Cell Type Note Sheet
Online Resource: Cells Alive
Module “How Big”: http://www.cellsalive.com/howbig.htm
Module “Cell Models”: http://www.cellsalive.com/cells/3dcell.htm
A. All organisms are made up of cells.
The cell is the basic unit of structure and function.
The cell is the smallest unit that can still carry on all life processes.
Both unicellular (single celled) and multicellular (many celled) organisms are composed of cells.
B. The Cell Theory
1. Cells are the basic units of life.
2. All living organisms are made of one or more cells.
3. All cells arise from the reproduction of existing cells.
C. Cell Diversity
Not all cells are alike.
Cells differ in shape, size, and function.
The female egg cell is the largest cell in the body and can be seen without a microscope.
Bacterial cells are some of the smallest cells and are only visible with a microscope.
Cells are generally classified as either prokaryotic or eukaryotic.
Relative size of cells and their components:
D. Cell Commonalities
ALL CELLS (both prokaryotic and eukaryotic) contain the following…
1. Plasma Membrane (aka cell membrane): This membrane functions to separate the interior of the cell
from the exterior environments and regulates the entry and exit of materials from the cell.
2. DNA: The nucleic acid that serves as the inherited information of the cell and directs cellular processes.
In prokaryotes, the cell’s circular DNA is found free floating in the nucleoid region of the cytoplasm. In
eukaryotes, the linear DNA is packaged within a membrane-bound nucleus.
3. Cytoplasm: The gel-like substance of a cell, containing an aqueous suspension of all the cell components.
4. Ribosomes: The site of protein synthesis.
PROKARYOTES
a. Prokaryotic cells are less complex and usually unicellular.
b. Prokaryotes do NOT have a nucleus or any other membranebound organelles.
c. Most have a cell wall surrounding the cell membrane and a single,
looped piece of DNA in the nucleoid region of the cytoplasm (NOT
within a nucleus!).
d. Prokaryotic cell types include bacteria and Archaea.
EUKARYOTES
a. Eukaryotic cells are more complex.
b. Can be both unicellular and multicellular organisms.
c. Eukaryotes have a nucleus and other membranebound organelles.
d. Membrane-bound organelles are internal structures
in the cells that perform specific functions, and which
are enclosed by either a single or double membrane.
e. The nucleus is located in the center of the cell and
contains the genetic material (DNA). It controls the
activities of the cell.
f. Eukaryotes include plant cells, animal cells, fungi,
algae, and protists.
Chloroplast
Mitochondrion
Golgi
Endoplasmic Reticulum
Nucleus
Comparing animals cells vs. plant cells…
Animal Cell
Plant Cell
Cell Shape
Round and irregular
Rectangular, fixed shape
Cell (Plasma)
Membrane
Present
Present
Cell Wall
Absent
Absent
Vacuole
One or more small vacuoles
One, large, central vacuole taking up 90% of
cell volume (for water storage).
Centrioles
Present in all animal cells.
Only present in lower plant forms.
Chloroplast
Absent
Present (for photosynthesis – plants are
autotrophs)
Cytoplasm
Present
Present
Endoplasmic
Reticulum
Present
Present
Ribosomes
Present (protein synthesis)
Present (protein synthesis)
Mitochondria
Present (cell respiration)
Present
Golgi Apparatus
Present
Present
Microtubules/
Microfilaments
Present
Present
Flagella
May be found in some cells
May be found in some cells
Lysosomes
Present ( have digestive enzymes)
Not usually present
Nucleus
Present (holds DNA)
Present (holds DNA)
Cilia
Present
Very rare