Ch 11 Carbohydrates Flashcards
What are the building blocks (monomers) of carbohydrates?
Monosaccharides
Monosaccharides are simple sugars that can combine to form more complex carbohydrates.
What are polymers of monosaccharides called?
Polysaccharides
Polysaccharides are long chains of monosaccharide units linked together.
What is the general formula for monosaccharides?
C_nH_{2n}O_n
Here, n varies from 3 to 8.
How are monosaccharides classified?
By their number of carbon atoms
The classification can also include whether they are aldoses or ketoses.
What does the suffix ‘ose’ indicate?
It designates a sugar
Commonly used in naming carbohydrates.
Define an aldose.
A monosaccharide containing an aldehyde group
Aldoses have a carbonyl group at the end of the carbon chain.
Define a ketose.
A monosaccharide containing a ketone group
Ketoses have a carbonyl group within the carbon chain.
What is a Fischer projection?
A 2D representation of monosaccharides
It is used to depict the structural formula of carbohydrates.
What is the carbon numbering for an aldose?
The carbonyl carbon is carbon 1
This is important for identifying the structure of the sugar.
What is the carbon numbering for a ketose?
The carbonyl carbon is carbon 2
This distinction helps in categorizing different types of sugars.
What is a chiral carbon?
A carbon that has four different groups attached to it
Chirality is crucial for the biological activity of sugars.
What are D and L configurations in monosaccharides?
D-monosaccharide has -OH on its penultimate carbon on the right, L-monosaccharide has it on the left
These configurations are used to describe the orientation of the hydroxyl group.
What is dextrose?
An old name for D-glucose
It is still commonly used in medical settings.
What are enantiomers?
Monosaccharides that are exact mirror images of each other
Examples include D and L glucose.
What are diastereomers?
Monosaccharides with the same number of carbons that are stereoisomers without being mirror images
They differ in configuration at one or more chiral carbons.
What are epimers?
Diastereomers differing at only one chiral carbon
They are a subset of diastereomers.
Name four monosaccharides you need to know by name.
- Glucose: aldohexose
- Fructose: ketohexose
- Galactose: aldohexose
- Ribose: aldopentose
Familiarity with these monosaccharides is essential for understanding carbohydrate metabolism.
What is a Haworth projection?
A representation of cyclic sugars viewed edge-on
It shows the arrangement of atoms in the ring form of monosaccharides.
What is mutarotation?
The spontaneous interconversion between alpha and beta conformations of a monosaccharide
It occurs due to the ring structure of monosaccharides.
What is a glycosidic bond?
The bond formed between monosaccharides when they join together
It is crucial for the formation of disaccharides and polysaccharides.
What is lactose composed of?
Galactose + glucose
Lactose is a disaccharide found in milk.
What are the two main types of starch?
- Amylose: unbranched alpha-glucose polymer
- Amylopectin: branched alpha-glucose polymer
Both are used by plants to store energy.
What is cellulose made of?
Polysaccharide of beta-D-glucose
It forms the structural component of plant cell walls.
How does penicillin work?
It stops the cross-linking of peptidoglycan in bacterial cell walls
This action weakens the cell wall, leading to bacterial cell death.
What are glycoproteins?
Carbohydrate units covalently bonded to a polypeptide chain
They play important roles in cell-cell recognition and signaling.
What are glycosaminoglycans?
Polysaccharides based on a repeating disaccharide where one sugar is an amino sugar
They often have a negative charge due to sulfate or carboxyl groups.
What is stevia?
A low-calorie sweetener derived from the stevia plant
It is often used as a sugar substitute.
What is the difference between alpha and beta glycosidic bonds?
Alpha bonds point downwards, beta bonds point upwards
This orientation affects the digestibility and function of polysaccharides.
