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Biology 3
Ch 2 Chemistry of Life
Dr. Terence Lee
LA Harbor College
Atoms
• There are 2 main parts to an atom:1. Electrons
i. Negatively charged
ii. Surrounds nucleus
iii. Almost no mass
2. Nucleus
Atomic Nucleus
1. Protons
i. Positively charged
ii. Same mass as neutrons
iii. Number of protons determines
the type of atom
2. Neutrons
2
Examples of Elements
important to Life
• H – Hydrogen
• C – Carbon
• O – Oxygen
• N – Nitrogen
• P - Phosphorus
What makes one element different from the next?
Molecule
H2O2
H2O
Chemical Reactions
1. Change in matter when in which different chemical
substances are created by forming or breaking
chemical bonds.
3
Covalent Bonds
1. Are bonds formed when
two atoms share a pair of
electrons.
Ionic Bonds
1. Ionic bonds occur when a positive ion bonds with a negative ion.
4
Hydrogen Bonds
Hydrogen Bonds
5
Water
• Essential to Life
• Has very unique properties
Water Fact
Water Facts
• Large bodies of water help insulate the surrounding land to prevent large fluctuations in temperature.
• .
6
pH Scale
� The amount of H+ in a solution is a measure of its acidity and is called pH.
Acids, Bases, and Salts
1. Acids – ionic compounds that release
hydrogen (H+ )
2. Bases – ionic compounds that remove H+
from solution, usually have –OH- groups.
3. Salts –
Chemistry Part 2: Organic
Molecules1. Carbohydrates
2. Proteins
3. Nucleic Acids
4. Lipids
7
Organic Molecules
Organic Chemistry - the chemistry of:
1. compounds containing carbon
Carbon
1. Four electrons on outer shell
2. Bonds are usually covalent
Methane (CH4)
Carbon
Double bonds
Hydrocarbon chain and a ring compound.
CO2
CH3COH
CH2CH2
CH2CHOH
shorthand
8
Carbohydrates
1. Composed of carbon, hydrogen, and oxygen.
2. Forms monomers called simple sugars or
monosaccharides
3. Are found in:
2.10 Complex carbohydrates are time-released packets of energy.
�More than 1 sugar (monosaccharide) unit
�Disaccharides• sucrose
• lactose
� Polysaccharides• starch
• cellulose
Polysaccharide
• Three main types
9
Complex Sugars
Animals can’t digest cellulose
Cow
Termite
Lipids
10
Lipids
• Saturated fatty acid =
11
Lipids
• Saturated fatty acid –
– Takes up less space
– Solid at room temperature
• Unsaturated –
Lipids
Lipids
Margarine
12
• Resemble neutral fats but contain a charged phosphate
group (PO4).
Phospholipids
Lipids
Steroids
• Characterized by their inter locking rings of carbon
• Types of steroids:
13
Proteins
A chain of amino acids makes a
protein
Nucleic Acids
• DNA = deoxyribonucleic acid
• RNA = ribonucleic acid
• Are all composed of
Nucleotides
• Nucleotide:
14
Nucleic Acids
• Binding rules for the
bases:
Nucleic Acids
• DNA
– Deoxyribonucleic acid
– Double stranded
– Contains bases A, T, G, and C
– Found in nucleus and mitochondria of cell
• RNA
Nucleic Acids
• Nucleic Acids -> DNA -> Chromosome