proteins Flashcards
how is there a variety of protein shapes and functions
due to different sequences of amino acids
and due to hydrogen bonds
what are the different functions of proteins
structural
hormones
antibodies
receptors
enzymes
mnemonic : S.H.A.R.E
what is the order of amino acids determined by
by the sequence of bases in DNA
role of STRUCTURAL protein
example
specific function
proteins are a major component of many tissues
example: muscles
function: contraction
role of ENZYME protein
example
specific function
speed up chemical reactions without changing themselves
example: lipase
function: breaks down fats to glycerol and fatty acids
role of HORMONES protein
example
specific function
chemical messengers which carry information in the blood
example: insulin
function: control of blood glucose concentration
role of ANTIBODIES protein
example
specific function
produced by lymphocytes to destroy pathogens
example: immunoglobulin
function: provides immunity, present in breast milk
role of RECEPTOR protein
example
specific function
recognition of chemicals arriving at a cell membrane
example: insulin receptor
function: recognition of insulin, present in plasma membrane
what are enzymes
enzymes function as biological catalysts and are made by all living cells. they speed up cellular reactions and are unchanged in the process.
how do enzymes speed up chemical reactions
by lowering the energy input (activation energy) needed for it to proceed
why are enzymes specific
enzymes are specific as each chemical reaction is catalysed by a particular enzyme.
the shape of the ACTIVE SITE of an enzyme molecule is COMPLEMENTARY to its specific SUBSTRATE.
how can an enzyme combine with another substrate molecule after speeding up one reaction?
because the shape of enzyme is unaltered during a chemical reaction
2 types of enzyme catalysed reactions
degradation and synthesis
definition of degradation reactions
example
degradation (breaking down) reactions catalyse the breakdown of large complex molecules into smaller simpler ones
definition of synthesis reactions
examples
synthesis (building up) reactions catalyse joining together of many simple molecules to form a larger more complex molecule
example of degradation reaction
digestive enzyme amylase breaks down starch into maltose (in pancreas)
lipase breaks down fat into glycerol (in liver)
example of synthesis reaction
phosphorylase builds up glucose-1-phosphate into starch (in muscle)
each enzyme is most active in its optimum condition.
what can enzymes and other proteins be affected by?
temp and pH
what happens if enzymes are denatured
a change in their shape of the active site, the rate of reaction decreases rapidly and activity stops
when can enzymes be denatures
at high temperatures such as 60 degrees Celsius
what factors affect enzyme activity
suitable temperature, pH and an adequate supply of substrate
what is the effect of temperature on the rate of reaction
at low temps, enzyme and substrate molecules move around slowly, collide RARELY, and rate of reaction is LOW
at high temps, enzyme and substrate molecules move around faster, MORE collisions occur, and rate of reaction INCREASES
what is the optimum temperature
what temp in human cell is this?
the temp at which the rate of reaction is the fastest
37 degrees Celsius
the temp at which rate of reaction is fastest is called
the enzyme’s optimum temperature
why does one specific enzyme only catalyse on reaction
enzymes are SPECIFIC because the shape of their ACTIVE SITE is COMPLIMENTARY to the SUBSTRATE. only then will a PRODUCT be produced.
catalase breaks down hydrogen peroxide into____
oxygen and water
why does enzyme activity decrease at temperatures above the optimum
the enzyme begins to denature, its active site’s shape starts to change
enzymes _____ the energy input required
enzymes ____ the rate of reaction
the shape of the _____ is complementary to its substrate
1) lower
2) increase
3) active site
why does a denatured enzyme no longer work
the shape of its active site changes such that it is no longer complementary to the shape of its substrate
