BIOLOGICAL MOLECULES- carbohydrates Flashcards
Define a monomer.
give some examples
smaller units that form together to form larger molecules (polymer).
-monosaccharides (glucose,fructose,galactose)
-amino acids
-nucleotides
Define a polymer.
Give some examples
molecules formed when many monomers join together
-polysaccharides
-proteins
-DNA/RNA
What happens during a condensation reaction?
A chemical bond is formed and a water molecule is produced.
What happens during a hydrolysis reaction?
A water molecule is used to break a chemical bond between 2 molecules.
name 3 hexose monosaccharides.
glucose
fructose
galactose
they all have the same molecular formula C6H12O6
Name the type of bond formed when monosaccharides react
Glycosidic bonds
draw alpha glucose.
diagram.
draw beta glucose
diagram.
what are the three main groups of carbohydrates called?
monosaccharides, disaccharides, polysaccharides
what are monosaccharides? general formula?
simple sugars, (CH20)n
alpha glucose,beta glucose,fructose,galactose
what are disaccharides and how are they formed?
they are double sugars, formed by the condensation reaction of 2 monosaccharides.
-maltose
-sucrose
-lactose
what are polysaccharides?
large molecules formed from many sugars. ie.many monosaccharides
they are created by condensation reactions between many glucose monomers.
what is starch made up of?
made up of 2 polysaccharides of a-glucose - amylose + amylopectin
description of amylose?
- has 1-4 glycosidic bonds.
-unbranched helix with a coiled structure. - helix can compact to fit in a lot of glucose in a small space.
description of amylopectin?
- has 1-4 and 1-6 glycosidic bonds.
- long branched molecules
-branched structure increases the surface area for rapid hydrolysis back to glucose.
Is starch soluble or insoluble?
starch is insoluble in water and doesn’t affect water potential. Doesnt cause water to enter the cell by osmosis.
where is starch found?
Starch is found in plant cells Store of glucose ,form of chemical energy.
Where is cellulose found?
plant cell wall
What is the function of cellulose?
It’s provide structural strength in the cell wall.
what is cellulose made up of?
- made up of unbranched chains of beta glucose
- 1-4 glycosidic bonds
- cellulose chains are linked together by hydrogen bonds to form strong fibres called microfibrils.
- many hydrogen bonds provide collective strength.
Is cellulose soluble or insoluble?
it is insoluble- wont affect water potential.
Where is glycogen found?
It is found in the animals – mainly in muscle and liver cells. It is a store of glucose which can be released quickly.
What is glycogen made up of?
-made up of alpha glucose
- 1-4 and 1-6 glycosidic bonds.
- highly branched molecule.
-large structure increases surface area for rapid hydrolysis back to glucose.
Is glycogen soluble or insoluble?
Insoluble – won’t affect water potential.
what is a reducing sugar?
all monosaccharides (eg glucose)
and some disaccharides (eg maltose and lactose)
- they gain electrons
Describe the Benedict’s test for reducing sugars?
1.add equal volume of Benedict reagent to a sample .
2.heat the mixture in a water bath between 75-95 degrees
3.positive results: colour change from blue to orange/brick red precipitate forms.
what is a non-reducing sugar?
most disaccharides and
some polysaccharides
you need to break them down into monosaccharides when testing non-reducing sugars.
Describe the Benedict’s test for non-reducing sugars?
1.negative results: Benedict’s reagent remains blue
2. hydrolyse the non reducing suagr. eg sucrose into their monomers (glucose and fructose) by adding 1cm^3 of HCl. heat in a boiling water bath for 5 mins.
3. neutralise with sodium hydrogen carbonate
4. proceed with Benedict’s test as usual/
Describe the test for starch
- add iodine solution
2.positive result: colour change from orange to blue-black
