2.1.2 Biological Molecules Flashcards
monomer
a small molecule which binds to many other identical molecules to form a polymer
polymer
a larger molecule made up of monomers chemically bonded together
covalent bond
strong bond formed when electrons are shared between 2 atoms
condensation reaction
occurs when 2 molecules are joined together with the removal of water
a covalent bond is formed
hydrolysis reaction
splitting a polymer apart with the addition of water
a covalent bond is broken
chemical elements of carbohydrates
carbon, hydrogen, oxygen
monomer of carbohydrates
monosaccharide (eg. glucose)
polymer of carbohydrates
polysaccharide (eg. glycogen)
chemical elements of proteins
carbon, hydrogen, oxygen, nitrogen (sulfur)
monomer of proteins
amino acid
polymer of proteins
polypeptide (eg. haemoglobin)
polypeptide
many amino acids joined together by peptide bonds
chemical elements of nucleic acids
carbon, hydrogen, oxygen, nitrogen, phosphorus
monomer of nucleic acids
nucleotide
polymer of nucleic acids
DNA
RNA
chemical elements of lipids
carbon, hydrogen, oxygen
chemical symbol for calcium ion
Ca 2+
functions of Ca 2+
nerve transmission
muscle contraction
bone formation
cofactor in blood clotting
chemical symbol for sodium ion
Na+
functions of Na+
nerve transmission
affects reabsorption of water in kidneys
chemical symbol for a potassium ion
K+
functions of K+
nerve transmission
in guard cells as a part of the stomatal opening mechanism
chemical symbol for hydrogen ion
H+
functions of H+
involved in ATP formation in photosynthesis & respiration
chemical symbol for ammonium
NH4 +
functions of NH4 +
needed for the production of nitrates by nitrifying bacteria
produced in the deamination of amino acids
chemical symbol for nitrate
NO3 -
functions of NO3 -
used as a source of nitrogen in plants to make amino acids
absorbed by root hair cells
chemical symbol for hydrogen carbonate
HCO3 -
functions of HCO3-
involved in the transport of CO2
regulation of blood pH
chemical symbol for chloride
Cl-
functions of Cl-
cofactor for amylase enzyme
chloride shift in red blood cells
chemical symbol for phosphate
PO4 3-
functions of PO4 3-
bone formation
component of ATP and nucleic acids
component of phospholipids
chemical symbol for a hydroxide ion
OH-
functions of OH-
regulation of blood pH
polar molecule
uneven charge distribution
partial positive and negative charges which do not cancel out
structure of water
covalent bonds within one molecule. hydrogen bonds between the molecules
water is a liquid at room temperature
provide a habitat
a major component of tissues
reactions medium for chemical reactions
effective transport medium
properties of water
chemical:
polar molecule - uneven charge distribution
hydrogen bonds between water molecules
hydrogen bonds are weak, large number of bonds collectively strong
physical:
ice insulates water below/ice freezes
liquid water is more dense than solid water (ice)
solvent for polar molecules
cohesion
adhesion
high surface tension
transparent
water is more dense than ice
ice floats so ponds are insulated against extreme temperatures which decreases heat loss - aquatic organisms have a stable environment
ice creates another habitat for animals e.g. polar bear
structure of ice vs water
ice: open lattice structure, hydrogen bonds are stable
water: hydrogen bonds break and reform
water is a solvent for polar molecules
molecules can move around in a solution and react together
molecules and ions can be transported when dissolved
removal of waste
water and non-polar molecules allow hydrophobic interactions to occur
allows tertiary structure of proteins to form
allows phospholipid bilayer to form
cohesion
the attraction of water molecules to one another
surface tension (of water)
the surface of water’s ability to resist force
cohesion and surface tension enables
columns of water to be pulled up the xylem
insects to walk on water
water has a high specific heat capacity
hydrogen bonds restrict the movement of water molecules so a large amount of energy is required to raise the temperature
high specific heat capacity of water means
water does not warm up or cool down easily
water keeps a stable temperature, giving aquatic organisms a stable environment in which to live
gases remain soluble in water
water has a high latent heat of vaporisation
hydrogen bonds mean large amounts of energy are required for water to evaporate
high latent heat of vaporisation in water
helps keep temperature stable and cool organisms
plants are cooled in transpiration
general formula for carbohydrates
Cx(H2O)y
types of carbohydrates
monosaccharides, disaccharides, polysaccharides
functions of carbohydrates
energy source
energy store
structural role
part of larger molecules
general formula for monosaccharides
(CH2O)n where n = 3-9
properties of monosaccharides
soluble in water -polar OH groups
insoluble in non-polar solvents
tastes sweet
isomers of monosaccharides
same molecular formula, different structural formula
e.g. alpha glucose and beta glucose
displayed formula of alpha glucose
OH group is below the plane of the axis
role of alpha glucose
energy source
component of starch and glycogen - acts as an energy store
displayed formula of beta glucose
OH group is above the plane of the axis
role of beta glucose
energy source
acts as a component in cellulose - provides structural support in plant cell walls
displayed formula of ribose
4 OH groups
role of ribose
component of RNA and ATP
displayed formula of deoxyribose
3 OH groups, 1 H off carbon-2
role of deoxyribose
component of DNA
solubility of glucose
freely soluble in water - polar
soluble in blood plasma, can be transported to cells for uptake
disaccharides
formed by two monosaccharides joining together in a condensation reaction
a glycosidic bond is formed
general formula for disaccharides
C12H22O11
maltose
alpha glucose + alpha glucose
formed in a condensation reaction with the removal of water
sucrose
alpha glucose + frictose
lactose
alpha glucose + beta glucose
cellubiose
beta glucose + beta glucose
