CHAPTER 4: CHEMICAL CHAPTER 4: CHEMICAL COMPOSITION OF CELLCOMPOSITION OF CELLCHAPTER 4: CHEMICAL CHAPTER 4: CHEMICAL COMPOSITION OF CELLCOMPOSITION OF CELL

Prepared by, Ms.RajaPrepared by, Ms.Raja

ELEMENTS IN CELL

• Common elements – oxygen, carbon, hydrogen & nitrogen

• Other elements – sulphur, phosphorus, calcium, potassium, magnesium, chlorine, sodium & iron

• Carbon, oxygen, hydrogen, nitrogen, sulphur, phosphorus– Combined each other to form

chemical compounds

- Example 1. Chemical compounds

- carbohydrates, lipids, proteins, nucleic acid & water

2. sulphur, phosphorus, calcium, potassium, magnesium, chlorine, sodium & iron- Exists as ions in cell

CHEMICAL COMPOUNDS

ORGANIC COMPOUND

INORGANIC COMPOUND

Chemical compounds that contain the element carbon

Chemical compounds that do not contain

element carbon

Eg: carbohydrates, lipids, proteins, nucleic acid

Eg: water

IMPORTANCE OF ORGANIC COMPOUNDS

CARBOHYDRATES

Provide energy during respiration

Build cell walls in plant cells

Form external skeletons of insects

Stored food in the form of glycogen in liver & muscles, as starch in plant cells

LIPIDS

Form phospholipid bilayer

Protects organs & its heat insulator

Stored product – adipose tissue in animals & fats or oils in seeds

Solvent for vitamin A,D,E,K

Source of energy

Produce liver bile – digestion of fats

Synthesise steroid hormones including sex hormones

Proteins

Form str of cell – eg: cytoplasm

Form connective tissue – eg: tendons, ligaments, muscle

Form protein molecules in plasma membrane Build up

muscles for movement

Synthesise enzymes & hormones to control chemical processes

Synthesise antibodies

Form haemoglobin

Produce new cells

Nucleic acids

Carry genetic information

Direct protein synthesis

Determine traits

control all the core activities

Nucleic acid DNARNA

water

Major component of protoplasm

Transport medium

Allows chemical changes

As medium for biochemical reactions

Solvent to dissolve respiration gases & allow diffusion

To provide support - esp non-woody plants (cells are turgid)

Carbohydrates – carbon, hydrogen & oxygen

CARBOHYDRATE

MONOSACCHARIDE DISACCHARIDE POLYSACCHARIDE

types

MONOSACCHARIDES

• Basic building blocks of carbohydrates

• Simple sugars – glucose, fructose, galactose

• Reducing sugars

– Detected by using Benedict’s test

– Color changes blue to green, yellow, orange & finally brick red precipitate is produced

DISACCHARIDES

• Complex sugars

• Consists of two monosaccharides – by condensation & a water molecule produced

• Eg: Maltose, sucrose, lactose

• Reducing sugars except sucrose

Monosaccharide + monosaccharide

Disaccharide + water

condensation

Glucose + glucoseGlucose + fructose

Glucose + galactose

Maltose + water

sucrose + water

lactose + water

Maltose + water

sucrose + water

lactose + water

Glucose + glucoseGlucose + fructose

Glucose + galactose

condensation

hydrolysis

POLYSACCHARIDE

• Large complex sugars

• Consists of many monosaccharides – joined together by condensation – form long chains of simple sugars called polymers

• Eg: starch, glycogen, cellulose

• Starch – produced by plants as a form of food storage

• Glycogen – formed by animals as a means of storing glucose

• Cellulose – structural polysaccharide in plant cell