Pathogens: An organism that causes disease. (Chp. 18/chp.39) see p.550

Types of Diseases Contagious…if it spreads quickly

• Non-communicable Disease: cannot be transmitted from one person to another

• Heart attach• Depression• Stroke• Hypertension/hypo.

• Cancer• Genetic disorders (only

to their children)

• Communicable Disease: can spread from one person to another

• Diarrhea• Pneumonia• Tuberculosis (TB)• Sexually transmitted

diseases (STD’s)

Bacteria• Unicellular and everywhere• Some damage cells and tissues

• Others release Toxins: poisons that travel through the body and may cause diseases

• There are environmental toxins: Lead and Mercury

Other toxins:Botulism> improperly prepare food

Disease Bacterium Effect on Body

Strep Throat Streptococcus Fever, sore throat swollen neck glands

Tuberculosis Mycobacterium Fatigue, weight loss, mild fever, chronic cough

Tetanus Clostridium tenani Muscle spasms, paralysis, death

Lyme Disease Borrelia burgdorferi Rash at site of tick bite, fever, chills

Bacterial Meningitis Neisseria meningitidis

High fever, headache, stiff neck, nausea

Diphtheria Corynebacterium diphtheria

Sore throat, low-grade fever

Diseases Caused by Bacteria

Viruses: Nonliving..Must have a LivingHost

• Consist of genetic material enclosed in a protein coat (Capsid [head], nucleic acid, Sheath, Tail)

• Bacteriophage (phage): a virus that infects a bacterium. The virus will attach its legs to a cell and then inject its genetic material into it. The virus takes control of the bacterial cell and directs it to produce viral material. A single infected cell may replicate thousands of viruses.

A typical Bacteriophage, a type of virus

Attaches to a cell

Protein coat

Viruses Cause….

• HIV• Influenza• Chickenpox• Colds• Measles• Rabies

Viral Replication Cycles p. 478/479

• (1)Lytic Cycle: immediately takes over killing the host cell

• (2) Lysogenic Cycle: does not kill host cell immediately integrates its genetic material with the host cell…creates a provirus…..sits dormant….then one day takes over the host

Viral Replication Cycles