Bacteria and Virus

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

- 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.

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)

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.

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

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

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

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.

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

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.

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

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

Graphic Organizer Nonliving Can be useful Treated with antibiotics

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

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

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

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

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

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

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

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

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