Transcript Chapter 4 Cell Structure and Function

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 Size
 Most 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 Cells
 Prokaryotes…
…include bacteria
 Eukaryotes…
…include plant and
animal cells
What’s the difference?
 PROKARYOTES
 EUKARYOTES
 1) no nucleus
 1) have a nucleus
 2) no membrane-bound
 2) membrane-bound
organelles
 3) smaller
 4) no mitochondria
organelles
 3) larger
 4) have mitochondria
Colonial Organisms
 A 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