Carbohydrates I - MEDCHEM.21

Flashcards based on the lecture notes on Carbohydrates I, covering key concepts and definitions related to medicinal and pharmaceutical chemistry.

What is a carbohydrate?

A broad class of polyhydroxylated aldehydes and ketones commonly called sugars.

What are monosaccharides?

Simple sugars that cannot be converted into more simple sugars by hydrolysis.

What distinguishes a disaccharide from a polysaccharide?

Disaccharides are made up of two simple sugars, while polysaccharides consist of many simple sugars linked together.

Give an example of a disaccharide.

Sucrose, comprised of one glucose and one fructose.

What is the molecular formula of glucose?

C6H12O6.

Define Fischer Projections.

A method to project a tetrahedral carbon onto a flat surface.

What is D-glyceraldehyde?

The dextrorotatory enantiomer of glyceraldehyde that occurs naturally.

Define aldoses and ketoses.

Aldoses are sugars with an aldehyde carbonyl group, and ketoses have a ketone carbonyl group.

What does the prefix 'aldo-' indicate?

It indicates the presence of an aldehyde carbonyl group in the sugar.

What does the suffix '-ose' signify?

It designates a carbohydrate.

What is the configuration of D-sugars in Fischer projections?

The hydroxyl group at the bottom chiral center points to the right.

What is an epimer?

A diastereomer that differs at only one specific chiral center.

How many chiral centers does glyceraldehyde have?

One chiral center.

What determines the number of stereoisomers in aldopentoses?

The number of chiral centers, which is 3 for aldopentoses.

What are the anomers of glucose?

⍺-D-Glucose and 𝛽-D-Glucose, differing at the anomeric carbon.

Describe the Haworth projection for monosaccharides.

A cyclic representation of monosaccharides that illustrates their ring structure.

How does D-glucose appear in aqueous solution?

Primarily as a six-membered pyranose ring form.

What is the significance of the carbonyl carbon in Fischer projections?

It is always placed at or near the top in Fischer projections.

What is the stereochemical configuration of L-glyceraldehyde?

It has an S configuration at the chiral center farthest from the carbonyl group.

How are D and L sugars related?

D and L sugars are enantiomers; they are mirror images of each other.

What is a glycosidic bond?

A bond formed between two sugars that links them together.

Name a polysaccharide and its components.

Cellulose, comprised of several thousand linked glucose units.

What happens during the cyclization of glucose?

The hydroxyl group at C5 attacks the carbonyl carbon to form a hemiacetal.

What configuration do most naturally occurring monosaccharides exhibit?

They exhibit the D configuration at the chiral center farthest from the carbonyl group.

Explain the term 'chair conformation' in the context of glucose.

It refers to the three-dimensional arrangement of atoms in a cyclic structure of sugars like glucose.

How is fructose classified?

Fructose is classified as a ketose sugar.

What are the two cyclic forms of D-fructose?

Five-membered furanose and six-membered pyranose forms.

What is the main difference between D-glucose and L-glucose in their structures?

Every group on L-glucose is in the axial position, opposite to that of D-glucose.

What do the designations D and L refer to in sugars?

They specify the stereochemical configuration at the chiral center farthest from the carbonyl group.

How do you convert Fischer projections to Haworth projections?

The aldehyde becomes a hemiacetal, and the positioning of hydroxyl groups changes based on their orientation.

What do chair structures help illustrate?

They help illustrate the structures and stability of cyclic sugars, especially aldohexoses.

What configuration do ⍺ and 𝛽 anomers differ in?

They differ in configuration at the anomeric carbon (C1, previously carbonyl).

Define the term 'hemiacetal' as it relates to carbohydrates.

A product formed when an alcohol reacts with an aldehyde or ketone.

Which simple sugar is a C2 epimer of D-glucose?

D-Mannose.

What is the epimer of D-glucose at C4?

D-Galactose.

What is the primary role of carbohydrates in biology?

They serve as energy sources and structural components in organisms.

What are the two types of simple sugars?

Monosaccharides and disaccharides.

What kind of bond links glucose units in cellulose?

Glycosidic bonds.

What is the characteristic of a cyclic structure in monosaccharides?

Cyclic structures have ring formations where the carbonyl carbon reacts with a hydroxyl group.

How do D and L sugars relate to their respective enantiomers?

D and L sugars are enantiomeric forms with opposite configurations at all chiral centers.

What does the carbon labeled as 'C1' represent in Fischer projections?

The carbonyl carbon, typically at the top.

What are the four D,L pairs of enantiomers mentioned?

Ribose, arabinose, xylose, and lyxose.

How is a disaccharide formed?

By the linkage of two monosaccharides through glycosidic bonds.

What does a Fischer projection reveal about the molecular structure?

It shows the spatial arrangement of atoms around the chiral centers in a linear form.

How is the configuration of D-fructose different from D-glucose?

D-fructose has a ketone group instead of an aldehyde group.

In what form does glucopyranose primarily exist in solution?

As a six-membered pyranose ring.

What happens during intramolecular nucleophilic addition in monosaccharides?

The carbonyl and hydroxyl groups of the same molecule react to form cyclic structures.