5 Animal Nutrients5 Animal Nutrients

The Body Owner’s Handbook by Nick Arnold

Topic Outline1.  Biochemistry

a. Macromolecules

2.  Carbohydrates2.  Carbohydratesa. Definitiona. Definitionb. Classificationb. Classificationc. Formation of glycosidic bondc. Formation of glycosidic bondd. Test for reducing, non-reducing sugars and d. Test for reducing, non-reducing sugars and starchstarche. Principle source and dietary importance of e. Principle source and dietary importance of carbohydrates and fibrecarbohydrates and fibre

3.  Proteins 4.  Fats5.  Role of the liver in the metabolism of glucose and amino acids6.  Vitamins C and D 7.  Minerals (calcium and iron) 8.  Balanced diet 9. World food supply problems

Internet sites

1)http://www.biologylessons.sdsu.edu/classes/lab6/lab6.html - general overview of chemicals of life

2)http://web.mit.edu/esgbio/www/lm/lmdir.html - structure and function of chemicals of life

3)http://www.pbs.org/wgbh/pages/frontline/shows/meat/safe/foodborne.html - Food-borne diseases

THE NEED FOR FOOD

1. For growth

- synthesis of new protoplasm, cells and tissues

2. For repair or replacement of worn and damaged tissues

- replace red blood cells, skin

- repair wounds

3. As a source of energy

- Energy store in food is called potential chemical energy

- Released and used for:

chemical reactions that build complex molecules

activities, eg movement (kinetic energy), heartbeat

maintenance of body temperature (mammals, birds)

4. To maintain health and prevent deficiency diseases

Taking in useful substances = feeding or nutrition

A FOOD CHAIN

Nasty Nature by Nick Arnold

THE WAY PLANTS FEED:

Simple inorganic substances (CO2, H2O, minerals)

taken in by plants

Built up to complex organic materials (sugars)

AUTOTROPHIC NUTRITION = plants can make their own food via photosynthesis

THE WAY ANIMALS FEED:

They feed on organic substances originally made by plants.

This is called HETEROTROPHIC NUTRITION

CONDENSATION – process whereby simpler substances built up to form a more complex substance by the removal of a water molecule.

HYDROLYSIS – process whereby complex substance is broken down into simpler substances by the addition of a water molecule.

COMPONENTS OF FOOD

3 main components: nutrients, fibre, water

NUTRIENTS: chemical substances in food that nourish the body, i.e. provide energy and materials required

5 groups of nutrients:

- Carbohydrates, fats, proteins

required in large quantities

supply energy and materials to make new protoplasm

- Minerals, vitamins

required in smaller quantities

maintain normal metabolism, no energy value

BIOCHEMISTRY (The study of chemicals in living

organisms)

Water1 . s m a ll M W

2. m o le c u le s in te ra c t w ith hyd ro ge n bo nds

C arbohydrates P rote ins L ipids N uc le ic ac ids

P olymers1 . la rge M W

2. un its o f m o no m e rs

3 . c o nde ns a tio n rx n

B ioc hemic als

Macromolecules  Giant molecules made from many repeating units

  Polymers made up of basic units called monomers

 

Four types of macromolecules/ polymers:

1)  PolysaccharidesPolysaccharides - made up of monosaccharides

2)  Fats - made up of fatty acids and glycerol

3)  ProteinsProteins - made up of amino acids

4) Nucleic acidsNucleic acids - made up of nucleotides

2. Carbohydrates

http://opbs.okstate.edu/~Blair/Bioch2344/Chapter10/Chapter10.htm#Anchor-D-Fructose

 

a. Definition

- Substances that contain the elements carbon, hydrogen and oxygen.

- General formulae: CnH2nOn

- The ratio of hydrogen to oxygen is 2:1

- Carbohydrates are made up of monosaccharides.

b. Classification Carbohydrates are classified into

monosaccharides, disaccharides and polysaccharides.

Monosaccharides

Greek monos means single and sacchar means sugars

Common simple sugars have six carbon atoms

glucose - found in all animals fructose - found in plants but uncommon in

animals galactose - formed when milk sugar is

digested

galactose

Disaccharides  Complex sugars Made up of twotwo molecules of simple sugars

(monsaccharides) Formed by condensationcondensation reaction and

involved the loss of a single water molecule Resultant bond formed between the two simple

sugars is called glycosidic bond Hydrolysis is the reverse of condensation where

water is added to break a disaccharide into its constituent monosaccharides.

