topic 1 Flashcards
monosaccharide
single sugar monomer
disaccharide
sugar made from 2 monosaccharides joined by a glycosidic bond in a condensation reaction
polysaccharide
polymer made up of long chains of monosaccharides joined by glycosidic bonds
what is the difference between alpha and beta glucose?
on alpha glucose the OH group on carbon-1 is below the plain of the ring
what bond/reaction joins monosaccharides?
condensation/glycosidic
what reaction splits a glycosidic bond between monomers?
hydrolysis reaction
glucose structure
contains 6 carbon atoms
major energy source for most cells
very soluble
main form carbs are transported around the body
starch structure
stored in plastids (leaves and potatoes)
produced from glucose in photosynthesis
broken down during respiration for energy
made of many alpha glucose molecules
amylose has a helical structure, 1-4 bonds
amylopectin is branched so more compact, 1-6
multiple chains ends - rapid hydrolysis as more attachment points for amylase enzyme
glycogen structure
insoluble
main carb storage molecule in animals and fungi
1-6 glycosidic bonds
compact so large amount of glucose is stored
stored in liver and muscle cells in animals - power respiration
cellulose
beta glucose
main component of plant cells
very high tensile strength
h-bonds form between adjacent hydrogen molecules
h-bonds between cellulose molecules form microfibrils which then form thicker fibre
fibres cross link - forms cell wall
stops cell wall bursting under pressure
allows turgidity
cannot be digested by most animals
triglyceride
one glycerol and 3 fatty acids joined by a condensation reaction where 3 water molecules are removed and an ester bond forms
ester bond
formed between the carboxyl group of a fatty acid and the hydroxyl group of glycerol in a condensation reaction
saturated fats
NO double bonds between carbon atoms
linear, lie parallel close to each other
more dense than unsaturated
solid at room temp
unsaturated fats
double covalent bonds between at least 2 carbons
cannot lie parallel
less dense than saturated
liquid at room temp
use of lipids
energy store
respiratory substrate
thermal insulation
buoyancy
electrical insulator
insoluble in water - don’t interfere with chemical reactions in cells
protect organs from mechanical shock
phospholipids
glycerol molecules with 2 hydrocarbon tails and a phosphate
phosphate is polar/hydrophilic
fatty acids are not polar/hydrophobic
form phospholipid bilayer in water
amino acid structure
r-groups control bonding between amino acids
control protein structure
polar or non-polar
forming proteins
hydrogen from amino group reacts with the hydroxyl group of the carboxyl group (of another amino acid) to form a peptide bond
water is produced in the condensation reaction
peptide bond
strong covalent bond
polypeptides
formed when many amino acids are bound togehter via a series of condensation reactions
can be several thousand amino acids
when folded its called a protein
protein bonding
ionic
disulphide
hydrogen
hydrogen bonding (proteins)
partially positive r-group and a partially negative r-group
weak bond which can be broken by increase temps or pH
ionic bonding (proteins)
r-group with a full negative charge and one with a full positive charge
stronger than hydrogen
broken by changes in pH
disulphide bonding (proteins)
R-group of 2 cysteine amino acids
very strong covalent bonds
holds together different polypeptide chains in proteins with quaternary structure
protein structure
primary
secondary
tertiary
quaternary
primary structure
linear sequence
number and order of amino acids determined by DNA sequence
only involves peptide bonding
determines 3D shape + properties of protein
varies:
number of amino acids
order of amino acids
type of amino acids used
secondary structure
hydrogen bonds between amine and carboxyl group of adjacent amino acids
most fibrous proteins have this structure
2 different types: alpha helix and b pleated sheet
- both hydrogen bonds occur between the oxygen of carboxyl group and hydrogen of amino group
- (alpha helix) 1 amino acid forms a hydrogen bond 4 places ahead of it in the chain
- (B pleated sheet) polypeptide is folded into regular pleats
tertiary structure
protein becomes folded and takes on a 3D shape
occurs in the ER
5 types of bonds holding the structure together
(ionic, hydrogen, disulphide, hydrophobic/hydrophilic interactions)
globular shape
quaternary structure
3D shape arrangment of more than one polypeptide chain
assosiation of 2 or more polypeptide chains with each other
fibrous proteins
polypeptide form long chains running next to each other
linked by disulphide cross bridges - stable + strong
structural functions a) keratin b)collagen
collagen
found in: tendons, cartilage, bone, sea anemones, egg cases of dogfish
strong
inelastic
flexible
(primary structure) repeat sequence of 3 amino acids, every 3rd amino acid is glycine
(quaternary) 3 helical polypeptides are wound very closely around each other, held by h-bonds
forms a tight coil
triple helix - tropocollagen
staggered ends so no line of weakness
globular proteins
most tertiary structure some quaternary
roughly globular
shape determines its function