MICROORGANISMS: Viruses, Prions, Archaea

What do Archaea and Bacteria have in common?

• Single celled• Microscopic• No membrane bound nucleus• Both essential to all other life on earth

What about viruses? Living or non-living?

• Can they perform the functions of independent cells? Do they make their own proteins, have waste disposal?

• Are they made of cells?

• Do they have genetic material of their own? If so how many genes are there?

• Can they replicate?

• Viruses are non-cellular replicating entities that invade living cells to carry out their replication.

• Because viruses cannot carry out replication by themselves, most scientists do not classify them as living things.

• The Human Immunodeficiency virus (HIV), which causes AIDS, has two structures common to almost all viruses: – genetic material and – a protein coat, called a capsid, surrounding this

material. – HIV also has one other structural element that many

viruses possess: a fatty membrane, called an envelope, which surrounds the capsid.

Viruses cause a host of human illness. New viruses harmful to human beings periodically come along by means of viruses that infect other animals mutating and then “jumping” to human hosts.

All forms of life are vulnerable to viral infections.

Viral Life Cycle

1.They insert their genetic material inside a “host” cell;

2.Turn out viral component parts, construct new virus clones or “particles” from these parts;

3.Move the new particles out of the cell, at which point the particles go on to infect more cells.

Viruses are non-cellular, replicating entities that must invade a host to carry out replication

T4 Virus (bacteriaphage)

HIV

PRIONS

They are not viruses?• Prions are small, proteinaceous infectious particles

that resist inactivation by procedures which affect nucleic acids.

• Prions are pathogenic variants of proteins that are naturally produced in nerve cells and certain other cells

• No detectable nucleic acids of any kind and no virus-like particles have been associated with prions.

• But the rogue prions seem to force the normal proteins to change shape.

A prion is an abnormal, transmissible agent that is able to induce abnormal folding of normal cellular prion proteins in the brain.

It leads to brain damage and the characteristics signs and symptoms of the disease.

Prion diseases are usually rapidly progressive and always fatal.

A family of rare progressive neurodegenerative disorders that affect both humans and animals.

Human Prion DiseasesCreutzfeldt-Jakob Disease (CJD) Gerstmann-Straussler-Scheinker Syndrome Fatal Familial Insomnia Kuru Animal Prion DiseasesBovine Spongiform Encephalopathy (BSE) (Mad Cow Disease)Chronic Wasting Disease (CWD) Scrapie Transmissible mink encephalopathy Feline spongiform encephalopathy

ARCHAEA

What makes Archaea different from Bacteria?

• Simplest form of life• Likely the oldest form of life• Live in extreme environments; extremeophiles• Several subgroups: we will cover 3 of them• Different Cell wall construction

Thermoacidophiles 80-9- degrees C and pH2

Image of the geothermal site at Pisciarelli (Napoli, Italy). Acidic sulphur fumes rise from a fissure in the rocks. The bright green biomat is populated by a diverse assemblage of eukaryotic thermoacidophiles, the Cyanidiales

Extreme halophiles- salt lovers, live in salt concetrations of 10-12% salt lake, dead sea

• Halophiles have turned the land that surrounds the Great Salt Lake in Utah a reddish color. This happens to the land after flood water spreads onto the land.

Methanogens- strict anaerobes. Produce methane gas.

• Methanogens thrive in extreme environments such as geothermal springs.

• Sewage treatment plants and intestinal tracts of animals (example cows) Dumps smell is from adding methanogens to decompose the garbage and produces methane gas, that’s what you smell. Often see metal tubes to pipe gas out so doesn’t explode. Can collect methane

• Francis H. Chapelle, of the US Geological Survey in Columbia, South Carolina, and colleagues analyzed DNA sequences recovered from the waters of Lidy Hot Springs in Idaho and found that more than 90 percent of the organisms were methanogens. This is the highest-known concentration of such microbes discovered so far in any one place