10d) What are the important differences

between bacteria and viruses with respect

to:

their requirements for growth and replication

the body’s primary defenses against bacterial

and viral infections

effective treatments of these infections?

Chapter 40Section 1

Infectious Diseases

What causes disease?

A disease is any change, other than

an injury, that disrupts the normal

functions of the body.

Pathogens cause disease.

Infectious diseases are caused by

pathogens.

Pathogens that can cause

disease:

•viruses

•bacteria

•protists

•worms

•fungi

Viruses are tiny particlesthat invade and replicate within living cells.

Viruses attach to a cell’s surface, insert their genetic material, and take over many of the functions of the host cell.

HIV Invasion

HIV Invasion & Infection

HIV Invasion & Infection

AIDS

Viruses can infect nearly every type of organism.

Diseases caused by viruses include hepatitis, the cold, herpes, influenza, and smallpox.

Smallpox

Smallpox

Chickenpox

Prokaryotes (bacteria):

• Are smaller than Eukaryotic cells and can be distinguished by the lack of a membrane-bound nucleus.

• Prokaryotic cells have 3 major shapes: cocci , bacilli or spirilla.

Bacteria Diversity

Most bacteria are harmless to humans

Bacteria that cause disease either:

break down tissues of the organism for food

release toxins that harm the body.

Bacterial diseases include streptococcus infections, gonorrhea, syphilis, diphtheria, and botulism (food poisoning).

Bacterial Diseases

Bacterial Diseases

Psoriasis

Untreated Syphilis

Untreated Syphilis

E. Coli - food poisoning

Botulism

Are spread from one person to another through coughing, sneezing, or physical contact.

Others are spread through contaminated water or food.

Still others are spread by infected animals.

Spread of infectious diseases

Spread of infectious diseases

Spread of infectious diseases

Medical Test for bacterial infection

Medical Test for bacterial infection

Fighting Infectious Diseases

Antibiotics:Are compounds that kill bacteria

without harming the cells of the host (humans or other organisms)

They work by interfering with bacterial cellular processes

Antibiotics have no effect on viruses.

Antibiotic Sensitivity

Antibiotic Resistance

Fighting Infectious Diseases

Antiviral drugs:

Have been developed to fight certain viral diseases (herpes, HIV, flu, hepatitis)

They do not destroy their target pathogen; instead they inhibit their development, at every stage of their life cycles

Antiviral Drugs

Viral infection But

Negative bacterial infection

Hepatitis Viral infection

Antivirals must be able to inhibit 6 processes in HIV infection, prevention

and spread

Antivirals

AIDS

AIDS

Over-the-Counter Drugs

You can buy them without a prescription.

They treat only the symptoms of the disease, not the cause.

The best treatment for most infections includes rest, a well-balanced diet, and plenty of fluids.

10d) What are the important differences

between bacteria and viruses with

respect to:

• their requirements for growth and

replication

• effective treatments of these

infections?

• Page 1035: 1- 5and Writing in Science