[bio] biological molecules Flashcards
definition of condensation reaction
chemical reaction whereby 2 or more simple molecules are joined together to form a larger biological molecule with the removal of water
definition of hydrolysis
splitting up of a complex biological molecules into its component units with the addition of water
bond formed during condensation reaction?
glycosidic bond
elements of carbohydrates
carbon, hydrogen, oxygen
special thing about elements present?
ratio of hydrogen atoms to oxygen atoms is 2:1
3 main groups of carbohydrates
monosaccharides, disaccharides, polysaccharides
examples of monosaccharides
glucose, fructose, galactose
properties of monosaccharides
- generally sweet-tasting
- soluble in water (able to lower water potential in cells)
why do we not store glucose in our bodies?
glucose is a monosaccharide, soluble in water, will lower the water potential of our cells, cells will burst when too much water enters
what happens to excess glucose in our bodies?
excess glucose goes through condensation reaction to form glycogen, which is insoluble in water
examples of disaccharides & their monomers
- maltose - glucose + glucose
- lactose - glucose + galactose
- sucrose - glucose + fructose
types of polysaccharides and their examples and where they are found
storage polysaccharides (starch in plants and glycogen in animals) and structural polysaccharides (cellulose in plants)
why are starch and glycogen suitable as storage polysaccharides
- insoluble in water, won’t affect water potential of cells
- compact, take up less space than individual glucose molecules that make up a glycogen/starch molecule
- too large to diffuse through the cell membrane, hence they will stay in the cell
- easily hydrolysed when needed
structure of starch and glycogen
starch - long straight chains (amylose) or branched chains (amylopectin)
glycogen - highly branched chains
how are storage polysaccharides formed
condensation reaction of large numbers of glucose molecules
structure of structural polysaccharides
can be in long straight/branched chains
properties of cellulose
- insoluble in water
- structure is rigid
- provide mechanical support for the plant
- able to resist expansion when water enters by osmosis
functions of carbohydrates
- forms lubricants like mucus
- forms nectar
- deoxyribose sugar/ribose sugar are used in the formation of nucleic acids like DNA
- glucose is a substrate of respiration
- cellulose forms the supporting structure of plants
elements that make up lipids
carbon, hydrogen, oxygen
number of oxygen as compared to hydrogen and carbon
much less oxygen as compared to carbon and hydrogen
example of lipids
triglycerides and phospholipids
properties of lipids
insoluble in water, but soluble in organic solvents like alcohol
what makes up a triglyceride
3 molecules of fatty acids and 1 molecule of glycerol
what are fatty acids
a long hydrocarbon chain that has a carboxyl functional group (COOH)
difference between saturated and unsaturated fatty acids?
saturated: absence of carbon-carbon double bonds
unsaturated: presence of 1 or more carbon-carbon double bonds
properties of fatty acids
- hydrophobic (do not mix well with water)
- uncharged