bio 178 lecture 7 cell structure copyright: j. elson-riggins
Post on 27-Dec-2015
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Reading
• Chapter 5 (& P 550)
Quiz Material
• Questions on P 104
• Chapter 5 Quiz on Text Website (www.mhhe.com/raven7)
Characteristics of Principle Cell Types2 structurally different types of cells:
PROKARYOTE EUKARYOTE
True Nucleus? No Yes
Membrane bound organelles?
No Yes
KingdomsBacteria
Archaebacteria
Protista
Fungi
Plantae
Animalia
Immunofluorescence Microscopy
Green = Anti-tubulin
Red = Anti-vimentin
http://www.img.cas.cz/dbc/gallery.htm
Prokaryotes
Characteristics
• Simple Organization
1. Little compartmentalization.
2. Nucleoid region with a simple circle of DNA.
3. Ribosomes.
• Size
~ 1 to 10 µm.
Prokaryote Characteristics (Cntd.)
• Support
Most prokaryotes have a strong cell wall (instead of internal support structures).
• Cell Shape
Variable - rod (bacillus), sphere (coccus), comma (vibrio), spiral (spirillum).
Staphylococcus epidermidis
Dr. Dennis Kunkel / Visuals Unlimited,
http://www.visualsunlimited.com/browse/vu285/vu285886.html
Prokaryote Cell Walls
• Bacteria have cell walls of peptidoglycan (protein-carbohydrate), but Archaebacteria use other materials.
• Gram Staining
Gram Positive:
A thick wall with many layers of peptidoglycan that blocks the escape of the gram stain Purple.
Gram Negative:
Only a thin peptidoglycan layer that allows the escape of the gram stain Red.
Eukaryotic Cells
Key Characteristic:
COMPARTMENTALIZATION:
• Membrane-bound organelles (including the endomembrane system).
• Nucleus.
• Plasma membrane.
The NucleusFunction
Control center of cell.
Structure
• Nuclear Envelope
1. 2 phospholipid bilayers.
2. Internal bilayer continuous with ER.
3. Nuclear pores that allow selective passage of proteins and RNA.
Nuclear Structure (Cntd.)• Nucleolus
1. Dark staining region of nucleus.
2. Contains genes that encode rRNA.
3. Function - rRNA synthesis and assembly of ribosomal subunits.
• ChromosomesDNA and protein (histones).
The Endomembrane systemStructureInterior membranes that are connected by either:
• direct physical continuity or
• vesicular transport
FunctionCompartmentalization, large surface area, and trafficking.
Components• Endoplasmic reticulum
• Golgi apparatus
• Lysosomes
Endoplasmic Reticulum
Structure
• Lipid bilayer with embedded proteins that forms an intracellular network.
• Cisternal space.
Intracellular Location
Continuous with nuclear envelope and concentrated around it.
Rough Endoplasmic Reticulum (RER)
Structure
ER with attached ribosomes.
Functions
• Lipid/membrane synthesis.
• Synthesis of proteins to be secreted from the cell - determined by the presence of a signal sequence on the polypeptide chain.
• Synthesis of proteins that will be embedded in the cell membrane or sent to lysosomes.
Smooth Endoplasmic Reticulum (SER)
Structure
Few attached ribosomes.
Functions
• Lipid/membrane synthesis.
• Detoxification.
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