Chemical Basis of Life

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Chemical Basis of Life

Chemistry

Atoms – smallest particle of an element
Subatomic particles:
* Protons
* Neutrons
* Electrons

Molecules – a unit formed by 2 or more atoms joined together Elements
Compounds

Mass

Weight

Inorganic Compounds – molecules that do not necessarily contain a carbon

Organic Compounds – always contain large amounts of carbon * theses are the molecules composing living things – organisms

Biologically important Inorganic Molecules
a. Water
Characteristics:
Water and H bond
* polar zones of negative and positive charges
* known as a weak bond because linking a hydrogen form between the negative corners of one water molecule and positive corners of another

Surface Tension
* result of cohesion or clinging together of water molecules * wetting capacity of water is its ability to coat a surface – depends on its capacity to adhere

Capillary Action – causes movements:
Rising (in glass tubes)
Creeping up in a piece of blotting paper
Moving slowly along the micropores of the soil

Imbibition
- movement of water molecules into substances which swell or increase in volume as a result of the interaction between them and the water molecules.

Specific Heat (Specific heat capacity)
* the measure of the heat required to increase the temperature of a unit quantity of a substance by a certain temperature interval.

Importance of Water
* the universal solvent
* component of the most living systems
* occupies approximately 75% of the earth’s surface
* requirement for photosynthesis

b. Carbon dioxide
- the principal structural element of living matter
Primary requirements of photosynthesis
Waste product of cellular respiration
It forms the backbone for the major molecules of life

c. Nitrogen gas
- comprises 78% of the atmosphere
Primary component of amino acids

d. Oxygen gas
- primary requirement of the cellular respiration
- Product of the photosynthesis
- exists primarily as a gas in terrestrial and aquatic ecosystems all over the world.

Organic Compounds – Biomolecules

a. Carbohydrates
- most abundant of the 4 biomolecules
Importance:
Stores and transports energy
Structural components

3 Types:
1. Monosaccharides – simple sugars
- simplest form of sugar, usually colorless, water soluble crystalline solids - have sweet taste
Ex. Glucose – most abundant monosaccharide, used as an energy source in most organisms

2. Oligosaccharides
a. Dissacharides
maltose
lactose
b. Trisaccharides

3. Polysaccharides – many sugar
- most abundant carbohydrates
- a macromolecule consisting of repeating units of simple sugars (glucose)

* Glycogen – form on which glucose is stored as an energy source in animal tissues – stored in the ________ & _________. * Cellulose – accounts for 50% or more of all carbon in plants * primary component of plants’ cell walls

* a structural carbohydrate

b. Lipids
Importance:
* storage depots of metabolic fuel
* makes up the plasma membrane
* insulates the body
* protective form of cell walls of many bacteria, higher plants and exoskeleton of insects

Types:
1. Triglycerides / Triglycerols – most abundant
* economical of reserve fuel storage because when metabolized they yield more energy. * “energy – storage molecules”

2. Saturated Fatty Acids – tend to be solid at room temperature

3. Unsaturated Fatty Acids – not fully saturated at room temperature

4. Monounsaturated – contain one double bond

5. Poly unsaturated – contain two or more double bonds

Phospholipids – belong to amphipathic lipids
* because of their properties, it allows lipids to form bilayers, making them uniquely suited to function as the fundamental components of all membranes

Carotenoids – orange and yellow pigment of plants
* insoluble in water
* essential in photosynthesis

c. Proteins
– macromolecule...
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