Biological Compounds

(1)

Biological Compounds

(2)

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

(3)

Other macronutrients…

Lipids: ENERGY

stored in body fat

and found in membranes

Proteins: growth and repair

(4)

Micronutrients

The 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 (PO₄^3-)

Vitamins: complex organic substances

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

(5)

Vitamin C

Vitamin C: connective tissue, bones, skin, teeth, endothelial cells deficiency can lead to scurvy

can contribute to CVD

(6)

Water & fibre: (roughage) holds water

provides bulk for intestinal muscles to work on

(7)

Organic Molecules

Carbohydrates

(8)

Carbon Chemistry!

Long chain of C atoms

2D version

The very lazy scientist….

(9)

Branched chain carbon polymer

Carbon ring structures

Buckminsterfullerine (‘Buckyball’)

(10)

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

(11)

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’)

(12)

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

(13)

Isomerism

C C C

O H

H

H H

OH OH

C C C

O H

H

H OH

OH

C₃H₆O₃

GLYCERALDEHYDE DIHYDROXYACETONE

(14)

Ribose & Deoxyribose

C₅H₁₀O₅

(15)

Glucose

(16)

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

(17)

Disaccharides

(18)

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

(19)

Building a disaccharide

(20)

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!!!)

(21)

Challenge!

• See if you can draw the structure of Lactose

(that’s glucose + galactose)

(22)

Breaking apart disaccharides (and polysaccharides)

(23)

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

(24)

Polysaccharides

(25)

What are they?

• Macromolecules

• Polymers

– Made up of monosaccharide monomers

Covalently bonded by Condensation

Polymerisation

(26)

Common ones

• Starch

• Glycogen

• Cellulose

• Chitin

• All made from glucose

Different properties depend on which ISOMER and

the type of GLYCOSIDIC bond

(27)

Polysaccharide Monomer Glycosidic

Bond Molecule Shape

Starch α-glucose

(amylose)

1,4

Unbranched

wound into a helix

Starch

α-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 1,4 Unbranched

straight chains

(28)

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

(29)

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

(30)

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

(31)

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

(32)

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 handout

Question pack

(33)

Cellulose

• Polymer of β-glucose

• 1,4 glycosidic bonds forming straight unbranched chains

• 1000’s of monomers

• Major constituent of the plant cell wall

(34)

(35)

• Hydrogen

bonding can

occur between

-OH groups on

adjacent chains

holding it together

(36)

Cellulose cont.

• Up to 2000 chains can be held together

– form microfibril giving high tensile strength

(37)

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

(38)

• What is cellulose called in the field of nutrition?

– fibre

• Can mammals break down cellulose?

– Ruminant mammals have bacteria in gut to

do it

(39)

Anaerobic bacteria in caecum and appendix Anaerobic bacteria in caecum and appendix

Package

(40)

Chitin

• Chitin is used structurally

• HOMEWORK – find out more!

• Hand in a ‘fact sheet’ on Chitin

• Maximum of one side

(41)

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 osmosis Starch is a polysaccharide found in plants

Glycogen is a polysaccharide found in animals

(42)

Lipids

Fats, Oils and Waxes

(43)

• Organic compounds

• Insoluble in water

• Soluble in organic solvents

(eg acetone, ether)

• Relatively small

(compared to polysaccharides)

• Tend to form together into globules

Due to not being soluble

(44)

• Naturally occurring fats and oils are esters

• Formed by condensation reactions

between glycerol (an alcohol) and fatty acids

Glycerol + Fatty acid Ester + 3 H

²

O

(45)

• Glycerol

– C

³

H

⁸

O

³

– 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

(46)

Fatty Acid

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

(47)

Condensation Reaction

(48)

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

(49)

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

(50)