Post on 06-Oct-2020
Viruses and Bacteria
Viruses
Discovered 1935
From the Latin meaning “poison”
Tiny non-living particles that reproduce in cells
Most are very specific- can only infect a certain type of cell
Viruses can infect all living things
Cold
Flu
Herpes
Some Cancers
HIV
Mumps
Chickenpox
These are all caused by viruses
Viruses can infect all living things
Bacteriophage-
virus that infects
a bacterium
Bacteriophage virus
Bacterium
Viruses- Bacteriophage
No!!!
The tulip mosaic virus
Produces highly
prized variegated tulips
Are all viruses bad?
Why are Viruses not
Considered Living?
They do not respire, eat, excrete, or reproduce.
By itself, a virus can not do anything.
Host cell- cell a virus invades to replicate (make copies), cannot reproduce on its own
What are the parts of a virus?
Capsid- outer coat of protein, protein coat determines shape
Nucleic Acid- DNA or RNA Bacteriophage
Capsid
DNA
RNA
DNA
Capsid
Capsid
Viruses come in many shapes and sizes depending on the cell they infect.
What are the
shapes of viruses?
Viruses come in many shapes and sizes depending on the cell they infect.
What are the
shapes of viruses?
10 x
smaller
100 x
smaller
1000 x
smaller
What are the sizes of viruses?
Viruses- The Lytic Cycle
Lytic Cycle
Attachment- virus attaches to cell
Entry-viral nucleic acids invades host cell
Replication-makes many copies of DNA and capsid
Assembly-viruses are put together
Lysis- host cell breaks open and viruses are released
Viruses Lytic Cycle
This is how viral replication appears in ‘Real Life.’
Viruses- The Lysogenic Cycle
Attachment-virus attaches to cell wall
Entry-viral nucleic acid enters cell
Provirus/Prophage formation-viral DNA is incorporated into the host’s DNA. Viral DNA is produced along with the host cell’s DNA. This is called a provirus or prophage
Can go into lytic cycle at any time
Lysogenic cycle
Viruses- Lytic and Lysogenic Cycle
Summary of Both
http://www.youtube.com/watch?v=wLoslN6d3Ec http://www.youtube.com/watch?v=Rpj0emEGShQ
Retrovirus
retrovirus- virus made of RNA, once RNA enters the cell, it is converted into DNA using an enzyme called reverse transcriptase
HIV is a retrovirus
Bacteria
Kingdom Monera
Kingdom Archaebacteria
Kingdom Eubacteria
Bacteria Structure
Structure p 503
Bacteria
Kingdom Archaebacteria
Live in extreme environments
Usually no oxygen present
Contains a cell wall
Prokaryotic cell
Archaebacteria- 3 types
o 1. heat and acid loving deep thermal vents
Bacteria in boiling hot springs in Yellowstone Park
Types of Archaebacteria
2. salt loving
Great Lakes, Dead Sea
Salt loving archaebacteria and algae swimming among salt crystals
Salt crystals appear pink because millions of halobacteria are trapped within the crystals.
Archaebacteria- 3 types
3. methane producing
found in swamps, cow’s gut, sewage plants
Swamps and wetlands
Guts of herd animals
Raw sewage
Bacteria
Kingdom Eubacteria
Types of nutrition
Parasitic- feed on living tissues
Saprophytic- feed on dead tissues
Autotrophic- make own food
Chemosynthetic- break down chemicals
Eubacteria- Nutrition
Parasitic bacteria like these rods cause Tuberculosis
Cyanobacteria- a photosynthetic bacterium
Eubacteria- Nutrition
Discovered during a dive to Hydrothermal Vents in 1977, Chemosynthetic Bacteria is a very unique organism.
These bacteria are the food source for many deep water organisms. Vent communities are completely isolated from other organisms from the marine world.
The discovery of chemosynthetic bacteria and the vent communities was as remarkable as finding life on another planet
Bacteria
Toxins- bacteria growing in anaerobic environment (sealed cans) produce these poisons-
causes botulism
Bacteria- Shapes
Shapes
Coccus –round
Bacillus- rod
Spirilla – spirals
Bacteria- Arrangements
o Diplococcus- two cells
o Streptococcus- chain
o Staphylococcus- like
bunches of grapes
Bacteria- Reproduction
Reproduction
1. Binary fission- asexual, cell splits in two
Bacteria- Reproduction
Conjugation- sexual, cells exchange genetic information
Bacteria
Colonies- large groups of bacteria cells
Antibiotics- inhibit growth of bacteria
Bacteria- Importance
1. Nitrogen Fixation- Important role is converting atmospheric/inorganic nitrogen to compounds plants can use
Bacteria- Importance
2. Decomposition- recycle nutrients
Bacteria- Importance
3. Food – yogurt, cheese, vinegar
Bacteria- Importance
4. Medicine –
streptomycin,
erythromycin,
neomycin