Chapter 10- microbial world Flashcards
Pathogen
A foreign invader that causes a disease
Virus
- smallest infectious agent
- considered biologically inert
- can’t be seen with light microscopes
- not all viruses affect humans
Biologically inert
Somewhere between simple biomolecules (proteins or DNA) and living organisms (bacteria)
Viruses do not meet the basic criteria scientists use to characterize life
- They do not perform metabolism
- They have no capacity for reproduction (by itself)
- Do not respond to stimuli
- No cellular composition (acellular)
- No complex growth
Acellular
No cellular composition
Eukaryotic cells
Membrane- bound nucleus
has organelles
Prokaryote cells
No membrane- bound nucleus
No organelles
Unicellular
Bacteriophage
Structure: rod and icosahedral (solid with 20 faces) mix
Only infect bacteria
Capsid
Protein she’ll that encloses the genetic material
- made up of smaller pieces called capsomeres
How do viruses replicate
By attaching to a host cell
Step 1: recognition
Viruses must be recognized by a cell to enter that cell
- usually contains specificity for one small group/ type of species
Envelope protein/spike protein needs to be recognized by the host cell’s receptors
Step 2: injection
The virus injects it’s genetic material or is brought into the cell (completely intact through endocytosis)
Step 3: transcription and translation
- The virus disassembles
- viral DNA is transcribed and translated by the host cell
Step 4: reassembly
Capsid protein re-assembles and releases new viral particles when there are many copies of viral DNA
- sometimes this destroys the cells
Lytic cycle
Host cell is terminated (lyses) at the end or replication cycle
- happens once many viruses have been generated
Lysogenic cycle
Rather than hijacking the cell, the virus inserts its viral DNA into the host’s genome creating a prophage
- cell continues to replicate, where the DNA remains silent
- host cell is not destroyed
- an environmental factor causes a switch into the lyric cycle causing the infected cell to lyse
Receptors
Allow virus to enter and exit without damaging the cell
Antibiotic
Inhibits then growth of or destroys bacteria
Shapes of bacteria
Cocci (ball)
Bacilli (rod-shaped)
Spirilla (spiral-shaped)
Shapes/2
Strepto: chain
Diplo: two
Staphylo: bunched together
Horizontal gene transfer
Exchanging genetic material
Conjugation
Plasmids are transmitted through pili
Binary fission
Produces two identical daughter cells
-begins at origin of replication
Cell elongates
-once there are two copies cell pinches in the middle
Bioremediation
Use of fungi to decompose pollutants in the soil
Mycology
Study of fungi
Morphology
Study of the forms of things
Hyphae
Filamentous network that supports the fungus
Mycelium
Collective network
-allows for nutrients, growth, and production
Mycorrhizae
Symbiotic relationship between the mycelium and roots
-allows for growth and life
Parasitic fungi
Infect and kill insects
Saprobic fungi
Have their mycelium relationship with dead organic matter
Cap
Reproductive function of a fungus
Gills
Site of spore production
Hymenium
Tissue layer of spore production
Stalk (stipe)
Stem-like feature that supports the cap
Annulus or partial veil
Ring of tissue below the cap
- covers hymenium throughout development and detached once hymenium matures
Asexual reproduction (fungus)
Cap produces spore that are carried by wind or water to new places
Sexual reproduction (fungus)
Hyphae from 2 colonies grow close together and share genetic info.
Protist
Eukaryotic organism that can’t be classified as animals, plants, or fungi
Animal-like protists
Food: heterotrophs Features: unicellular Movement: free-swimming Reproduction: asexual and sexual Common name: protozoans
Zooflagellates (animal-like)
Swim with flagella
Ciliates (animal-like)
Move using cilia and feed using cilia
Plant-like protist
Food: autotrophs Features: unicellular and multicellular Movement: free-swimming or attached Reproduction: asexual and sexual Common name: algae (unicellular) and seaweed (multicellular)
Diatoms (plant-like)
Produce thin, delicate cell walls rich in silicon (Si- main component of glass)
Fungus-like protists
Food: heterotrophs (absorb nutrients from dead and decaying matter)
Features: unicellular, but often live in colonies
-fungus-like protists have centrioles but lack cell walls made of chitin
Movement: move during some parts of their life cycle
Reproduction: asexual
Slime molds (fungus-like)
Play key role in recycling organic matter
-use spores to reproduce
