UNIT 3
BIOCHEMISTRY
READING:
Chapter 2
Chemistry of Life
OBJECTIVES
At the end of this unit of study the student will be able to:
1.
Define matter and list some of its properties.
2.
Describe the structure of atoms.
3.
Distinguish between elements, compounds, and mixtures.
4.
Describe two types of chemical bonds.
5.
Compare solutions, suspensions, and colloids.
6.
Distinguish between inorganic and organic compounds.
7.
Distinguish between dehydration synthesis and hydrolysis.
8.
Define carbohydrates and describe the various types of carbohydrates.
9.
Describe proteins and its component amino acids.
10. Describe lipids and name and briefly describe the various types.
11. Name and describe the two types of nucleic acids.
ASSIGNMENTS:
1.
2.
3.
4.
5.
6.
7.
BIOCHEMISTRY
I.
UNIT 3
MATTER
A. Anything that has mass and occupies space
B. Living things are made up of matter.
1. Some matter is changed chemically to produce energy.
2. Energy is used to carry out cell activities.
C. Properties of Matter
1. Exists in 3 states
a. SOLID - definite volume; definite shape
b. LIQUID - definite volume; indefinite shape (takes shape of its container)
c. GAS - indefinite volume; indefinite shape - occupies available space
2. Chemical and Physical Properties
a. PHYSICAL PROPERTIES - physical appearance or characteristics of a substance.
1) Color
3) Hardness
2) Boiling or Melting Point
b. CHEMICAL PROPERTIES - shows how one kind of matter reacts with other matter.
1) Burning of a substance.
3. Physical and Chemical Changes
a. PHYSICAL CHANGES - form of matter changes but kind of matter stays the same.
1) Change of state
a) FREEZING - change from liquid to solid
b) MELTING - change from solid to liquid
c) EVAPORATION - change from liquid to gas
d) CONDENSATION - Change from gas to liquid
e) SUBLIMATION - change from solid to gas
2) Change in size - cutting up paper
b. CHEMICAL CHANGE - chemical reaction; change in the makeup of the matter.
1) Iron reacts with oxygen to produce rust (iron oxide)
2) Law of Conservation of Matter - during a chemical reaction matter is neither created nor destroyed,
only changes form.
D. Atoms and Elements
1. ATOM - tiny unit that makes up matter.
a. Composed of subatomic particles.
1) PROTON - positive charge, mass of 1 atomic mass unit found in nucleus
2) NEUTRON - no charge, mass of 1 atomic mass unit; found in the nucleus
3) ELECTRON - negative charge, very little mass; found in energy levels around nucleus
b. Most of atom's mass is in the NUCLEUS of the atom.
2. ELEMENT - substance that contains only one type of atom.
a. Atoms of same element always contain the same number of protons.
1) Number of protons in atom determines the ATOMIC NUMBER.
a) All Hydrogen atoms have 1 proton.
b) All Oxygen atoms have 8 protons.
2) Number of protons plus the number of neutrons in atom gives ATOMIC MASS NUMBER.
b. Atoms may have varying numbers of neutrons and thus have different atomic mass numbers –
these atoms are called ISOTOPES.
1) Hydrogen - 3 isotopes
a) Ordinary Hydrogen - 1 p; 0 n; AMN = 1
b) Deuterium - 1 p; 1 n; AMN = 2
c) Tritium - 1 p; 2 n; AMN = 3
c. Number of electrons in energy levels normally equal the number of protons in the nucleus –
result is that atom is electrically neutral.
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d. Element Symbols
1) Many consist of first 1 or 2 letters of English name.
a) Hydrogen - H
b) Helium - He
2) Others come from Latin or other foreign language
a) Silver - Argenitum (Latin) - Ag
b) Tungsten - Wolfran (German) - W
3) First letter always capitalized while second is always lower case.
E. Compounds and Molecules
1. Atoms want to be stable - want a complete outer energy level.
a. Complete outer level usually will have 8 electrons
b. May complete level by combining with other elements - becomes stable.
c. COMPOUND - substance formed when 2 or more elements are chemically bonded.
d. Stability can be achieved by either sharing or transferring electrons.
1) COVALENT BOND - electrons are shared by atoms
a) MOLECULE - bonded set of atoms that share electrons
b) example - water
2) IONIC BOND - electrons are transferred from one atom to another atom.
a) ION - an electrically charged atom
b) Negative ion - gains electrons
c) Positive ion - loses electrons
d) Bond forms due to attraction between oppositely charged ions.
e) example - Sodium Chloride
e. CHEMICAL FORMULA
1) Expression of the chemical makeup of a compound
2) Show kinds and number of atoms (elements) in the compound
H2O - 2 atoms of hydrogen; 1 atom of oxygen
3) Coefficients show number of molecules of compound
2 H2O - 2 molecules of water; 4 atoms of hydrogen; 2 atoms of oxygen.
F. MIXTURE
1. Made up of 2 or more substances that can be separated by physical means.
2. May be homogeneous or heterogeneous.
a. HOMOGENEOUS - every part of mixture looks the same.
b. HETEROGENEOUS - some sections of the mixture may look different from other parts of the
mixture.
3. Types
a. SOLUTION - Homogeneous mixture in which one substance is dissolved in another substance individual molecules or ions evenly distributed; appears clear.
