CHEMICAL SUBSTANCES OF THE CELL

Cell organisation?What made up an organism?

Organism

System

Organ

Tissue

Elements

Cell

Learning outcome

State the elements of the cell

List chemical compounds in the cell

Explain the importance of organic compounds in the cell

Explain the importance of water in the cell

What is an element?A substance composed of only one kind of atom which cannot be broken down into simpler substances by a chemical reaction.25 from about 92 elements needed in building up living organism4 most common are carbon (C), hydrogen (H), oxygen (O) and nitrogen (N)

= CHON

Refer to figure 4.1 and table 4.1 (page 58)

Trace element?required in a very small quantity yet very important to an organism.

Chemical reaction

Elements

Chemical compound

Organic compound

Contain the element of carbonConsist of:

Carbohydrates

Proteins

Lipids

Nucleic acid

Inorganic compound

Do not contain the element of carbonEg: water

2.Protein

Energy store

Structure & shape

Movement

Defense

Enzyme

Blood coagulation

Hormones

3. Lipid

Fats & oilsInsulate heatProtect organEnergy storePhospholipid control cell permeabilityWaxes

Prevent water loss

Waterproof

Steroids

Makes plasma membrane rigid and stable

4. Nucleic acid

What is nucleic acid?

Complex macromolecules that store genetic information in the form of a code.

Building blocks: nucleotides (consist of a nitrogenous base, a phosphate group and a pentose sugar)

2 types:

Deoxyribonucleic acid (DNA)

Double helix structure

Can be found in nucleus, chloroplast and mitochondria

Contains genetic information that will be passed from parent to the offspring

Refer to Figure 4.3 (page 60)

Ribonucleic acid (RNA)

Single strand of nucleotides

Found in cytoplasm, ribosomes and nucleus

Genetic materials for some viruses

Copies information carried by DNA for use in protein synthesis

The importance of nucleic acid

Store genetic information

Stable storage

Easy to duplicate for transmission

Transmission of genetic information

Makes up 70% of our body (cell, lymph, blood plasma and interstitial fluid)Its chemical and physical properties allow it to sustain lifeConsist of 2 hydrogen atom and 1 oxygenPolar? Because of unequal distribution of charges

The importance of water:

Solvent

- polar molecule (unequal distribution of charge)

- attract one another as well as ions

Transport medium

- transport dissolved substances inside and outside the cell

Medium for biochemical reactions

- eg: breaking down of proteins, lipids and sugars

Maintaining a stable internal environment

Lubrication

- eg: mucus (composed mostly of water) assist the movement of food substances in the intestinal tract.

High cohesion

- tend to stick each other and move in long unbroken column through vascular tissues in plants

Learning outcome:

At the end of the lesson, you should be able to:

State the elements of carbohydrates

State the types of carbohydrates

Explain the formation and breakdown of disaccharides and polysaccharides

Build up by Carbon, Hydrogen and Oxygen in ratio of C:H:O is 1:2:13 main types:

Monosaccharide

Disaccharides

Polysaccharides

Monomers of carbohydratesKnown as simple sugarLong chain monosaccharide can combine to:

Protein glycoprotein

Phospholipid glycolipid

Example: Glucose (plants and fruits)Fructose (sweet fruits and honey)Galactose (milk)monosaccharides are reducing sugar

Combination of two monosaccharides by process of condensationCondensation?

Process removal of water molecules when bond is formed between two monosaccharides

Monosaccharide + monosaccharide

Hydrolysis

Condensation

Disaccharide + water

Condensation Hydrolysis Two monosaccharides join togetherRemoval of water moleculeA disaccharides split into two monosccharidesAddition of water moleculeCan occur by heating disaccharide solution with dilute hydrochloric acidProcess catalyze by enzymeSucrase hydrolysis of sucroseMaltase- hydrolysis of maltoseLactase hydrolysis of lactose

condensation

Maltose and lactose are reducing sugar while sucrose not

Hydrolysis

Monosaccharides(+ H2O) Disaccharide (- H2O)Source Glucose + glucoseMaltose Malt Glucose + fructoseSucrose Cane Glucose + galactoseLactose Milk

Polysaccharides? Polymers form by condensation of hundreds glucose monomersInsoluble in waterDo not taste sweet and do not crystalliseEg:

starch (reserved in plant);

Glycogen (animal and human); and

Cellulose (made up cell wall)

Many monosaccharide join together in a condensation reaction

This reaction called as polymerisation

In polymerisation, individual monosaccharide called as monomer

Result:

Animal = glycogenPlant = cellulose and starch

Undergoes hydrolysis monosaccharidesHeating a starch with dilute hyrochloric acid hydrolyses starch release glucose monomersHydrolysis by enzyme:Amylase (from saliva) hydrolyses starch maltose Then, maltase hydrolyses maltose glucose

Do activity 4.3 (PAGE 64)

- form group of 3 person; and

- Focus practice 4.2

Submission date: 2nd March 2010