Unifying Characteristics of Life

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

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

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

• 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)

• The polarity of water results in….. ()

Hydrogenbond()

()()

()

()

()

()

The Structure of Water

Fig 2.10

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

Cohesion =

Microscopic tubes

What are plants made of?

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