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 respirationNo 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.

- Viruses

HOW VIRUSES MULTIPLY Active viruses enter cells and immediately begin to

multiply, leading to the quick death of the invaded cells.

- Viruses

VIRAL REPLICATION – LYTIC CYCLE

1. Attachment – to host cell2. Entry – injects nucleic acid3. Replication – uses energy to

replicate viral nucleic acid4. Assembly – New viruses made (in

30 minutes, 200 new viruses)5. Lysis and Release – Host cell

breaks open, and virus particles are released

THE BACTERIAL CELL Bacteria are

prokaryotes. The genetic material in the cells is not contained in a nucleus.

- Bacteria

WHAT IS BACTERIA? Small cell with all the structures

necessary to carry out its life functions.

2 types of Bacteria:1. Archaebacteria – inhabit extreme

environments2. Eubacteria – live almost

everywhere else.

BACTERIAL REPRODUCTION AsexualBinary Fission – 1. Chromosome replicates, attaches

to plasma membrane2. Cell grows and splits Sexual ReproductionConjugation –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:1. Damage cells and tissues of

the infected organism directly, by breaking down the cells for food.

2. Release toxins (poisons) that travel throughout the body interfering with homeostasis of the host.

- Viruses, Bacteria, and Your Health

COMMON BACTERIAL DISEASES Many bacterial diseases can be cured

with antibiotics.

COMMON VIRAL DISEASES Unlike with bacterial diseases, there are

currently no medications that can cure viral infections.

- Viruses, Bacteria, and Your Health

GRAPHIC ORGANIZER

Nonliving Can beuseful

Treated withantibiotics

WHITE BOARD QUESTIONS Use your notes and boards to answer

the following questions

WHAT IS AN INFECTIOUS DISEASE? 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 tissuesGiant 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 –

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