Carbohydrates Flashcards
Roles of carbohydrates
Provide energy.
Energy Storage.
Provide Strength.
What do carbs contain (Structure)
Carbon, Hydrogen, Oxygen
What are the three groups of carbs
Monosaccharides, Disaccharides, Polysaccharides
What is a monosaccharide
Simple sugars, General formula (CH20)n, where n can be 3-7
What are Disaccharides
‘Double sugars’ formed from 2 monosaccharides
What are polysaccharides
Large molecules formed from many monosaccharides
Examples of monosaccharides
Glucose (Energy source for cell),
Fructose (Found in fruit),
Galactose (Sugar in milk)
Whats the most important monosaccharide and why
Glucose, Main form in which carbohydrates are transported around the body of animals, major energy source for most cells, highly soluble
What are the three structures of glucose
Straight chain, ring, simplified ring
How are the Carbons numbered in a glucose ring
Taking the position of the individual O atom (in a ring), and going in a clockwise direction, each carbon atom is numbered from 1 to 6.
What are the different forms glucose exist in called
Structural Isomers
What are two common isomers called
Alpha and Beta glucose
Whats the only difference between the two glucose isomers
The position of the -OH group attached to C1
Where is the -OH in an alpha glucose
Below C1
Where is the -OH in a Beta glucose
Above C1
Solubility of fructose
Very soluble - main sugar in fruits and nectar, sweeter than glucose
Solubility of Galactose
Not as soluble as glucose - Has important role in the production of glycolipids and glycoproteins
Examples of dissaccharides
Maltose (Energy source for cell).
Sucrose (Found in fruit).
Lactose (Sugar in Milk).
How are dissaccharides formed?
When 2 monosaccharide molecules join together with a glycosidic bond
How is a glycosidic bond formed
Forms between a hydroxyl (OH) group on one monosaccharide molecule and a Hydroxyl group on another monosaccharide
Where is the bond in Maltose, Sucrose and lactose
Between C1 on one monosaccharide and C4 on the other
What type of reaction is a glycosidic bond and why
Condensation Reaction - The bond creates water
How can you break a glycosidic bond
Adding water in a hydrolysis reaction
How is maltose formed
two glucose molecules joined by an alpha 1-4 glycosidic bond
How is sucrose formed
From a glucose and a fructose joined by an alpha 1-4 glycosidic bond
How is lactose formed
From a galactose and glucose joined by a beta 1-4 glycosidic bond
How are polysaccharides formed
Condensation reactions
What are polysacchardies used for mainly
Energy store, and as structural components of cells
What are the major polysaccharides
Starch and cellulose in plants, glycogen in animals
What are the two structural units of starch
amylose (Straight chains)
Amylopectin (Branched chains)
Structure of amylose
Contains glucose molecules joined mainly with alpha 1-4 glycosidic bonds which result in unbranched chains forming a compact helical structure
Structure of amylopectin
contains glucose molecules joined by alpha 1-4 glycosidic bonds, but it also contains many more alpha 1-6 glycosidic bonds. 1-6 bond causes branches
How much amylopectin in starch
70-80%
Where is starch stored
Stored as intracellular starch grains in plastids
How is starch produced
From glucose made during synthesis. It is broken down during respiration to provide energy and is also a source of carbon for producing other molecules
What is glycogen
Animals store carbohydrates as glycogen - has similar structure to part of starch molecule
How is glycogen stored
As small granules particularly in muscles and liver
Properties of glycogen
Less dense, more soluble than starch, broken down more rapidly.
Glycogen structure
1-4 glycosidic bonds and also 1-6
What is cellulose
It is another polysaccharide, main part of plant cell wall. Most abundant organic polymer
Properties of cellulose
Unlike starch, very strong, prevents cells from bursting when taking in excess water
Structure of cellulose
long chains of beta glucose molecules 1-4 glycosidic bond. Glucose chains form rope-like microfibrils layered to form a network
How do every other glucose molecules rotate
through 180 degrees so that hydroxyl groups are adjacent
Why do cellulose have hydrogen bonding
Gives tensile strength, ideal for providing structural support to plant cells
