chemical composition 230210
DESCRIPTION
NOTETRANSCRIPT
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CHEMICAL SUBSTANCES OF THE CELL
- Cell organisation?What made up an organism?
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Organism
System
Organ
Tissue
Elements
Cell
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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
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Organic compound
Contain the element of carbonConsist of:Carbohydrates
Proteins
Lipids
Nucleic acid
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Inorganic compound
Do not contain the element of carbonEg: water -
2.Protein
Energy store
Structure & shape
Movement
Defense
Enzyme
Blood coagulation
Hormones
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3. Lipid
Fats & oilsInsulate heatProtect organEnergy storePhospholipid control cell permeabilityWaxesPrevent 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)
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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)
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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
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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
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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
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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
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condensation
Maltose and lactose are reducing sugar while sucrose notHydrolysis
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)
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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