Living Things in the BiosphereLesson 3 - Viruses, Bacteria, Protists and Fungi

I. Microorganisms (in general)A. Protists

1. Eukarya Domain.2. Simpler than plants, animals, fungi

B. Archaea and Bacteria1. Less complex than protists2. Unicellular; no nucleus3. Archaea live in extreme conditions such as hot springs,

salty water, deep underground.4. Some bacteria are autotrophs; some are heterotrophs;

some are decomposers.5. Bacteria found everywhere.

II. Viruses● Not in any domain because they are not considered living.● Tiny, nonliving particle that enters a cell and reproduces.● Lack most characteristics of life (cannot reproduce on its own,

do not use food for energy or to grow, do not respond to surroundings)

A. Shapes and Names1. Round, thread, brick, bullet, robot-like.2. Measures in units called nanometers (1 billionth of a

meter).3. Named after a disease they cause or where they were

discovered.

B. Reproduction

1. Contain genetic material with a protein coating.2. Attaches itself to a host cell (an organism that provides a

source of energy or a suitable environment for a virus to live).

3. Enters or injects genetic material into host cell.4. Genetic material takes over the host cell and makes copies

of itself.5. Host cell bursts open, releasing many new viruses, which

repeat the process.

C.Disease1. Many copies attacking may cause disease.2. Mild (cold) to sever (HIV).3. Vaccines are weakened or killed viruses that are introduced

to the body, the body is triggered to produce chemicals that will destroy that pathogen (virus).

III. Bacteria● Make up the majority of organisms on earth.● Very small.● Three shapes - ball, rod, spiral.

A. Infectious Bacteria1. E.coli, Streptococcus, Staphylococcus2. Release toxins that damage surrounding cells.3. Rare - <1% of bacteria.

B. Bacteria Cell Structure1. Unicellular, Prokaryote - lack a nucleus.2. Cell wall - prevents it from drying out.3. Cell membrane - controls what enters and exits the cell.4. Flagella - like a “whip” to propell the bacteria to move

around.

C.Obtaining Food1. Make food from sunlight2. Make food from chemicals3. Absorb food through cell walls (milk, sugar, meat, dead

cells)4. Use energy from food to make toxins.

D. Survival1. Cannot survive harsh conditions.2. Some may grow a thick shell called an endospore which

can grow back into a cell when conditions improve.E.Bacterial Reproduction

1. Reproduce asexually by binary fission.2. Rapid reproduction.3. Conjugation - pass genetic information to a neighboring

cell; can create resistance (antibiotic resistance).IV. Protists

● Eukaryotic - not plants, animals, or fungi● Moist environments; around humans● Most harmless● Some harmful parasites (Giardia; Plasmodium)

V. Fungi● Eukaryotic cells with cell walls● Largest living thing on Earth - honey fungus colony● Heterotrophs that feed by absorbing food through cell wall.● Hyphae - threadlike tubes that allow fungi to spread; food

source; release chemicals.● Some are decomposers, some are parasites.A. Fungal Reproduction

1. Fruiting Bodies - like the mushrooms we eat; release spores that are carried to new location and grow into new fungal colonies.

2. Sexually through hyphaeB. Role of Fungi

1. Some benefits - nutritious foods, medicines, dyes perfumes, bake bread/beverages

2. Some harmful - rashes, disease, infections.