Transcript Bio1A - Lec 1 slides File

Lecture Outline:
Reading
Introduction
Chemistry of Life
Properties of Water
Biological Molecules: Proteins
Ch 1-3: Chemistry
Ch 4: Proteins
Mon: Bring in sow bugs
Homework
Ch 1 Prequiz
Ch 2-4 Prequiz
Ch 5 pt Prequiz
aka – rolly pollies
Homework 1
What is Biology?
Biology is the scientific study of life
Characteristics
of Living
Organisms:
The Core Theme: Evolution accounts for
the unity and diversity of life
Evolution is the process of change that
has transformed life on Earth
• “Nothing in biology makes sense except in the light of
evolution”—Theodosius Dobzhansky
• Organisms living on Earth are modified descendents of common
ancestors
• Origin
• Gradual changes in a population
• Selection process
Natural Selection simplified
Origin
Variation
(through mutation)
Selective Pressure
Energy Conversion
• Work requires a source of energy
• Energy can be stored in different forms, for
example, light, chemical, kinetic, or thermal
• The energy exchange between an organism and
its environment often involves energy
transformations
• Energy flows through an ecosystem, usually
entering as light and exiting as heat
• Life can be studied at different levels from
molecules to the entire living planet
• The study of life can be divided into different
levels of biological organization
Chemical Connection to Biology
•Biology is a multidisciplinary science
•Living organisms are subject to basic laws of physics
and chemistry
Essential Elements of Life
• About 25 of the 92 elements are essential to life
• Carbon, hydrogen, oxygen, and nitrogen make up 96% of
living matter
• Most of the remaining 4% consists of calcium, phosphorus,
potassium, and sulfur
• Trace elements are those required by an organism in
minute quantities
• Each element consists of unique atoms
• An atom is the smallest unit of matter that still
retains the properties of an element
Periodic table of elements
Top 12 elements in human body
H C N O S Ca Na K P Cl Mg
Be able to read
periodic table of
elements
Atomic Number = # protons
determines the element
NEVER CHANGES
Atomic Weight = # protons + # neutrons
Neutral Atom = no charge
therefore # electrons = # protons
Subatomic configuration
{#p+; #n0; #e-}
Atomic Structure
Model of an atom
Includes:
Charge
1. (p+) proton
+1 Positive
weight
Mass
1 AMU
2. (n) neutron
0 Neutral
1 AMU
Circling 3. (e-) electron
Orbital, shell
Energy Level
-1 Negative
0 AMU
In the
Center
Subatomic configuration : {#p+; #n0; #e-}
AMU = unit of
measurement
Like lbs
Octet Rule : shell 1 wants 2 electrons,
shells 2 & 3 want 8 electrons
Energy Shells
Valence electrons are those in the outermost shell,
or valence shell
Fig. 2-8
(a) A ball bouncing down a flight
of stairs provides an analogy
for energy levels of electrons
Third shell (highest energy
level)
Second shell (higher
energy level)
First shell (lowest energy
level)
(b)
Atomic
nucleus
Energy
absorbed
Energy
lost
Electron Distribution and Chemical
Properties
• The chemical behavior of an atom is determined
by the distribution of electrons in electron shells
• Valence electrons are those in the outermost
shell, or valence shell
• The chemical behavior of an atom is mostly
determined by the valence electrons
• Elements with a full valence shell are chemically
inert
= Si-28 or
28Si
If 1 number indicates
specific isotope
Si
{14p+; ?n0; 14e-}
or closest #
Indicates avg
All isotopes
This is what we
normally use
Chemistry or Biology Boot camps
Ions
atoms that have gained or lost electrons
electrolytes – electrically conductive – can move a charge
(11p+; 12n0; 10e-)
Overall positive
charge
(17p+; 18n0; 18e-)
Overall negative
charge
Fig. 9-UN1
Typically needs a donor and recipient
(reducer and oxidizer) redox
becomes oxidized
(loses electron)
Reducing agent
Causes Cl to be
reduced
Oxidizing
agent
becomes reduced
(gains electron)
Ca
{20p+; 20n0; 20e-}
Ca 2+
Included to show
difference in electrons
{20p+; 20n0; 18e-}
H+ Li+ Na+ K+ Mg2+
{17p+; ?n0; 17e-}
{17p+; 18n0; 18e-}
Cl
Chemical
symbol
F
Chemically Inert Elements
• Inert elements have their
outermost energy level fully
occupied by electrons
2 Factors
Full shell
neutral
Chemically Reactive Elements
Chemical reaction
When electrons move
Orbitals NOT full
Covalent Bonds – Strongest – shares electrons
(50-200kcal/mole)
Shell is full
Shell NOT full
In a sense
Like we did with ion
something to
indicate difference
in electrons
Symbol + ______
Chemical
symbols
1 line = 2 e-
CH4
Chemical
formula
Subscript vs superscript