme-catalysed reaction
define metabolites
reactants, intermediates and products in enzyme-controlled reactions
what is the turnover number
the number of reactions that an enzyme molecule can catalyse per second
what kind of protein are enzymes
globular
what provides the active site
a specific tertiary structure
what are enzymes affected by
temperature and pH
what is the optimum
the temperature or pH at which the enzyme works fastest
what is denaturation
when enzymes lose their specific tertiary structure and shape and are unable to catalyse reactions
why are enzymes specific
they are only able to catalyse one reaction with a particular substrate
how do enzymes speed up reactions
by lowering the activation energy
what are the two types of enzymes
extracellular and intracellular
what are intracellular enzymes
enzymes that work inside cells
give four examples of intracellular enzymes
- catalase
- ATP synthase
- DNA polymerase
- carbonic anhydrase
what is the function of catalase
breaks down hydrogen peroxide into water and oxygen
what is the function of ATP synthase
converts ADP to ATP and inorganic phosphate
what is the function of DNA polymerase
catalyses the synthesis of DNA molecules from free nucleotides
what is the function of carbonic anhydrase and where is it found
found in red blood cells
converts carbon dioxide to carbonic acid, which dissociates to produce H+ ions
what are extracellular enzymes
enzymes that work outside cells
give three examples of extracellular enzymes
- amylase
- trypsin
- lipase
what is the function of amylase and where is it made
made in salivary glands (acts in mouth) and pancreas (acts in small intestine).
breaks down starch into maltose
what is the function of trypsin and where is it made
made in pancreas (acts in small intestine).
digests proteins into smaller peptides by hydrolysing the peptide bonds
what is the function of lipase
breaks down fats in food so they can be absorbed in the intestines
how do enzymes work
by randomly colliding with substrate molecules. the substrates are held in a way that encourages the product to be formed.
what are the two types of enzyme reactions
- catabolic
- anabolic
what are catabolic reactions
substrates are broken down
what are anabolic reactions
substrates are joined to make a larger product
what makes enzymes specific
the shape of the active site is complementary to the shape of the substrate
how do enzymes lower the activation energy
by providing an active site where reactions can occur more easily than elsewhere
what are the two models of enzyme action
- lock and key
- induced fit
which model is more widely accepted
induced fit
describe the lock and key model
the complementary shape of the active site and the substrate molecule are like a lock and key
describe the induced fit model
- the enzyme’s active site changes slightly upon collision, making the active site fit closer to the substrate.
- there may also be changes to the amino acids in the active site that contribute to holding the substrate in place
