Transcript H - Tacoma Community College

Unifying Characteristics of Life
1. Order - the smallest unit of life is the cell; all living
things have complex organization
2. Regulation –
3. Metabolism—synthesis and break down of molecules,
producing energy to power life processes.
4. Responsiveness—
5. Development—from simple to more complex
organism
6. Reproduction/Heredity—
7. Evolution— populations change over time as they
adapt
Biological
Organization
4. Cell :
Fig 1.1
3. Organelle :
A structure
within a cell
that performs a
specific function
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: all
populations of all species
occupying a specific area
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
– Prokaryotic cells
– Eukaryotic cells
• The prokaryotic cell is simple and contains no
organelles
• The eukaryotic cell
Nucleus
(contains
DNA)
Eukaryotic cell
Prokaryotic cell
DNA
(no nucleus)
Organelles
Fig 1.3
• 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
Archaea:
PROKARYOTES
Universal Ancestor
The Three Domains of Life
• The three domains
of life are:
1. Bacteria
2. Archaea
3. Eukarya: consists of four kingdoms:
1.
2.
3.
4.
Protista
Animalia
Plantae
Fungi
Domain
Archaea
Domain
Bacteria
Domain Eukarya
Kingdom
Protista
Kingdom
Plantae
Kingdom
Fungi
Kingdom
Animalia
Fig 1.5B
Unity in the Diversity of Life
• Underlying the diversity of life is a striking unity,
especially at the lower levels of structure
– Example:
– 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
• Life evolves
Ancestral bear
The Darwinian View of Life
• The evolutionary
view of life came
into focus in 1859
when Charles
Darwin published
The Origin of
Species
• Darwin’s book developed two main points
1. .
2. .
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
• Fourteen
species of
Galápagos
finches have
beak shapes
adapted to
suit their
environments
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
Common ancestor from
South American mainland
Warbler finches
Darwin’s Conclusion
• Darwin synthesized the concept of natural selection
from two observations:
• Fact 1: Struggle for existence
• Fact 2: Individual variation
• Conclusion:
– The product of natural selection is adaptation
Fig 1.6B:
Natural Selection
The Evolution of Diversity
• Different species have different traits. These arise
from:
• Mutations –
• Evolution – heritable changes in the line of descent over
time. Caused by:
• Natural selection - adaptive traits tend to increase over
time. It is the mechanism of evolution
Observing Artificial Selection
• Artificial selection is the selective breeding of
domesticated plants and animal by humans
Fig 13.2
Observing Natural Selection
• There are many examples of natural selection in
action
• 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
Chapter 2: Chemical Basis of Life
BASIC CHEMISTRY
• Organisms and all other things in the universe
consist of matter
• Matter
• Matter is composed of chemical elements
– There are 92 naturally occurring elements on
Earth
Periodic table of the elements
Atomic number
Element symbol
Mass number
• 25 Elements are essential to life
Elements
• Elements can combine to form compounds
• Compounds
• Examples of Compounds:
• Table salt (sodium chloride): NaCl
• Water: H2O
• Glucose: C6H12O6
• Is O2 gas a compound?
Atom: smallest unit of matter that retains the
properties of an element
(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
 Positive charge

 Negative charge
•Participates in
chemical reactions
•
Neutron
 No charge
Nucleus
• Consists
of neutrons
and protons
• Elements
– differ in the number of protons in their atoms
• 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
determines the chemical properties of an atom
• Atoms of the four elements most abundant in life
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
Nitrogen (N)
Atomic number = 7
Oxygen (O)
Atomic number = 8
Chemical Bonding and Molecules
• Chemical reactions:
– Atoms give up, acquire, or share electrons in order to
complete their outer shells
– Result:
– 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 2.7A
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
Table 2.8
• A covalent bond forms when
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
• Your cells are composed of 70%–95% water
The Structure of Water
• The polarity of water
results in
()
()
()
Hydrogen
bond
()
()
()
()
()
• These interactions
are called hydrogen
bonds
Fig 2.10
Water’s Life-Supporting Properties
•
Hydrogen bonding explains most of water’s lifesupporting properties:
1. Water as a solvent
2. Cohesion
3. Water moderates temperature
4. Ice floats
1. Water as the Solvent of Life
• A solution is a liquid consisting of two or more
substances evenly mixed
Ion in solution
Fig 2.14
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 = attraction of identical molecules
• Water molecules
stick together as a
result of hydrogen
bonding
Microscopic tubes
• Surface tension
– is the measure of how difficult it is to stretch or break
the surface of a liquid
Fig 2.11
Figure 2.13
3. Water Moderates Temperature
• Because of hydrogen bonding, water has a strong
resistance to temperature change
• How?
• Earth’s Oceans cause temperatures to stay within limits
that permit life
4. Ice floats
• Water is less dense as a solid than as a liquid (due to
hydrogen bonds!)
• This allows fish and other organisms to survive
under the ice.
Acids and Bases
• Acid – a compound that donates H+ ions to
solutions
• pH scale – describes how acidic or basic a solution
is.
Fig. 3-9
Fig 2.15
pH Scale
0
1
Gastric juice,
2 lemon juice
H+
H+
Battery acid
+
– H
H+ OH
+
OH– H H+
H+ H+
3 Vinegar, beer,
wine, cola
4 Tomato juice
Acidic
solution
5
Black coffee
Rainwater
6 Urine
OH–
H+
OH–
H+
OH–
OH– OH– +
H+ H+ H
Neutral
solution
Neutral
[H+] = [OH–]
Saliva
7 Pure water
Human blood, tears
8 Seawater
9
10
OH–
Milk of magnesia
OH–
OH– H+ OH–
–
OH– OH
OH–
+
H
Basic
solution
11
Household ammonia
12
Household
13 bleach
Oven cleaner
14
Ch. 3 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: glucose, fructose
(CH20)n
 Structural units, used to make larger,
storage compounds:
1. Starch –
2. Glycogen –
3. Cellulose – plant cell walls (structure,
protection)
Fig 3.7
Glucose
Fructose
Monosaccharides
C6H12O6
(Simple sugars)
Glucose
Fructose
H2O (water)
Sucrose
A portion of a
polysaccharide
2. Lipids
•
Non-polar, hydrophobic (don’t dissolve in water)
•
(CH)nCOOH
•
Functions:
•
4 main types:
a) Fats
b) Phospholipids
c) Steroids
d) Waxes
A) Fats
• Triglycerides –
Fig. 3.8B,C
-
-
B) Phospholipids
C) Steroids
• No fatty acid chains
• Cholesterol:
Cholesterol
Fig 3.9B
D) Waxes
• Repel water
• honeycombs
3) Proteins
• Made of amino acids
joined by peptide bonds
Fig. 3.12A
Fig 3.12C
Proteins continued
• DNA specifies the order of AA
Primary structure
Fig 3.14A-D
Anemia, circulatory problems, kidney failure,
enlarged spleen…..
4) Nucleic Acids
• DNA & RNA
• Monomers of
Nucleotides
Fig 3.16A
The nitrogenous
bases of DNA
RNA contains:
Fig 3.16B,C: The
structure of DNA