Biological molecules Flashcards
specific heat capacity
amount of energy needed to heat 1kg of a substance by 1 degree Celsius
water
is polar, electron spends more time around the O - making it negative, and H positive, water molecules bond together via hydrogen bonds
latent heat of vaporisation
the amount of energy required to change the physical state of a substance
solvent
liquid substance which can dissolve a wide range of molecules
adhesion
the tendency of molecules to be attracted to other molecules of a different type
cohesion
the tendency of molecules of a substance to attract one another
which elements make up alpha-glucose?
carbon, oxygen and hydrogen
monomers
can be defined as molecules that can be joined together with additional identical molecules to make larger molecules called polymers. monomers are a single molecule of them
carbohydrates general formula?
CnH2nOn
monosaccharides
single sugars, classified according to the number of carbon atoms they contain, 3 carbon sugars - trioses, 5 carbon sugars - pentoses, 6 carbon sugars - hexoses
polymers
comprised of repeating units of monomers
what is the process called of joining molecules together?
polymerisation
what is a condensation reaction?
the removal of a H2O
what is a hydrolysis reaction?
addition of water to break bonds
two examples of pentose sugars?
ribose and deoxyribose, found in RNA and DNA
how do glucose give you energy?
has many C-H bonds, which can be broken to release energy during respiration to make ATP
disaccharides
formed when two monosaccharides are joined together in a condensation reaction, the bond formed between the two are known as glycosidic bonds, function as energy sources, soluble and easily transported
reducing sugars
all monosaccharides and some disaccharides are known as reducing sugars, reducing sugars will reduce Benedict’s reagent from blue to an orange red in colour
starch
mixture of two polymers of alpha glucose, one of the polymers is amylose joined by 1,4 glycosidic bonds and will cause them to have a helical shape, helical shape is compact and makes it a good molecule for energy storage, amylopectin is the other polymer and is branched
glycogen
structurally similar to amylopectin but has many more branches and the branches are shorter, the increased number of branches allows faster hydrolysis of glucose
cellulose
main structural polysaccharide found in plant cell walls, it is an unbranched polymer of thousands of beta glucose molecules, it is a straight chain
lipids
they are marcomolecules, do not contain repeating units or monomers, contains the elements: C,H and O but in different proportions to carbohydrates
triglycerides
they are not monomers or polymers, composed of three fatty acids joined to a glycerol molecule, reserves energy, insulation, mechanical protection, metabolic water, if all or most are saturated then a saturated fat is formed, types of fatty acids effects it’s chemical and physical properties, tend to be solid at room temperature, fats are most often found as energy stores in animals, molecule is insoluble, if all or most are unsaturated then an oil is formed, oil is found in plants as energy stores in seeds
phospholipids
hydrophilic phosphate head and hydrophobic fatty acid tails, one fatty acid can be replaced by a polar phosphate group
cholesterol
cholesterol molecules located between the tails of the phospholipid molecules where they serve to stabilise the membrane, classed as lipids although they belong to different subgroup - steroids
amino acids
20 different amino acids polymerised into proteins, all amino acids have same general structure, the only difference is the R group, in an amino acid there is 3 groups: amino group, R group and carboxyl group, amino acids bond together by a condensation reaction with water being lost and the bond formed is called a peptide bond
polypeptide
can contain any number if each of the 20 amino acids
primary structure in proteins
describes type, number and sequence in which amino acids are joined together, this structure forms the polypeptide backbone
secondary structure in proteins
the way the polypeptide chain/backbone is coiled or folded, either it is coiled like a spring to form an alpha helix or can line up side by side to produce a beta-pleated sheet, secondary structure held together by hydrogen bonds
tertiary structure in proteins
produced when the secondary structure is further folded and coiled, maintained by disulphide bridges, ionic bonds, hydrophobic interactions, hydrogen bonds
quaternary structure in proteins
if a protein is made up of more than one polypeptide chain then it has quaternary structure, these are globular proteins that contain a non-protein component called the prosthetic group, for example haemoglobin
globular proteins
very diverse in structure, well developed tertiary or quaternary structure, soluble in water, tertiary structure critical to function, polypeptide chains are folded into a spherical shape, amino acid sequence is varied, catalytic - enzymes, regulatory - hormones, transport - haemoglobin, protective - antibodies
conjugated protein
a globular protein with a prosthetic group
fibrous proteins
proteins in which secondary structure dominates, form long shapes and are only found in animals, insoluble in water, very tough physically, may be stretchy, parallel polypeptide chains in long fibres or sheets, amino acid sequence not varied, structural role in cells and organisms - for example collagen or keratin, contractile - for example myosin or actin
name given to positive ion?
cation
name given to negative ion?
anion
meaning of the word organic?
contains carbon, hydrogen and oxygen
biuret test
tests for proteins, adding sodium hydroxide and copper sulphate to a food sample, if protein present the biuret reagent changes colour from blue to purple
iodine test
tests for starch, iodine solution added to sample, if starch present colour changes from orange/brown to blue-black
emulsion test
tests for lipids, add ethanol to sample and shake for 60 seconds, put solution into water, if lipid present then solution goes milky colour, no lipid present the solution remains colourless
benedict’s test for reducing sugars
add benedict’s reagent and heat in a water bath, if sample changes colour from blue to either green, yellow, orange or brick red then reducing sugar present, reducing sugars can reduce benedict’s reagent if heat is added, benedict’s changes colour from blue to brick red
benedict’s test for non-reducing sugars
if test for reducing sugars is negative then test for non-reducing sugars, heat sample with dilute hydrochloric acid- hydrolysises glycosidic bonds - and neutralise with sodium hydrogencarbonate, heat sample with benedict’s solution, if sample forms either green, yellow, orange or brick red ppt then non-reducing sugar present
calibration curve
series of known concentrations of a solution can be prepared and the absorbance of each on measured using colorimeter, graph can be plotted, calibration curve can be used to calculate the concentration of glucose in the unknown sample
chromatography
dip a sheet of absorbent paper into a solvent, solvent will slowly rise up the paper, spot chemicals onto the paper near the bottom but above solvent level, molecules contained in the spots will be carried up the paper, carried at a speed proportional to their size and solubility
RF value claculation
RF = distance moved by compound/distance moved by solvent