reducing agent
a chemical species that donates an electron to an electron recipient, reducing the recipient
oxidising agent
a substance that gains an electron from a reducing agent, oxidising the reducing agent
test for reducing sugar
add benedict’s solution
heat in water bath
positive result for reducing sugar
colour change from blue to green-yellow-orange to brick red
qualitative
a positive or negative result
tells us if a particular substance is present
quantitative
tells us how much of a substance is present
why is excess benedict’s used when testing for reducing sugar
to ensure all sugar will react
equation for volume of stock solution required
(total volume wanted/conc. of stock solution) x conc. wanted
validity
it is suitably designed to answer the question being asked
testing what is being tested
polysaccharides
polymers which consist of hundreds or thousands of monosaccharides
joined by condensation reactions resulting in glycosidic bonds
examples of polysaccharides
cellulose, glycogen, starch, callose
starch
polymer of alpha glucose
made up of two components, amylose and amylopectin
amylose
1,4 glycosidic bonds
between carbon-1 and carbon-4
amylose helix
coil = more compact shape
held together by hydrogen bonds
properties of lipids
insoluble in water
high in energy
differences between saturated and unsaturated fatty acids
S: single C-C bonds, max. hydrogens, solid at room temperature, high melting point
U: 1 < double C=C bond, not max. carbons, low melting point
structure of a triglyceride
3 fatty acids, 1 glycerol
functions of triglycerides
energy source
energy store
insulation
buoyancy
protection
triglyceride as an energy source
ester bonds can be hydrolysed to form 1 glycerol and 3 fatty acids
used in respiration and release energy
triglyceride as an insoluble energy store
can be stored without affecting the water the water potential of cells
triglycerides as an energy store: high energy density
they have a greater proportion of hydrogen atoms compared to carbohydrates
triglycerides as a heat insulator
whales have blubber (adipose tissue)
triglycerides as an electrical insulator
fatty myelin sheath around some neurones. insulates and increases conduction speed of impulses
triglycerides - buoyancy
fat is less dense than water
aquatic organisms can float. eg. frogs
triglycerides - protection
fat acts as a shock absorber around delicate organs
test for lipids
emulsion test
structure of a saturated fatty acid
no double bonds
structure of an unsaturated fatty acid
at least one double C=C bond
simplified structure of a phospholipid
hydrophilic phosphate head
hydrophobic fatty acid tail
structure of a phospholipid
amphipathic
both hydrophobic and hydrophobic parts
phospholipid fatty acid tails
non-polar
hydrophobic
move away from water and interact with each other
phospholipid phosphate heads
polar
hydrophilic
interact with water extracellularly and intracellularly
structure of cholesterol
function of cholesterol
regulates and maintains the fluidity of the membrane
cholesterol at high temperatures
it stabilises the membrane and raises the melting point
cholesterol at low temperatures
it intercalates between the phospholipids and prevents clustering
without cholesterol, the bilayer is too hot
too fluid/flexible
won’t hold shape
functions of proteins
an essential component of cell membranes
antibodies
enzymes
form structural components of animals
structure of an amino acid
amine group, carboxylic group, hydrogen atom, R group
a zwitterion
a compound with no overall electrical charge, which contains separate parts which are positively and negatively charged
a buffer
a substance that helps to resist large changes in pH
basis of the test for protein
a test for peptide bonds
colour formed by a complex between the nitrogen atoms in the peptide chain and the Cu 2+ ions
primary structure of a protein
sequence of amino acids held together by peptide bonds
secondary structure of a protein
folding of amino acid chain into alpha helix or beta pleated sheet due to hydrogen bonding between amino acids
tertiary structure of a protein
folding of the secondary structure to form a specific (3D) shape. 4 different types of bonding/interactions can hold this shape together
two types of secondary structure of a protein
alpha helix
beta pleated sheet
quaternary structure of a protein
a protein which is made up of 2 or more polypeptide chains. 4 different types of bonding/interactions can hold this shape together
examples of fibrous proteins
keratin, elastin, collagen
examples of globular proteins
antibodies, hormones, enzymes
4 different types of bonding/interactions in protein structure
ionic
disulfide
hydrogen
hydrophilic/hydrophobic
primary structure of a fibrous protein
repetitive regular sequence of amino acids
primary structure of a globular protein
irregular amino acid sequence
shape of fibrous protein
long parallel polypeptide chains cross-linked at intervals from long fibres
shape of globular proteins
folded into a spherical shape
stability of fibrous proteins
stable structure - unreactive
solubility of fibrous protein
insoluble
solubility of globular proteins
easily soluble - hydrophilic R groups point outwards
stability of globular proteins
relatively unstable structure
function of fibrous proteins
support + structural functions
function of globular proteins
metabolic functions
properties of collagen
provides high mechanical strength due to covalent bonds linking triple helix molecules together
flexible and insoluble
found in the outer wall of artery where it prevents bursting under high pressure
properties of elastin
strong and can stretch and recoil without breaking
insoluble
found in alveolar walls where it allows them to stretch during inhalation and recoil during exhalation to expel air
found in blood vessel walls, skin
properties of keratin
very strong molecule - lots of disulfide bonds, the degree of these determines flexibility
insoluble
mechanical protection
waterproof
found in hair, skin, nails, claws, hoofs, scales, horns, fur, feathers
