1.4 (biological molecules) Flashcards
enzymes
enzymes are biological
catalysts
enzymes are catalysts because they
speed up the rate of chemical reactions without being used up or changed
critical to the enzymes function is the active site where the what binds
substrate
metabolic pathways are controlled by
enzymes in a biochemical cascade of reactions
enzymes can be what referring to whether they are active inside or outside the cell
- intracellular
- extracellular
intracellular enzymes are
- produced and function
- inside the cell
extracellular enzymes are
- secreted by cells
- catalyse reactions outside cells (eg. digestive enzymes in the gut)
hydrogen peroxide is produced as a by- product of many metabolic reactions, it is harmful to cells, catalase does what
- converts hydrogen peroxide into water and oxygen
- preventing any damage to cells or tissues
- intracellular
digestion is usually carried out by extracellular enzymes, this is because
- macromolecules being digested
- too large to enter the cell
amylase is involved in carbohydrate digestion it
hydrolyses starch into simple sugars
amylase is secreted by
- the salivary glands and the pancreas
- for digestion of starch in the mouth and small intestine
enzymes have an active site where specific substrates bind forming an
enzyme-substrate complex
the active site of an enzyme has a specific shape to fit a
specific substrate
extremes of heat or pH can change the shape of the
- active site
- preventing substrate binding
extremes of heat or pH can change the shape of the active site, preventing substrate binding, this is called
denaturation
the specificity of an enzyme is a result of the
- complementary nature
- between the shape of the active site on the enzyme and its substrates
the shape of the active site (and therefore the specificity of the enzyme) is determined by the complex what structure of the protein that makes up the enzyme
tertiary
proteins are formed from
chains of amino acids held together by peptide bonds
the order of amino acids determines the what of an enzyme
shape
the enzyme-substrate complex is only formed
temporarily
the enzyme-substrate complex is only formed temporarily, before the enzyme
catalyses the reaction and the product(s) are released
enzyme reactions can either be
catabolic or anabolic
catabolic reactions involve the
breakdown of complex molecules into simpler products
catabolic reactions involve the breakdown of complex molecules into simpler products, which happens when
a single substrate is drawn into the active site and broken apart into two or more distinct molecules
catabolic reaction diagram
examples of catabolic reactions include
- cellular respiration
- hydrolysis reactions
anabolic reactions involve the
building of more complex molecules from simpler ones
anabolic reactions involve the building of more complex molecules from simpler ones by
- drawing two or more substrates into the active site
- forming bonds between them
- and releasing a single product
anabolic reaction diagram
examples of anabolic reactions include
protein synthesis and photosynthesis
enzymes work by lowering the
activation energy of a reaction
for a reaction to proceed there must be enough
activation energy
activation energy is the
- amount of energy needed by the substrate to become just unstable enough for a reaction to occur - and for products to be formed