Studied by 4 people
what defines recombination
an event in which one bacterium donates DNA to another bacterium- type of genetic transfer
what is the end result of recombination
a new strain of DNA different from both the donor and the original strain
what are the extrachromosomal DNA in bacteria called
plasmids
what does it mean to be recombinant
be an organism who’s genes contain any genes originated from another organism
what is horizontal gene transfer
any transfer of DNA that results in organisms acquiring new genes that did not come directly from parent organisms
what is vertical gene transfer
acquiring genes from parent organisms during reproduction
what are plasmids
small, circular pieces of DNA that contain their own origin of replication
how do plasmids replicate
independently of the bacterial chromosome, due to containing their own origin of replication
besides plasmids, what else is prevalent in the transfer of genetic information between bacterial cells
chromosomal fragments
what is an importance difference between chromosomal fragments and plasmids in terms of how they replicate
fragments must integrate themselves into the bacterial chromosome in order to be replicated
whereas plasmids have its own mode of replication
what is required for conjugation
the attachment of two related species and the formation of a bridge that can transport DNA
what entails of transformation
the transfer of naked DNA, requires no special vehicle
what entails of transduction
the transfer of DNA from one bacterium to another via a bacterial virus
what mode(s) of horizontal gene transfer are direct
conjugation
what mode(s) of horizontal gene transfer are indirect
transformation
transduction
what denotes a gram-negatives cells role in conjugation
its fertility factor- called F factor. Either F+ (has the factor) or F- (lacks the factor)
what is the F+ gram-negative cells role in conjugation
to grow a sex pilus that attaches to the F- cell, pulling them closer together so DNA can be exchanged across this ‘bridge’
what is conjugation
the horizontal transfer of genetic information between two cells via a sex pilus
what happens in gram-positive cell conjugation
an opening between two adjacent cells is created and genetic information is replicated and passed across from one cell to the other
what does it mean to say that conjugation is a conservative process
the donor bacterium generally retains (converses) a copy of the genetic material being transferred
what are the two modes of conjugation for the conjugative plasmid of E. coli
Transfer of the F plasmid
Transfer of chromosomal DNA (also called high-frequency recombination [Hfr])
what happens in transfer of the F plasmid in conjugative plasmids (specially the E. coli species)
the F+ cell makes a copy of its F factor and transmits it to a recipient F- cell, the cell is thereby changed into a F+ cell and is capable of initiating conjugation with other F- cells
what happens in transfer of chromosomal DNA [Hfr] in conjugative plasmids (specially the E. coli species)
the plasmid becomes integrated into the F+ donor chromosome, which becomes replicated, then begins to transfer to the recipient cell.
Meaning, some of the chromosomal genes get transferred to the recipient (plasmid genes may or may not be transferred)
what type of conjugation is this
F factor transfer
what type of conjugation is this
Hfr transfer
whats the importance of conjugation in a biomedical since
special (R) plasmids or R factors, that have genes for resisting antibiotics and other drugs are commonly shared among bacteria through conjugation
what is transformation
the nonspecific acceptance of small DNA fragments from the surrounding environment by a bacterial cell
what is transformation facilitated by
special DNA-binding proteins on the cell wall that capture DNA from the surrounding medium
what does it mean to be ‘competent’ in terms of horizontal gene transfer
that a cell is capable of accepting free DNA from their environment
what happens after DNA is taken in during transformation
the new DNA is transported into the cytoplasm where some of it is inserted into the bacterial chromosome
due to transformation requiring to special accessories how can this process be utilized in recombinant DNA technology
foreign genes from a completely unrelated organism can be inserted into a plasmid and introduced to a competent cell
adding foreign genes to a completely unrelated organism during recombinant DNA transformation technology is called what if it occurs in Eukaryotes
transfection
what does it mean to be a genetic vector- viruses can serve as these
it means to be entity that can bring foreign DNA into a cell
what is transduction
the process by which a bacteriophage serves as the carrier of DNA from a donor cell to a recipient cell
what are the two versions of transduction
Generalized
Specialized
what occurs in generalized transduction
random fragments of disintegrating host DNA are taken up by the phage during assembly. Meaning, virtually any gene from the bacterium can be transmitted through this means
what occurs in specialized transduction
a highly specific part of the host genome is regularly incorporated into the virus. This specifically is explained by the prior existence of a temperate prophage inserted in a fixed site on the bacterial chromosome. When activated, the prophage DNA separates from the bacterial chromosome, carrying a small segment of host genes with it
whats the biomedical importance of transduction in certain virulent strains of bacteria
these strains produce toxins with profound physiological effects. As it turns out this toxicity arises from the presence of bacteriophage genes that have been introduced during transduction.
