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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