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Unifying Characteristics of Life. Order — the smallest unit of life is the cell Metabolism — Responsiveness —perceive and react to their environment Development — Heredity —genes are passed from parent to offspring Evolution —populations change over time as they adapt.

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Unifying Characteristics of Life

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Unifying Characteristics of Life

  • Order— the smallest unit of life is the cell

  • Metabolism—

  • Responsiveness—perceive and react to their environment

  • Development—

  • Heredity—genes are passed from parent to offspring

  • Evolution—populations change over time as they adapt


4. Cell:The simplest

entity that has all

the properties of life

Biological Organization

Fig 1.3

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 func-

tion 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

Plants

Animals

Fungi

Protists

Bacteria

Archaea:

Bacteria adapted to

extreme environments

PROKARYOTES

Universal Ancestor


The Three Domains of Life

  • The three domains of life are:

  • Bacteria

  • Archaea

  • Eukarya


Domain Archaea

Domain Bacteria

Domain Eukarya

Kingdom Protista

Kingdom Plantae

Kingdom Animalia

Kingdom Fungi

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

Small

tree finch

Medium

tree finch

Woodpecker

finch

Large cactus

ground finch

Large

ground

finch

Small

ground

finch

Gray

warbler

finch

Green

warbler

finch

Large

tree finch

Vegetarian

finch

Mangrove

finch

Sharp-beaked

ground finch

Cactus-flower-eaters

Bud-eater

Seed-eaters

Insect-eaters

Tree finches

Ground finches

Warbler finches

Fig 1.13

Common ancestor from

South American mainland


Darwin’s Conclusion

  • Fact 1:

  • Darwin synthesized the concept of natural selection from two observations:

  • 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


Atomic number

Periodic table of the elements

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

(c) Oxygen atom

Proton

Neutron

Electron

First

shell

Second

shell

Atomic nucleus

Fig. 2.02


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

Nitrogen (N)

Atomic number = 7

Oxygen (O)

Atomic number = 8

Fig 2.7


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

    • Ionic bonds

Sodium atom

Chlorine atom

Complete outer shells

Na

Cl

Fig 2.8

Sodium chloride (NaCl)


Atoms: electrically neutral

Ions: Electrically charged

(a) Hydrogen atom (H)

(b) Hydrogen ion (H+)

1 electron

No electron

1 proton

1 proton

No electrical charge

(c) Sodium atom (Na)

(d) Sodium ion (Na+)

11 electrons

10 electrons

11 protons

11 protons

No electrical charge


Covalent Bonds

Fig 2.9


Covalent bonding in water

Water molecule (H2O)

Oxygen atom with unfilled shell

Full shell with 8 electrons

Slightly negative

Covalent bond

(shared pair

of electrons)

+

+

Slightly positive

Full shells with 2 electrons each

Hydrogen atoms with unfilled shells


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 life-supporting properties:


1. Water as the Solvent of Life

Salt crystal

Ion in solution

Fig 2.16


Dissolving of Sodium Chloride, NaCl, in Water

Salt

Electrical

attraction

Water molecules dissolve NaCl,

breaking ionic bond

Water

Water

molecules

(H2O)

Hydrogen

bonds

Ionic bond

Edge of one

salt crystal


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

  • Carbohydrates

  • Lipids

  • Proteins

  • Nucleic Acids


1) Carbohydrates

  • C:H:O ratio is 1:2:1 (CH20)n

  • Simple sugars:

    • Structural units, used to make larger, storage compounds:

      • Starch –

      • Glycogen –

      • Cellulose –


Fig 3.13


Glucose

Fructose

Monosaccharides

C6H12O6

(Simple sugars)

Glucose

Fructose

Formation of a Disaccharide

C12H22O11

H2O (water)

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


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