The Diversity of Cells Ch. 3-1 How were they discovered? ~ 1665 - Robert Hooke looked at a slice of cork - saw "little boxes" and called them "cells" ~ 1675 - Anton von Leeuwenhoek first to observe pond water under a microscope Over next 150 years, people like Schleiden, Schwann, and Virchow researched cells This led to… Cell Theory - 3 parts 1.) All living things are composed of 1 or more cells 2.) In organisms, cells are basic units of structure and function 3.) Cells are produced only from existing cells

Cells must be small! ~ must be able to exchange materials in and out of the cell ~ move materials within the cell ~ efficiency depends on ratio of surface area to volume *small cells are more efficient ~ Cell shape can affect how it works too... ex: skin cells are flat and thin, nerve cells are long and skinny - these shapes help it to work better!

Characteristics of all cells: 1.) Cell membrane - (plasma membrane) * separates the cell's insides from the material outside the cell * regulates what moves in and out of the cell *necessary for life 2.) Cytoplasm - everything inside the cell except the cell's genetic make-up (DNA) * cytosol - fluid portion! 3.) Ribosomes - structures on which proteins are made * found in cytosol

Extremophiles! 2 Types of cells: 1.) Prokaryotes - single-celled organisms ~ NO NUCLEUS!! * 3.5 by old - very small * cannot do many specialized functions * some have flagella or cilia to help move around a.) Eubacteria - these are common bacteria! * ARE EVERYWHERE!! * can be very helpful - in your gut * can also be harmful - cause disease b.) Archaebacteria - similar to bacteria but have different ribosomes, different type of cell wall, and live in harsh environments ~ 3 types: *heat-loving - live in hot springs or by thermal vents *salt-loving - live in very salty water *methane-making - live near volcanic vents and in swamps Extremophiles!

2.) Eukaryotes * have a true nucleus * eu: true karyote: kernel * have organelles that carry out specific functions Can be unicellular or multicellular!

Eukaryotic Cells Ch. 3 - 2 is selectively permeable!! Each cell has many compartments- * divided by membranes that make little areas for specific structures Cell membrane - made of phospholipids hydrophilic heads hydrophobic tails sticks to water repels water ~ framework called a cytoskeleton ~ made of microfilaments, microtubules, and intermediate fibers ~ all work to give the cell support, shape, help it move, and stay organized is selectively permeable!!

Nucleus: ~ has nuclear envelope with pores (holes) ~ contains DNA ~ has nucleolus that makes ribosome parts *these parts are put together outside the nucleus

Ribosomes: ~ make proteins to be used in or outside the cell a put these in a package called a vesicle The organelles that do this packaging? ER and Golgi apparatus! Endoplasmic Reticulum (ER): ~ moves proteins through the cell 2 kinds: * Rough ER - has ribosomes on it! ~ looks rough! ~ makes and packages proteins to go to the GA *Smooth ER - no ribosomes ~ makes lipids and breaks down toxic substances

Golgi Apparatus! Golgi Apparatus (GA): ~ modifies, sorts, and packages cell products ~ when finished, the package leaves the GA and often leaves the cell Golgi Apparatus!

Storage and Maintenance: Lysosomes: ~ vesicle that has enzymes to break down large molecules ~ also recycles old, damaged, or unused organelles Vacuoles: ~ large spaces for storage ~ plants have large central vacuoles for water storage Chloroplasts: ~ PLANTS ONLY!! ~ uses light energy to make sugar

mitochondrion Mitochondria: ~ Powerhouse of the cell - like a battery! ~ makes ATP - energy currency, remember? mitochondrion

Organization of Living Things 3-3 We can order cells into different levels of organization: 1.) Tissues - group of cells with similar structures and functions Ex: muscle tissue

2.) Organs - dif. tissues come together to make an organ that has a specialized structure and function Ex: heart - made of muscle, nerve and other tissues

3.) Organ systems - organs working together with major body functions Ex: circulatory system - made of heart, blood vessels, and blood 4.) Organism - anything that can perform life processes by itself *unicellular - made of just one cell ~no specialization Only eukaryotes have true multicellularity (more than one cell) ~ they come from one cell that divides and then those cells differentiate, or become specialized