Pg. 68

Observed the first cells; dead plant cells (cork)

Coined the term “cell”

First person to observe living cells

Ground microscope lenses with precision

Called the organisms, animalcules

(We call them protists.)

Cell-the basic unit of life

1) All living organisms are composed of one or more cells.

2) Cells are the basic unit of structure and function in an organism.

3) Cells come only from other cells.

M. Schleiden- “All plants are composed of cells”

T. Schwann-”All animals are composed of cells.”

Cell division

There is a large variety of cells:

Skin cells

Nerve cell

Bacterial cell

Onion cells

There are 1000 micrometers in one millimeter!!

WHY ???

As a cell grows its volume

increases much faster than its surface area.

If the cell’s volume were too large, it’s surface area would not be able to meet the cell’s needs.

How would you answer this?

As a cell becomes smaller, its surface area-to-volume ratio ___________________.

A. increases B. decreases C. stays the same D. becomes less important

Cell Diversity“Form follows function” - the shape of a cell is often related to its

function

The long extensions of a nerve cell are specialized for sending and receiving impulses

Cell SizeMost cells are between 10-50 micrometers The smaller the cell the more efficient it

is at moving materials across its membrane

How many cells would fit on the head of a pin that is 2mm in diameter???

Two Basic Types of CellsProkaryotes… Eukaryotes…

…include bacteria…include plant and animal cells

What’s the difference?PROKARYOTES1) no nucleus2) no membrane-bound

organelles3) smaller4) no mitochondria

EUKARYOTES1) have a nucleus2) membrane-bound

organelles3) larger4) have mitochondria

Colonial OrganismsA collection of

identical cells living in a colony, NOT a multicellular organism

Volvox

Regulates movement of substances into and out of cells; outer boundary of the cell

Composed of proteins, carbohydrates, and lipids

*All important in the functioning of the membrane

1 ) They serve as attachment sites for molecules in the extracellular fluid

2) Transport materials across the cell membrane

Helps cells recognize each other

1) forms vesicles with cell membrane

2) provides a boundary between cell and surroundings

3) transports substances into and out of the cell

S.A. = 4πr2

2µm cell = 12. 56 20 µm cell= 1256

Increased by 100 times

-controls cell functions-houses (holds) DNA/ chromosomes

Contains: 1) Nuclear Envelope- contains pores that serve

as passageways for RNA to enter and leave

2) Nucleolus- the site where ribosomes are made