UNIT 2 - CHEMICAL AND CELLULAR BASIS OF LIFE

TRY !!!

Essential Elements

Out of the 92 elements found in nature, the 20 - 25% of elements (25- humans, 17 - plants) essential to continue healthy life and reproduction.

What are some essential elements which make up 96% of living body

Carbon, Hydrogen, Oxygen, Nitrogen

Which elements make up the remaining 4% of the mass of the organism ?

P, K, Ca, S (additionally, Na, Cl, Mg, B, Co, Cu, Cr, F, I, Fe)

Why is water important ?

1. Vital Chemical constituent in living cell

2. Provides a biological medium for all organisms

What is Polarity ?

The uneven charge distribution within a molecule

What is Water ?

A small, polar, angular molecule

What is Polarity in Water ?

In a Water molecule, the oxygen atom is slightly negative and the hydrogen atom is slightly positive.

Hydrogen Bonds ?

Weak attractions between slightly polar hydrogen atom of one water molecule and slightly polar oxygen atom of adjacent water molecule.

When water is in Liquid form, are the H bonds fragile or strong ?

Fragile

Mention some Physical properties of water

1.Cohesive Behaviour

2.Ability to moderate temperature
3. Expansion upon freezing

4.Versataility as a Solvent

What is Cohesive and Adhesive nature of water, respectively ?

Cohesive - The attractions between water molecules due to Hydrogen Bonds/ Bondings

Adhesive - The attractions between water molecules and other substances

What is the act allowed by those propeties for water ?

Ability to act as a Transport medium.

What are the sub properties of “Cohesive Behaviour”?

• High adhesion and High Cohesion

• High Surface Tension

How does high cohesion help water to be a transport medium ?

Due to cohesion between water molecules, water and dissolved substances such as minerals are transported as a continous column through the xylem against gravity.

How does high adhesion help water to be a transport medium ?

Adhesion between water molecules and cell wall, also helps in conduction of water and dissolved substances.

How does water have High surface tension ?

This ability is given to water due to cohesion between water molecules. In aquatic system, the water molecules in upper surface are attracted by Lower surface water molecule and it forms a water film.
- Water Skaters

What are the sub properties of “Ability to moderate temperature’?

1. High Specific Heat

2. High heat of vaporization

What is High Specific Heat ?

Water can absorb or release a relatively high amount of heat energy and by a slight change in its own temperature.

Quality given to water due to “high specific heat“?

Water will function as a thermal buffer in living system and aquatic bodies during temperature fluctuation on earth

What is High heat of Vaporization ?

Due to it, with the minimum loss of water an organism can release much heat energy.

What does it help with ?

Helps organisms to cool their body surface.
Evaporation of sweat from human skin helps to maintain body temperature at constant level.

Transpiration is plants helps to cool the plant body surface and prevent from becoming too warm in the sunlight.

When does water have a maximum density ?

At 4C

Why is Expansion upon Freezing an important property of water ?

It is an important property of water in polar regions, where, organisms in aquatic bodes can survive during the winter.

What quality is given to water due to its polarity ?

Versatility as a solvent

What are some substances which can dissolve in water ?

Polar molecules (Glucose)

Ionic Compounds (Na Cl)
Molecules with both polar and ionic regions. ( Lysozymes)

How does dissolving happen ?

Water molecules surround each of the solute molecules and form hydrogen bonds with them.

What does the solubility of a solute depend on ?

On the Polarity (not in their ionic nature)

What is the most abundant organic compound on Earth ?

Carbohydrates

What is the proportion of H:O in the hydrates of Carbon ? (Carbohydrates)?

2:1

What is the general formula of Carbohydrate ?

Cx (H2O)y

What are the three major groups of Carbohydrates ?

1. Monosaccharides - sugar

2. Disaccharides - sugar

3. Polysaccharides

What is the simplest Carbohydrate ? what is its molecular formula ?

Monosaccharide ( (CH2O)n

How much does the number of C atoms vary ?

from 3 - 7

Mention some qualities of Monosaccharides ?

Reducing sugars
Crystalline
Water soluble

How are Monosaccharides named according to the number of C atoms ?

1. Triose - Glyceraldehyde ( Phosphoglyceraldehyde is a derivative of Triose)

2. Tetrose - Erythrose (rare in nature)

3. Pentose - Ribose, Ribulose, Deoxy Ribose ( RUBP - derivative of Ribulose

4. Hexose - Glucose, Fructose, Galactose

5. Heptose

According to the type of Carbonyl group ?

Aldo Group - G, G
Keto Group - F

In aqueous form some monosaccharides form what shape ?

Ring shape

What are Disaccharides ?

Sugars formed by joining 02 monosaccharides by a Glycosidic Bond

How is a Glycosidic bond formed ?

It is formed by the removal of a water molecule from 02 adjacent monosaccharides by a Condensation reaction.

What are the reducing sugars and non reducing sugars in Disaccharides ?

Reducing Sugars - M, L

Non Reducing Sugars - S

What are Polysaccharides?

They are macromolecules and biopolymers, made up of few hundred to few thousand monosaccharide subunits.

Mention some qualities of Polysaccharides ?

No Crystalline
Not Water soluble
Not considered as sugars

What are the 02 ways polysaccharides can be categorized ?

Based on Function - Structure / Storage

Based on Architecture - Linear / Branched

Mention how its categorized based on Storage ?

1. Starch - Stored in Plants and chlorophytes

2. Glycogen - Stored in animals and fungi

3. Inulin - Stored in tubers of Dhalia

Mention how its categorized based on Structure ?

Cellulose - Component of plant and chlorophytes
Hemicellulose - Component of plant cell wall
Chitin - Component of fungi cell wall and exoskeleton of Arthropods
Pectin - Component of middle lamella of plant cell wall

Mention functions of Monosaccharides ?

1. Energy source

2. Building blocks of Disaccharides and Polysaccharides

3. Components of Nucleotides (DNA, RNA)

Mention function of Disaccharides ?

1. Storage sugar in Milk - Lactose

2. Storage sugar in Sugar cane - Sucrose

3. Translocation in phloem - Sucrose

Mention function of Polysaccharides ?

a) Storage Polysaccharides

• Starch stores glucose as energy source in plants

• Glycogen stores glucose as energy in animals

• Inulin stores fructose as energy in dhalia tubers

b) Structural Polysaccharides

• Cellulose in the cell walls of plants and chlorophytes

• Chitin in cell wall of fungi and exoskeleton of arthropods

• Hemicellulose in cell wall of plants

• Pectin in middle lamella of plant tissues

Mention characteristics of Lipids ?

Diverse group of Hydrophobic molecules

Large biological molecules but not considered as Polymers or Macromolecules

Comparatively more H than O

What are some Biologically important type of lipids ?

• Fats

• Phospholipids

• Steroids

What are Fats made up of ?

Fatty Acids and Glycerol

To what group does Glycerol belong to ?

Alcohol group having 3 carbons where each bear a single hydroxyl group.

What are Fatty Acids ?

Hydrocarbon chains with long ( usually 16 - 18) carbon skeleton with a carboxyl group at its one terminal.

Through which bond do the Fatty acids bind to each Hydroxyl group ?

Ester Bond

What are the resulting fat molecules called as ?

Triacylglycerol (Triglyceride)