Biological Compounds

Macronutrients‘BIG’ nutrients – these are complex ‘chemicals’

Carbohydrates

ENERGY

Cellular respiration

XS stored as FAT

Broken down into glucose

Stored as glycogen

Glucose + oxygen water + carbon dioxide + ENERGY

Other macronutrients…

Lipids: ENERGY

stored in body fat

and found in membranes

Proteins: growth and repair

MicronutrientsThe body only needs VERY SMALL amounts of these

Inorganic Ions:Calcium (Ca2+) for teeth, muscles, bones, blood clotting

Sodium (Na+) for nerves, heartbeat, muscle contraction

Magnesium (Mg2+)

Iron (Fe2+)

Phosphate (PO43-)

Vitamins: complex organic substances

water soluble (in blood) e.g. vit C

fat soluble e.g. vit A

Vitamin C

Vitamin C: connective tissue, bones, skin, teeth, endothelial cells

deficiency can lead to scurvy

can contribute to CVD

Water & fibre: (roughage)

holds water

provides bulk for intestinal muscles to work on

Organic Molecules

Carbohydrates

Carbon Chemistry!

Long chain of C atoms

2D version

The very lazy scientist….

Branched chain carbon polymer

Carbon ring structures

Buckminsterfullerine (‘Buckyball’)

Carbon Chemistry KEY FACTS

Organic molecules contain: Carbon, hydrogen, oxygen, (sulphur, nitrogen, phosphrous)

One carbon atom can bond with four other atoms forming a TETRAHEDRAL shape

Carbon can form long chains, branched chains or ring structures

They can ‘fold-up’ to make three-dimensional structures

The bits of the body that are not WATER are ORGANIC molecules

Carbohydrates (CHO’s)

Sugars: sucrose (white crystalline ‘sugar’)

glucose (energy supplier – sports drinks)

starch (flour, potatoes)

Carbohydrates fall into four main groups:

1. Monosaccharides (one ‘sugar-structure’)

2. Disaccharides (two ‘sugar-structures’)

3. Oligosaccharides (3-11 ‘sugar-structures’)

4. Polysaccharides (over 11 ‘sugar-structures’)

Monosaccharides (‘simple’ sugars)

Just one sugar-structure

Have an empirical formula of (CH2O)n

Triose – found in mitochondria

Pentose – found in DNA or RNA

Hexose – glucose

galactose

fructose

Empirical formula for hexoses is C6H12O6

triose

ribose

glucose

Isomerism

C

C

C

O

H

H

H

H

OH

OH

C

C

C

O

H

H

H

H OH

OH

C3H6O3

GLYCERALDEHYDE DIHYDROXYACETONE

Ribose & DeoxyriboseC5H10O5

Glucose

Monosaccharides you need to know…

all of the carbon atoms are numbered 1-6 α-glucose has a side chain at position 6 fructose has a side chain at position 1 and position 6

SIDE CHAINS AFFECT THE WAY IN WHICH THE MOLECULE IS USED BY THE BODY

Disaccharides

Disaccharides

These are 2 monosaccharides JOINED TOGETHER

glucose + glucose makes MALTOSE

glucose + fructose makes SUCROSE

glucose + galactose makes LACTOSE

Monosaccharides join together by CONDENSATION REACTION and the bond that joins them together

is a GLYCOSIDIC BOND

Building a disaccharide

Disaccharide summary

The three common disaccharides you need to know:

All of these are formed by CONDENSATION REACTION

(the one you need to be able to draw and label is maltose!!!)

Challenge!

• See if you can draw the structure of Lactose

(that’s glucose + galactose)

Breaking apart disaccharides (and polysaccharides)

Disaccharides – KEY FACTS

Disaccharides are formed from two monosaccharides

glucose + glucose makes MALTOSE glucose + fructose makes SUCROSE glucose + galactose makes LACTOSE

The reaction that joins two monosaccharides is called a condensation reaction

(break them up with hydrolysis)

The bond formed between two monosaccharides is called a GLYCOSIDIC BOND – the number of the carbon atoms nearby that are joined gives the bond its name e.g. 1,4 glycosidic bond

for maltose

Polysaccharides

What are they?

