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49 Cards in this Set
- Front
- Back
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Vertical Gene Transfer
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Passing on of DNA between Parent and daughter cells (reproduction)
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Horizontal Gene Transfer
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Transfer of genes between cells of same generation
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Transformation
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genes transferre from one bacterium to another as "naked" DNA in solution
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What competent mechanism allows cells to pick up "naked" DNA in transformation?
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Change of a cell wall due to environmental conditions and addition of receptors for DNA
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Artificial Transformation
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Electroporation
Allows the uptake of double stranded DNA fragments |
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Griffith's experiment tested what bacteria with what animal
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Steptococcus
Mice |
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What 2 strands of streptococcus were use in Griffith's experiments?
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R cells (non-encapsulated)
S cells (encapsulated) |
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When the heat killed encapsulated cells and regular un-encapsulated cells were inserted into an animal, what happened? Why?
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Mouse died.
S strand bacteria were produced due to the R strands acquiring the DNA to become encapsulated |
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Transduction
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Transport of DNA from one bacterium to another bacterium by a virus
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Generalized Transduction
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Randomly, bacterial DNA will be inserted into a phage and transported to a new bacterium and therefore obtaining new DNA
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Specialized Transduction
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Gal-gene
Phage obtains a galactose positive gene (able to catabolize galactose) and transports it to a galactose negative bacterium, therefore making it able to metabolize galactose. |
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When does each form of transduction typically occur?
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Generalized: Lytic cycle
Specialized: Lysogenic cycle |
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Conjugation
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Direct transfer of DNA from bacterial donor cell to recipient
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What mediates conjugation and how does it occur?
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Plasmid.
Cell to cell contact in gram negative cells. Transfers a plasmid from one cell to the next through horizontal transfer. |
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What is required in order for conjugation to occur?
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Cell to cell contact
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How does Hfr donation occur?
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F plasmid is taken up by DNA of host
Host cell connects to F- cell In the middle of the F plasmid, the DNA is donated to the new cell stopping in the middle of DNA chromosomes As the new F- cell did not receive the whole F plasmid, the host is still F-; but the new host cell has received chromosomes from the old Host cell and may now integrate and use those chromosomes during reproduction. |
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R plasmids
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resistant plasmids
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F plasmids
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Fertility plasmids
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Nonessential functions on plasmids are deleted how?
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spontaneously
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What are Transposons?
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Segments of DNA that can move from one region of DNA to another
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What do transposons carry?
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Other genes (resistance, etc)
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What enzyme cuts and reseals DNA?
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transposase
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Why are transposons useful
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Allows DNA sequence (resistance) to move between a chromosome and plasmid and therefore be transferred to other bacterium.
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What are mutations?
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change in a base sequence of DNA
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How may mutations affect a cell? (3 ways- general)
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Neutral, beneficial, harmful
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Base Substitution
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switch between nucleotides (same # of nucleotides as b4)
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When do base substitutions occur?
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During DNA synthesis
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What are the 4 types of base substitutions?
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Point mutations
Missense mutation Nonsense mutation Silent mutation |
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What are the 2 MAIN types of substitutions?
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Base substitutions
Addition/deletion mutations |
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Addition/deletion mutations
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insertion/deletion of nucleotide pairs
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What do addition/deletion mutations result in?
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Frameshift
difference in nucleotides than before |
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How does an addition/deletion mutation vary from a base substitution mutation in relevance to nucleotides?
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Addition/deletion --> change in number of nucleotides
Base sub --> no change in number of nucleotides |
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What are the risks of addition/deletion mutations?
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almost always dangerous and make protein non-functional
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What are the 2 causes of mutations?
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Spontaneous
Induced |
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When do spontaneous mutations occur?
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In the natural environment
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Why do spontaneous mutations rarely occur?
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Repair rate is high in organisms
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When do induced mutations occur?
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Caused by mutagens (chemicals and radiation)
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What are two types of mutagens?
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Chemicals
Radiation |
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What increase in likelihood of a mutation occurs due to induced mutations?
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1/million (spontaneous) --> 1/1000 (induced)
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What are two types of chemical mutagens that occur?
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Base analog pairing
Intercalating agents |
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Base analogs
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chemicals that are structurally similar to nitrogenous bases but have slightly altered base pairing properties
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What is an example of base analog mutation?
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5-Bromouracil nucleoside (Br instead CH3) inplace of Thymine nucleoside
Binds with guanine instead of A (adenosine?) |
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What are three examples of intercalating agents?
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Acridine (dye used as mutagen in genetic research)
Benzopyrine (soot) Ethidium bromide (used in labs to stain DNA) |
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Intercalating Agents
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Molecules that insert themselves between adjacent bases therefore creating a bulge and skipping over the nucleotides that are on both sides of the bulge
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What two types of radiation create mutations?
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UV light
Xrays |
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What is considered ionizing radiation?
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Xrays
Gamma rays |
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What does ionizing radiation do?
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Create alterations in DNA and breaks between strands
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What is an example of non-ionizing radiation?
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UV rays
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What do UV rays cause?
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Thymine dimers to bond together, preventing the replication of the DNA strand
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