Prokaryotes

1
Prokaryotes Eukaryotes

• By
• Diana L. Duckworth
• Rustburg High School
• Campbell County

2
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)

3
Prokaryotic Cells

• 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//www.prof2000.pt/users/biologia/tipocelu.htm
4
http//darwin.nox.ac.uk/gsc/gcat/mashup?queryStre
ptococcus
http//www.bact.wisc.edu/themicrobialworld/Structu
re.html
http//www.kimicontrol.com/edu-e.html
5
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/t
imeline/eukaryotes/eukaryotes.html
6
chloroplast
Cell wall
vacuole
http//library.thinkquest.org/3564/gallery.html
http//www.sinauer.com/cooper/4e/micrographs0102.h
tml
Plant Cell
Animal Cell
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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.

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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_m
embrane/
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Electron Micrograph of Cell Membranes
8 nm thick
Cell membranes
http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
BioBookCELL2.html
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Membrane Proteins

• Ends of proteins are hydrophyllic
• Center is hydrophobic
• Integral proteins go through membrane
• Peripheral proteins are only on surface
• Proteins have many functions (later)

http//library.thinkquest.org/C004535/cell_membran
es.html
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Other Components of Membranes

• Carbohydrate chains attached to proteins
  (glycoproteins) or lipids (glycolipids)
• (blood types)
• In animal cells cholesterol molecules are
  embedded in membrane
• Keeps membrane fluid at low temps (homeostasis)

http//sun.menloschool.org/cweaver/cells/c/cell_m
embrane/
Membranes are fluid Phospholipids move
10 million times/second Some proteins move
others dont
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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
• Inside of vacuole is same as outside of cell

http//employees.csbsju.edu/hjakubowski/classes/ch
331/cho/ergolgi.jpeg