Carbohydrates Flashcards
Give the properties of monosaccarhides
Hydrophilic - Soluble in water because they have a large number of hydroxyl groups, which can form hydrogen bonds with water molecules
What is a monosaccharide?
Monomers from which larger carbohydrates are formed
Give examples of monosaccarhides
Glucose, fructose and galactose
Describe the difference between alpha and beta glucose
The position of the hydroxyl group on each carbon 1 differs, in alpha glucose its below carbon 1 and beta glucose is above carbon 1
How do disaccharides form?
When two monosacharides chemically bond together in a condensation reaction releasing water from a hydrogen from one monosacharide and a hydroxyl from the other.
How is maltose formed?
Two alpha glucose monosacharides chemically bonding together in a condensation reaction.
What is a glycosidic bond?
The bond that is formed when two monosacharides bond during a condensation reaction is a glycosidic bond
What happens when you add water to a disachharide?
It reforms back into a monosachharide by breaking the glycosidic bond in a hydrolysis reaction.
How is sucrose formed?
Glucose and fructose
How is lactose formed?
Glucose and galactose
Describe the differences between glycogen and starch.
- Glycogen is found in animals whereas starch is found in plants.
- Glycogen has many more branched ends than starch
Give the structure of glycogen and describe how this relates to its function.
- Compact so a lot can be stored in a small space.
-Insoluble so does not draw water in by osmosis and does not effect water potential
-More higher branched than starch meaning it has more ends that can be acted simultaneously on by enzymes so it is more rapidly broken down into glucose monomers which are used in respiration and this is important because animals have a higher metabolic rate and therefore a higher rate of respiration than plants.
Large so it cannot diffuse out of cells.
Name the polysachharides made by polymers of alpha glucose
Amylose, amylopectin and glycogen
How is cellulose formed?
Monomers of beta glucose where every second beta glucose is flipped.
Give a key feature of cellulose
This is an unbranched polysacharride
Describe the structure of cellulose and how this relates to its function
Forms long, straight unbranched chains of beta glucose , which are parallel allowing hydrogen bonds to form between the chains of beta glucose , which also form crosslinks, and because a large number of hydrogen bonds are made this makes cellulose very strong. These cellulose molecules grouped together are called microfibrils, meaning in plant cell
What is it called when cellulose molecules join together? And how does this relate to its function?
Microfibrils, then these will join together to make larger macrofibrils, then these join together to form cellulose fibres. This provides yet more strength to cellulose.
How does the strength of the cellulose allow the cell wall to carry out its functions?
Cellulose is very strong meaning that when water moves through osmosis into the permeable membrane of the cell wall, outwards pressure from the contents of the cell is resisted by the inwards pressure of the cell wall due to its strength, preventing the plant cell from bursting. This means the plant cell is turgid.
Why is glucose extremely soluble in water?
Because it has a large number of hydroxyl groups, and these hydroxyl groups are polar due to the slight negative charge on the oxygen atoms and the slight positive charge on the hydrogen atoms. This means these hydroxyl groups can form hydrogen bonds with water molecules, making glucose hyrdrophilic.
What two molecules make up starch?
Amylose and amylopectin
How is amylose formed?
Polymer of alpha glucose molecules forming glysosidic bonds in a condensation reaction removing one water molecule for each bond.
This then twists into a complex helix ( helping starch become a very compact molecule) with hydrogen bonds forming between glucose molecules along the chain.
How is starch converted back into glucose?
Water is used to break the glysosidic bonds in a hyrdolysis reaction
Give a key difference between amylose and amylopectin
Amylose is an unbranched polysaccahride whereas amylopectin is a branched polysaccarhide
How does the structure of starch relate to its function?
- Insoluble meaning the water potential is not affected so water is not drawn into cells by osmosis
- Helix shape meaning it is very compact so alot can be stored in a small space
-When hydrolysed it forms alpha glucose which is easily transported and readily used in respiration
-Branched form has many ends so enzymes can act simultaneously on each branch meaning glucose monomers are released very rapidly
-Large so it does not diffuse out of cells, cant pass across cell membranes
