Carbohydrates Carbohydrates Commonly known as sugars and starches - - PowerPoint PPT Presentation

Carbohydrates

Carbohydrates

• Commonly known as sugars and starches
• Composed of carbon, hydrogen and oxygen

atoms

Monomers and Polymers of Carbohydrates

• The monomer of a carbohydrate is called a

monosaccharide (“one sugar”)

• Monosaccharides are commonly known as

simple sugars

• Polymers of carbohydrates include

disaccharides and polysaccharides

Monomers and Polymers of Carbohydrates

Molecular Formula for Carbohydrates

• The molecular formula for a 6-carbon

simple sugar is C6H12O6

• The ratio of hydrogen atoms to oxygen

atoms in a carbohydrate is 2:1 or 2 hydrogen atoms for every one oxygen atom

Simple Sugars

• The 6-carbon sugars are the most common

sugars in nature

• Many other simple sugars also exist, for

example, the sugar molecules found in DNA and RNA

Chemical Names for Sugars

• The chemical names for sugars end in -ose
• Examples include: glucose, galactose and

fructose

Isomers

• Isomers are molecules that have the same

molecular formula but different structures (arrangement of atoms is different)

Reaction - Dehydration Synthesis

• Monosaccharides are joined together to

form carbohydrate polymers by dehydration synthesis

Disaccharides

• Maltose is a disaccharide composed of two

glucose molecules

Disaccharides

• Sucrose (table sugar) is a disaccharide

composed of one glucose molecule and

• ne fructose molecule

Disaccharides

• Lactose (milk sugar) is a disaccharide

composed of one glucose molecule and

• ne galactose molecule

Polysaccharides

• Polysaccharides consist of many

monosaccharides bonded together by dehydration synthesis

Common Polysaccharides

• Common polysaccharides include glycogen,

cellulose, chitin and pectin

– Glycogen – animal starch, stored in the liver and muscles – Cellulose – composes the cell walls of autotrophs (i.e. plants) – Chitin – composes the exoskeleton of arthropods (crabs, lobsters, insects, etc.) – Pectin – found in the skin of fruit

Glycogen

• A polysaccharide commonly known as

animal starch - polymer of glucose molecules

• Serves as an energy storage molecule in the

liver and muscles

Cellulose

• A polysaccharide commonly known as plant

starch - polymer of glucose molecules

• A tough, fibrous material found in plant cell

walls

How are carbohydrate used by the cells of living organisms?

• Used as fuel for cells (glucose)
• Used as fuel storage for cells (glycogen)
• Plays a structural role in cells (cellulose and

chitin)

You Are What You Eat

• Healthy food sources for carbohydrates

include: fruits, vegetables, pasta, bread, whole grains and beans

Reaction - Hydrolysis

• Polymers are broken down into monomers

by hydrolysis

• These reactions are usually facilitated by

enzymes