Transcript Prokaryotes & Eukaryotes

Prokaryotes & Eukaryotes
By
Diana L. Duckworth
Rustburg High School
Campbell County
Features in common
• All cells are surrounded by a plasma
membrane
• Inside membrane is semifluid substance
called cytosol (cytoplasm)
• All cells contain chromosomes carrying
genes in form of DNA
• All cells contain ribosomes (site of protein
manufacture)
Prokaryotic Cells
http://www.prof2000.pt/users/biologia/tipocelu.htm
• DNA found in region
called nucleoid
• No membrane isolates
DNA from cytosol
• No specialized organelles
in cytosol
• May have cilia or flagella
for locomotion
• Cell wall – rigid structure
outside membrane
• May have a capsule
around cell wall
http://darwin.nox.ac.uk/gsc/gcat/mashup?query=
Streptococcus
http://www.kimicontrol.com/edu-e.html
http://www.bact.wisc.edu/themicrobialworld/Structure.html
Eukaryotic Cell
• DNA combines with histones
to form chromosomes
• Inside a nuclear membrane
(DNA isolated from
cytoplasm)
• Well defined nucleus
• Numerous specialized
organelles in cytoplasm
• Many internal membranes
• Much larger than
prokaryotes
http://www.physci.wsc.ma.edu/young/hgeol/geoinfo/timeline/eukaryotes/eukaryotes.html
chloroplast
Cell wall
http://library.thinkquest.org/3564/gallery.html
vacuole
http://www.sinauer.com/cooper/4e/micrographs0102.html
Plant Cell
Animal Cell
Why be small?
• Cells must obtain nutrients & expel wastes
across cell membranes
• As size decreases, surface area
increases.
• Amount of surface area/volume increases.
• Cell functions more efficiently.
Cell or Plasma Membranes
• Phospholipid Bilayer
• Hydrophobic lipid tails
orient away from water
in cytoplasm & outside
cell
• Hydrophyllic heads
contain phosphate
groups
• Lipid tails either
saturated or unsaturated
http://sun.menloschool.org/~cweaver/cells/c/cell_membrane/
Electron Micrograph of Cell
Membranes
8 nm thick
Cell membranes
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCELL2.html
Membrane Proteins
http://library.thinkquest.org/C004535/cell_membranes.html
• Ends of proteins are
hydrophyllic
• Center is hydrophobic
• Integral proteins go
through membrane
• Peripheral proteins
are only on surface
• Proteins have many
functions (later)
Other Components of Membranes
• Carbohydrate chains
attached to proteins
(glycoproteins) or
lipids (glycolipids)
– (blood types)
http://sun.menloschool.org/~cweaver/cells/c/cell_membrane/
Membranes are fluid
Phospholipids move 10
million times/second
Some proteins move;
others don’t
• In animal cells
cholesterol molecules
are embedded in
membrane
– Keeps membrane fluid
at low temps
(homeostasis)
Membranes are “sided”
• Selective permeability
– Allow some things in
and not others
• Vacuoles expell some
waste & proteins to
outside
• Vacuole membrane
must merge with cell
membrane
http://employees.csbsju.edu/hjakubowski/classes/ch331/cho/ergolgi.jpeg
– Inside of vacuole is
same as outside of cell