Bacteria and Virus

1. Bacteria and Virus

2. Standard • d. Students know there are important differences between bacteria and viruses with • respect to their requirements for growth and replication, the bodysprimary defenses against bacterial and viral infections, and effective treatments of these infections.

3. - Viruses What Is a Virus? • A virus is a tiny nonliving particle that enters and then reproduces inside a living cell. Virus particles are tiny compared to bacteria.

4. What is a Virus? • Cause disease by disrupting homeostasis • Don’t exhibit all life criteria: Don’t carry out respiration No growth or development (all they can do is replicate) • Host Cell – where a virus replicates • Cannot be killed by antibiotics (medicines)

5. - Viruses The Structure of Viruses • All viruses have two basic parts: a protein coat that protects the virus and an inner core made of genetic material. Some viruses are surrounded by an outer membrane envelope.

6. - Viruses How Viruses Multiply • Active viruses enter cells and immediately begin to multiply, leading to the quick death of the invaded cells.

7. Viral Replication – Lytic Cycle • Attachment – to host cell • Entry – injects nucleic acid • Replication – uses energy to replicate viral nucleic acid • Assembly – New viruses made (in 30 minutes, 200 new viruses) • Lysis and Release – Host cell breaks open, and virus particles are released

8. - Bacteria The Bacterial Cell • Bacteria are prokaryotes. The genetic material in the cells is not contained in a nucleus.

9. What is Bacteria? • Small cell with all the structures necessary to carry out its life functions. • 2 types of Bacteria: • Archaebacteria – inhabit extreme environments • Eubacteria – live almost everywhere else.

10. Bacterial Reproduction • Asexual Binary Fission – • Chromosome replicates, attaches to plasma membrane • Cell grows and splits • Sexual Reproduction Conjugation – Transfers all or part of chromosomes to another bacteria through its pilus

11. How do bacteria make you sick? • Produce disease in one of 2 ways: • Damage cells and tissues of the infected organism directly, by breaking down the cells for food. • Release toxins (poisons) that travel throughout the body interfering with homeostasis of the host.

12. - Viruses, Bacteria, and Your Health Common Bacterial Diseases • Many bacterial diseases can be cured with antibiotics.

13. - Viruses, Bacteria, and Your Health Common Viral Diseases • Unlike with bacterial diseases, there are currently no medications that can cure viral infections.

14. Graphic Organizer Can be useful Nonliving Treated with antibiotics

15. White Board Questions • Use your notes and boards to answer the following questions

16. What is an Infectious Disease? • Disease = • a change that disrupts the homeostasis in the body • Pathogens = • disease causing agents (what makes you sick)

17. Our Bodies Defense Mechanisms: • Skin – • the first line of defense • Phagocytes, B-lymphocytes, and T-lymphocytes – • the 2nd line of defense • Antibiotics and Vaccines– • outside sources of help

18. What is the role of Phagocytes? • Phagocytes – White blood cells that surround and destroy pathogens. • Macrophages – Located in body’s tissues Giant Scavengers – engulf pathogens and damaged cells

19. What if phagocytes don’t help? • Acquired Immunity– • defense against a specific pathogen by building up resistance • Lymphatic System – • the body’s system that is in charge of keeping it healthy • Uses • T-cells and B-cells

20. What are T and B cells all about? Produced in bone marrow • Helper T-cell • – activates B-cells • Cytotoxic T-cell – • “killer T-cells” • B-cells – • produce antibodies once activated by helper T-cells • Memory B-cells • – remain in blood stream armed and ready for a 2nd attack

21. What are antibodies? • Antibodies – • proteins produced to react with and disable antigens • Antigens– • Foreign substances that stimulate an immune response in the body

22. What about Antibiotics? • Substance produced by a microorganism that kills or inhibits the growth of other microorganisms • Use to fight and kill • bacteria • Does NOT work • with viruses

23. How can Vaccinations help? • Vaccine – • substance with weakened, dead, or incomplete portions of pathogen • Produces an • immune response • Creates • antibodiesin the body