Cell Structure
& Function
Cell Theory
• 1. All organisms are composed of one or
more cells. (Schleiden & Schwann)(183839)
• 2. The cell is the basic unit of life in all
living things. (Schleiden &
Schwann)(1838-39)
• 3. All cells are produced by the division of
preexisting cells. (Virchow)(1858)
Modern Cell Theory
• Modern Cell Theory contains 4 statements, in
addition to the original Cell Theory:
• The cell contains hereditary information(DNA)
which is passed on from cell to cell during cell
division.
• All cells are basically the same in chemical
composition and metabolic activities.
• All basic chemical & physiological functions are
carried out inside the cells.(movement, digestion,
etc.)
• Cell activity depends on the activities of subcellular structures within the cell(organelles,
nucleus, plasma membrane)
What is a Cell?
• A cell is the smallest unit that is
capable of performing life functions.
• Cells are the basic unit of life.
• Cytology can be considered the most
important area of biology
• Cloning, embryology, cancer research
• 3 centuries of research
Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Two Types of Cells
•Prokaryote
•Eukaryote
•Pull out worksheet on Prokaryote
vs. Eukaryote
Prokaryotes
• Do not have a
nucleus
• Do not have
membrane bound
organelles (eg. NO
mitochondria, NO chloroplasts)
Eukaryotes
• Contain a nucleus and membrane bound
organelles.
Plant
http://library.thinkquest.org/C004535/eukaryotic_cells.html
Animal
Prokaryotes are cells that do not have a nucleus
and do not have membrane bound organelles. These
cells are smaller than eukaryotes and are believed to
have existed over 2.5 billion years ago as the first
cells on earth.
Examples: bacteria, blue-green bacteria
(cyanobacteria) and archeabacteria are prokaryotes.
Archeabacteria are the bacteria that are found in very
harsh conditions such as thermal vents and hot
springs.
Eukaryotes are cells that contain a nucleus and
membrane bound organelles such as mitochondria.
The nucleus is the control center for all cell activity.
The mitochondria is where cell respiration takes place. In
the mitochondria energy is released to support cell
activities.
Examples: all plant, protist, fungi and animal cells are
eukaryotes.
• Video Prokaryote and Eukaryote Cells
“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 the
movement of materials
in and out of the cell
• Double layer
Cell Wall
• Most commonly found
in plant cells, bacteria
and fungi (NOT FOUND IN
ANIMAL CELLS)
• Supports & protects
cells
Inside the Cell
Cytoplasm
• Gel-like fluid
• Contains the organelles except for the
nucleus
Nucleus
• Directs cell activities
• Separated from cytoplasm by nuclear
membrane
• Contains genetic material - DNA
NUCLEUS
Nuclear Membrane
• Surrounds nucleus
• Made of two layers
• Nuclear pores allow
material to enter and
leave the nucleus
NUCLEAR MEMBRANE
The nuclear membrane is also called the nuclear envelope
Nucleolus
• The dense area
inside the nucleus
• Contains RNA to build
proteins
NUCLEOLUS
RiboNucleic Acid: The nucleic acid that is used in key metabolic
processes for all steps of protein synthesis in all living cells and carries
the genetic information of many viruses. Its principal role is to act as a
messenger carrying instructions from DNA for controlling the synthesis of
proteins,
Chloroplast
• Found in plant cells
• Contains the green
pigment chlorophyll
• Where photosynthesis
takes place
Mitochondria
• Releases energy through
chemical reactions –
breaking down fats &
carbohydrates
• Controls level of water and
other materials in cell
• Recycles and decomposes
proteins, fats, and
carbohydrates
Endosymbiosis
• How was shift made from small prokaryotic to
large eukaryotic cells?
• Endo (within) symbiosis (together) bio (living)
• Aerobic bacterium – respiration/breaking down
food (oxygen)
• Cyanobaterium – photosynthesis
• Came together to become the mitochondria and
chloroplast we have today
• Endosymbiosis Video
Vacuoles
• Membrane-bound sacs
for storage, digestion,
and waste removal
• Contains water solution
• Help plants maintain
shape
Animal cells have one or more small vacuoles (much smaller than
plant cells).Plant cells have one, large central vacuole taking up 90%
of cell volume.
Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on rough
endoplasmic
reticulum & freely
floating throughout
the cell in the
cytoplasm
Golgi Bodies/Apparatus
• Protein 'packaging
plant'
• Move materials within
the cell
• Move materials out of
the cell
• Also called the Golgi
apparatus
Lysosome
• Vesicles that bud from
the Golgi apparatus
• Contain digestive
enzymes
• Within a cell, lysosomes
digest worn-out
organelles and destroy
cells that are no longer
functioning properly
Endoplasmic Reticulum
• Moves materials around in the
cell
• Smooth type: lacks ribosomes
• Rough type: ribosomes
embedded in surface
• Tour of a cell
• Animation showing structure and function
of a plant and animal cells Video