Chapter 1 – The Study of Life

Biology – The study of life and living organisms

Organism – Anything capable of carrying on all of the processes of life

Branches of biology – •There are many subtopics within biology – a few examples we’ll hit upon this year:

•Biochemistry – Chemical substances and processes in organisms•Genetics – Inheritance – passing of traits from one generation to nextEvolution – Change in organisms over timeCell biology/cytology – Cell structure and functionZoology – AnimalsAnatomy – Structures of organismsPhysiology – Functions, activities, and processes of organismsEcology – Interactions of organisms and environment

Characteristics of Life – Life is diverse yet all organisms share a set of characteristics:1. Living things are organized – levels of organization varyIn general: atoms molecules cells tissues organs organ systems organisms (Cells grouped based upon roles)

2. Living things are made of one or more cellsMulticellular organisms (more than 1 cell) will have the above system based on jobs cells perform (although some organisms may not have complex organs or systems – more primitive, ex: sponge)

Cells in these organisms are considered specialized (have certain jobs)Examples: some fungus, plants, and animals

Unicellular organisms (one cell) will be organized up to the cellular level

1 cell does all jobs for organismExamples: bacteria, protists, and some fungus

3. Living things requires energy Metabolism – all the chemical

reactions in cell Heterotrophs are organisms that

obtain nutrients from food eaten Ex: some bacteria and

protists, fungus, & animals

Autotrophs are organisms that make their own food through photosynthesis

Take CO2, H2O, and solar energy to make glucose, a simple sugar that can be used as a source of energyEx: plants, some protists, and

some bacteria

4. Living things reproduce Reproduction – production of

offspring Prevents extinction of species

(group of organisms that can breed and produce fertile offspring)

Uses DNA (hereditary information) – which can be copied

Can be sexual or asexual

•Asexual reproduction – used by unicellular and some multicellular organisms; only 1 parent; offspring has DNA identical to parent•Sexual reproduction – used by multicellular organisms; 2 parents, each parent contributes ½ genetic information to offspring; offspring has mixed traits from parents

5. Living things respond to stimuli• Stimuli is external, and causes a

reaction• May be seen as movement, such as

movement away from danger, or reactions to other organisms.

• Response – observable, coordinated reaction to environmental stimuli

• Examples: plant growing toward light, hair raising on back of cat’s neck, pupils dilating in response to light

6. Living things are homeostatic Homeostasis – maintaining

(relatively) constant internal conditions (such as body temperature, pH, blood pressure, water balance) regardless of external changes

Examples of homeostatic behavior: sweating or shivering to maintain body temperature; urinary system ridding body of wastes

7. Living things grow and develop Growth – an increase in the number of

cells/ increase in the size Occurs through cell division and

enlargement; part of development Example – getting taller

Development – Changes an organism undergoes between conception and death Example – going through puberty

8. Adaptations evolve over time Adaptations – modifications that

make an organism suited to its way of life Examples – hollow bones of birds

for flight, gills for fish to breathe in water

Adaptations come about through evolution – a process through which a species changes over time

This is the source of the diversity of lifeOrganisms do not develop adaptations during the course of their lives

Classification•Systematics - the study of biological diversity with an emphasis on evolutionary history

•Taxonomy – The study of identifying and classifying organisms according to specific criteria

•Taxa –the categories into which organisms are classified   

Why do we need scientific names?•Common names don’t tell you enough information

•What kind of frog? Is it poisonous???•Common names are misleading

•Jellyfish – you mean it’s not a fish?•Ringworm – what do mean it’s not a worm?

•Common names vary from country to country

•Mountain lion, cougar and puma all refer to the same animal

Earliest classification system•Designed by Aristotle (384-332 b.c.)•Everything was classified as either a plant or an animal•Animals divided according to presence of blood, then habitats and morphology (form and structure)•Plants divided by size and structure as trees, shrubs, or herbs

•Limitations of Aristotle’s system:•Failed to include bacteria, fungus and protists•Did not take evolution into account (he saw species as distinct, separate and unchanging)•Failed to show evolutionary relationships between organisms•Some organisms didn’t fit (ex: birds that don’t fly, frogs living on both land and water)

Linnaeus’s classification systemDeveloped by Carolus (Carl) Linnaeus in the 18th centuryGrouped according morphology and behaviorFirst formalized means of classifying organismsBinomial nomenclature – each organism has a two-part name

Modern system of classification: 

•Grouped according to their presumed evolutionary relationship as well as morphological and behavioral characteristics

• Those placed in the same genus will be most closely related, those in different domains most distantly relatedEx: Those in genus Felis are more closely related to each other than organisms in the domains Eukarya and Archaea are to each other.

The taxa:Domain Kingdom

Phylum (Division for plants) Class

Order Family

Genus  Species

Did King Phillip Come Over For Good Spaghetti????

Domain Archaea – Unicellular prokaryotesMay have been first cells

Live in aquatic environments that lack oxygen or are too salty, too hot, or too acidic for most other organisms – like primitive Earth(?)

Domain BacteriaUnicellular prokaryotes

Found almost anywhere – in soil, water, atmosphere, on and inside living organisms

Domain EukaryaCells contain membrane-bound nucleusFour Kingdoms within –

Protists (Protista)Fungus (Fungi)Plants (Plantae) Animals (Animalia)

Writing scientific names:Ex: Homo sapiens or Homo sapiens

Can be abbreviated H. sapiensIf typed – should be italicized.If handwritten – should be underlined.First word is genus – capitalizedSecond word is specific epithet of species within a genus – lower case