what are transposons
‘jumping genes’ another means of genetic transfer that have the distinction of shifting from one part of the genome
what is the overall effect of transposons
they can be beneficial or adverse
what are some examples of effects of transposons
changes in traits such as colony morphology, pigmentation, and antigenic characteristics
replacement of damaged DNA
the intermicrobial transfer of drug resistance (in bacteria)
what does it mean for a bacteria to be a ‘wild type’
a microorganism that exhibits a natural, nonmutated characteristic
what does it mean for a bacteria to be a ‘mutant strain’
if the microorganism bears a mutation
what is a spontaneous mutation
a random change in the DNA arising from errors in replication that occur randomly
what are induced mutations
mutations that result from exposure to mutagens
what are mutagens
physical or chemical agents that interact with DNA in a disruptive manner.
Ex: radiation (UV, X rays), certain chemicals
what is a point mutation
the addition, deletion, or substitution of single bases
what is a missense mutation
any change in the code that leads to placement of a different amino acid
what are some of the results of a missense mutation
create a faulty, nonfunctional (or less functional protein)
produce a protein that functions in a different manner
cause no significant alteration in protein function
what is a nonsense mutation
changes a normal codon to a stop codon
what is a silent mutation
a mutation that alters a base but does not change the amino acid and thus has no effect
what is a back mutation
when a gene that has undergone mutation reserves back (through mutation) to its original base composition
what is a frameshift mutation
a mutation when one or more bases are inserted into or deleted from a newly synthesized DNA strand
what is a single nucleotide polymorphism (SNP)
a mutation in which only a single nucleotide is altered
how are most DNA mutations repaired
through the use of enzymatic systems specialized for finding and fixing defects
what is the only thing that can restored DNA that has been damaged by ultraviolet radiation
photoactivation- or light repair
what is excision repair
refers to a series of enzymes that can cut out and remove the incorrect bases and add the correct ones
what are restriction endonucleases
they come from bacterial cells. And function to recognize foreign DNA and are capable of breaking the phosphodiester bonds between adjacent nucleotides on both strands of DNA, leading to a break in the DNA strand
how are restriction endonucleases used in a lab setting
the enzymes can be used be cleave DAN at desired sites and are necessary for the techniques of recombinant DNA technology
what are palindromes
sequences of DNA that are identical when read from the 5’ to 3’ direction on one strand and the 5’ to 3’ direction on the other strand
what does heating a DNA strand do
causes the two strands to separate
what does cooling a DNA strand do
causes the two strands to rejoin
are endonucleases usually named
by combining the first letter of the bacterial genus, the first two letters of the species, and the endonuclease number
what are restriction fragments
pieces of DNA produced by restriction endonucleases
what gives rise to restriction fragment length polymorphisms (RELPs)
differences in the cutting pattern of specific restriction endonucleases, resulting in restriction fragments of differing lengths
what is the function of ligase
to seal the sticky ends of DNA together by rejoining the phosphate-sugar bonds cut by endonucleases
what is the function of reverse transcriptase (RT)
converts RNA into DNA
what can complementary DNA (cDNA) be made from
messenger, transfer, ribosomal, and other forms of RNA
what is the importance of cRNA being made from various forms of RNA
it provides a means of synthesizing eukaryotic genes from mRNA transcripts
what is the role of primers (specifically in PCR)
they serve as landmarks to indicate where DNA amplification will begin
what are the 3 repetitive cycles of PCR
denaturation
priming
extension
what is DNA profiling
a pattern of restriction enzyme fragments that is unique for an individual organism
what is DNA sequencing
determining the exact order of nucleotides in a fragment of DNA. Most commonly done using the Sanger dideoxy sequencing method
what causes DNA fragments to move through gel electrophoresis
the phosphate groups in DNA give the entire molecule an overall negative charge, which causes the DNA to move toward the positive pole in the gel
what are sequence maps
a sequencing technique that give an exact order of bases in a plasmid, a chromosomes, or an entire genome
what are genomics
the systematic study of an organisms genes and their functions
what are proteomics
the study of an organisms complement of proteins and functions mediated by the proteins
what are metagenomics
the study of all the genomes in a particular ecological niche, as opposed to individual genomes from single species
what is metabolomics
the study of the complete complement of small chemicals present in a cell at any given time. Provides a snapshot of the physiological state of the cell and the end products of its metabolism
