Topic 1 – Key Concepts in Biology-Enzymes Flashcards
what are enzymes?
biological catalysts that increase rate of chemical reaction without being permanently altered themselves
what is an advantage of enzyme in body?
enable cellular reactions to take place at lower temperatures
what is an active site of enzyme?
region of enzyme to which substrate molecule binds and reaction take place.
why are enzymes described as having a high specificity for their substrate?
only substrates with a specific complementary shape can fit into enzyme active site
describe lock and key model
1) substrate collides with active site of enzyme
2) substrate binds, enzyme substrate complex forms
3) substrate converted to product
4) product released from active site which is now free to bind to another substrate
what factors affect rate of enzyme controlled reaction?
temperature
pH
substrate concentration
explain how increasing temperature initially affects rates of an enzyme controlled reaction
as temperature increases molecules have more Kinetic Energy
Movement of molecules increase
Probability of successful collision increases
more enzyme substrate complexes form
rate of reaction increases
explain how increasing temperature above optimum affects rate of an enzyme controlled reaction?
temperature increases above optimum
increased vibrations break bonds in enzyme structure
active site changes shape, enzyme is denatured
no more enzyme substrate complexes can form
rate of reaction decreases
explain how pH affects rate of enzyme controlled reaction
enzymes have optimum pH pH shifts from optimum bonds in enzyme structure are altered active site changes shape, enzyme is denatured rate of reaction decreases
explain how substrate concentration affects rate of enzyme controlled reaction
substrate concentration increases
number of substrate molecules in same volume increases
probability of successful collision increase
how can rate of enzyme controlled reaction be calculated when given a value of time
1/time
what are units for rate?
s^-1
why must large organic molecules be broken down into smaller, simpler molecules in the body?
large molecules are too big to be absorbed across the surface of the gut wall
large molecules are broken down into smaller molecules for absorption into bloodstream.
give an example of the breakdown of large molecules into smaller molecules in plants
starch is broken down by enzymes into simple sugars which are respired to release energy.
what type of molecules are proteins and carbohydrates?
polymers
what are the monomers of carbohydrates?
simple sugars
which group of enzymes catalyse breakdown of carbohydrates?
carbohydrases
which type of carbohydrate catalyses the breakdown of starch?
amylase
what are monomers of proteins?
amino acids
which type of enzyme catalyses the breakdown of protiens?
proteases
what is function of lipases?
enzymes which catalyse breakdown of lipids into fatty acids and glycerol
why are small molecules synthesised into larger organic molecules in the body?
large molecules are used for storage or are used to build structures
which enzyme catalyses formation of glycogen from glucose?
glycogen synthase
how can amount of energy contained in food be measured?
measured using calorimetry
what is calorimetry?
method of measuring heat transfer during a chemical reaction
describe method used to measure amount of energy in a sample of food
1) add set volume of water to boiling tube, record initial temperature
2) record mass of small sample of food
3) stick sample onto mounted needle
4) using bunsen burner light the food sample
5) hold sample under boiling tube until burns up
6) record max temperature reached by water
7) record final mass of food sample
how can amount of energy in food sample be calculated?
energy in food (j)=mass of water (g) x temperature change of water (c) x 4.2
energy= energy in food/mass of food burnt (g)
