Question

Define the following terms: polysaccharide, furanose, pyranose, aldose, ketose, glycosidic bond, oligosaccharide, glycoprotein.

Short answer

Polysaccharide: carbohydrate polymer. Furanose: five-membered sugar. Pyranose: six-membered sugar. Aldose: sugar with aldehyde. Ketose: sugar with ketone. Glycosidic bond: carbohydrate linkage. Oligosaccharide: few sugars. Glycoprotein: protein with carbohydrate.

Step-by-step solution

Define Polysaccharide

A polysaccharide is a carbohydrate (such as starch or cellulose) whose molecules consist of a number of sugar molecules bonded together.

Define Furanose

A furanose is a simple sugar containing a five-membered ring consisting of four carbon atoms and one oxygen atom.

Define Pyranose

A pyranose is a simple sugar containing a six-membered ring consisting of five carbon atoms and one oxygen atom.

Define Aldose

An aldose is a monosaccharide (simple sugar) that contains an aldehyde group (-CHO).

Define Ketose

A ketose is a monosaccharide that contains a ketone group (C=O).

Define Glycosidic Bond

A glycosidic bond is a type of covalent bond that joins a carbohydrate molecule to another group, which can be another carbohydrate.

Define Oligosaccharide

An oligosaccharide is a carbohydrate polymer containing a small number (typically three to ten) of simple sugars (monosaccharides) bonded together.

Define Glycoprotein

A glycoprotein is a protein that has carbohydrate molecules covalently attached to polypeptide side-chains.

Key concepts

Polysaccharide

Polysaccharides are complex carbohydrates. They consist of long chains of sugar molecules bonded together. Think of starch and cellulose, which are common examples. These chains can be straight or branched. Polysaccharides play various roles in nature:
* Storage: Starch in plants and glycogen in animals store energy.
* Structural: Cellulose gives plants their rigidity and strength.
Understanding polysaccharides is essential to grasp how organisms store energy and build structural components.

Furanose

The term 'furanose' refers to a type of simple sugar. Its name comes from its structure, which resembles the organic compound furan. Furanose sugars have a five-membered ring that includes:
* Four carbon atoms
* One oxygen atom
These sugars usually form in aqueous solutions. Examples include ribose and fructose, which are important in biochemistry and metabolism.

Pyranose

Pyranose is another type of simple sugar. Unlike furanose, pyranose has a six-membered ring. Its structure consists of:
* Five carbon atoms
* One oxygen atom
The name 'pyranose' comes from its resemblance to pyran, a six-membered ring compound. This form is common in glucose and galactose, crucial sugars in energy metabolism.

Aldose

An aldose is a type of monosaccharide, which are the simplest forms of carbohydrates. Aldose compounds contain an aldehyde group (-CHO). This means:
* The carbon atom is double-bonded to an oxygen atom
* The carbon atom is also bonded to a hydrogen atom
Examples include glucose and galactose. Understanding aldoses helps in recognizing how these sugars are involved in chemical reactions and energy production.

Ketose

A ketose is another kind of monosaccharide. It differs from an aldose by having a ketone group (C=O) instead of an aldehyde group. The structure features:
* A carbon atom double-bonded to an oxygen atom
* This bond occurs within the carbon chain, not at the end
Examples of ketoses include fructose and ribulose. These sugars play significant roles in metabolism and cellular processes.

Glycosidic Bond

A glycosidic bond is a type of covalent bond that connects carbohydrate molecules. This bond forms when a sugar reacts with another group, which can be another sugar or different molecule altogether. Key points about glycosidic bonds include:
* They link the anomeric carbon of a carbohydrate to another molecule
* They can form either alpha or beta linkages depending on the configuration
This type of bond is crucial in forming macromolecules like polysaccharides and oligosaccharides.

Oligosaccharide

Oligosaccharides are short chains of monosaccharides, typically comprising three to ten sugar units. These molecules aren't as complex as polysaccharides but still play significant roles, such as:
* Cell recognition
* Signal transduction
They often attach to lipids and proteins on cell surfaces, aiding in various biological functions. Examples include raffinose and stachyose, which are important in plants and some foods.

Glycoprotein

Glycoproteins are proteins that have carbohydrate groups covalently attached to their polypeptide chains. These structures are vital in many biological processes, including:
* Cell-cell interactions
* Immune responses
The carbohydrate part of glycoproteins can influence the protein's properties and functions. Many enzymes, hormones, and antibodies fall into this category, making glycoproteins crucial for cellular functions and immune defense.