Post on 04-Jan-2016
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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