Sucrose- made up of glucose and fructose Found in cane sugar, sugar beet and carrots

Maltose - made up of two molecules of glucose Found in malted cereals, barley grains, and

sprouted grains Formed in the partial digestion of starch

Lactose - made up of glucose and galactose Found in milk

Polysaccharides Macromolecule; polymers made up of several

hundred to several thousand monosaccharides linked by glycosidic bonds.

Process of joining the monosaccharides is called polymerisation

Two classes of polysaccharides: Storage polysaccharides (starch and glycogen) -

when hydrolysed/ broken down, supply sugars to cells for energy production

Structural polysaccharides (cellulose) - building materials for structures that protect cells or even whole organisms.

Starch Made up of up to 200 glucose

molecules condensed together Found in cereals, potato, tapioca Not formed and stored in animals but in

plants When starch is hydrolysed by amylase,

maltose is formed. Maltose is hydrolysed by maltase to form glucose.

Glycogen

 Made up of glucose molecules condensed together and are highly branched

 Storage form of carbohydrate in animals, stored in liver and muscle cells of mammals

When glucose is needed, glycogen is converted to glucose by hormones (glucagons)

unbranched branched

extensively branched

Biology by Campbell, Reece & Mitchell

Starch and glycogen are ideal storage materials:

- They are insoluble in water, so does not change the osmotic pressure in the cell.

- They are large molecules, so cannot diffuse through cell membrane.

- They can be hydrolysed to glucose.

- They have compact shapes, so occupy less space.

Cellulose Made up of glucose molecules

condensed together Main component of plant cell wall to

prevent the bursting of plant cells and keep the cells turgid

 Inert and few animals can digest itUsed to make cotton goods and a constituent of paper.

STRUCTURAL FUNCTIONSTRUCTURAL FUNCTION

Parallel arrangement of unbranched cellulose molecules

Biology by Campbell, Reece & Mitchell

Since both starch and cellulose are made of glucose units joined together, why then only starch can be digested in our bodies but not cellulose?

STARCH

CELLULOSE

Biology: Principles and Processes by Roberts, Reiss & Monger

c.  Formation of glycosidic bond A condensation reaction which

involved the loss of a water molecule

Glucose + Fructose Sucrose

Condensation (water lost)

Hydrolysis (water added)

Test for reducing sugarsName of test: Benedict’s solution Test

Benedict’s solution = copper (II) sulphate in an alkaline solution (blue) Method: 1. Add 2cm3 of reducing sugar into a test tube.2. Add an equal volume of Benedict’s solution.3. Shake and boil in a boiling water bath for

2 - 3 minutes.

NB:Water level in water bath must always be above the solutions in the test tubes

Precautions to take when comparing samples

1) Same volume of Benedict's reagent

2) Same duration of heating time (3 mins) and

3) Same volume of sample used.

4) Place tubes into water bath only after the water in water bath

has boiled

Test for reducing sugarsTest for reducing sugars

Results:

A brick-red precipitate will be formed.

Soluble blue copper (II) sulphate is reduced by reducing sugar to form insoluble copper (I) oxide which is a brick-red precipitate

Principle of the test

Glucose is a reducing sugar. Cu2+ ions (blue) are reduced to brick-red (Cu2O) precipitate.

The colours obtained can therefore range from

blue

green

Yellow

orange

brick-red

Colour and amount of precipitate gives a rough estimate of amount of reducing sugars present

It is a semi-quantitativesemi-quantitative test.

increasing concentration of reducing sugars

Blue, clear

Green, opaque

Orange, opaque

Brick-red opaque

Blue, clear

Increasing concentration of reducing sugarsControl

Control

Remained clear, blue

Remained clear, blue

Red, cloudy

Dark red, opaque

Green, cloudy

Qty of RS: 4>2>5>1,3Qty of RS: 4>2>5>1,3

Sensitivity of Benedict’s Test

0.001% - Remained clear, blue0.01% - Slightly cloudy, blue0.1% - Slightly cloudy, red ppt

in blue solution, 1% - Opaque, orange-red 10% - Opaque, reddish brown

(Different amounts of glucose)

Test for non-reducing sugarsName of test: Non-reducing sugar Test Not a specific test for non-reducing sugars.  Based on inability to give a positive result in

Benedict’s solution test.  The non-reducing is then hydrolysed by boiling with

dilute hydrochloric acid to break down the non-reducing sugars into its monosaccharides.

