2.1.4 Enzymes Flashcards
Suggest 2 reasons why students chose potato rather than liver as a source of catalase
- easier to control SA
- less chance of ethical objection
- lower risk of infection
Potato cylinders were cut to equal lengths. Suggest a further precaution that students should have taken when preparing them, to ensure investigation was valid.
consistent potato variety/ same age
Suggest 2 reasons why the value the students recorded for the volume of oxygen collected might not accurately reflect the volume of oxygen produced
- some oxygen dissolved in solution
- gas other than oxygen collected
- some gas escaped
Explain how induced fit mechanism of enzyme action observed in chitinase increases the rate of chitin breakdown
- stronger bonds between chitin and chitinase
- bonds in chitin are WEAKENED
- lowers activation energy
Explain which type of pipette would reduce the uncertainty when transferring solution?
- one with fewer uses required
- fewer random errors
- highest resolution
- lowest percentage error
what are co-enzymes?
small, organic non protein molecules that bind TEMPORARILY to active site of enzyme molecules, and assist/activate them
chemically changed so need to be recycled to their original state
what is the role of amylase?
- extracellular
- produced in salivary glands and acts in mouth to digest starch into maltose.
- also produced in pancreas and acts in duodenum to catalyse same reaction
- must have Cl-
What are protease inhibitors?
treat viral infections
prevent replication of virus particles by competitively inhibiting protease enzymes so viral coats cant be made
Why are enzymes so efficient?
Small amount of catalyst can catalyse a large number of reactions. they are able to function in conditions that sustain life.
What is a buffer? What is an example of one?
resist changes in pH by accepting or donating H+ ions
certain chemicals in blood so blood pH is close to 7.4
Which vitamin is thiamine pyrophosphate derived from? What is the human deficiency disease if this vitamin is insufficient?
thiamine, B1
beriberi
What happens as enzyme conc increases?
more active sites available
more successful collisions
more ES complexes can form per unit time = rate increases
limiting factor initially
however, it will then not be the limiting factor. all substrates will end up occupying an active site or are now products
if enzyme conc increases further, no inc in rate since lack of substrate molecules is preventing this
what is the effect of substrate conc on rate of reaction?
more substrate added = more ESC can form = more product molecules formed = inc rate.
substrate conc is limiting factor
as conc increases more, maximum rate will be reached
adding more substrate will NOT increase the rate, since all active sites are occupied, so it is no longer the limiting factor.
Which vitamin is co enzyme A derived from? What is the human deficiency disease if this vitamin is insufficient?
pantothenate
elevated blood plasma triglyceride levels
What are the roles of enzymes?
- biological catalysts: speed up metabolic reactions in living organisms, remaining unchanged.
what is the temperature coefficient?
Temperature coefficient = (rate of reaction at (T + 10) °C) ÷ (rate of reaction at T°C)
Why is aspirin (salicylic acid) used as a medicinal drug?
binds to enzymes that catalyse formation of prostaglandins (cell signalling molecules) which are produced by cells when tissues get infected or damaged and make nerve cells more sensitive to pain
can reduce risk of blood clots
What are co-factors? What are their roles?
small, non protein molecules that ensure the reaction occurs at the appropriate rate by changing tertiary structure
inorganic ions may bind temporarily to ease formation of ESC and rate of reaction
- acting as co-substrates (them and substrate form correct shape to bind to active site)
- changing charge distribution on surface of enzymes a.s or on substrate and make temporary bonds in the complex easier to form.
What is needed for enzymes to catalyse some reactions?
cofactors or coenzymes
what is the effect of increasing temperature on enzyme activity?
molecules have more KE = move faster
more frequent collisions + increases force with which they collide
rate of ESC formed increases and rate of reaction increases TO A POINT.
Why are ACE inhibitors used?
inhibit ACE which normally operates in a metabolic pathway that ultimately increases blood pressure
used to lower blood pressure in those with hypertension, to treat a heart failure, and minimise risk of 2nd heart attack in those who have suffered a myocardial infarction.
Why are ATPase inhibitors used?
treat heart failure or abnormal heart beat -> inhibit Na+/K+ in cardiac muscle membrane -> More Ca2+ ions enter to inc muscle contraction