Covers Chapter 4 Structure and Function of the Cell Pages

* S cientists have studied the cells of over 2 million different species * But, scientists estimate there are over 40 million species on Earth! * After studying so many species, scientists observed that although cell size, shape and function is very diverse, all cells have some similarities.

* All cells are surrounded by a protective layer * Known as a cell membrane * Def. – thin layer that forms the outer boundary of the cell * Protects cell by being selectively permeable * Def. – only allows certain substances into the cell * All cells contain cytoplasm * Cytoplasm – anything that is inside the cell (except nucleus), includes cytosol * Cytosol – gelatin-like fluid inside the cell

* All cells contain genetic material (DNA) * How DNA is stored is how scientists classify the type of cell * Prokaryotic cell – DNA not contained * Eukaryotic cell – DNA contained in a nucleus

* All cells contain internal cellular structures known as organelles * The kinds of organelles they contain is how scientists classify the type of cell * Prokaryotic cells do not contain organelles that are surrounded by a membrane

ProkaryoteEukaryote Genetic Information (DNA) Clumped, not contained in an organelle Single chromosome DNA stored in nucleus Chromosomes usually come in pairs Nucleus No nucleus Has a nucleoid region Has a nucleus Organelles Only has organelles WITHOUT membranes Contains organelles with and without membranes Membrane is same material as cell membrane Examples Bacteria Protist, Fungus, Plant, Animals

* Covers Chapter 18, Classification * Pages 336 – 353

* Every year, scientists discover thousands of new species. * By examining the organisms’ cells, structure, habitat, feeding patterns, etc., the organisms are grouped into different categories * TAXONOMY – science of grouping organisms according to their characteristics and evolutionary history

* Early Taxonomy * Classified organisms according to where they lived, internal structures, external structures * Organisms were given common names * Could incorrectly describe the organism * Same organism could have different name around the world

* Today, we use many techniques and information to classify organisms. Some examples: * Morphology * Def. – study of internal and external structures * Examples: type of cell, type of organelles, type and arrangement of tissues and organs, etc. * Phylogeny * Def. – evolutionary history of a species, tries to group similar species together

* Fossil record * Provides clues about the evolution of the species * Embryo development * Protein structure * DNA sequence * Number of chromosomes

* Once species are classified, scientist can use the information to study relationships between similar species * Phylogenetic Tree * Also known as evolutionary tree * Def. – “Family Tree” showing evolutionary relationship between various species * Changes as new information is discovered

* Cladogram * Diagram showing the order that new features evolved in various species

* Based on the classification and naming system devised in the 1700s by Carolus Linnaeus (1707 – 1778) * Levels of Classification – Each category gets more specific * Domain * Kingdom * Phylum * Class * Order * Family * Genus * Species

* Binomial nomenclature – Scientific naming system * Linnaeus’ classification gave every organism a scientific name * The scientific name has 2 parts 1. Genus2. species identifier * Genus name is always capitalized * species name is never capitalized * Homo sapiens * Scientific name must be either: * Underlined : Homo sapiens OR Italicized: Homo sapiens

* 3 Domains * Domain Archaea * Kingdom Archaebacteria * Domain Bacteria * Kingdom Eubacteria * Domain Eukarya * Includes all eukaryotic organisms * Kingdom Protista * Kingdom Fungi * Kingdom Plantae * Kingdom Animalia