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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