enzymes and kinetics Flashcards
what are enzymes ?
catalyses all biochemical reactions
play a role in metabolism , diagnosis and therapeutics
levels in blood use as indictors for disease
can be used therapeutically
what ending of the word do enzymes usually end with ?
-ase
what are the six classes of enzymes ?
transferases
ligase
oxidoreductases
isomerase
hydrolase
lyases
what do transferases do ?
transfer functional groups from one molecule to another
what do ligases do ?
join two molecules together
what do oxidoreductases do ?
move electrons between molecules
what do isomerases do ?
convert a molecule from one isomer to another
what do hydrolases do ?
break bonds using water
what do lyases do ?
break bonds without using water or oxidation
how do enzymes act as a biological catalyst ?
globular protein with specific shapes
control rates of metabolic reactions
lower activation energy
not consumed in reactions
substrate specific
shape of active site determines substrate
what is activation energy?
the input of energy to start the chemical reaction
what effect does enzymes have on activation energy for chemical reactions ?
lowers activation energy
what is lock and key model ? [ emil fischer 1894]
active site is rigid shape
only substrate with matching shape can fit
no change in active site on binding substrate
what is the induced fit model? [daniel koshland 1958]
active site is flexible , not rigid
greater range of substrate specificity
what are the factors which effect enzyme activity ?
enviromental conditions
temperature
ph
substrate concentration
inhibitor and activators
what is majority of enzymes optimum temperature?
37 degrees
what temperature will most enzymes denature at ?
70 degrees
what is the optimum ph for enzymes?
7
what happens when there is a small change in ph ?
change shape of active site
when does maximum rate of activity occur ?
when enzymes are fully saturated
what effect does an inhibitor have on activity of enzymes ?
Decreases it
what is a reversible inhibitor ?
can associate and dissociate with an enzyme to regulate activity
what is a non reversible inhibitor ?
Covalent attachment of the inhibitor to the enzyme
Can only be overcome by making more enzyme
what is a competitive inhibitor ?
has similar substrate to the substrate
competes with substrate for active site
how do you reduce the effect of competitive inhibitor ?
increasing the substrate concentration
what is a non competitive inhibitor ?
substrate is diff from substrate
binds to enzyme away from active site [ allosteric site ]
changes shape of active site
can the effect of a non competitive inhibitor be reversed by adding more substrate ?
cannot be reversed
what does activator have effect on enzymes ?
increases activity
where does activators bind ?
allosteric site
what is metabolism ?
chemical reaction that occur in a living organism
conversion of one compound to another compound
what is the purpose of metabolism ?
energy production
biosynthesis
excretion
what is anabolism ?
synthesis from smaller to larger molecules
requires energy
provides substance for cellular growth and repair
what is catabolism ?
involves breakdown of larger molecules into smaller ones
releases energy
used to decompose carbs , lipids and protein
what are the three main sources of energy ?
carbohydrates
lipids
proteins
what does glycolysis convert glucose into ?
pyruvic acid
what is the net gain in which happens glycolysis
2 molecules of ATP per glucose molecule
what is glycogenolysis ?
converts glycogen into G-6-P
G-6-P enters glycolysis
what is TCA cycle ?
central to all respiratory oxidation
oxidises actyl-co A from glucose, lipid and protein catabolism in aerobic respiration
maximises energy gain
what happens in oxidative phosphorylation ?
formation of ATP by transfer of electrons
major source of ATP production in aerobic organisms
why are triglycerides important ?
stored energy in form of fat droplets within adipose tissue
what process to fats occur during starvation ?
lipolysis
what happens during lipolysis ?
switches fast carbohydrates into slow lipid energy
only brain continues to use carbohydrates
what are the three stages of processing triglycerides ?
- Triglycerides are degraded to fatty acids and glycerol in the adipose tissue and transported
to other tissues - At these tissues, fatty acids are activated and transported into the mitochondria for
degradation - Fatty acids are broken down into two-carbon acetyl-Co A units and fed into the TCA cycle
where does metabolism of proteins begin ?
in the stomach
where does the completed metabolism of proteins end ?
intestines
what is the primary proteolytic enzyme in stomach for metabolism of proteins ?
pepsin
what enzyme is secreted from pancreas for metabolism of proteins ?
zymogens
