3.1.2 Carbohydrates Flashcards
main functions of carbohydrates
Short term energy storage (ATP)
Long term energy storage
Building bonds
What elements make up carbohydrates
Oxygen
Carbon
Hydrogen
What does a monosaccharide mean?
Mono=one
Saccaride =sugar
What is the name of the molecule when you combine 2 monosaccharides
Disaccharide
What carbohydrate do you make when you combine many monosaccharides?
Polysaccharide
Give examples of polysaccharides
Starch, glycogen , cellulose
What class of carbohydrate is
A) soluble in water
B) sweet tasting
Monosaccharides and disaccharides
(Answer for both part A and B)
What is the general formula for a monosaccharide
(CH2O)n
What are the three monosaccharides?
Triose(3 carbons)
Penrose (5 carbons)
Hexose (6 carbons)
Draw hexose
H O
\ //
H-C-OH
|
HO-C-H
|
H-C-OH
|
H-C-OH
|
CH2OH
What the different between alpha and beta glucose ?
On alpha the OH on the 1st carbon is down
Draw beta glucose
Define isomer
Molecules that have the same chemical formula but different structural formula
How is a disaccharide formed?
2 monosaccharides joined by covalent bonds-condensation reaction
What is a condensation reaction?
Water being a product
How to form maltose?
Alpha glucose + alpha glucose = maltose + H2O
G2 Manky
How to make lactose ?
Alpha glucose + galactose = lactose + h2O
(GGL)
How to make sucrose?
Alpha glucose + fructose = sucrose + H2O
(GFS)
What is a hydrolysis reaction?
Water inserted into a disaccharide to split it into 2 monosaccharides
Formula for disaccharides
Cn(H2O)n-1
What are reducing sugars? And what are they called reducing?
A)All monosaccharides and disaccharides
B) they will gain an electron (oil RIG)-
Reduction of charge Is Gain of electron
Method for testing for reducing sugars
1) add Benedict’s reagent to about 2 cm3 of test solution
2) shake and heat for a few minutes in 95oC in a water bath
3) a precipitate forms
What are the results in reducing sugars test?
0%= blue(sucrose)
0.5%=green
1%= yellow
2%=BRICK RED
Is Benedict’s test quantitative or qualitative?
Qualitative (interpretation based)
Method to test for non-reducing sugars
1)Test for reducing sugars - if negative continue with method below
2) and 2cm3 dilute hydrochloric acid to 2cm3 of the sample solution and boil for a few minutes to hydrolyse the glycosidic bond
3) add sodium hydrogen carbonate solution to neutralise the hydrochloric acid
4)re test with Benedict’s reagent
5) if non reducing sugar present then original solution will change color
What is a polysaccharide?
Many monosaccharides bonded together
What are the 2 types of polysaccharides?
1) storage-starch and glycogen
2) structural- cellulose
What is the role of starch?
It’s an insoluble store of glucose in plants
What makes starch?
2 glucose polymers - amylose and amylopectin
What bond and molecule makes amylose?
1,4 glycosidic bonds and alpha glucose
What is the shape of amylose?
How is it formed?
Why is this beneficial ?
1) coils into a helix
2) formed by the angle of glycosidic bonds - hydrogen bonds help hold the stricter in place
3) its compact and can store a lot(of amylopectin)
What formed amylopectin?
What are the bonds?
Alpha glucose
1,4 and some 1,6 glycosidic bonds (every 25 units)
Why is the strictest of starch beneficial?
1) compact shape - a lot can be stored in a little
2)insoluble - dosent affect water potential
3) easily hydrolysed- to alpha glucose for respiration
4) branched form- means that enzymes can act in multiple ends at the same time meaning it’s quick for the glucose monomer to be released
Method to test for starch
Put 2cm3 of iodine on test subject
If positive test subject turns a blue/black
Where is glycogen found and what does it store?
In animals and bacteria-in animals it is stored as small grains mainly in the muscles and the liver
What forms glycogen?
Bonds
Alpha glucose
1,4 and 1,6 glycosidic bonds
Function to structure with glycogen
1)compact shape
2)insoluble
3) easily hydrolysed
4) the speed of hydrolysis if important- it has more branches than starch so it’s quicker
What forms cellulose?
Bonds?
Beta glucose
1,4 glycosidic bonds
Why is every 2nd glucose flipped 180 degrees in cellulose
To form the oxygen bridge for the condensation reaction
Structer of cellulose?
Long unbranched parallel chains boned with hydrogen bonds
Description of cellulose
Cellulose molecules become tightly cross linked to form bundles (microfibrils) these join together to form macrofibril which bundle to form cellulose fibres. The cell wall has multiple fibres in different directions which increases strength
Microfibrills are very strong and rigid to give huge structural stability to the cell