 The mixture is then neutralized/ made alkaline before performing the Benedict’s solution test.

Thus a non-reducing sugar is said to be present when it shows a negative Benedict’s solution test and a positive test after hydrolysis.

Method:

1. Add 2cm3 of non-reducing sugar into a test tube

2. Add 1cm3 of dilute hydrochloric acid.

3. Boil the mixture for 1 minute.

4. Cool

5. Carefully neutralize with sodium hydrogen carbonate (check with ph paper) – be careful because vigorous effervescence may occur

6. Carry out Benedict’s solution test.

Results:

A brick-red precipitate will be formed.

Note that in Tube 3, sucrose did not reduce the copper ions in the Benedict's solution. It remained blue and clear.

Non-reducing sugars (eg, sucrose)Non-reducing sugars (eg, sucrose)

Test for starchName of test: Iodine starch Test  Iodine solution or iodine in potassium iodide

solution Method: 1. Add 2cm3 of 1% starch solution into a test

tube2. Add a few drops of iodine/ KI solution3. Or add a few drops of iodine/ KI solution to

the solid form of starch

Results:

A blue-black colouration is formed.

Potato stained with I/KI X 100

Potato stained with I/KI X 200

Starch granules

Onion stained with I/KI X 100 - The nuclei of these cells are light brown in this photograph. The numerous starch granules seen in potatoes are absent.

The same test when done with onion epidermis.

100x magnification

Principle source and dietary importance of carbohydrates and fibre

http://www.nutramed.com/nutrition/carbohydrates.htm - detailed descriptions of carbohydrates and fibre in diet

http://www.americanheart.org/presenter.jhtml?identifier=4471

Principle source of carbohydrates and fibre Carbohydrate intake should come mainly from

complex carbohydrates - vegetables, fruits and grains - rather than the simple carbohydrates found in sugars. Complex carbohydrates add more fiber, vitamins and minerals to the diet than foods high in refined sugars. Foods high in complex carbohydrates are usually lower in calories, saturated fat and cholesterol. The American Heart Association recommends 25-30 grams of fiber per day.

Balanced Food pyramid

Which foods are sources of complex carbohydrates?

Starches - Flour, bread, rice, corn, oats, barley, potatoes, legumes, fruits and vegetables

Fiber - Insoluble: whole-wheat breads and cereals, wheat bran, cabbage, beets, carrots, Brussels sprouts, turnips, cauliflower and apple skin (pectin)

Fiber - Soluble: oat bran, oats, legumes, citrus fruits, strawberries, apple pulp, psyllium, rice bran and barley

Which foods are sources of simple carbohydrates? Sucrose - Table sugar, brown sugar, confectioners sugar, raw

sugar and turbinado Glucose - Dextrose, corn syrup and glucose syrup Fructose - Fruits, vegetables and honey High fructose corn syrup - Liquid sweetener that contains 42-

90 percent fructose Honey - Made up of glucose, fructose and water Sugar alcohols - Sorbitol, mannitol, xybitol Lactose - milk and milk products Maltose, dextrose - cereals and some baked goods

Dietary importance of carbohydrates – Main source of energy– To form supporting structures eg cellulose

cell walls in plants– To be converted to other organic compounds

such as amino acids and fats– For the formation of nucleic acids (DNA)– To synthesize lubricants eg mucus which

consists of a carbohydrate and a protein– To produce the nectar in some flowers.

DIETARY FIBRE (ROUGHAGE)

- Cell walls of plants consist mainly of cellulose

- No enzymes to digest cellulose

- Cellulose is not absorbed into the bloodstream

- Reaches the large intestine (colon)

- Undigested part of diet = fibre or roughage

- Egested in the faeces

Functions of fibre

1. Fibre prevents constipation.

Fibre + bacteria add bulk to contents of colon

Help it to retain water

Softens the faeces

Reduces time for undigested residues to pass out

2. Fibre helps peristalsis.

Peristalsis moves food along digestive tract

Harder, indigestible food stimulates muscles to contract more than soft food

Sources: fruits, vegetables, bran, wholemeal bread

In short…..

Biology by Jones & Jones