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
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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