Cell Structure and Function
Discovery of Cells

Hooke (1665)


Leeuwenhoek (1674)


Observed plant cells, discovered the
importance of the nucleus.
Schwann (1839)


Observed the first living cells
Schleiden (1838)


Examined cork cells
Concluded that all living things are made
of cells
Virchow (1855)

Proposed that all cells come from other
cells

Father of Modern Pathology
Cell Theory



All organisms are made of
cells.
All existing cells are
produced by other living
cells.
The cell is the most basic unit
of life.
Cell Types

Prokaryotic

Do not have a nucleus
or other membranebound organelles.

DNA is suspended in
cytoplasm.

All prokaryotes are
microscopic singlecelled organisms.

ex. bacteria and
archaea
Cell Types

Eukaryotes

Have a nucleus and
membrane-bound
organelles

The nucleus, the
largest organelle,
encloses the genetic
information.

May be multicellular
or single-celled
organisms.
Movement in Cells

Flagellum


Cilia


Whip-like structure
common in motile
protists or gametes.
Hair-like organelles
located on the exterior
of some cells
Pseudopods

“fake-feet”; extensions
of cytoplasm, also used
to capture prey
Organelles
Nucleus


Control center of the
cell
Contains material
that forms the genetic
code (DNA)

Present in
eukaryotic cells

Both plant and
animal cells
Parts of the Nucleus

Nucleolus


Nuclear membrane (envelope)


Controls what enters and
leaves the nucleus
Nucleoplasm


Involved in cell division and
ribosome synthesis
Inside the nuclear membrane
(goo)
Chromosome (chromatin)

Carry the code (DNA) that
controls the cell
Cell (plasma) Membrane

Controls substances that enter and leave the cell.

Semi-permeable

Made of a phospholipid bi-layer

Both plant and animal cells
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Cytoplasm

Contains a variety of cell
structures and dissolved
ions


Provides a medium
for cell reactions to
take place
Matrix between the cell
membrane and the
nuclear membrane
includes protoplasm and
organelles

Both plant and
animal
Endoplasmic Reticulum



Both plant and animal
Rough Endoplasmic
Reticulum (RER)

Has ribosomes
on its surface.

Makes proteins
for EXPORT
Smooth Endoplasmic
Reticulum (SER)

No ribosomes

Makes proteins
to be used IN
the cell
Ribosomes


Located on the RER and throughout the
cytoplasm
Site of protein synthesis

Both plant and animal
Centrioles

Animal cells only

Involved in cell division


Spindle formation
Located near the nucleus
Mitochondria


Site of cellular
respiration

Releases
energy for the
cell in the form
of ATP

Has its own
DNA passed
from mother to
child
In both plant and
animal cells
Golgi Apparatus

Stores and packages
information

It receives proteins
made by the
endoplasmic
reticulum in one
end, modifies them,
and ships them out
the other end.

Cisternae—stacks
of membranous
sacs

In both plant and
animal cells
Lysosome



Found only in animal cells
Packages of digestive
enzymes that break down
nutrients into smaller
chemicals.
Self-destruct mechanism

Will break down food
and worn out cell
parts

Programmed for cell
death

Will “lyse”--break
open and recycle cell
parts
Vacuole


Stores water and
dissolved materials

In plants very
large (central
vacuole)

In animals small
or nonexistant
Contractile vacuole

Some protists
can force water
out of the vacuole
and use it for
movement.
Cytoskeleton

Supporting matrix of
protein fibers

Maintains cell
shape and acts as
a scaffold on
which organelles
are attached

Composed of
microfilaments and
microtubules

In both plant
and animal
cells
These animal cells are stained to show
the cytoskeleton. microtubules (green),
microfilaments (red), and nuclei (blue).
Cell Wall


In plants only
Provides shape and
support

Made of cellulose

Undigestable
carbohydrate,
fiber
Chloroplasts

In plants only

Contains chlorophyll

Traps light used in
making food
(carbohydrate)
through the
process of
photosynthesis
Leucoplasts and Chromoplasts

In plants only

Leucoplasts


Store food such
as starch,
proteins, and
lipids
Chromoplasts

Give color to
flowers and
leaves
Plant Cells vs. Animal Cells
Different Kinds of Plant Cells
Onion Epidermal Cells
root hair
Root Hair Cell
Guard Cells
Different Kinds of Animal Cells
white blood cell
Amoeba
red blood cell
muscle cell
cheek cells
sperm
nerve cell
Paramecium
Differences between Plant Cells
and Animal Cells
Animal cells
Plant cells
Relatively smaller
in size
Relatively larger
in size
Irregular shape
Regular shape
No cell wall
Cell wall present
26
Differences between Plant Cells
and Animal Cells
Animal cells
Plant cells
Vacuole small or
absent
Large central
vacuole
Glycogen as food
storage
Starch as food
storage
Nucleus at the center
Nucleus near cell
wall
27