ProteinsProteinsCarbohydratesCarbohydrates

LipidsLipidsWaterWater

Edited by Janet A Renshaw

School ofBiological Sciences

Introduction Carbohydrates Proteins Lipids Water Questions and Answers

EXIT

They are all based on the chemical elements carbon, hydrogen and oxygen.

Proteins can also contain the elements nitrogen, sulphur and phosphorous

The three main organic molecules are carbohydrates, proteins and lipids.

These molecules are very important in living organisms, they can be used as building blocks for cells and also for energy

The structures of these molecules are The structures of these molecules are

of key importance to their functionsof key importance to their functions

Carbohydrates

ProteinsLipids

Water is a very important molecule, it makes up between 45- 75% of the body mass of most organisms and without it life on earth would not have evolved.

Carbohydrates have roles in all forms of life and make up most of the organic matter on earth.

Monosaccharides are the basic monomer units of which carbohydrates are composed.

The most common monosaccharide is glucose

sta

rche

s

cellulose

glycogen

suga

rs

carbonhydrogenoxygen

Carbohydrate molecules consist of 3 elements

H

in the form the OH is hereOH

HOOH

OH

H

H

O

H2COH

H

This has a great effect on the property of molecules made when glucose molecules link together.

in the form the OH is here

H

OH

H

in the form the OH is hereOH

H

in the form the OH is hereOH in the form the OH is hereOHOH

HOOH

OH

H

H

O

H2COH

H

HOOH

OH

H

H

O

H2COH

H

HOOH

OH

H

H

O

H2COH

H

HOOH

OH

H

H

O

H2COH

Hin the form the OH is here

H

OH in the form the OH is here

H

OHOH

Glucose Glucose Glucose can exist in two forms, the form and the form.The two forms of glucose have the same properties.

The only difference between them is the position of one of the OH groups.

DisaccharidesDisaccharidesWhen 2 monosaccharides join together they form a larger disaccharide

molecule.

The linkage is via a glycosidic bond where they share an oxygen molecule and a water molecule is eliminated.

Monosaccharide

Monosaccharide

Removal of H20

Disaccharide

share

oxygen

Two monosaccharides can become linked by a condensation reaction.

H2O

Glycosidic Bond

Condensation Reaction between 2 glucose monomers

Examples of DisaccharidesExamples of DisaccharidesMaltose

Formed from 2 glucose molecules, formed in germinating seeds from the breakdown of starch, providing energy

Sucrose

Formed from 1 glucose and 1 fructose molecule and is the form in which carbohydrates are transported in the phloem in plants

Lactose

Formed from 1 glucose and 1 galactose molecule, it is an energy source found in the milk of nearly all mammals

PolysaccharidesPolysaccharidesCarbohydrates which are made from many linked monosaccharide

monomers form long chain-like molecules

called polymers.

- made from glucose

monomers

polysaccharides cellulose

glycogen

starch

StarchStarch

The other form is amylopectin which consists of branched chains of glucose, this forms a branched compact brush.

One form is amylose which consists of un-branched chains of glucose,this coils into a helical compact structure

Found in two forms, which are both made up of glucose

Starch is the main storage carbohydrate in plants.

Hydrolysis reaction:- A chemical process whereby a compound is cleaved into two or more simpler compounds along with the uptake of water

Amylase(enzyme)

Breaks down

maltose

glucose

sources of

energy

Starch

H2O

It is the main storage carbohydrate in

mammals found in liver and muscle cells.

It is more branched in structure than amylopectin.

The more branched the molecule, the quicker it can be made and broken.

GlycogenGlycogen

A polymer of glucose monomers.

Is a polymer of glucose

monomers.

It is an important component

of plant cell walls.

It does not spiral as with

glucose

glucose consists of chains that are straight and long, they lie parallel to each other bound together by hydrogen bonds.

