Unifying Characteristics of Life
1. Order— the smallest unit of life is the cell
2. Metabolism—
3. Responsiveness—perceive and react to their
environment
4. Development—
5. Heredity—genes are passed from parent to offspring
6. Evolution—populations change over time as they adapt
Biological
Organization
Fig 1.3
4. Cell :The simplest
entity that has all
the properties of life
3. Organelle :
2. Molecule :
1.Atom:smallest unit
of an element that
still retains the
element’s properties
7. Organ System:A group of body
parts that carries out a particular
function in an organism
6. Organ :
5. Tissue :A group of
similar cells that carries
out a particular function in an organism
9. Population:
10. Community:
8. Organism:
individual
composed of
many
coordinated
organ systems
11. Ecosystem:
12. Biosphere:
Those regions of the
earth’s waters, crust
and atmosphere in
which organisms can
exist.The global
ecosystem
Cells and Their DNA
• The cell is the simplest structure that can perform
all activities required for life
• Cell Theory:
• There are two major types of cells
1.
2.
• All cells use DNA as the
chemical material of genes
– Genes:
The Diversity of Life
• The diversity of known life includes 1.7 million species
• Estimates of the total diversity range from 5 million to
over 30 million species
The Unity
and
Diversity of
Life
EUKARYOTES
Animals
Plants
Fungi
Protists
Bacteria
PROKARYOTES
Universal Ancestor
Archaea:
Bacteria adapted
to
extreme
environments
The Three Domains of Life
• The three domains
of life are:
1. Bacteria
2. Archaea
3. Eukarya
Domain
Archaea
Domain
Bacteria
Domain Eukarya
Kingdom
Protista
Kingdom
Plantae
Kingdom
Fungi
Kingdom
Animalia
Fig 1.9
Unity in the Diversity of Life
• Underlying the diversity of life is a striking unity,
especially at the lower levels of structure
• Evolution accounts for this combination of unity
and diversity
EVOLUTION: BIOLOGY’S UNIFYING THEME
• The history of
life is a saga of a
restless Earth
billions of years
old
– Fossils
document this
history
Fig 1.10
• Life evolves
Each species is one twig of a branching tree of life
extending back in time
Fig 1.11
Ancestral bear
• Darwin’s book developed two main points
1. Descent with modification
2. Natural selection
Natural Selection
• Darwin was struck by the diversity of animals on
the Galápagos Islands
• He thought of origin of new species and adaptation
to the environment the as closely related processes
Descent with modification
Cactus
ground
finch
Medium
ground
finch
Large
ground
finch
Small
ground
finch
Large
cactus
ground
finch
Small
tree finch
Vegetarian
finch
Medium Woodpecker
tree finch
finch
Large
Mangrove
tree finch
finch
Gray
Green
warbler warbler
finch
finch
Sharp-beaked
ground finch
Seed-eaters
Cactus-flower Bud-eater
-eaters
Ground finches
Insect-eaters
Tree finches
Fig 1.13
Common ancestor from
South American mainland
Warbler finches
Darwin’s Conclusion
•Darwin synthesized the concept of natural selection
from two observations:
• Fact 1:
• Fact 2:
• Conclusion: Unequal reproductive success
Fig 1.14:
Natural Selection
The Evolution of Diversity
• Different species have different traits. These arise
from:
• Mutations – – heritable changes in DNA. Mutations are
adaptive if they change the organism’s ability to get
food, mate, etc.
