Biological Molecules: Carbohydrates Flashcards
What is a monosaccharide?
A monomer from which larger carbohydrates can be made.
What is an isomer?
Molecules with the same molecular formula, but have different arrangements of their atoms
Name three monosaccharides:
Galactose
Glucose
Fructose
What is the difference between the structure of alpha-glucose and beta-glucose:
Alpha-glucose = OH group is on bottom
Beta-glucose = OH group is on top
What are the two isomers of glucose?
Alpha glucose
Beta glucose
What happens in a condensation reaction?
Two monomers bond at their OH/HO groups
Water (H20) is lost
What is a disaccharide?
Two monosaccharides joined together.
How are disaccharides formed?
In the condensation reaction of two monosaccharides
Name three disaccharides:
Maltose
Lactose
Sucrose
_______ + _______ = Maltose
Glucose + Glucose = Maltose
_______ + _______ = Sucrose
Glucose + Fructose = Sucrose
_______ + _______ = Lactose
Glucose + Galactose = Lactose
What is the function of cellulose?
Provides rigidity and strength to plants cell wall.
How does the structure of cellulose help its function?
- As cellulose molecules are unbranched, they are able to get close together.
- Hydrogen bonds are able to form between neighbouring chains
- As many hydrogen bonds are formed, cellulose is extremely strong.
What is a cellulose microfibril?
Strong threads (made of long cellulose chains) that are parallel to one another, joined together by hydrogen bonds.
What is a cellulose macrofibril?
Many straight cellulose microfibrils joined together.
Give two ways in which the structure of starch is similar to the structure of cellulose?
Both have glycosidic bonds
Both have hydrogen bonds
Give two ways in which the structure of starch is different to the structure of cellulose?
Starch is branched, cellulose isn’t
Starch contains alpha-glucose, cellulose contains beta-glucose
What does benedict’s solution test for?
Sugars
Why is glycogen and starch coiled?
So it is compact so more glycogen/starch can fit in a smaller area.
Why is glycogen and starch being large an advantage?
Means it can’t cross the cell membrane when it is stored in a cell.
Why is glycogen and starch being insoluble an advantage?
Will not affect the water potential of a cells cytoplasm when it is stored inside a cell.
What are the three features that make glycogen and starch good storage molecules:
Compact
Large
Insoluble
Why are starch and glycogen good molecules for respiration?
They are coiled and highly branched
Enzymes have many ends for hydrolysing enzymes
Quicker for glucose molecules to be released
What is a glycosidic bond?
A covalent bond formed between monosaccharides, resulting in a condensation reaction.
In alpha glucose the OH group is at the _____.
Bottom
In beta glucose the OH group is at the _____.
Top
Describe the structure of amylose:
- Long
- unbranched chain
- A-glucose, 1-4 glycosidic bonds
Polymerisation of alpha glucose can form ______ or _______.
Starch or glycogen.
What are the two forms of starch?
- Amylose
- Amylopectin
Why is amylose a good storage molecule for small spaces?
Angles of glycosidic bonds give it a coiled structure = can fit more in a small space.
Why is amylopectin a good storage molecule for quick energy release?
Side branches allow enzymes to break down the molecule to get to the glycosidic bonds easily = quick glucose release.
What does the polymerisation of alpha glucose produce?
Glycogen
Starch
What does the polymerisation of beta glucose produce?
Cellulose
Why doesn’t starch affect a cells water potential?
It is insoluble in water.
What two polysaccharides is starch a mixture of?
Amylose
Amylopectin
Animals store excess glucose as ________.
Glycogen
Plants store excess glucose as ________.
Starch
Describe the structure of glycogen:
- Long
- Very branched
- Made of alpha-glucose
- Compact
Why is glycogen being very branched an advantage?
Stored glucose can be released quickly.
Describe the structure of cellulose:
- Long
- Unbranched chains
- Beta-glucose, 1-4 glycosidic bonds
Describe the structure of amylopectin:
- Long
- Branched
- Alpha glucose, 1-4 and 1-6 glycosidic bonds
Cellulose chains are linked together by _________.
Hydrogen bonds.
Cellulose chains are linked together by hydrogen bonds to form ______.
Microfibrils.
Why are microfibrils important in a plant?
Provides structural support.
A condensation reaction between two monosaccharides forms a ______ bond.
Glycosididic
