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Chemical composition of the cell
Elements• All living and non-living things are made of
subtances called elements• A subtance• Composed of only one kind of atom• Cannot be broken down into simpler
subtances by a chemical reaction• Most common C-carbon, O-oxygen, H-
hydrogen, N-nitrogen.
Elements• It accounts for about 96% of the mass of
human body.• Other elements make up the remaining 4%.• Organic compound-Chemical compounds
that contain the element carbon eg carbohydrates, proteins, lipids and nucleic acids.
• Water is an inorganic compound-composed of hydrogen and oxygen
The importance of Organic compound
Proteins
Carbohydrates
Lipids
Amino acids
Sugars, starch, glycogenand cellulose
Fats, Oils, waxes, Phospholipids and steroils
1
2
3
So, what are the function of these organic compound???
Food Digestion
What happens to
the food you eat??
Consist largely of Proteins, lipids and
carbohydrates
Complex organic molecules
Small solublemolecules
Digestion1. The process that breaks
down complex food to simpler soluble small molecules
complex small
Starch
glucose
Proteins
Amino acids
Lipids
Glycerol andfatty acids
Energy Synthesizenew protein
Plasma membranecomponent
Nucleic acid nucleotides
4
Phosphate group
Pentose sugar Nitrogenous base
2 types of nucleic acids
DNA(deoxyribonucleic acid)
RNA( Ribonucleic acid)
-double stranded polynucleotide-two strands-strands twisted around eachother-double helix
-Contains genetic information-In chloroplast and mitochondria
-Found in cytoplasm,ribosomesand the nucleus-Used for protein synthesis-genetic material for some viruss
The importance of water• Polar molecule• Transport medium• Medium for biochemical reactions• Lubrication• High cohesion
Polar moleculeThe solvent of lifeDissolve many ionic compound eg salt, polar molecules (sugar)
Transport medium• In blood ,lymphatic, excretory and
digestive systems and in vascular tissues of plants.
• Blood plasma is made up of 90% of water• Also contains many biological molecules
eg sugar, amino acid and respiratory gases.
• Waste products are excreted from the body through the urine.
Biochemical reaction• Biochemical reactions take place in the
cell can only occur when there is water• Water used in many digestive reactions• Breaking down the proteins,lipids and
sugars.
Types of carbohydratesMonosaccharides
Disaccharides
Polysaccharides
Monosaccharides Monomers of carbohydrates
Simplest type of carbohydrates
Simple sugars (main source of energy formany cells)
Long chain monosaccharides can combine with Proteins and lipids to form glycoproteins and glycolipids
Reducing sugars and reducing agent
Glucose, fructose ( sweet fruit and honey) and Galactose(milk)
Disaccharides• When 2 monosaccharides combine in
condensation process• What is condensation?• Maltose, Sucrose and Lactose
Glucose + Glucose Maltose + waterCondensation
Hydrolysis
Glucose + Fructose Sucrose + water Condensation
Hydrolysis
Glucose + Galactose Lactose + waterCondensation
Hydrolysis
Maltose- Malt sugar Sucrose – cane sugar
Polysaccharides• Hundreds of monosaccharides can
combine through condensation to form a long chain of molecules.
• Polymers formed by the condensation of glucose monomers.
• Insoluble in water due to large molecular size
• Do not taste sweet and do not crystallise• Starch, glycogen and cellulose
Starch Is the main carbohydrate reserve in plants
Found in plants such as wheat , rice ,potatoes, bread and corn
Glycogen• The main reserve of carbohydrates in
animals and yeast• Human and animals store glycogen mainly
in the liver and muscle cells• Glycogen-----animal starch• The polysaccharide chains are highly
branched• What happens when poly+diluted acid n
enzymmatic reaction????
Polysaccharides + water monosaccharidesHydrolysis
Proteins• Large complex organic molecules• Made up of elements carbon, hydrogen,
oxygen and nitrogen• Some contains sulphur and phosphorus• Foods ( fish, meat, milk, nuts and eggs)
Proteins• Made up of monomers or units called
amino acids.• A dipeptide consists of two molecules of
amino acids that are linked by a peptide bond through condensation.
Amino acid + amino acid dipeptide + watercondensation
hydrolysis
Proteins• Further condensation can form a
polypeptide chain.• There are 20 types of amino acids in living
cells.• Proteins or polypeptides that are broken
down through hydrolysis into amino acids by the digestive enzymes are absorbed into the bloodstream.
Polypeptide + water dipeptides or amino acidsHydrolysis
Proteins structures
Primary structure• The linear sequence of amino acid in a
polypeptide chain• Different types of proteins have different
sequences of amino acids.• The sequences are determined by the
genetic code carried in the DNA in the nucleus
Secondary structure• The polypeptide chain that is
coiled to form an alpha-helix or folded into beta-pleated sheets
• The coiling and folding of polypeptide chain by hydrogen bonds
Tertiary structure• Helix chain or beta-pleated sheets
are folded into 3D shape of polypeptide
• Eg: enzymes,hormones,antibodies and plasma proteins
Quarternary structure• Combination of two or more
tertiary structure polypeptide chains to form one large and complex protein molecule
• For example: haemoglobin