Chapter 21 Viruses and Prokaryotes

Viruses

Where do viruses come from ?

Bacteriophage Replication

HIV Replication - Retrovirus

HIV_replication.swf

What Do These Pictures Have in Common?

gov.mb.ca

k8science.org

gsbs.utmb.edunuclearfamilywarhead.com

Brain Tissue

learn.genetics.utah.edu

Protein Structure

new-science-press.com

Prions

stanford.edu

Dr. Stanley Prusiner.

cmu.edu

ViroidsConsist of short,

fragments of single-stranded RNA.

Only found in plants (so far).

Can interfere with plant’s metabolism, resulting in the plant being stunted or killed.

Ex. Potato spindle tuber

Left: normal potatoes; Right – infected potatoeswww.unece.org

Prokaryotic Cells

Yersinia pestis – Bubonic Plague. science.nationalgeographic.com

Clostridium botulism. www.nih.gov

Evolutionary History and Classification

Prokaryotic Nutritional Modes

Prokaryotic Body Plan

Prokaryotic Cell Size and ShapeProkaryotic cells are

much smaller than eukaryotic cells (about the size of mitochondria)

Prokaryotes have three typical shapes:

http://www.bio.miami.edu/~cmallery/150/proceuc/c8.27x3.bact.shapes.jpg, http://sharon-taxonomy2009-p2.wikispaces.com/Archaea

Prokaryotic FissionEsherichia coli undergoing prokaryotic fission

Conjugation

Bacterial Cell WallGram-positive

Bacteria Thick layer of

peptidoglycan (60-100%)

Gram-negative BacteriaThin layer of

peptidoglycan (10-20%)Has outer membrane

composed of mostly lipids (80-90%)

Gram-positive Bacteria

Gram-negative Bacteria

pathmicro.med.sc.edu

Gram Stain Results

Gram-positive bacteria stains violet to blue.

Gram-negative bacteria stains pink to red.

homepage.ntlworld.com

Cyanobacteria

Anabaena. http://www.biologie.uni-hamburg.de/b-online/fo42/anabaena.jpg

Oscillatoria. http://t2.gstatic.com/images?q=tbn:LsEmj27QxYGiHM:http://botit.botany.wisc.edu

Endospores

Methanogenic Archaeans

0.5 µm

Life in Extreme Environments

The End