Biological molecules Flashcards
What is a monomer?
Small, single units from which larger molecules are made
what is a polymer?
Molecules made from a large number of monomers joined together
what is a condensation reaction?
A reaction that joins two molecules together with the formation of a chemical bond
involves the elimination of a molecule of water
What is a hydrolysis reaction?
a reaction that breaks a chemical bond between two molecules, involving the addition of a water molecule.
What is the function of carbohydrates?
store energy and can provide structural support to plant cells.
What are monosaccharides?
the monomers from which larger carbohydrates are made
e.g - glucose, galactose and fructose
What are disaccharides?
Formed by the condensation on 2 monosaccharides held together by a glyosidic bond
E.g - maltose, sucrose and lactose
What is a polysaccharide?
formed by the condensation of many monosaccharide units
E.g - starch, glycogen and cellulose
What is cellulose?
Polysaccharide in plant cell walls formed by the condensation of beta glucose.
provides structural support to plants
What is glycogen?
polysaccharide in animals formed by the condensation of alpha glucose
What is starch?
Polysaccharide in plants formed by the condensation of alpha glucose
contains 2 polymers - amylose ad amylopectin
What is a Glycosidic bond?
C-O-C link
between 2 sugar molecules formed by a condensation reaction
a covalent bond
Amylose
polysaccharide in starch
made of alpha glucose joined by 1,4-glycosidic bonds
coils to form a helix
Amylopectin
Polysaccharide in starch
made of alpha glucose joined by 1,4 and 1,6 glycosidic bonds
Branched structure
Alpha v Beta glucose
Alpha - hydroxyl group on bottom
Beta - hydroxyl group on top
How are the three disaccharides formed?
glucose + glucose = maltose
glucose + Galactose = lactose
glucose + fructose = sucrose
properties of glycogen
insoluble - cant be dissolved - wont change water potential - no lysis of cell
highly branched = readily hydrolysed - can fulfil animals higher metabolic rate
Properties of starch
insoluble - it can stored within cells and not dissolve - wont change water potential
Amylose - spiral-shaped - can be readily compacted
Amylopectin - branched - provides larger SA for enzymes to attach to - readily hydrolysed back into glucose for respiration
structure of cellulose
long, straight chains of beta glucose lie parallel and are held together of hydrogen bonds
called Fibrils
properties of cellulose
insoluble - wont change water potential - wont call lysis of cell
Lots of hydrogen bonds = very strong polysaccharide
Triglyceride
formed by the condensation of one molecule of glycerol and 3 fatty acids
forms 3 ester bonds
phospholipid
formed by the condensation of 1 molecule of glycerol and 2 fatty acids
held by 2 ester bonds
phosphate group attached to the glycerol
induced-fit model
The enzyme active site is not initially complementary to the substrate
the active site moulds around the
substrate
this puts tension on bonds lowers the activation energy
competitive inhibitor
A molecule that is the same/similar
shape as the substrate binds to the active site
prevents enzyme-substrate complexes from forming
Non-competitive inhibitor
A molecule that binds to an enzyme at the allosteric site
causing the active site to change
shape
preventing enzyme-substrate
complexes from forming
Primary structure
The sequence of amino acids on a polypeptide chain
secondary structure
The folding or coiling of the chain to create a beta pleated sheet or an alpha helix
held in place by hydrogen bonds
Tertiary Structure
the further folding to create a 3D shape
held in place by hydrogen, ionic and disulphide bonds
Quaternary structure
more than one polypeptide chain in protein
peptide bond
covalent bond joining amino acids together in protein
C-N link between 2 amino acids molecules
formed by a condensation reaction
What is the effect of temperature on an enzyme-controlled reaction?
At low temperatures, there is not
enough kinetic energy for successful collisions between the
enzyme and substrate.
At too high a temperature,
enzymes denature, the active site
changes shape and enzyme- substrate complexes cannot form.
What is the effect of pH on enzyme-controlled reaction
Too high or too low a pH will
interfere with the charges in the
amino acids in the active site.
This breaks the ionic and hydrogen bonds holding the tertiary structure in place therefore the active site changes shape and the enzyme denatures
Different enzymes have a different
optimal pH
What is the effect of substrate concentration on enzyme controlled reaction
At low substrate concentrations,
there will be fewer collisions
between the enzyme and substrate.
At high substrate concentrations,
the rate plateaus because all the enzyme active sites
are saturated
What is the effect of enzyme concentration on enzyme-controlled reaction?
At low enzyme concentrations,
there will be fewer collisions
between the enzyme and substrate.
At high enzyme concentrations, the rate plateaus
because there are more enzymes
than the substrate, so many empty
active sites.
Ester bond
-COO- chemical bond
formed between glycerol and fatty acids
Hydrophilic
the ability to mix, interact or attract water
Hydrophobic
the tendency to repel and not mix with water
isomer
molecules with the same molecular formula but the atoms are arranged differently
polypeptide
polymer chain of a protein made up of amino acids bonded together by peptide bonds following condensation reactions
amino acid
the monomer of a protein
contains a carboxyl group, amine group and an R group
carboxyl group
COOH group
double bonded O to C
found in amino acids and fatty acids
Amine group
NH2 group found on amino acids
R group on amino acids
The variable group
the part of each of the 20 amino acids that is different
activation energy
The minimum amount of energy required for a reaction to occur
saturated fatty acid
A long hydrocarbon chain with a carboxyl group at one end
only single bonds between carbon atoms
unsaturated fatty acid
a long hydrocarbon chain with a carboxyl group at one end
at least one double bond between carbon atoms
polar molecule
a molecule that has an uneven distribution of charge
Phospholipid bilayer
2 charged regions
heads exposed to water and tails are not
Reducing sugar
sugars that can reduce Cu2+ ions in benedict’s reagent to Cu+ ions
which forms a brick-red precipitate
Test for reducing sugar
add benedicts reagent
heat
observe green/yellow/orange/brick red precipitate
How does the structure of a triglyceride relate to its function?
large ratio of energy-storing
carbon-hydrogen bonds compared
to the number of carbon atoms; a
lot of energy is stored in the
molecule
high ratio of hydrogen to oxygen
atoms they act as a metabolic
water source
do not affect water potentials and
osmosis
have a relatively low mass
How does the structure of a phospholipid relate to its function?
Phospholipids have two charged
regions, so they are polar
In water, they are positioned so
that the heads are exposed to
water and the tails are not.
This forms a phospholipid bilayer
which makes up the plasma
membrane around cells.
Test for non-reducing sugar
Following a negative benedicts test
boil sample in acid and then neutralise with alkaline
add benedicts reagent and heat
observe orange/brick red colour
test for starch
add iodine
turns blue/black
test for lipids
add ethanol and shake to dissolve
add water
white emulsion forms
test for protein
add biuret
turns purple
