3 Proteins and enzymes Flashcards
what are the six functions of proteins?
enzymes
antibodies
cell membranes
structure
hormones
transport
what is the monomer unit for a protein?
an amino acid
what is the bond formed between two amino acids? what is the resulting molecule called?
condensation reaction between C-N producing a peptide bond and expelling H(2)O
dipeptide formed
what is the biruet test and its results?
presence of proteins
copper (II) sulfate solution added drop by drop - turns lilac in the presence of proteins
what is the primary structure of proteins?
the sequence of amino acids (a.a.) in a polypeptide chain
what is the secondary structure of proteins?
alpha helices
beta pleated sheets
held in place by H bonds between -NH and -C=O
what is the tertiary structure of proteins?
interactions between R groups to hold the chain in place:
- H bonds between -C=O and -NH
- disulfide bridges between the sulfurs on 2 cysteine a.a.
- ionic bonds between carboxyl and amino groups on R groups
- hydrophobic interactions between non-polar R groups in a.a. (in centre of protein)
what is the quaternary structure of proteins?
more than one polypeptide chain joined together
may require the addition of a prosthetic group
what are the differences between fibrous and globular proteins? give an example of each
fibrous:
- long and insoluble
- structural roles
- e.g. collagen/keratin/elastin
globular:
- compact and soluble
- metabolic roles
- e.g. haemoglobin/enzymes/hormones
what is chromatography?
separation of chemicals according to their solubility in different mediums
what is the retardation factor?
the distance travelled by the chemical / the distance travelled by the solvent
which compound is used to identify amino acids in chromatography?
ninhydrin
what are the features of enzymes?
globular proteins
biological catalysts
specific
sensitive to temperature and pH
how do enzymes lower the activation energy of a reaction?
alternative metabolic pathway
bring reactants together to form an enzyme-substrate complex
puts strain on the reactants ∴ bonds break/form more easily
why does high temperature cause an enzyme to denature?
high kinetic energy changes the tertiary structure which changes the shape of the active site by causing bonds between a.a. to break
∴ substrate no longer complementary to the active site
∴ enzyme can no longer catalyse reactions
∴ rate of reaction decreases
what is the difference between anabolic and catabolic enzymes?
anabolic = joining small molecules in condensation reactions ∴ endergonic
catabolic = breaking large molecules down in hydrolysis reactions ∴ exergonic
what are the five most common types of enzymes?
dehydrogenases
decarboxylases
proteases
lipases
carbohydrases
what is the turnover rate?
the amount of molecules that can be converted in a given period of time by a single catalytic site
what is a cofactor?
a non-protein molecule that aids enzyme function
how does a cofactor increase the efficiency of enzyme-controlled reactions?
cause an allosteric change to the active site, making it more complementary
what is a competitive inhibitor?
a molecule that competes with the substrate for the active site
what is a non-competitive inhibitor?
a molecule that binds to the enzyme not at its active site, altering its structure and shape of active sites
what are poisons?
irreversible inhibitors that cause a permanent change to the active site
why is coagulation of blood necessary?
prevent excess bleeding
prevent entry of pathogens
seal wounds and maintain blood volume