1) SOLUTE - Substance that is dissolved
2) SOLVENT - Substance that does the dissolving
b. SUSPENSION - Heterogeneous mixture containing substances that are larger than individual
molecules or ions.
1) Particles may settle to bottom
2) Some particles permanently suspended - gives cloudy appearance.
3) example - blood
c. COLLOID - Homogeneous mixture containing particles larger than in a solution but smaller
than the particles in a suspension.
1) May consist of clusters or groups of atoms, ions, or molecules.
2) examples - gelatin; homogenized milk.
II. Compounds important to Life
A. 99% of atoms in human body are hydrogen, oxygen, carbon, and nitrogen.
B. INORGANIC COMPOUNDS
1. Composed of elements other than carbon
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2. Most abundant inorganic compound in all living things is water.
a. Can dissolve many things - called "universal solvent" - due to polarity of molecule
b. Makes up large percentage of all living things
c. Dissociates to form H+ and OH- ions. Both equal in pure water (10-7 ions)
d. Gives us the pH scale - 7 is neutral
1) Below 7 - acidic - more hydrogen ions(H+)
2) Above 7 - basic or alkaline - more hydroxide ions (OH-)
3. Carbon dioxide - another important inorganic compound
a. Inorganic even though it contains carbon.
b. Important because it is a source of carbon and oxygen.
C. ORGANIC COMPOUNDS
1. Contain the element carbon
2. Before 1828, was believed that all organic compounds had to be produced by living organisms
a. Urea - First organic compound synthesized in the laboratory
3. Often described using structural formulas
a. Show kind of atoms
b. Show number of atoms
c. Show how atoms are attached to each other
H H
| |
H-C-C-H
Ethane C2H6
| |
H H
4. Organic compounds important to life.
a. Carbohydrates
b. Proteins
c. Lipids
d. Nucleic Acids
5. Processes important to organic compounds
a. DEHYDRATION SYNTHESIS - production of a more complex molecule (polymer) from 2 or
more simpler molecules (monomers) by the removal of a molecule of water.
b. HYDROLYSIS - Breakdown of a complex molecule into simpler molecules by the addition of a
molecule of water - usually occurs during digestion.
D. CARBOHYDRATES
1. Group of organic compounds that are made of carbon, hydrogen, and oxygen.
a. Proportion of hydrogen to oxygen atoms is always 2 to 1.
2. Used as source of energy, structure, and energy storage.
3. Classes
a. MONOSACCHARIDES - single sugars
1) Contains one sugar molecule
2) Have chemical formula - C6H12O6 - have different structural formulas
3) examples - glucose (most common); fructose, galactose
4) glucose - food product of photosynthesis
b. DISACCHARIDES - double sugars
1) Composed of 2 monosaccharides that combine during a dehydration synthesis
2) Have molecular formula - C12H22O11
3) examples - Sucrose (table sugar) - glucose + fructose
Lactose (milk sugar) - glucose + galactose
c. POLYSACCHARIDES - many sugars
1) composed of many monosaccharides that combine during a series of dehydration syntheses.
2) Types
a) Cellulose - in plants; structural compound
b) Starch - in plants; storage of energy
c) Glycogen - in animals; called animal starch; energy storage compound in the liver.
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E. PROTEINS
1. Group of organic compounds containing carbon, hydrogen, oxygen and nitrogen; sometimes sulfur
2. Used to build and repair cells.
3. Large molecule made up of 20 different amino acids strung together.
a. Molecule of an amino acid has 3 basic part around a carbon atom.
1) Amino group - NH2
H
/
-N
\
H
2) Carboxyl group - COOH
O
//
-C
\
O-H
3) R group - a hydrogen atom or group of carbon and hydrogen atoms
b. Amino acids combine by dehydration synthesis - amino group of one amino acid joins with
carboxyl group of another amino acid - forms a PEPTIDE BOND.
c. DIPEPTIDE - 2 amino acids; POLYPEPTIDE - many amino acids
F. LIPIDS
1. Group of fatty organic compounds containing hydrogen, carbon, and oxygen.
a. Contains a larger number of Carbon and Hydrogen atoms and a lower number of Oxygen atoms
than carbohydrates.
b. Do not dissolve in water.
c. Made up of FATTY ACIDS - large, straight hydrocarbon chain with a carboxyl group at one end
1) Carboxyl end - hydrophilic - attracted to water; "water loving"
2) Hydrocarbon end - hydrophobic - repelled by water; "water fearing"
2. Found in cell membranes; also serve as energy storage compounds
3. Kinds
a. TRIGLYCERIDES - 3 fatty acids joined to a glycerol (type of alcohol)
1) OILS - triglycerides that are liquid at room temperature
2) FATS - triglycerides that are solid at room temperature
b. WAX - long fatty acid chain joined to a long alcohol chain.
c. STEROIDS - composed of 4 carbon rings; found in hormones, nerve tissue, and some plant and
animal poisons.
G. NUCLEIC ACIDS
1. Complex organic molecules that store important information about the cell.
2. Involved with transmission of characteristics during cell reproduction.
3. Types
a. Deoxyribonucleic Acid - DNA
1) Stores information essential for almost all cell activities
2) Found mostly in cell nucleus
b. Ribonucleic Acid - RNA
1) Stores and transfers information for protein manufacture.
4. RNA and DNA composed of thousands of nucleotides
a. Nucleotide parts
1) Phosphate group
2) 5-carbon sugar - either ribose or deoxyribose
3) Nitrogen base
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