CelluloseCellulose

Proteins have many roles in living organisms and are extremely important. There are many different types of proteins with different functions, for example,

Antibodies are protective proteins and as part of the immune system they help fight disease

Biological molecule with enzyme

Biological moleculeBiological molecule

with enzymeBiological molecule

with enzymeEnzyme

Enzymes are proteins which speed up the rate of biological reactions

Haemoglobin is a protein that transports oxygen in the blood.

ANTIBODIESDISEASE

The R group can contain hydrogen and/or carbon and sometimes oxygen, sulphur and nitrogen.

This is the basic structure of an amino acid.

Proteins are polymers made up of monomers called amino acids.

There are 20 different amino acids, amino acids can join in any order to

produce an infinite number of different proteins.

The only thing that changes between different amino acids is the R group

A condensation reaction joins two amino acids together forming a dipeptide. The bond formed between them is called a peptide bond

H2O

Peptide Bond

A chain of many amino acids linked by peptide bonds is called a polypeptide. A protein can consist of one or more polypeptides.

Proteins can get broken down by hydrolysis reactions into polypeptides, dipeptides and amino acids.

The primary structure :- this is the sequence of amino acids in the polypeptide formed from many condensation reactions

Protein StructureProtein Structure

There are four different levels of protein structure.

aminoacid

aminoacid

aminoacid

aminoacid

aminoacid

aminoacid

aminoacid

aminoacid

aminoacid

aminoacid

H2O H2O H2O H2O H2O H2O H2O H2O H2O

The secondary structure :- where the polypeptide chains can fold

into stable 3D regular shapes. One secondary structure is the -helix

where the chains fold into a helical shape. Another structure is the

strand

-helix structure

The tertiary structure :- this is when further folding occurs and this is the overall shape of the polypeptide chain.

This is the tertiary structure of the alpha chain of the protein, haemoglobin.

This 3D shape is maintained by a series of weak interactions which are mostly hydrogen bonds.

The quaternary structure :- polypeptides can associate with other polypeptides and they way in which they bind together to form the molecule is the quaternary structure.

Quaternary Structure taken by means of rasmol (www.dkfz-heidelberg.de)

Globular proteins, for example

enzymes, form roughly a spherical

shape and most of them are soluble

in water.

Proteins fit into two subgroups, globular proteins and fibrous proteins.

The function of a globular protein is determined by its shape, so its shape

is vital.

The usual function for this subgroup is a chemical function.

Molecular representation of an enzyme

Substrate

Protein SubgroupsProtein Subgroups

Fibrous proteins do not form a spherical structure they form long chains

and they are insoluble.

Fibrous proteins have structural roles, like giving strength or elasticity to

certain tissues.

Muscle Fibre (www.uoguelph.ca)

Proteins can become denatured causing their shape to change therefore affecting their function.

Example shows an enzyme becoming denatured and losing hold on a substrate

A protein can vibrate due to an increase in temperature, which can cause it to become denatured, causing the weak bonds holding the tertiary or quaternary structure together to break.

Lipids are insoluble.

They are important dietary constituents as they are full of energy, contain certain vitamins and have a major role in cell membranes.

Two major types of lipids are triglycerides and phospholipids.

fats

oils

stero

ids

wa

xes carbon

hydrogen

oxygen

Unlike carbohydrates and proteins, lipids do not form polymers.

Lipid molecules consist of 3 elements

The formula for fatty acids is R-COOH, where the R, which is the hydrocarbon chain can be saturated or unsaturated.

They are formed from a glycerol molecule linked by ester bonds to three fatty acids.

Ester bond:-This is formed from a condensation reaction where the carboxyl group of a fatty acid and an OH group from the glycerol join and water is lost so they share an oxygen atom.

TriglyceridesTriglycerides

This group of lipids are the

fats and oils.

Glycerol 3 saturated fatty acids

ester bond

3H2O

Triglyceride Molecule

The phosphate group is soluble in water, it is water loving, which is termed hydrophillic.

The fatty acids are insoluble in water, they repel water, which is known as hydrophobic.

