chemical composition of cell
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Chap 4: Chemical Composition of the Cell
Carbohydrate (C, H, O)• Monosaccharide• Disaccharide• Polysaccharide
Lipid (C, H, O)• Fat & Oil•Wax• Phospholipid• Steroid
Saturated
Importance
Unsaturated
Importance
Proteins (C, H, O, P, N, S)• Primary• Secondary• Tertiary• Quaternary
Essential Non-essential
Importance
Nucleic Acid (C, H, O, P, N)
Nucleotide
RNADNA
Function
Water
Function
Enzyme
Function
Intracellular Extracellular
Synthesis Mechanism of action
Click purple-coloured box for more info.
Monosaccharide is the simplest form of carbohydrate. Some common ones are glucose, fructose & galactose.
Carbohydrate has a composition of CnH2nOn
Let’s assume that I’m glucose & these are my
friends, lactose & galactose. I’m the most common
monosaccharide
I’m fructose and I’m found in most sweet fruits and honey
too… Of course, the real monosaccharide molecule is not as
attractive as us…
I’m galactose and I’m found in milk. This is how
monosaccharide molecules look like…. Hrmmm….
We’re reducing sugar. We form red-brick precipitate when heated in Benedict’s
solution
Carbohydrate is important for providing energy.
Disaccharide
Monosaccharide + Monosaccharide = Disaccharide. They are formed through condensation (release 1 H2O)
Glucose + Glucose Maltose (malt sugar) I’m ingredient used in brewing of beer
Glucose + Fructose Sucrose (cane sugar) I’m found in sugar cane, sweet fruits and roots of some plants like
carrot Used as sweetener in beverages and cooking.
Glucose + Galactose Lactose (milk sugar) I’m present in milk of mammals, including human
This is the molecular structure of sucrose (disaccharide). Only sucrose is a non-reducing
sugar.
Polysaccharide
Many glucose undergo condensation to become polysaccharides
Polysaccharides are insoluble in water, do not taste sweet and do not crystallise.
There are basically 3 types of polysaccharides, ie. starch, glycogen and cellulose.
Starch is the main energy storage in plants Found in wheat, rice, corn, potato and bread Changes iodine solution from brown to blue-black
Glycogen is the main energy storage in animals and yeast
Stored in liver & muscle
Cellulose is the polysaccharides that makes up cell wall
Cell wall provides support for plants
Polysaccharides can be broken down into smaller molecules via hydrolysis
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Proteins (C, H, O, P, N, S)• Primary• Secondary• Tertiary• Quaternary
Importance: Cell growth & renew damaged cells Synthesis of enzymes, antibodies &
some hormones Form keratin (skin), collagen (bone) Part of plasma membrane (structure
& regulate movement of substances) Synthesis of haemoglobin
Essential
Non-essential
• Can’t be synthesised• Obtained from diet• Found in animal protein
• Can be synthesised• Derived from other amino acids
http://www.youtube.com/watch?v=lijQ3a8yUYQ
http://www.youtube.com/watch?v=Q7dxi4ob2O4&feature=related
More complete
On protein structure
An analogy on the structure of proteins
A straight wire
Coiled / Folded wire
A tangled wire
Few tangled wires
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Enzyme
Intracellular
Extracellular
For use within the cellTo be secreted outside the cell
Synthesishttp://www.youtube.com/watch?v=983lhh20rGY&feature=related
Extracellular enzyme after synthesis
Synthesis of enzyme is the same as that of protein as enzyme is also a types of protein
Mechanism of action
Functionhttp://www.youtube.com/watch?v=870MWm0peRI&playnext=1&list=PL40704FD8A12981B7&feature=results_video
From 0:00 – 2:54.Don’t bother abt the Induced Fit Theory. It’s the new correct theory but ur text book still use “Lock & Key”… So, just stay with txt book.. Hmph…
KPM
Y U No Upgrade?
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Lipid (C, H, O)
Importance:o Source of energy o Insulate heato Protection to major organs
1 glycerol 3 fatty acids
consists
Fats & oilsa)Saturated fat
Fatty acid that has no double bond such as animal fat.
Don’t react with additional hydrogen bonds as has maximum number of hydrogen.
Contain more cholesterol and solid at room temperature.
b) Unsaturated fat At least one fatty acid has one double bond such
as corn oil & palm oil. Can react with additional hydrogen atoms. Contain less cholesterol and is liquid at room
temperature.
divided into
Waxes Long-chained molecule causing it to be waterproof. Cuticle of epidermis of certain plants. Sebum excreted by oil gland in skin.
Phospholipids Main component of plasma membrane
Steroids Cholesterol – a mojor part of the plasma membrane
and also a precursor for synthesis of steroids & vitamin.
Other example of steroids are hormones (oestrogen, progesterone & testosterone)
Saturated & unsaturated fat
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NucleotideNucleic Acid Store genetic information Basic structure is
nucleotide
Double-stranded nucleic acid
Single-stranded nucleic acid
Mostly found in nucleus, but also in chloroplasts & mitochondria
Found in cytoplasm, ribosome & in nucleus
Holds genetic information of organism
Helps in synthesis of proteinGenetic material for some viruses
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Water
Function
Medium for biochemical reaction
Universal solvent• Due to polarity
Transport medium• Blood plasma (90% water)
carries many biological molecules
Maintain osmotic balance & turgidity• Maintain osmotic balance
by regulating salt concentration• In animals, this happen
between blood & interstitial fluid • In plants, it helps plant
cells become turgid
Provide support• Support structure
of the cell
Provide moisture• Moist the surface of
respiratory tract• Allows diffusion of gas
Maintain body temperature• Help distribute heat in
body• Transpiration in plants help
keep tissue cool
High surface tension & cohesion• Allow continuous flow of
water up the stem to leaves
Lubricant• Mucus (intestinal tract)• Synovial fluid (in joints)
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