Chapter !6 - Genomes of Prokaryotes Code : KSI0015
<Index of Genomes of Prokaryotes>
Prokaryotes have several claims on our interest.
1.They have cause infectious diseases. Some diseases, such as tuberculosis, are major public health problems. It's a challenge to control these diseases in the face of the development of antibiotic resistance.
2.Molecular biologists study prokaryotes as examples of relatively simple cells, to understand fundamental principles of metabolism, genetics, and development
3.Prokaryotes represent the earliest forms of life, from which all others are derived.
4.Prokaryotes are imporatnt mediatos of ecolofical processes and geological cycles. Indeed, geological and biological phenomena are linked in an intimate marriage, which has seen its turbulent episodes.
Major types of prokaryotes.
1. Some genes in archaea but non in bacteria contain introns
2. They are systematic differences in tRNA sequences between archaea and bacteria.
3. Enzymes involved in DNA replication such as DNA polymerase and some of the tRNa synthetases involven in protein synthesis, differ between archaea and bacteria.
4. Archaea but not bacteria contain DNA-associated proteins resembling histones.
5. Membranes of all cells contain phospholipids. Compounds combining a glycerol molecule with long chain organic molecules.
6. Cell wall structures : Bacterial but not archaeal cell walls contain peptididoglycan, a combination of sugar derivatives and peptides.
7. Archaea and bacteria differ in their complement of metabolic pathways.
Evolution and phylogenetic relationships in prokaryotes
-Major types of prokaryotes
-Do we know the root of the tree of life?
Archaea
EX > Methanogens as sources of greenhouse gas emission. : The case of New Zealand.
-The genome of Methanococcus jannaschii
> Hydrothermal vents are underwater volcanoes emitting hot lava and gases through cracks in the ocean floor
-Life at extreme temperatures
EX > Effet of beta - branched sidechains on protein stability.
-Comparative genomics of hyperthermophilic archaea
-Thermococcus kodakarensis and pyrococci
Bacteria
Genomics of pathogenic bacteria : virulence factors
Horizontal gene transfer is a common theme in development of virulence and antibiotic resistance.
Genomics and the development of vaccines.
The future of antibiotic development
Our descendants may well look back at the second half of the 20th century as a narrow window during which bacterial infections could be controlled, and before and after which they could not.
Metagenomics : The collection of genomes in a coherent environmental sample
-Marine cyanobacteria - an in-depth study
-Clarify evolutionary relationships.
-Use high-throughput sequencinng methods to study a cross-section of the life in a natural sample.
-Study the majority of strains that are difficult to grow in culture.
-Appreciate the relationships and interactions among different species that share an ecosystem.
-A milliitre of ocean water may contain 100-200 species. A gram of soil may contain 400.
> How are different procholorococcus strains adapted to differences in ambient light itensities and spectral distributions?
Protection against photochemical damage
-Utilization of nitrogen sources.
-Protection aginst predators and viruses.
