CARBOHYDRATES & LIPIDS

September 10th, 2012

WHAT ARE CARBOHYDRATES?

Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen that serve as energy sources and structural materials for cells of all organisms

STRUCTURE OF CARBOHYDRATES

Carbohydrates consist of carbon, hydrogen, and oxygen

They may be monomers or polymers

WHAT ARE MONOMERS?Monomers are molecules that can

be bonded to other identical molecules to form polymers

The monomer form of carbohydrates are known as monosaccharides

Glucose is an example of a monosaccharide

DISACCHARIDESDisaccharides: consist of two

monosaccharides. Ex: maltose & sucrose

Disaccharides form by dehydration synthesis – where a molecular of water is split out as the bond is formed

Disaccharides are broken down into monomers by hydrolysis

WHAT ARE POLYMERS?Polymers are substances that have

a molecular structure built up chiefly or completely from a large number of similar units bonded together

The polymer form of carbohydrates are polysaccharides

Polysaccharides are large carbohydrate molecules that are polymers of monsaccharides

Ex: starch, glycogen and cellulose

Glycogen is a polymer of glucose

Glucose

Glycogen

WHAT IS STARCH?Starch is the energy storage

molecule in plants and a good source of energy for human cells

Produced by all green plants It is the most common carbohydrate

in the human diet and is contained in large amounts in such staple foods as potatoes, wheat, maize (corn), rice and cassava

WHAT IS GLYCOGEN?Glycogen is the short-term energy

storage molecule in human cells

WHAT IS CELLULOSE?Cellulose is the molecule that makes

up plant cell walls in green plants

POLYSACCHARIDES CONTINUED

Differences between the polysaccharides are caused by differences in their molecular structure

Organisms must break down polysaccharides to obtain usable glucose molecules. For example: our body breaks down starch and glycogen by hydrolysis

However, we cannot break down cellulose into molecules of glucose. Instead, cellulose passes undigested through our digestive system

WHAT ARE LIPIDS?Lipids are organic compounds that

include: fats, phospholipids, waxes, and steroids

Long-term energy storage Insoluble in water

FATS In human cells, fats serve as long-

term energy storageUseful long-term energy storage

molecules in both plants and animals – because of the many energy containing carbon-hydrogen bonds

Very concentrated source of energyStored fat helps cushion and protect

important organs such as the kidneys

FATS, CONTINUED…Fats are made up mainly of two types

of molecules: fatty acids and glycerol Fatty acids may be either saturated or

unsaturatedSaturated fatty acids have no double

bonds between their carbon atoms. They are relatively straight structurally

Unsaturated fatty acids have one or more double bonds between carbons and so are not saturated with hydrogen

SATURATED VS. UNSATURATED FATTY ACIDS

SATURATED VS. UNSATURATED FATTY ACIDSWhen referring to the structure of a

fatty acid, wherever you see a double bond, it causes a kink in the molecule

The kinks prevent unsaturated and polyunsaturated fatty acids (more than one double bond) from packing together tightly – therefore these are liquid at room temperature

The linear saturated fatty acids are able to pack together more tightly and tend to be solids at room temperature

SATURATED VS. UNSATURATED FATTY ACIDS Saturated Fatty Acids = Saturated Fats - found in red meat and dairy products - associated with health problems

usually cardiovascular related Unsaturated Fatty Acids = Unsaturated

Fats - Come from plants like: canola, corn and

olives. Also some animals - Some may benefit your health - Linoleic acid is actually essential for

your body!

GLYCEROLGlycerol is an organic molecule with

3 carbons and 3 hydroxyl groupsBonds with 2 or 3 fatty acids to form

a fatGlycerol bonded to 3 fatty acids

TriglycerideTriglycerides – long-term energy

storage in animals. Stored in adipose tissue

Adipose tissue body fat

GLYCEROL CONTINUED…Fat cells usually cannot grow.

Therefore we can’t create new fat cells in our body, instead we can just add to the triglycerides existing in our fat cells

PHOSPHOLIPIDSPhospholipids are an important

part of cell membranes. They help the cell membrane perform its role of monitoring the passage of molecules into and out of the cell

Consist of a hydrophilic phosphate molecule and two hydrophobic fatty acid tails

Hydrophilic – water-lovingHydrophobic – water-hating

STEROIDSSteroids is a group of organic

compounds that include: cholesterol and the sex hormones – estrogen and testosterone

Cholesterol is necessary for many different functions, including the proper formation of cell membranes. However, too much cholesterol can cause for the onset of cardiovascular disease

STEROIDS CONTINUED…Estrogen and testosterone are

present in both males and females It is the amount of estrogen and

testosterone that vary in males and females

Testosterone – more in malesEstrogen – more in females