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 cellsThis led to…

Cell Theory - 3 parts1.) All living things are composed of 1 or more cells 2.) In organisms, cells are basic units of structure and function3.) Cells are produced only from existing cells

The Diversity of Cells Ch. 3-1

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

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!

Each cell has many compartments-* divided by membranes that make little areas for specific structures

Cell membrane - made of phospholipids

hydrophilic heads

hydrophobic tails

hydrophilic heads

Eukaryotic CellsCh. 3 - 2

repels water

sticks to 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 (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

Mitochondria:

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

mitochondrion

Organization of Living Things3-3

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