• Evolution –
• Natural selection - adaptive traits tend to increase over
time. It is the mechanism of evolution
• Darwin’s publication of The Origin of Species
fueled an explosion in biological research
– Evolution is one of biology’s best demonstrated,
most comprehensive, and longest lasting theories
– Evolution is the unifying theme of biology
BASIC CHEMISTRY
• Organisms and all other things in the universe
consist of matter
• Matter is anything that occupies space and has
mass
Periodic table of the elements
Atomic number
Element symbol
Mass number
• 25 Elements are essential to life
• C, H, O, N: 96% of the weight of the human body
Fig 2.3
Elements
• Elements can combine to form compounds
• Compounds
• Examples of Compounds:
Atom:
(a) Hydrogen
atom
(b) Carbon atom
Proton
Neutron
Atomic nucleus
Electron
(c) Oxygen atom
First
shell
Second
shell
Atomic Structure
• The subatomic particles of an atom
Electron
Proton
Neutron
Nucleus -Consists
of neutrons and
protons
• Elements
• Atomic Number:
• Mass number sum of the number of protons and
neutrons
Chemical Properties of Atoms
• Electrons
• The number of electrons in the outermost shell…
First
electron shell:
can hold
2 electrons
Outermost
electron shell:
can hold
8 electrons
Electron
Hydrogen (H)
Atomic number = 1
Carbon (C)
Atomic number = 6
Fig 2.7
Nitrogen (N)
Atomic number = 7
Oxygen (O)
Atomic number = 8
Chemical Bonding and Molecules
• Chemical reactions:
– 2 types of molecular bonding:
• Ionic Bonds
• Covalent bonds
Ionic Bonds
• When an atom loses or
gains electrons, it
becomes electrically
charged = ion
Sodium atom
Chlorine atom
– Ionic bonds
Complete outer shells
Na
Fig 2.8
Cl
Sodium chloride (NaCl)
Atoms: electrically neutral
Ions: Electrically charged
(b) Hydrogen ion (H+)
(a) Hydrogen atom (H)
1 electron
No
electron
1 proton
1 proton
No electrical
charge
(d) Sodium ion (Na+)
(c) Sodium atom (Na)
11
electrons
11 protons
No electrical
charge
10
electrons
11 protons
Covalent Bonds
Fig 2.9
Covalent bonding in water
Oxygen atom with
unfilled shell
Water molecule (H2O)
Full shell with 8
–
Slightly
electrons
negative
Covalent
bond
(shared
pair
of
electrons)
+
+
Full shells with 2
electrons each
Hydrogen atoms with
unfilled shells
Slightly
positive
WATER AND LIFE
• Life on Earth began in water and evolved there for
3 billion years
• The abundance of water is a major reason Earth is
habitable
The Structure of Water
• The polarity of water
results in…..
()
()
()
Hydrogen
bond
()
()
()
()
()
Fig 2.10
Water’s Life-Supporting Properties
•
Hydrogen bonding explains most of water’s lifesupporting properties:
1. Water as the Solvent of Life
Ion in solution
Fig 2.16
Salt crystal
Dissolving of Sodium Chloride, NaCl, in Water
Salt
Electrical
attraction
Water molecules dissolve
NaCl,
breaking ionic bond
Water
Water
molecules
(H2O)
Hydrogen
bonds
Edge of one
salt crystal
Ionic bond
2. Cohesion =
Microscopic tubes
Fig 2.12
3. Water Moderates Temperature
• Because of hydrogen bonding, water has a strong
resistance to temperature change
• Water can absorb and store large amounts of heat while
only changing a few degrees in temperature.
• How?
The Four Most Important Organic
Biological Compounds
1.
2.
3.
4.
Carbohydrates
Lipids
Proteins
Nucleic Acids
1) Carbohydrates
•
C:H:O ratio is 1:2:1
•
Simple sugars:
(CH20)n
 Structural units, used to make larger,
storage compounds:
1. Starch –
2. Glycogen –
3. Cellulose –
Fig 3.13
Glucose
Fructose
Monosaccharides
C6H12O6
(Simple sugars)
Glucose
Fructose
Formation of a
Disaccharide
H2O (water)
C12H22O11
Sucrose
A portion of a
polysaccharide
2. Lipids
•
Non-polar, hydrophobic (don’t dissolve in water)
•
(CH)nCOOH
•
Functions:
A) Fats
• Triglycerides – most abundant lipids in
body, abundant energy!
Fig. 3.15
B) Phospholipids
3) Proteins
Fig. 3.20
Fig 3.21
Proteins continued
Primary structure
Fig 3.22
Fig 3.24
4) Nucleic Acids
• DNA & RNA
• Monomers of
Nucleotides
Fig 3.26
Fig 3.27 The
nitrogenous
bases of DNA
RNA contains: ribose instead of deoxyribose, and uracil
instead of thymine
Fig 3.29
Fig 3.28: The
structure of DNA