Carbodydrates Flashcards
What is monosaccharide?
A single sugar unit, which joins to form a polysaccharide.
What is a disaccharide?
When ONLY two monosaccharides join together.
What is the bond that joins monosaccharides together?
Glycosidic bond
What type of bond are glycosidic bonds?
Covalent
How are the glycosidic bonds formed between the monosaccharides?
Condensation reaction, produces water molecules.
What is the difference between alpha and beta glucose?
The hydroxyl group is attached differently on carbon 1 of each.
Why is the solubility of glucose important?
It can be dissolved in the cytosol.
Similarity and difference between constitutional (structural) isomers and stereoisomers?
Same chemical formula.
In constitutional isomers the atoms are attached differently whereas in stereoisomers the atoms are geometrically orientated differently.
Define isomer
Compounds with the same chemical formula but different chemical structure e.g. alpha beta glucose
Two types of isomers?
Constitutional and stereoisomers
Why is glucose soluble in water?
Because of the hydrogen bonds that can form between the hydroxyl group and the water molecules.
What is ribose present in?
What is deoxyribose present in?
RNA nucleotides
DNA nucleotides
Monosaccharides with
- 3 carbons?
- 4 carbons?
- 5 carbons?
- 6 carbons?
3- triose
4- tetrose
5- pentose
6- hexose
Name two pentose carbohydrates.
Ribose
Deoxyribose
What do two alpha glucose molecules react to make?
Maltose
How is sucrose formed?
alpha glucose + fructose
How is lactose formed?
alpha/beta glucose + galactose
What is lactose?
The sugar found in milk
What is sucrose?
Found mainly in plants and in sugar canes and used to make ‘table sugar’.
What is maltose?
The sugar found in large concentrations in germinating seeds, first product of starch digestion
What two starch polysaccharides can alpha glucose form?
amylose
AND
amylopectin
What are amylose and amylopectin collectively known as?
Starch
Bonds in amylose?
Amylose - 1,4 glycosidic bonds
Bonds in amylopectin?
Amylopectin - 1,4 and 1,6 glycosidic bonds every 25 subunits
Where and how is starch used?
In plants, it is the product of photosynthesis and is an energy story.
What is the structure of amylose and how does it help it’s function?
The angle formed by the 1,4 glycosidic bonds means that the chain twists to form a helix, which is further stabilised by hydrogen bonding within the molecule.
This makes the molecule compact and much more insoluble than the glucose that made it.
What is the structure of amylopectin and how does it help it’s function?
Branched due to 1,6 glycosidic bonds, and so much more compact than amylose. Makes it good for storage.
What is the animal and fungi equivalent to starch?
Glycogen
What is the structure of glycogen?
Very similar to amylopectin, 1,4 and 1,6 glycosidic bonds every 10 subunits, very very branched and very very compact.
How does the structure of glycogen aid it’s function?
animals, branch, compact, energy
Glycogen is very branched and compact so more energy storage and this helps as glycogen is an energy store in ANIMALS, and animals are much more mobile than plants so need more energy.
The branching means that there are many free ends where glucose molecules can be added or removed EFFICIENTLY.
What happens when starch or glycogen are needed to release glucose for respiration?
They undergo HYDROLYSIS reactions.
Why is branching useful?
Glucose molecules can be added do removed quickly via HYDROLYSIS.
Why is compactness useful?
Much more energy can be stored.
Why is being insoluble useful?
Can be used for long term storage.
What is cellulose?
Key component of plant cell walls, composed of monomers of beta glucose.
What is the molecular structure (arrangement) of cellulose?
- beta glucose cannot react the same way that alpha glucose does due to the positioning of the hydroxyl groups on its carbon 1 and 4.
- thus EVERY ALTERNATE beta glucose must flip over to get the hydroxyl groups close enough to react
- this way, the a 1,4 glycosidic bond is formed.
What is the overall structure of cellulose?
-due to the way in which beta glucose joins up to form bonds, cellulose does NOT coil up or branch like alpha glucose polysaccharides, instead it forms a STRAIGHT chain molecule.
What is the further structure of cellulose?
Cellulose chains form hydrogen bonds with each other to form MICROFIBRILS. Microfibrils join together to make MACROFIBRILES. Macrofibrils join to make fibres.
How does the structure of beta glucose aid it’s function?
The fibres are STRONG and INSOLUBLE , and this is helpful as cellulose helps make cell walls in plant cells
What is cellulose in our diet?
Cellulose forms the ‘fibre’ and roughage required for a healthy digestive system.
