Viruses & Bacteria One is the ultimate bad guy. One is an ultimate good guy Gone bad guy. But still good guy.
Viruses A virus is a non-cellular particle made up of genetic material (DNA or RNA) and protein that can invade living cells. ALL VIRUSES ARE PARACITIC (the bad guy) Viruses are MUCH smaller than bacteria They are not CURRENTLY considered alive (they fall into a gray area of nonclassification)
Structure of Viruses A typical viruses is composed of a core of nucleic acid surrounded by a protein coat called a capsid. The capsid protects the nucleic acid core The nucleic acid is either DNA or RNA (depending on the virus)
Capsid
Capsid
Bacteriophage A more complex structure occurs in some viruses called Bacteriophages These viruses invade bacteria as their hosts (not found in humans) A bacteriophage is composed of: A head region capsid called a protein coat Nucleic acid (inside the protein coat) A tail region tail fiber (used in attachment to the bacterial cell)
Bacteriophage
Bacteriophage
Bacteriophage
Bacteriophage
2 Life Cycles of viruses
The Differences The lysogenic cycle may (but not always) eventually lead into the lytic cycle However, first the DNA of the virus is inserted into the DNA of the host cell Once inserted into the host s cells DNA, the viral DNA is known as a prophage The prophage may remain part of the DNA of the host cell for many generations.
Retrovirus Retroviruses contain RNA as their genetic information. When a retrovirus infects (not invades) a cell, they produce a DNA copy of their RNA genes. This DNA is inserted into the DNA of a host much like a prophage (The information is copied backwards. From RNA to DNA) AIDS is a retrovirus
HIV
Interferons One possible approach in the treatment of viral disease is the use of interferons These proteins, released by the cells of an infected individual, make it much more difficult for the virus to attack other cells If used correctly, they may be the best vaccination to many viral disorders, with little to no chance of infection
Bacteria Bacteria are Prokaryotes Prokaryotes are cells that do not have a nucleus. All prokaryotes are classified in 2 Kingdoms: Either Eubacteria or Archaebacteria This was once called the kingdom Monera
Eubacteria The Eubacteria make up the larger group of prokaryotes. Most all Eubacteria are surrounded by a protective cell wall made of various carbohydrates Within the cell wall is either 1 or 2 cell membranes, making Eubacteria incredibly resistant to damage
Eubacteria Eubacteria range in variety from organisms that cause deadly diseases to incredibly helpful organisms that keep us all safe from serious ailments Eubacteria live in the soil, on our skin, and on practically every millimeter of land on earth Eubacteria can be incredibly good or incredibly dangerous and bad.
Eubacteria
Cyanobacteria One of the most important types of bacteria are the incredibly hardy group, Cyanobacteria (also called blue-green algae and blue-green bacteria) Cyanobacteria are a unique bacteria that have the ability to carryout photosynthesis They are responsible for massive amounts of oxygen production and make up a large carbon sink They also are one of the few organisms able to fix Nitrogen
Cyanobacteria
Archaebacteria These bacteria are prokaryotes that lack a very important carbohydrate in their cell walls. They also have different lipids in their cell walls, different ribosomes, and very different gene sequences This gives them the ability to live in incredibly harsh environments
Types of Archaebacteria Methanogens: Live in oxygen free environments that may contain high levels of the usually toxic methane gas Thermophiles: Live in incredibly cold or hot environments Halophiles: Live in incredibly saline (salty) environments
Cell Shape There are three basic shapes of bacteria: Rod (bacilli) or (bacillus) Sphere (cocci) or (coccus) Spiral (Spira) or (Spirus)
Coccus
Bacillus
Spirillus
Bacterial Shapes
Gram + or - The chemical nature of bacterial cell walls allows us reason to study and defeat the particular organism You do this by a method called gram staining Bacteria with only one thick layer of their cell wall will adhere to a gram stain, crystal violet dying it purple (This is gram +) The bacteria with a second layer of lipid and carbohydrates take up the second dye called safranine. This causes them to be red, making it gram negative
Gram +
Gram -
Autotrophs & Heterotrophs Some bacteria obtain energy from photosynthesis, therefore these organisms are Autotrophs. (phototrophic autotroph) Some bacteria obtain energy from eating other organisms, therefore these animal are Heterotrophs. (Heterotrophic autotroph)
Aerobic vs. Anaerobic Organisms (like many bacteria) require a constant supply of oxygen to survive are called Obligate aerobes Organisms that (like many other bacteria) do not require oxygen to survive in fact, they often are poisoned by bacteria are called Obligate anaerobes Organisms that do not require oxygen to survive, but are not harmed by oxygen, are called Facultative anaerobes
Bacterial Reproduction Asexual reproduction: A bacteria has the ability double its genetic information and size and then split in half. This is called Binary Fission
Bacterial Reproduction Sexual Reproduction: Some bacteria have the ability to form a protein bridge that connects the 2 cells. Genetic information can be exchanged by use of this bridge. This is called Conjugation
Medication One of the major problems with treating bacterial and viral infections is their amazing resilience under the pressure of natural selection Every medication we use causes tremendous change in many viral and bacterial strains Some viruses we still have no idea how to damage, much less destroy them