Unifying Characteristics of Life
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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
Fig 1.3
2. Molecule :
4. Cell :The simplestentity that has all
the properties of life
3. Organelle :
Biological Organization
1.Atom:smallest unit of an element that still retains the element’s properties
7. Organ System:A group of bodyparts that carries out a particularfunction in an organism
6. Organ :
5. Tissue :A group ofsimilar cells that carries
out a particular func-tion in an organism
8. Organism: individual composed of many coordinated organ systems
9. Population:
10. Community:
11. Ecosystem:
12. Biosphere: Those regions of the earth’s waters, crust and atmosphere in which organisms can exist.The global ecosystem
• The cell is the simplest structure that can perform all activities required for life
• Cell Theory:
Cells and Their DNA
• There are two major types of cells
1.
2.
• All cells use DNA as the chemical material of genes
– Genes:
• 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 Diversity of Life
EUKARYOTES
Universal Ancestor
Bacteria
Archaea: Bacteria adapted
to extreme
environments
Protists
PlantsAnimals
Fungi
PROKARYOTES
The Unity and
Diversity of Life
• The three domains of life are:
The Three Domains of Life
1. Bacteria
2. Archaea
3. Eukarya
Domain Bacteria
Domain Archaea
Domain Eukarya
Kingdom Protista
Kingdom Plantae
Kingdom Fungi
Kingdom Animalia
Fig 1.9
• Underlying the diversity of life is a striking unity, especially at the lower levels of structure
Unity in the Diversity of Life
• Evolution accounts for this combination of unity and diversity
• The history of life is a saga of a restless Earth billions of years old
EVOLUTION: BIOLOGY’S UNIFYING THEME
– Fossils document this history
Fig 1.10
• Life evolvesEach species is one twig of a branching tree of life
extending back in time
Ancestral bear
Fig 1.11
• Darwin’s book developed two main points
1. Descent with modification
2. Natural selection
• Darwin was struck by the diversity of animals on the Galápagos Islands
Natural Selection
• He thought of origin of new species and adaptation to the environment the as closely related processes
Mediumgroundfinch
Cactusgroundfinch
Smalltree finch
Mediumtree finch
Woodpeckerfinch
Largegroundfinch
Smallgroundfinch
Large cactusground finch
Vegetarianfinch
Largetree finch
Mangrovefinch
Greenwarbler
finch
Graywarbler
finch
Sharp-beakedground finch
Seed-eaters Cactus-flower-eaters
Bud-eater Insect-eaters
Ground finches Tree finches Warbler finches
Common ancestor fromSouth American mainland
Descent with modification
Fig 1.13
• Fact 1:
• Fact 2:
• Conclusion: Unequal reproductive success
Darwin’s Conclusion
•Darwin synthesized the concept of natural selection from two observations:
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
• Organisms and all other things in the universe consist of matter
• Matter is anything that occupies space and has mass
BASIC CHEMISTRY
Atomic number
Element symbol
Mass number
Periodic table of the elements
• 25 Elements are essential to life
• C, H, O, N: 96% of the weight of the human body
Fig 2.3
• Elements can combine to form compounds
• Compounds
• Examples of Compounds:
Elements
Atom:
(a) Hydrogen atom
(b) Carbon atom (c) Oxygen atom
Proton Neutron Electron
Atomic nucleus
Firstshell
Secondshell
• The subatomic particles of an atom
Atomic Structure
Proton
Neutron
Electron
Nucleus -Consists of neutrons and protons
• Elements
• Atomic Number:
• Mass number sum of the number of protons and neutrons
• Electrons
• The number of electrons in the outermost shell…
Chemical Properties of Atoms
Electron
Firstelectron shell:can hold2 electrons
Outermostelectron shell:can hold8 electrons
Carbon (C)Atomic number = 6
Nitrogen (N)Atomic number = 7
Oxygen (O)Atomic number = 8
Hydrogen (H)Atomic number = 1
Fig 2.7
• Chemical reactions:
– 2 types of molecular bonding:
• Ionic Bonds
• Covalent bonds
Chemical Bonding and Molecules
• When an atom loses or gains electrons, it becomes electrically charged = ion
– Ionic bonds
Ionic Bonds
Sodium atom Chlorine atom
Complete outer shells
Na Cl
Sodium chloride (NaCl)Fig 2.8
(a) Hydrogen atom (H)
(c) Sodium atom (Na)
(b) Hydrogen ion (H+)
(d) Sodium ion (Na+)
1 electron
1 proton
No electrical charge
11 electrons
11 protons
No electrical charge
No electron
1 proton
10 electrons
11 protons
Atoms: electrically neutral Ions: Electrically charged
Covalent Bonds Fig 2.9
Covalent bonding in water
Full shell with 8 electrons – Slightly
negative
Hydrogen atoms with unfilled shells
Full shells with 2 electrons each
+ Slightly positive
+
Covalent bond(shared pairof electrons)
Oxygen atom with unfilled shell
Water molecule (H2O)
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 polarity of water results in….. ()
Hydrogenbond()
()()
()
()
()
()
The Structure of Water
Fig 2.10
• Hydrogen bonding explains most of water’s life-supporting properties:
Water’s Life-Supporting Properties
1. Water as the Solvent of Life
Ion in solutionSalt crystal
Fig 2.16
Dissolving of Sodium Chloride, NaCl, in Water
Salt
Water
Electricalattraction
Watermolecules(H2O)
Hydrogenbonds
Edge of onesalt crystal
Ionic bond
Water molecules dissolve NaCl,breaking ionic bond
2. Cohesion =
Microscopic tubes
Fig 2.12
• 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?
3. Water Moderates Temperature
The Four Most Important Organic Biological Compounds
1. Carbohydrates2. Lipids3. Proteins4. Nucleic Acids
• C:H:O ratio is 1:2:1 (CH20)n
• Simple sugars:
Structural units, used to make larger, storage compounds:
1. Starch –
2. Glycogen –
3. Cellulose –
1) Carbohydrates
Fig 3.13
Glucose
Fructose
Formation of a Disaccharide
C12H22O11
Glucose Fructose
H2O (water)
Sucrose
A portion of a polysaccharide
Monosaccharides
C6H12O6
(Simple sugars)
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
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