Biology - 1.1, 1.2 - monomers and polymers, carbohydrates
what is a monomer?
smaller units from which larger molecules are made
what is a polymer?
molecules made from a large number of monomers joined together
give 3 examples of monomers
amino acids, monosaccharides, and nucleotides
describe a condensation reaction
joining of 2 molecules with the formation of a chemical bond and the loss of a water molecule
describe a hydrolysis reaction
the chemical bond between 2 molecules is broken and a water molecule is used
what is a monosaccharide
monomers used to make larger carbohydrates
give 3 examples of a monosaccharide
glucose, fructose, galactose
are monosaccharides water soluble
yes - they have a large number of OH groups which can form hydrogen bonds in water
what is an isomer
a different form of the same molecule
which glucose has OH above the ring
beta
which glucose has OH below the ring
alpha
how is a glycosidic bond formed
carbon 1 loses a hydrogen molecule and carbon 4 loses an OH group, causing the loss of one water molecule and the formation of an oxygen bridge (covalent)
what is maltose
alpha glucose + alpha glucose
what is sucrose
glucose + fructose
what is lactose
alpha glucose + galactose
describe the structure of glycogen (3)
highly branched every 10 monomers
condensation of alpha glucose
well compacted and stored
describe the function of glycogen
used as a carbohydrate store in animals, found in muscle and liver cells
branched structure and lots of terminal glucose means that glucose may be hydrolysed by enzymes simultaneously
where is glycogen frequent
muscle and liver cells, where rate of respiration is higher and lots of glucose is needed
describe the structure of starch
30% amylose, 70% amylopectin
describe the structure of amylose in starch
unbranched chain of glucose molecules
bonded by 1-4 glycosidic bonds
coiled and compact storing lots of energy
describe the structure of amylopectin in starch
branched chain of glucose molecules
bonded by 1-4 and 1-6 glycosidic bonds
acted on simultaneously due to frequent terminal glucose
give 3 features of starch
large and insoluble so cannot diffuse out of cells
insoluble so does not affect water potential
compact so lots stored in a given volume
describe the structure of cellulose
condensaton of beta glucose
every other monomer is inverted 180 to allow for OH group and O group to be available for 1-4 glycosidic bonding
inversion causes strong hydrogen bonds
describe the function of cellulose
long straight chains of beta glucose with strong hydrogen bonds between parallel chains creates microfibrils, main component of cell walls due to strength
do microfibrils have high tensile strength
yes - allows for the cell to be stretched without bursting from hydrostatic pressure as a result of osmosis, allowing turgidity
what are macrofibrils
collections of microfibrils
form a mesh like material used to strengthen cell walls
what bond is formed between 2 monosaccharides
glycosidic
how is a polysaccharide formed
formed by the condensation of many monomer units