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Cells
And Differentiation
What is a Cell?
• A cell is the basic structural unit of all living things
• It is a microscopic structure which contains organelles along with
cytoplasm enclosed within a membrane and/or a cell wall
Sayer, J. (2011) Cells [Picture]
http://wakeup-world.com/2012/01/14/the-flame-of-cell-life-death-in-the-miracle-of-regeneration
Groups of Cells
• There are two basic groups of cells:
– Eukaryotic
• Animal
• Plant
http://www.phschool.com/science/biology_place/biocoach/cells/review3.html
– Prokaryotic
• Bacteria
http://www.daviddarling.info/encyclopedia/B/bacteria.html
What’s the Difference?
• Prokaryotic Cells
– bacterial cells
– They do not have a nuclear membrane
– They are unicellular
– Lack membrane bound organelles
• Eukaryotic Cells
– There are two basic types:
• Animal Cells
• Plant Cells
– They have a nuclear membrane
– They can be unicellular and multicellular
– They have membrane bound organelles
What are organelles?
• Organelles are
structures that have a
specific function (job) in
the cell
• Some of the most
common organelles are:
–
–
–
–
Cell membrane
Cell wall
Cytoplasm
Cytoskeleton
–
–
–
–
–
Nucleus
Nucleolus
Centrioles
Ribosome
Endoplasmic Reticulum
• Smooth
• Rough
– Golgi Apparatus
– Mitochondria
– Lysosome
Cell Membrane
• Found on the outside of the
cell
• Made up mainly of
phospholipids and proteins
• Hydrophobic tails
• Hydrophilic heads
– Aka plasma membrane
– Fluid Mosaic Model
• Some proteins have
carbohydrate chains
attached (glycoproteins)
• Function is to control
what goes in or out of
the cell and to aid in
providing shape by
latching on to the
cytoskeleton
Burns, D., Cell Membrane, http://www.molecularstation.com
Cell Wall
• Found in Plants, Fungi,
and Bacteria
• Outside of the plasma
membrane
• Function: Protects cell
and gives it structure
• Made of cellulose
Plant Cell, http://www.teacherthomas.com
/
Cytoplasm
• Gel-like material which
is found between the
nucleus and cell
membrane
• Function: Holds all the
organelles in place and
carries water, ionic
solutions, proteins and
sugars that will be used
by the cell. It also helps
to give the cell structure
http://www.scsc.k12.in.us/SMS/Teachers/Martin/cytoplasmrep
lacement.htm
Cytoskeleton
• Made of a network of
filamentous proteins
and microtubules
• Function: gives the cell
structure
http://middletownhighschool.wikispaces.com/201011+Cytoskeleton++%26++Cytoplasm
Nucleus & Nucleolus
• Nucleus is a specialized
organelle
• Function is to hold DNA
and regulates cell
activity
• Nucleolus is not
membrane bound and
is found inside the
nucleus
• Function is to
manufacture ribosomes
Centrioles
• Small structure found
close to the nucleus of
animal cells
• Usually found in pairs
• Aids in cell division
• Made of microtubules
in a 9+3 pattern
http://www.shayda.us/WebCT/AP1/AP1_Ex2_Materials/Ce
ntrioles.htm
http://rpdp.net/sciencetips_v2/L12B1.htm
Ribosome
• Small dense structures
• Can be found free
floating or attached to
endoplasmic reticulum
http://www.nigms.nih.gov/About/Budget/Statements/Februar
y29_2000.htm
• Function: Aids in
making proteins during
translation and
transcription
http://hyperphysics.phy-astr.gsu.edu/hbase/biology/ribosome.html
Endoplasmic Reticulum
Smooth ER
• Does not have ribosomes
attached
• Both are found in plant and
animals cell, not in bacteria
Rough ER
• Has attached ribosomes
• Both are pathways used to
transport molecules such as
proteins and lipids
http://micro.magnet.fsu.edu/cells/endoplasmicreticulum/endoplasmicreticulum.html
Golgi Apparatus
• Stacked membrane
bound organelle
• Function: Packaging
materials for export out
of the cell by enclosing
them in a vesicle and
releasing them.
http://academic.pgcc.edu/~kroberts/Lecture/Chapter%203/membran
ous.html
Mitochondria
• Considered the
“powerhouse” of the
cell
• Has its own DNA
• Function: Used in
cellular respiration
where the cell utilizes
and produces energy
for use in other cellular
processes
• Makes ATP (Energy
molecule)
Lysosome
• Small membrane bound
organelle that is used in
the “cleanup” of the cell
• Lysosomes contain
enzymes that break
down particles, digest
them and release out of
the cell through
exocytosis
Levels of Organization
• Cells are the basic building block of all living things
• Cells make more cells that combine to make tissue which combines to
make organs. Organs combine to make organ systems that will combine to
make the organism.
http://www.doctortee.com/dsu/tiftickjian/bio101/animal-structure.html
Different Types of Cells
• There are many different types of cells that will combine to make tissue
How do cells differentiate?
• During embryonic formation stem
cells are produced. Stem cells are
specialized cells that can
differentiate to become other
types of cells or they can
continue as a stem cell
• Stem cells are important because
they can be manipulated to
differentiate into any type of cell
and they can generate new cells.
• Embryonic Stem Cells are found
in the blastocyst during early
embryonic development
http://www.allthingsstemcell.com/2009/04/human_embryonic_stem_cells
/
http://robby.nstemp.com/photo6.html
What’s the Difference
• Three basic types of stem cells:
– Totipotent: These cells have the greatest potential to become any
type of cell. These are found around the 3rd day of germination of the
fetus from the blastocyst and can actually form a complete organism
– Pluripotent: These cells can also form different tissue types but
cannot form a complete organism. They can form the three cell layers:
endoderm, mesoderm and exoderm and will give rise to the types of
tissue that form from those layers
– Multipotent: These will usually form tissue from the area they
originated (Stem cells in brain can form nerve cells)