Due to these properties

phospholipids form cell

membranes when in water

PhospholipidsPhospholipidsFatty acid

Fatty acidglycerol

phosphate

water

glycerol glycerolglycerol

fatty acids

phosphates

Simplified structure of a phospholipid molecule used in

diagrams of membranes

Phospholipid Bilayer formed in

water

H2O

H2O

H2OH2O

H2O

H2O H2O

Water is an inorganic substance.

It has many essential properties, it has these properties because of the way in which the molecules in water bond together.

The biological importance of water is dependent on its

physical properties.

Some Important Properties of WaterSome Important Properties of Water

Solvent Properties

Water is a polar molecule and it’s polarity makes it an excellent solvent

for other polar molecules.

There is a whole range of other polar molecules, which

include small organic units such as glucose and amino

acids, also ions like calcium,potassium and sodium.

Non-polar substances do not dissolve in water.

Specific Heat Capacity

Water has a high specific heat capacity,

which means it has temperature stability.

It takes a large amount of heat (energy)

to raise the temperature of water

measurably. Due to this water containing

organisms are stable thermally.

Latent Heat of Evaporation

Due to the high specific heat capacity, water resists

evaporation into gas better than other liquids do.

This is significant to humans and other animals as we

rely on the evaporation of water from our body surface as

a cooling device.

Now go to the next page to start testing your knowledge.

This section is to test your knowledge on what has been covered in this package.

To get the answer click on the answer button

You will need paper and a pen to help you answer some of the questions

Question 1 What is the name of this

carbohydrate monomer ?

Question 2 Draw a diagram to show how two of these monomers form a

disaccharide and label the bond

CARBOHYDRATESCARBOHYDRATES

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Click here to see diagram

Question 4 What are the two forms of the polysaccharide starch ?

Question 5 What are the differences between the two forms ?

Question 3 What is the name of the disaccharide formed ?

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PROTEINSPROTEINS

Question 6 What three elements can be found in proteins but not in

carbohydrates and lipids ?

Question 7 There are two subgroups of proteins, globular proteins and

fibrous proteins.

Which subgroup -

a) is soluble in water ?

b) has structural roles ?

c) form long chains ?

d) is spherical in shape ?

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Question 8 What type of reaction occurs to join amino acids together?

Question 9 What is the name of the bond formed between amino acids

in a protein ?

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LIPIDSLIPIDS

Question 10 What are the two major types of lipids?

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Question 11 How is an ester bond formed in a triglyceride?

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Question 12 The phosphate group of a phospholipid is soluble in water,

what is the term used for this type of molecule

Question 13 Fatty acids are insoluble in water, what is the term used for

this type of molecule?

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Question 14 Name two important properties of water.

WATERWATER

Question 15 Water is a polar molecule do Non-polar substances

dissolve in water?

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Q1

Answer Answer This carbohydrate monomer

is glucose

Q2

Glycosidic Bond

AnswerAnswer

H20

Q3

Answer Answer The disaccharide formed

is maltose

Q4

AnswerAnswer The two forms of starch are amylose and amylopectin

Q5

Answer Answer Amylose consists of unbranched chains of glucose and has a helical compact structure

Amylopectin consists of branched chains of glucose and has a branched compact structure

Q6

Answer Answer Nitrogen, sulphur and phosphorous

Q7

Globular proteinsa) soluble in water ?

Fibrous proteinsb) structural roles ?

Fibrous proteinsc) form long chains ?

Globular proteinsd) spherical in shape ?

AnswerAnswer

Q8

AnswerAnswer A condensation reaction

Q9

AnswerAnswer A peptide bond

Q10

Answer Answer Triglycerides and phospholipids

Q11

Answer Answer

An Ester bond is formed from a condensation reaction where the carboxyl group of a fatty acid and an OH group from the glycerol join and water is lost so they share an oxygen atom.

Q12

Answer Answer The phosphate is termed

as a hydrophillic molecule

Q13

Answer Answer Fatty acids are

hydrophobic molecules

Q14

Answer Answer

Two from any of these

- solvent properties

- high specific heat capacity

- high latent heat of evaporation

Q15

Answer Answer No