INFECTIOUS DISEASES #1

Pathogens

THE COLD AND FLU SEASON IS

HERE

Please cover your mouth

Pathogen: agent that causes disease• Can be a prion, viroid, virus, bacteria, protozoan

eukaryotics cells10,000-100,000 nm

bacteria cells200-10,000 nm

viruses50-200 nm

viroids5-150 nm

prion2-10 nm

1 nanometer (nm) = one billionth of a

meter

100 nm

a. How they cause harm:• Some are benign, but many

harm their host organism by destroying or altering its cell structure.

b. How the body combats them:• Generally the body

perceives viruses as antigens and produces antibodies to counteract the virus.

c,. How doctors combat them:• They can’t. Antibiotics

DON’’T work!

d. Replication:• Lytic cycle – destroys the

host cell in replication• Lysogenic Cycle – host cells

not immediately destroyed.

VirusA non-living pathogen made of DNA or RNA and a protein coat.

Can infect many organisms.

RNA or DNA

Capsid (protein coat)

Lysogenic Cycle

a. How they cause harm:• Attacking cells• Making toxins that

get carried by blood to sites throughout the body.

b. How the body combats them:

• Bacteria and their toxins are perceived as antigens by the body, which in turn produces antibodies.

c. How doctors combat them:• Antiseptics – Kill

bacteria.• Antibiotics – Stop

bacteria from replicating.

d. Replication:• Asexual replication

Bacteria

Cell wall

DNA

Cellmembrance

Bacillus Coccus Spiral

Bacteria commonly come in three forms

Bacillus anthracis

Anthrax

Staphylococcus

Food Poisoning

Treponema pallidum

Syphilis