• Macromolecules• Polymers

– Made up of monosaccharide monomers

Covalently bonded by Condensation Polymerisation

Common ones• Starch• Glycogen• Cellulose• Chitin

• All made from glucose

Different properties depend on which ISOMER and the type of GLYCOSIDIC bond

Polysaccharide Monomer Glycosidic Bond

Molecule Shape

Starchα-glucose(amylose) 1,4

Unbranched wound into a

helix

Starchα-glucose

(amylopectin)

1,4 with some 1,6

Tightly packed

branched chain

Glycogen α-glucose

1,4 with more 1,6 than

amylopectin

Very branched compact molecule

Cellulose β-glucose 1,4Unbranched

straight chains

Starch• Mixture of amylose (30%) and amylopectin

(70%)

• Amylose: – unbranched chains– 1,4 glycosidic bonds– >300 glucose monomers, helical shape– coils have 6 monomers/turn held

together by hydrogen bonds

Starch

• Amylopectin:– Glucose monomers– 1,4 glycosidic bonded chains– Branches in chains due to 1,6 glycosidic bonds– Branches every 20-30 residues– Molecule several 1000 monomers, very

branched and coiled compactly

Starch

• Functions as storage in plants:– Compact– Insoluble– No osmotic effects– Doesn’t interfere in cell reactions– Easily hydrolysed to sugars when required

• Build up into grains in structures called amyloplasts in plant cytoplasm

Polysaccharides

Complex carbohydrates – many monosaccharides joined together by glycosidic bonds

In plants strings of α-glucose joined by glycosidic bonds form starch, which is made up of amylose & amylopectin

Amylase breaks the glycosidic bonds from the ends of amylose, and amylopectin (branched) which releases energy

Glycogen• Polymer of α-glucose with 1,4 and 1,6 glycosidic bonds• Very similar to amylopectin but it branches more often,

every 8 – 12 residues.• Very compact

• Energy storage in animals –liver and muscle cells• Cytoplasm of bacteria

• Well suited to its role– Compact– Rapidly hydrolysed to sugars when needed

Page 6 of molecules handoutQuestion pack

Cellulose

• Polymer of β-glucose• 1,4 glycosidic bonds forming straight

unbranched chains• 1000’s of monomers• Major constituent of the plant cell wall

• Hydrogen bonding can occur between -OH groups on adjacent chains holding it together

Cellulose cont.

• Up to 2000 chains can be held together

– form microfibril giving high tensile strength

Cellulose cont.

• Microfibrils embedded in a matrix (like a cement) making it a composite material

• Few organisms can break it down (digest) using enzyme cellulase– A few prokaryotes and fungi can

• What is cellulose called in the field of nutrition?– fibre

• Can mammals break down cellulose?– Ruminant mammals have bacteria in gut to

do it

Anaerobic bacteria in caecum and appendixAnaerobic bacteria in caecum and appendix

Package

Chitin

• Chitin is used structurally

• HOMEWORK – find out more!• Hand in a ‘fact sheet’ on Chitin• Maximum of one side

Polysaccharides – key facts

Complex carbohydrates – many monosaccharides joined together by glycosidic bonds

They often fold-up on themselves to become more complex or are branched

The body/plants uses polysaccharides as storage – these molecules can be broken down into smaller components

Breaking glycisidic bonds is referred to as HYDROLYSIS and releases a lot of ENERGY

Polysaccharides are INSOLUBLE so do not interfere with other chemical functions of the cell and have little impast on osmosisStarch is a polysaccharide found in plants

Glycogen is a polysaccharide found in animals

Lipids

Fats, Oils and Waxes

• Organic compounds

• Insoluble in water• Soluble in organic solvents (eg acetone, ether)

• Relatively small (compared to polysaccharides)

• Tend to form together into globulesDue to not being soluble

• Naturally occurring fats and oils are esters• Formed by condensation reactions

between glycerol (an alcohol) and fatty acids

Glycerol Fatty acid Ester 3 H2O+ +

• Glycerol– C3H8O3

– 3 hydroxyl groups

each can undergo condensation reaction with a fatty acid.

Produces an ester called a triglyceride

(triacylglycerol)

H – C – C – C – H

H H H

OH OH OH

Fatty Acid

Long non-polar Hydrocarbon chain Polar carboxyl (COOH) end

Condensation Reaction

Triglycerides containing saturated fatty acids have a high melting point and tend to be found in warm-blooded animals. At room temperature thay are solids (fats), e.g. butter, lard. Triglycerides containing unsaturated fatty acids have a low melting point and tend to be found in cold-blooded animals and plants. At room temperature they are liquids (oils), e.g. fish oil, vegetable oils.

Triglycerides

They are used for storage, insulation and protection in fatty tissue (or adipose tissue) found under the skin (sub-cutaneous) or surrounding organs.

They yield more energy per unit mass than other compounds so are good for energy storage.

Water released in oxidisation called metabolic water, important to organisms in dry climates

Carbohydrates can be mobilised more quickly, and glycogen is stored in muscles and liver for immediate energy requirements.

Triglycerides

Phospholipids

• Like lipids, are esters of glycerol and fatty acids. BUT, one of the fatty acid chains is replaced by a polar phosphate group

Phospholipid

Phospholipids

• Polar (phosphate) group is soluble in water• The fatty acid chains are not

• So at air-water or oil-water interfaces, phospholipids orientate so the polar head is in the water.

• Important constituent in cell membranes.

Fats and health.

• Saturated or unsaturated? Which is best?• What are the risks of the wrong type?• How much is too much?• Who says?• What’s BMI?

Question Pack