Bacteria Viruses Chapter 7 Lesson 1 Lesson 3

Bacteria & Viruses Chapter 7: Lesson 1 & Lesson 3

What are Bacteria? Lesson 1

Characteristics of Bacteria • Microscopic • Prokaryotic: No membrane bound organelles • Can live in both living or dead organisms • Bacteria outnumber your cells 10 to 1 in your own body! • Archaea are similar to bacteria • live in extreme environments (Very Warm or Cold , No Oxygen

Structure of Bacteria • Cytoplasm • DNA • Cell Membrane and Cell Wall • Ribosomes • Protective Capsule • Prevents white blood cells from surrounding bacterium

Sizes and Shapes of Bacteria • Much smaller than plant or animal cells • Bacteria = 1 -5 micrometers • Average Eukaryotic cell = 10100 micrometers

Obtaining Food and Energy • Many bacteria feed on dead organisms, we call them decomposers! • Parasites: can cause tooth decay, feeding on sugars • Photosynthetic bacteria: Use light energy to make their own food, like plants. • Chemosynthetic bacteria: Use energy from Chemical reactions.

Aerobic vs. Anaerobic Aerobic Bacteria • Need Oxygen to survive • Most bacteria are Aerobic bacteria Anaerobic Bacteria • Do not need Oxygen to survive

Movement • Flagella: Long whiplike structures used for movement • Twisting and spiraling as they move • Pili: Grappling hooks!

Reproduction Conjugation Binary Fission

Endospores Archaea

What are Viruses? Lesson 3

Characteristics of Viruses • Virus: • Strand of DNA or RNA surrounded by a layer of protein • Can infect and replicate itself in a host cell • No Cell Wall, Nucleus or any other organelles • 20 to 100 times smaller than most bacteria

Dead or Alive? • Scientists do not consider a virus to be alive • Viruses: • Are not organized • Don’t respond to stimuli • Don’t use energy • Don’t grow • Don’t reproduce on their own (need a host)

Viral Replication

Viral Mutations • During replication, DNA or RNA frequently mutates. • Mutations enable viruses to adjust to changes in host cells • Host cells change over time to prevent viruses from attaching to the cell • Mutations produce new ways to attach to host cells

Viral Diseases • Chicken Pox • Influenza • Pneumonia • Common Cold • Rabies • Latent Viruses: HIV • Attacks White blood cells

Treating and Prevention • Immunity: • Unable to develop a disease • Antibody: • a protein that can attach to a pathogen and make it useless • Antibodies bind to viruses and other pathogens to prevent attack

Vaccines • Vaccine: • A mixture containing material from one or more deactivated pathogens, such as viruses.