Control of Gene Expression and Mutations (8.3 - 8.5) Flashcards
What is horizontal gene transfer?
Any transfer of DNA that results in organisms acquiring new genes that did not come from parent organisms
What is Conjugation? Is Conjugation direct or indirect? List an example of it.
Mode of genetic exchange in which a plasmid or other genetic material is transferred by a donor to a recipient cell via direct connection.
Direct ;
The F+ cell has a plasmid and builds a bridge connecting it to the F- cell. It then transfers its plasmid to the F- cell so that it become F+.
What type of plasmids can be transferred through conjugation?
Resistance (R) Plasmids
What is Transformation? Is it direct or indirect? List an example of it
Transformation is when chromosome fragments from a lysed cell are accepted by a COMPETENT cell. ; Indirect .
There is none, it requires no special appendages because its non-specific (meaning every bacterial cell does it differently)
What is Transduction? Is it direct or indirect? List an example.
Transduction is using viruses to move DNA (bacteriophages- viruses that enter bacteria) ; indirect
when a bacteriophage enters Cell A and replicates with part of the bacterias DNA then the cell lyses, releasing those phages which then inject their DNA into Cell B. Cell B survives because the virus is now inactive and just uses the DNA.
What are Transpoons and how do they move?
- Genes that can shift from one part of a genome to another or one cell to another.
- Can be transferred from a chromosome to a plasmid or vice versa
- some replicate themselves before jumping to the next location and some simply move
What are Transpoons involved in?
- Changes in traits such as colony morphology and pigmentation
- Replacement of damaged DNA
- Intermicrobial transfer of drug resistance ( in bacteria)
What is considered a mutation?
Any change in the nucleotide sequence in the genome.
What is spontaneous mutation?
A random change in the DNA arising from errors in replication
What is induced mutation?
Mutation due to physical or chemical agents that disrupt DNA (Radiation: UV light, x RAYS) and Chemicals like nitrous acid
What are the five categories of mutations?
Point Missense Nonsense Silent Frameshift
What is a point mutation?
An addition, deletion or substitution of a single base
What is a missense mutation?
Any change in the code that leads to the placement of a different amino acid
What is a nonsense mutation?
Changes a normal mutation into a stop codon.
What is a silent mutation?
Doesnt usually change the wobble, alters a base but does not change the amino acid, has no effect.
What is a back-mutation?
When a gene that has undergone mutation reverses back to its original base composition.
What is a frameshift mutation?
changes the reading Frame of mRNA because codons are red in sets of 3. usually results in a nonfunctional protein.
Explain UV/DNA photolyase reparation.
DNA photolyase repairs damage done by UV rays. because UV light damage is so common, bacteria created DNA photolyase
What is excision repair?
Enzymes break the bonds between bases and sugar-phosphate strand at the site of error, a different enzyme removes the defective base and DNA poly. 1 and ligase fill it.
What is the significance of Single nucleotide polymorphisms (SNPs) ?
Only a single nucleotide is altered and it is passed on genetically.
Identification is critical to medicine because its within a persons genetic makeup.
Ex: thrombophilla (a blood-clotting disorder)
