biological molecules - 3.12 (carbohydrates) Flashcards
what is a monomer?
monomers are the smaller units from which larger molecules are made
what is a polymer?
molecules made from a large number of monomers joined together
name 3 examples of monomers
monosaccharides, amino acids, nucleotides
what is a condensation reaction?
joining of two molecules, with the formation of a chemical bond and involves the elimination of a molecule of water
what is a hydrolysis reaction?
breaks a chemical bond between two molecules and involves the use of a water molecule
what are monosaccharides?
the monomers from which larger carbohydrates are made
name 3 common monosaccharides
glucose, fructose, galactose
what is maltose?
a disaccharide formed by the condensation of two glucose molecules
what is sucrose?
a disaccharide formed by condensation of a glucose monomer and a fructose molecule
what is lactose?
a disaccharide formed by condensation of a glucose molecule and a galactose molecule
what polysaccharides are formed from the condensation of alpha-glucose?
starch, glycogen
what polysaccharide is formed from the condensation of beta-glucose?
cellulose
what is the structure of a starch molecule?
Chains may be branched or unbranched. Unbranched chain wound into a tight helix shape, making it very compact. Made up of alpha-glucose monosaccharides linked by glycosidic bonds (1-4) formed by a condensation reaction. Branched form has 1-4 and 1-6 alpha-glucose glycosidic bonds. Consists of amylose and amylopectin.
What is the main role of starch?
storage of glucose/energy
how is the starch structure suited to its function?
-insoluble - doesn’t affect water potential, so water is not drawn into cell by osmosis
- large and insoluble - doesn’t diffuse out of cells
- compact - a lot can be stored in a small space
-when hydrolysed. alpha-glucose is formed which is easily transported and readily used in respiration
-branched form has many ends - each of which can be acted on by enzymes simultaneously meaning glucose monomers are released very rapidly
what is the structure of glycogen?
highly branched - alpha-glucose molecules joined by alpha 1-4 glycosidic bonds and alpha 1-6 branches every 20-30 monomers.
what is the function of glycogen?
- main carbohydrate storage of glucose in animal cells.
how is the structure of glycogen related to its function?
- insoluble - does not tend to draw water into cells by osmosis and doesn’t diffuse out of cells
-compact - a lot stored in a small space - ## more highly branched than starch - has more ends that can be acted on simultaneously by enzymes. This rapidly releases glucose monomers, which are used in respiration. Useful as animals are more active than plants and therefore have a higher metabolic rate and therefore higher respiratory rate.
what is the structure of cellulose?
straight unbranched chains, joined by 1-4 beta-glucose glycosidic bonds
- these chains run parallel to each other, allowing hydrogen bonds to form cross-links between adjacent chains. The sheer overall number of hydrogen bonds adds collective strength to the molecule, making it the valuable structural material that it is.
- these molecules join together to form microfibrils which in turn are grouped together to form fibres all of which provides yet more strength.
what is the function of cellulose?
main structural component of cell walls
