Levels of Organization Molecules Cells Tissues (next slide) Organs Organ systems Organism Population Community Ecosystem Biosphere

Molecule –The smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms held together by chemical forces

Cell –The basic unit of structure and function for all living organisms

Tissues and organs Tissue –An anatomical unit composed of cells organized to perform a similar function One kind of cell makes up tissue

Organ –An anatomical unit composed of tissues serving a common function Consists of different tissues Organ System –An anatomical system composed of a group of organs that work together to perform a specific function or task Organism –A form of life; animal, plant, fungi, etc.

Population –A group of individuals of the same species living in a specific geographical area and reproducing Community –Different populations of organisms interacting in a shared environment

Ecosystem –A system composed of organisms and nonliving components of an environment Biome – a large area or geographical region with distinct plant and animal groups adapted to that environment

Biosphere – the zone of life on earth: sum total of all ecosystems on earth

The history of the cell Exploring the cell… A Time line

1665 Robert Hooke-looked at cork using one of the first microscopes. Coined the term “cells” 1674 Anton van Leeuwenhoek – views tiny living organisms in pond water Robert Brown – discovered the cell’s nucleus 1838 Matthias Schleiden – concludes that all plants are made up of cells Theodor Schwann – concludes that all animals are made up of cells 1855 Rudolph Virchow – proposes that all cells come from existing cells

Cell Theory Completed in All living things are made of one or more cells. 2. Cells are the basic units of structure and function in living things 3. All cells come from other cells

Prokaryotes and Eukaryotes The two main cell categories Classified on whether they contain a nucleus or not.

Prokaryotes Do Not contain a nucleus –DNA within the nucleoid region No membrane bound organelles DNA spread throughout the cell Contain a cell membrane Contain a cell wall Contain ribosomes

Bacteria are prokaryotes Label the prokaryote cell with the following –DNA (nucleoid region), ribosomes, cell wall, cell membrane, flagella, pili

Images of Bacteria - Prokaryotes Soil bacteria Pseudomonas aeruginosa E. Coli Staphylococcus aureus

Endosymbiosis eukaryotic cells were formed from simpler prokaryotes Endo – within Symbiosis – together –Organisms living together, within one another –Bozeman science video-endosymbiosis

Eukaryotes Contain a nucleus –Contains genetic material (DNA) inside. Contain membrane bound organelles All have a cell membrane Contain ribosomes Some have a cell wall Generally larger than prokaryotes

Eukaryote Cells plant Animal

Examples of eukaryotes Some Eukaryotes are single-celled organisms Plants, animals, fungi and protists are examples of multicellular eukaryotes. Activity next slide