1.2- biological molecules 1 Flashcards
what are organic compounds?
-compounds which contain carbon atoms
-they also contain; hydrogen, oxygen and sometimes nitrogen suplfur and phosphorus
how many bonds can each carbon make
4
why are carbohydrates important?
-important in cells as a usable energy store
-storing energy, and in plants, fungi and bacteria and form an important part of the cell wall
-
basic structure of carbs
-made up of carbon, hydrogen and oxygen
-3 main groups; monosaccharides, disaccharides, polysaccharides
what are monosaccharides?
-simple sugars in which there is one oxygen atom and two hydrogen atoms for each carbon atom present in the molecule
-general formula can be written as (CH2O)n+
triose sugars
-n=3
-have 3 carbon atoms and the molecular formula C3H6O3
-they are important in mitochondria, where glucose is broken down into triose sugars during respiration
pentose sugars
-n=5
-have 5 carbon atoms and the molecular formula C5H1O5
e.g. ribose and deoxyribose
hexose sugar
-n=6
-have six carbon atoms and the molecular formula C6H12O6
-often taste sweet including glucose, galactose and fructose
examples of monosaccharides
glucose
fructose
ribose
examples of disaccharides
sucrose
maltose
lactose
exmaples of polysaccharides
starch
cellulose
glycogen
how do monosaccharides form disaccharides
condenstaion reaction occurs to join the 2 monosaccharides, monosacs joined by a glycosidic bond (covelant)
-a molecule of water is removed
which disaccharide is not a reducing sugar
sucrose
test for reducing sugars
-add benedicts solution
-heat in hot water bath 90degrees
-reducing sugar reacts with benedicts and reduces copper (ii) ions to copper (i) ions
-colour changes from blue to orange/red
test for non reducing sugars
-heat non reducing sugar with few drops of hydrochloric acid
-neutralise with sodium hydrogen carbonate
-this produces sugars which are monosacs to give a pos benedicts test
why are monosaccharides soluble in water
have lots of hydroxyl (OH) groups which can readily engage in H bonding with water
what are polysaccharides
-polymers containing monosaccharides linked by glycosidic bonds
-formed by condensation reactions
-mainly used as energy store and structural components
e.g. starch and cellulose
oligosaccharides vs polysaccharides
-3-10 is a oligosaccharide
-more than 11 sugar units is a polysaccharide
why are polysaccharides so good for storage
-the glygosidic bond is easily broken meaning monosaccharides can be released quickly for respiration
-can be very compact, so many stored in cells
-not soluble, no no effect on water potential
starch- amylose
-long chain of a glucose
-unbranched with 1,4 glycosidic bonds
-coiled to make it compact and good for storage
starch-amylopectin
-long chains of a glucose
-branched
-1,4 and 1,6 glycosidic bonds
-branches allow enzymes to break down easily so glucose can be released quickly
cellulose
-polymer of b glucose
-each monomer inverted
-forms chains which run parallel with H bonds between the chains to form microfibrils
-these are very strong
-structurally important in plant cell walls as it is fibrous
glycogen
-animals store carbs as glycogen
-made of a glucose
-1,6 glycosidic bonds
-branched structure
-glycogen stored as small granules
-broken down more rapidly than starch, less dense and more soluble
-to meet higher metabolic demand in animals
what are the 2 types of lipids
1.triglycerides
2.phospholipids
2 examples of triglycerides
1.fats
2.oils
what 2 molecules make up triglycerides
glycerol
3 fatty acids
what bond joins glycerol and fatty acids
ester
triglyceride formation
-triglyceride formed when each hydroxyl group on the glycerol combines with carboxyl group on fatty acid
-this is a condensation reaction
-esterfication
-water removed in reaction
how to tell if it is saturated or unsaturated
-unsaturated have double bonds
-they have a low melting point and tend to be liquid at normal temps
saturated fatty acids
-carbons joined by single covelant bond
-carbon atoms bonded to max number of atoms
-chain is relatively straight
-tend to be solids (fats) at room temp
unsaturated fatty acids
-one or more double covelant bond present in carbon chain
-not bonded to max number of other atoms
-2 or more have double bonds
-usually liquid at room temp (oils)
phospholipid structure
-2 fatty acid chains attached to glycerol
-polar phosphate group
what do phospholipids make up
plasma membranes
-hydrophillic (polar) head and hydrophobic tail
summary of phospholipids
-Glycerol phosphate (polar) head is hydrophilic.
-non polar, oily, hydrophobic tail
-said to be amphipathic
-gived cell membranes fluid properties and allow lipid soluble substances through
bonds in proteins
-peptide between amino acids
-hydrogen
-disulphide’
-ionic
hydrogen bonds
singally weak
-collectively strong
-easily broken
disulphide bond
Formed in an oxidation reaction between 2 sulfur containing groups.
Results in a strong covalent bond.
ionic bonds
-Not as common
-Form between strongly positive and negative amino side chains.
-Can be known as salt bridges.
primary protein structure
-sequence of amino acids in polypeptide chain
-peptide bonds
secondary protein structure
-a helices
-b pleated sheets
-form as a result of hydrogen bonding between different amino acids in the chain
tertiary protein structure
-secondary structure folds up to form a very precise 3D structure
forces responsible;
1.hydrogen bonds
2.ionic bonds
3.disulphide bonds
4.van der waals forces
how can all 4 forces be split
hydrogen- high temp and altered pH
ionic- changing pH
disulphide- reducing agent
van der waal- rise in temp
what is van der waals forces
-weak forces of attraction between non polar groups
quaternary structure
- Some proteins consist of more than one polypeptide chain held together in a precise three-dimensional structure
-2 main types are globular and fibrous
-can also involve the addition of non-amino acid derived groups known as prosthetic groups
globular proteins
-form a spherical mass
-They fold up so that hydrophillic groups are on the outside and hydrophobic groups are inside the molecule
-e.g.haemoglobin
fibrous proteins
-form long chains or fibres
-fibrous nature makes them insoluble in water
-form triple helix of polypeptide chains
-held by hydrogen bonds
-e.g. collagen
