Organisms
•Organisms are complete individual living things.
•Organisms vary in size and shape.
Traits of living things
Organization
•All living things are organized.
They are single cells (unicellular)
or
they are composed of many cells. (multicellular)
The cell is the basic unit of living things.
Traits of living things
•Living things grow and develop
- Growth of a multicellular organism is mostly due to an increase in the number of cells.
- Growth in one-cell organisms is due to an increase in the size of cell.
•The length of time an organism is expected to live is its life span.
Traits of living things
•Living things are able to adjust to changes in the environment.
•A change in the environment is a stimulus.
•The reaction of an organism to a stimulus is a response.
Traits of living things
•Living things are able to maintain homeostasis, keep stable internal conditions.
Traits of living things
•All living things use energy
Traits of living things
•Living things are able to reproduce, make offspring similar to the adults.
Needs of living things
•A habitat, a place to live that fits the organism.
•Water – most organisms are made of at least 50 % water.
•Food – all organisms need proteins, fats and carbohydrates (sugars and starches)
Classification
•Aristotle was one of the first to classify (group) organisms.
• He classified animals as land, water, or air
•He classified plants as trees, shrubs, or herbs
Classification
•Carolus Linnaeus developed a system of grouping organisms that is used by most scientists.
•It is a two word naming system using Latin names, called Binomial nomenclature. (Genus and species names are used)
•Organisms are grouped by similar structures.
Why Use Scientific Names
•1st - they help avoid mistakes.
•2nd - organisms with similar evolutionary histories are classified together.
•3rd - scientific names give descriptive information about the species.
•4th - scientific names allow information to be organized easily and efficiently.
The classification system
•Kingdoms
•Phyla
•Classes
•Orders
•Families
•Genus
•Species – the only natural group – this group is able to reproduce.
Six kingdoms
•Animals
•Plants
•Protists
•Fungi
•Eubacteria
•Archaebacteria
Tools for identifying organisms
•Field guides – books with pictures and descriptions or organisms.
•Dichotomous keys – series of choices that help identify organisms.
Cells
•Anton van Leeuwenhoek, a Dutch fabric merchant, made the first simple microscope with a tiny glass bead for a lens.
•Robert Hooke cut a thin slice of cork which seemed to be made up of empty little boxes, which he named cells.
Cells
•Matthias Schleiden used a microscope to study plant parts, deciding plants are made of cells.
•Theodor Schwann, after observing many different animal cells, concluded that all animals also are made up of cells.
Cells
•Rudolf Virchow hypothesized that cells divide to form new cells.
•Virchow proposed that every cell came from a cell that already existed.
•Together these men are responsible for the Cell Theory.
The Cell Theory
•All organisms are made of cells.
•The cell is the basic unit of structure and function in all organisms
•All cells come from pre-existing cells
Cell structure
•There are two main groups of cells
–Prokaryotic - Cells without membrane-bound structures
–Eukaryotic – Cells with membrane-bound structures