[OLD] Biological Molecules - Carbohydrates Flashcards
What are monosaccharides?
single sugars
what are disaccharides?
2 sugars bound to each other
Are monosaccharides or disaccharides soluble and sweet tasting
Both
What are polysaccharides?
Many monosaccharides bound to each other?
Are polysaccharides soluble or insoluble?
Insoluble
Are polysaccharides sweet tasting?
No
2 examples of polysaccharides
starch and cellulose
2 examples of monosaccharides or disaccharides
glucose and maltose
how many carbons does glucose contain in its structure?
6
is glucose a monosaccharide of a disaccharide?
Monosaccharide
How are the carbons in glucose arranged?
Into a ring
What are isomers?
the same molecules but with their atoms arranged in a different structure
How many isomers can glucose exist as?
2
Describe the alpha glucose isomer
carbon number 1 in the ring has an H group above the ring and an OH group below the ring
Describe the beta glucose isomer
carbon number 1 in the ring has an OH group above the ring and an H group below the ring
which carbons do bonds form between when glucose molecules bind to each other to form a polysaccharide?
1 and 4
Why does a chain of beta glucoses have every other molecule rotated ‘upside down’?
because the OH groups are on opposite sides of the ring between a carbon 4 and carbon 1, then second molecule must turn upside down in order to line up the 2 OH groups
What is maltose?
a disaccharide formed by 2 alpha glucose molecules binding to each other
What is the bond in maltose?
an alpha 1, 4 glycosidic bond
What reaction makes the bond in maltose?
A condensation reaction
How is the bond formed in maltose?
Between two OH groups. H2O is lost and the 2 glucoses join through the remaining O
Which 2 molecules does starch consist of?
amylose and amylopectin
describe amylose
a straight chain of alpha glucose joined by alpha 1, 4 glycosidic bonds coiled into a spiral
describe amylopectin
branched chains of alpha glucose joined by alpha 1, 4 glycosidic bonds but with 1, 6 glycosidic bonds wherever there is a side chain formed
What is starch the energy reserve in?
plants
why cannot glucose be stored in plants?
it is soluble and would affect osmotic balance of cells
What is glycogen the energy reserve in?
animals
Describe the structural shape of glycogen
Highly branched
Why does glycogen have a lot of branches?
so there are lots of terminal glucose molecules that can be removed by enzymes at the same time i.e rapid release of glucose possible
where is glycogen stored and what for?
in the muscles or liver for sudden movement or maintain blood sugar levels through actions of glucagon and insulin.
What is the structural shape of cellulose?
Linear, unbranched, long, straight chains (where every other monomer is inverted)
what is cellulose used for?
as a structural polysaccharide used in plant cell walls
Why can’t we digest cellulose?
We do not have enzymes with an active site complementary to the shape of a beta glucose molecule
How does cellulose go through our digestive tracts?
as fibre
3 ways in which starch molecules may be different from each other
Different numbers of glucose
Different proportions of amylose/amylopectin
Different number of branches / branches in different places
How is the structure of cellulose linked to its function?
Hydrogen bonds for strength and rigidity in plant cells
Monomer used in starch
Alpha glucose
Is starch found in plants or animals?
Plants
What are the types of bonds found in starch?
Amylose - alpha 1, 4 glycosidic
Amylopectin - alpha 1, 4 glycosidic and 1, 6 branches
What is the structural shape of starch?
Amylose - long unbranched chain coiled into a spiral by hydrogen bonds
Amylopectin - branched chain
What is the function of starch?
Storage of energy
How does the structure of starch and glycogen relate to their function?
Insoluble so osmotically inactive
Folded to make a compact shape
Large molecule too big to cross membranes
Easily hydrolysed to release glucose
Monomer used in glycogen
Alpha glucose
Is glycogen found in plants or animals?
Animals
What is the type of bond found in glycogen?
Alpha 1, 4 glycosidic bonds with 1, 6 glycosidic bonds
What is the function of glycogen?
Storage of energy
Monomer used in cellulose
Beta glucose
Is cellulose found in animals or plants?
Plants
What type of bond is found in cellulose?
Beta 1, 4 glycosidic
How does the structure of cellulose relate to its function?
Insoluble
Fully permeable to dissolved substances
Hydrogen bonds between cellulose strands gives strength
Alternate bonding makes cellulose molecules very straight
Fibres are criss-crossed in cell walls making them resistant to stretching in any direction
