Chapter 1: The Science of Life

Biology – The study of life Organism – A living thing; anything that can carry out life processes independently Branches of biology – There are many subtopics within biology – a few examples we’ll hit upon this year:

Biochemistry – Study of the chemistry of life Genetics – Study of how organisms pass traits to their offspring Evolutionary theory – Study of changes in types of organisms over time Cell biology – Study of life on the cellular level Microbiology – Study of microscopic organisms Botany – Study of plants Zoology – Study of animals Physiology – Functions, activities, and processes of organisms Ecology – Study of how organisms interact with eachother and the environment

Properties of Life 1. Cellular organization Cell – a highly organized, tiny structure that in enclosed in a thin covering called a membrane A cell is the smallest unit capable of all life functions

Organisms can be unicellular or multicellular Multicellular organisms – more than 1 cell Cells in these organisms are considered specialized (have certain jobs) Examples: some fungus, all plants, all animals

Unicellular organisms - one cell 1 cell does all jobs for organism Examples: bacteria, protists, and some fungus

There are various levels of cellular organization –vary based on how complex the organism is In general: cells tissues  organs  organ systems  organisms Cells are the smallest unit of life, organisms the biggest

2. Homeostasis Maintaining a stable internal environment in order to function properly (such as body temperature, pH, blood pressure, water balance) regardless of changes in the external environment Example: sweating or shivering to maintain body temperature

Metabolism – the sum of all of the chemical reactions carried out in an organism Reactions carried out to obtain energy Organisms can obtain energy in one of two ways: heterotrophs and autotrophs

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 Ex: plants, some protists, and some bacteria

Responsiveness – living organisms must respond to their external environment Ex: plants bend toward the light, birds fluff feathers to stay warm in winter

5. Reproduction – the process by which organisms make more of their own kind from one generation to the next Prevents extinction of species Can be sexual or asexual 6. Heredity – process through which an organism passes on its own traits to its offspring during reproduction

Asexual reproduction only 1 parent offspring has DNA identical to parent Sexual reproduction 2 parents each parent contributes ½ genetic information to offspring offspring has mixed traits from parents

7. Growth - an increase in the number of cells/ increase in the size Example – getting taller As organisms grow, they may change, or develop Development – Changes an organism undergoes to reach adult form Example – baby  kid  teen  adult; tadpole to frog; caterpillar to butterfly

Classification   Taxonomy – The practice of naming and classifying organisms Taxa –the categories into which organisms are classified   

The taxa: Domain Kingdom Phylum (Division for plants) Class Order Family Genus  Species Did King Phillip Come Over For Good Spaghetti???

Domain Archaea – Unicellular prokaryotes May 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 Bacteria Unicellular prokaryotes Found almost anywhere – in soil, water, atmosphere, on and inside living organisms

Domain Eukarya Cells contain membrane-bound nucleus Four Kingdoms within – Protists (Protista) Fungus (Fungi) Plants (Plantae) Animals (Animalia)

Why can’t we just use common names? Not very specific Ex: What KIND of frog? Misleading Ex: Jellyfish is NOT a fish, ringworm is NOT a worm Vary by language and geography Ex: Puma, mountain lion, and cougar are ALL the same animal! A robin in one country is not the same as what is named a robin in another country

What was wrong with the early systems of classification? Forgot to include bacteria, fungus and protists Failed to show proper relationships between organisms Too general – ex. Aristotle classified animals by where they lived (air, land, or water)

Modern system of classification:  Modern system of classification: Based in part on Carl Linnaeus’ system of binomial nomenclature (“two names”) Grouped according to: physical features (morphology) the ancestral relationships between species (phylogeny)

Those placed in the same genus will be most closely related, those in different kingdoms most distantly related Ex: Those in genus Felis are more closely related to each other than organisms in the Kingdoms Plantae and Animalia are to each other.

Writing scientific names: Writing scientific names: Ex: Homo sapiens or Homo sapiens Can be abbreviated H. sapiens If typed – should be italicized. If handwritten – should be underlined. First word is genus – capitalized Second word is species - lower case