1. BACTERIA & VIRUSES MR. HUMES CHAPTERS 23 & 24

2. PROKARYOTES Single celled organisms that do not have a membrane bound nucleus

3. DOMAIN ARCHAEA Differ from bacteria in the make up of cell walls, lipids, genetics, and metabolism Methanogens Convert H 2 and CO 2 into methane gas for energy, anaerobic Found in deep waters, mud, and sewage Halophiles Live in high salt concentrations Thermoacidophiles Live in acidic environments with high temperatures

4. DOMAIN BACTERIA Most prokaryotes are bacteria Occur in many shapes and sizes Bacilli – rod shaped Cocci – sphere shaped Streptococci – chains of spheres Staphylococci – grapelike clusters of spheres Spirilla – spiral shaped

5. GRAM STAIN Bacteria are grouped by characteristics of their cell walls Technique called gram staining Gram-negative bacteria Cells appear red under microscope Gram-positive bacteria Cells appear purple under the microscope

6. IMPORTANT BACTERIAL GROUPS Proteobacteria – aerobic and anaerobic Rhizobium – nitrogen fixing bacteria found in the roots of legumes. Fix nitrogen into ammonia for plants to use ex: E.coli Gram-positive bacteria Streptococcus - causes strep throat Clostridium botulinum - causes botulism, release toxins into environment Lactobacilli - turns milk sour and makes yogurt Bacillus anthracis - makes the biological weapon anthrax Actinmyocetes - form of bacteria that make antibiotics

7. IMPORTANT BACTERIAL GROUPS Cyanobacteria - make own food through photosynthesis Lack a nucleus and membrane bound organelles Believed to be the first oxygen producing organism on Earth and responsible for putting O 2 into our atmosphere Spirochetes - responsible for syphilis and Lyme disease Chlamydia - another STI

8. BIOLOGY OF PROKARYOTES Cell Wall - made of peptidoglycan instead of cellulose Cell membrane - regulates what enters and leaves the cell DNA - circular loop attached to the cell membrane It is not enclosed in a nucleus Capsule - an outer covering of the cell that protects bacteria from dry harsh conditions

9. BIOLOGY OF PROKARYOTES Pili - short hair like projections on the surface that allow to attach to other bacteria and to host cells Endospores – a form some bacteria become when in unfavorable conditions Flagella - long hair like projections that help the bacterium move Some bacteria release a slime layer and move through it

10. BACTERIA AND HEALTH Pathology - scientific study of disease Bacteria and other organisms that cause disease are called pathogens Some bacteria cause disease by making certain poisons called toxins Exotoxins - Toxic substances that bacteria secrete into their environment Ex: Tetanus is caused by the bacteria Clostridium tetani Endotoxins - Toxic substances that are not released until the cell dies Can cause fever, body aches, diarrhea, hemorrhage, and weakness

11. BACTERIA AND HEALTH Antibiotics affect bacteria by interfering with certain cellular activity Penicillin blocks the ability to build new cell walls Tetracycline blocks protein synthesis Antibiotics are made naturally by some fungi and bacteria Antibiotic resistance is a major problem Mutations have allowed bacteria to become resistant to some antibiotics

12. VIRUSES Non-living particles made up of nucleic acid and a protein or lipid coat Lack key characteristics of life Can not reproduce on their own No metabolism No homeostasis Do not grow

13. VIRUS CHARACTERISTICS Viruses basic structure Nucleic acid (DNA or RNA) Protein coat surrounding the genome called capsid Some contain a bilipid membrane surrounding capsule called an envelope Classified by their structure Whether they contain DNA or RNA Whether the nucleic acid is single or double stranded Ex: ssRNA in HIV Whether they contain an envelope over their capsid

14. REPLICATION Since viruses are not alive, they cannot reproduce on their own Must recognize a host cell, infect the cell, and replicate using the enzymes and organelles from the host

15. REPLICATION DNA Viruses DNA gets transcribed into mRNA and make proteins using organelles and amino acids from host cell DNA from virus inserts itself into host’s genome Called a provirus

16. REPLICATION RNA Viruses RNA strand serves as the mRNA to make proteins Some viruses can perform reverse transcription where RNA gets coded into DNA and then inserts into host genome Called retrovirus

17. VIRUSES INFECTING PROKARYOTES Bacteriophages Viruses that infect only bacteria Made of a protein capsid, tail fibers, and nucleic acid

18. LYTIC CYCLE OF VIRUSES Lytic – to break Viruses that reproduce by this process are called virulent Virulent viruses destroy their host cells Virus releases the nucleic acid into the host, the host cell then produces viral proteins and assembles new viruses, new viruses burst the cell and repeat the process Ex: common cold, influenza

19. LYSOGENIC CYCLE This process is when the virus hides in the host’s genome Can hide for days, months, or years The viral nucleic acid is inserted into the host’s genome, remains there and the cell continues its normal function, the viral nucleic acid can then become lytic and begin to produce new viruses Ex: herpes virus, mononucleosis Sneaky Ninja Virus

20. VIRAL DISEASES Chickenpox and Shingles Caused by the same virus Multiplies in the lungs and travels to blood Contagious through direct contain with the skin and in the air May stay in the nerve cells as a provirus Can later cause shingles in its lytic cycle form

21. VIRAL DISEASES Acquired Immune Deficiency Syndrome (AIDS) Human immunodeficiency virus (HIV) causes AIDS Destroys the immune system Can be spread by sexual contact or contact with bodily fluids such as blood Virus integrates itself into host’s genome by reverse transcription and is lytic (targets helper T cells of immune system)

22. PREVENTION & TREATMENT Vaccinations Contains harmless version of virus that is introduced to the body By exposing the cells to the virus, this builds an immunity for it Best treatment for viral infection is the body’s own immune system Drug Therapy Some anti-viral drugs can help by interfering with nucleic acid synthesis Not as common since viral infections take place within the patient’s own cells