Microorganisms Flashcards
How do fungi reproduce?
- Asexual spores- seeds that grow into a new organism
- Sexual spores- act like sperm and ova to form a new organism
- Vegetative growth- portion breaks off to form new fungus
- Budding- new fungus grows off the side of the old one.
Fungi
- Multicellular eukaryotes
- Heterotrophic- feed on decaying material
- Absorptive feeders- secrete enzymes that digest their food outside their bodies
How can bacteria genetically recombine?
- Transformation- picking up new DNA from extracellular environment
- Conjugation- bacterium replicates its DNA and donates some of it through a pilus.
- Transduction- virus carries DNA from one bacterium to another during infection
Pilus
A bridge allowing bacteria to donate its DNA.
What is antibiotic resistance/sensitivity determined by?
DNA. If it changes, that means the DNA has changed.
How do bacteria reproduce?
- Produces asexually through binary fission- replicates its chromosome, then splits in half. Gets half the organelles and cytoplasm.
- Binary fission doesn’t allow for genetic recombination
Bacteria
- Single celled prokaryotes
- Singular, circular chromosome protects DNA from damage.
- Have ribosomes and cell walls
Saprobes
Bacteria that are decomposers, get nutrients from breakout of dead matter.
Parasites
Bacteria that get nutrients from the host, which harms the host.
Symbionts
Bacteria that get nutrients from the host, but don’t harm it.
Obligate aerobes
Bacteria that need oxygen to survive.
Obligate anaerobes
Bacteria that are poisoned by oxygen and will die if exposed to it.
Facultative anaerobes
Bacteria that are fine with or without oxygen.
Auxotroph
- An organism that requires supplementary nutrition. Most bacteria aren’t auxotrophs.
- Auxotrophic bacteria need additional substances added to their growth medium. If they don’t get that substance, they can’t grow.
- If a bacteria can grow with a missing amino acid, they aren’t auxotrophic for that amino acid. Denoted with a plus sign
- The ability to synthesize a substance, like an amino acid, is a genetic trait.
Wildtype
Bacteria that can synthesize all building blocks they need with access to a carbon source, like glucose.
Mutualistic Relationship
Relationship where both individuals benefit, such as the relationship between legumes and nitrogen fixing bacteria. Bacteria live in roots and give plants nitrogen, and plants give the bacteria nutrients. Extra nitrogen goes into the soil.
Viruses
- Viruses aren’t cells, and aren’t alive, but possess genetic information and are subject to natural selection
- Consist of a coat made of protein (capsid) and nucleic acid (genome) which can be DNA or RNA.
- Can’t reproduce without a host cell
Viral life cycle
Attaches to the host cell, typically using a receptor, then infects it by injecting its genome into the cell. Then begins a lytic or lysogenic cycle.
Lytic cycle
- Viral genome is transcribed and translated using host RNA to make viral proteins
- Host DNA replicates the viral genome, and new genomes are packages into capsids
- Host is broken open (lysed) by a viral enzyme so the viruses can escape and infect new hosts
Lysogenic cycle
- Virus is integrated into a host’s genome and remains dormant
- Viral genome is replicated whenever the host replicates, infecting daughter cells.
- If the host experiences stress, the virus can begin the lytic cycle.
Envelope
Plasma membrane that covers the virus as it buds out.
How can a virus become more severe in animal cells?
Animal cells don’t have a cell wall, so the virus can go through the cell membrane to escape. This allows the infected cell to stay alive for longer and produce more virus cells.
Viruses with RNA genomes
- This viruses need an RNA polymerase to replicate, because the host cell only has DNA
- Uses an enzyme called RNA-dependent RNA polymerase
- The virus must carry the enzyme with it to inject into the host, or synthesize it during translation of the viral genome.
Yeast
Eukaryotes that reproduce by budding.
Retroviruses
- RNA viruses that go through the lysogenic life cycle. Requires RNA dependent polymerase.
- Reverse transcriptase- the enzyme runs reverse transcription, creating DNA from RNA.
- Many cancer causing viruses are retroviruses
Palindrome
Reads the same in both directions
Staggered cut
Leave single stranded tails called sticky ends that allow it to be reattached to a piece of DNA cut by the same enzyme. The tails must overlap in a complementary fashion.
Blunt cut
DNA is cut straight across both strands. Can be reattached/ligated to a piece of DNA cut with any other enzyme that produces blunt ends.
Restriction enzymes
- Enzymes that recognize a particular DNA sequence and cut the strand within it
- Bacteria use enzymes to cut and destroy foreign DNA like viral DNA, restricting the growth of the virus.
- The bacterium’s DNA is protected by addition of CH3 to prevent the enzyme from binding there.
- The sequence is usually palindrome
- Give us the ability to cut and paste DNA into custom combinations.
Plasmids
- Small circular piece of DNA found in bacteria or yeast
- Not part of a genome and can reproduce independently. Its sequence contains restriction sites
- Some carry genes making bacteria resistant to antibiotics.
Vector
Shuttle to move DNA in between species, like a virus
DNA ligase
Enzyme that seals together cut pieces of DNA.
Restriction map
- Map of the location of restriction sites within a piece of DNA
- You can isolate a gene if you know it’s bounded on either side by a certain restriction site and use an enzyme to cut it.
Recombinant DNA technology
- Creation of new DNA molecules by cutting and splicing DNA with restriction enzymes
- If a plasmid is mixed with the DNA, it can be inserted into the bacteria, which will rapidly reproduce, and reproduce the DNA. The DNA can then be extracted.
