Cell Structure
& Function
http://koning.ecsu.ctstateu.edu/cell/cell.html
Definition of Cell
A cell is the smallest unit that is
capable of performing life
functions.
Cell Theory
• All living things are made up of cells.
(Schleiden and Schwann)
• Cells are the smallest working units of all
living things. (Schwann)
• All cells come from preexisting cells
through cell division. (Virchow)
Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Two Types of Cells
•Prokaryotic
•Eukaryotic
Prokaryotic
• Do not have
structures surrounded
by membranes
• Few internal
structures
• NO NUCLEUS
• Circular loop of DNA
• Ex: Bacteria
http://library.thinkquest.org/C004535/prokaryotic_cells.html
Eukaryotic
•
•
•
•
Contain organelles surrounded by membranes
HAS A NUCLEUS
DNA in chains
Animals, plants, protists, fungus
Plant
Animal
http://library.thinkquest.org/C004535/eukaryotic_cells.html
Comparison of Eukaryotes and Prokaryotes
Eukaryotic Cells
Animal Cell
Plant Cell
NO cell wall
cell wall
DNA in chains
Membrane
bound
organelles
Nucleus
small/no
vacuoles
DNA in chain
Membrane
bound
organelles
Nucleus
LARGE
vacuoles
Prokaryotic
Cells
Bacterial Cell
cell wall
Circular loop of
DNA (plasmid)
NO membrane
bound organelles
NO nucleus
no vacuoles
“Typical” Animal Cell
http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif
“Typical” Plant Cell
http://waynesword.palomar.edu/images/plant3.gif
Cell Parts
Organelles
Surrounding the Cell
Cell Membrane
• Outer membrane of cell
that controls movement
in and out of the cell
• Double layer
http://library.thinkquest.org/12413/structures.html
Cell Wall
• Most commonly found
in plant cells &
bacteria
• Supports & protects
cells
http://library.thinkquest.org/12413/structures.html
Inside the Cell
Nucleus
• Directs cell activities
• Separated from cytoplasm by nuclear
membrane
• Contains genetic material - DNA
Nuclear Membrane
• Surrounds nucleus
• Made of two layers
• Openings allow
material to enter and
leave nucleus
http://library.thinkquest.org/12413/structures.html
Chromosomes
• In nucleus
• Made of DNA
• Contain instructions
for traits &
characteristics
http://library.thinkquest.org/12413/structures.html
Nucleolus
• Inside nucleus
• Contains RNA to build
proteins
http://library.thinkquest.org/12413/structures.html
Cytoplasm
• Gel-like mixture
• Surrounded by cell membrane
• Contains hereditary material
Endoplasmic Reticulum
• Moves materials around
in cell
• Smooth type: lacks
ribosomes
• Rough type (pictured):
ribosomes embedded in
surface
http://library.thinkquest.org/12413/structures.html
Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on ribosomes
& floating throughout
the cell
http://library.thinkquest.org/12413/structures.html
Mitochondria
• Produces energy through
chemical reactions –
breaking down fats &
carbohydrates
• Controls level of water and
other materials in cell
• Recycles and decomposes
proteins, fats, and
carbohydrates
http://library.thinkquest.org/12413/structures.html
Golgi Bodies
• Protein 'packaging
plant'
• Move materials within
the cell
• Move materials out of
the cell
http://library.thinkquest.org/12413/structures.html
Lysosome
• Digestive 'plant' for
proteins, fats, and
carbohydrates
• Transports undigested
material to cell
membrane for removal
• Cell breaks down if
lysosome explodes
http://library.thinkquest.org/12413/structures.html
Vacuoles
• Membrane-bound
sacs for storage,
digestion, and waste
removal
• Contains water
solution
• Help plants maintain
shape
http://library.thinkquest.org/12413/structures.html
Chloroplast
• Usually found in plant
cells
• Contains green
chlorophyll
• Where
photosynthesis takes
place
http://library.thinkquest.org/12413/structures.html
Cell Specialization
• Not all cells are similar looking. Cells may
have different sizes, structure, and function.
Many cells have a specialized structure that
enables them to better carry out their
specific function.
Red Blood Cell
• Bi - concave
• Larger surface area to
exchange gases
(oxygen and carbon
dioxide)
• Flexible so it can
squeeze into small
places
Sickle Cell Anemia
• Change in shape of
red blood cell
• Can not carry enough
oxygen
Nerve Cell
• Fatty sheath for
insulation and for
speeding up nerve
impulses
• Long/thin and nerve
impulses travel in one
direction only
Skin Cell
• Thick layer of thin cells for protection
White Blood Cell
• squeeze through
capillary walls and
into infected tissue
where they engulf
invaders (bacteria) by
a process known as
phagocytosis
Cell Processes - How to
survive?
• Grow/Use energy - photosynthesis and
respiration
• Maintain - maintain homeostasis through cell
transport in and out of cell
• Reproduce - make copies through mitosis and
meiosis
• Move - flagella (tail) and cilia (hairs) that allow
single celled organisms to move