Cell Structure and Function Cellular Basis of Life, Homeostasis Chapter 7-1

Early Microscopes A series of lenses that could make small things easier to look at (1500) 3 major types:

1. Compound light microscope Most common Has 2 lenses Ocular lens (eyepiece) (10x) Objective lens (near specimen) (4x, 10x, 40x) Total Magnification = ocular lens x objective lens Ex: High power=10 x x 40 x = 400 x

2. Stereomicroscope Aka: dissecting scope Have ocular and objective lens for each eye Used for larger specimens

3.Electron Microscope Used to observe tiny dead things Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM)

Robert Hooke (1665)-first to see cells. Looked at a slice of cork. Came up with the name “cell” because the empty chamber he saw looked like tiny rooms in a monastery. Anton van Leeuwenhock (1665) – used a hand lens to look at pond water. First to see living cells.

1. All organisms are made of cells 2. Cells are the basic unit of structure & function in all organisms 3.All cells come from pre-existing cells. (1 exception: the first cell—came from nonliving) Cell Theory

Size and Shape Size & shape vary; related to function Examples:  Human skin cells—flat, irregular, small-- -for protection  Nerve cells—long, thin, string-like— transmit information throughout body  White blood cells can change shape to escape vessels—fight disease

Size is limited by surface area (L x W x # of sides) As surface area increases, volume increases faster. (V = L x W x H)

2 major types of cells ProkaryotesEukaryotes No nucleusNucleus No membrane-boundMembrane-boundorganelles Size 1-10 umSize um about 3.5 byaabout 1.5 bya Ex: bacteriaEx: all other living things