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MMBio Chap 12
MMBio Chapter 12 EVANS
48
Microbiology
Undergraduate 1
03/14/2011

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Term
Alu element
Definition
is a short stretch of DNA originally characterized by the action of the Alu restriction endonuclease. These are the most abundant mobile elements in the human genome. Is a retrotransposon
Term
conservative site specific recombination
Definition
is a type of genetic recombination in which DNA strand exchange takes place between segments possessing only a limited degree of sequence homology.
Term
cut and paste transposition
Definition
Theses transpositions are catalyzed by various types of transposase enzymes. The enzyme makes a staggered cut, producing sticky ends, cuts out the transposon, and ligates it into the target site. DNA poly. fills in the resulting gaps, DNA ligase seals the nick
Term
excisionase (Xis)
Definition
manages excision and insertion of phage genome into the hosts genome.
Term
insertion sequence
Definition
is a short DNA sequence that acts as a simple transposable element. They have two characteristics- they are small (700-2500 bp) and only code for proteins implicated in the transposition activity (means they are different from transposons which have accessory genes)
Term
inverted repeat
Definition
is a sequence of nucleotides that is the reversed complement of another sequence further downstream.
Term
mobile genetic element
Definition
are a type of DNA that can move around within the genome- they include
-transposons
-retrotransposons
-Plasmids
-bacteriophage elements (Mu)
-Group II introns
Term
replicative transposition
Definition
is a mechanism of transposition in molecular biology in which the transposable element is duplicated during the reaction so that the transposing entity is a copy of the original element
Term
resolvase
Definition
any group of enzymes that repress transposases
Term
transposable element
Definition
the things that can move inside a cell
Term
transpoase
Definition
is an enzyme that binds to the ends of a transposon and catalyzes the movement of the transposon to another part of the genome by a cut and paste mechanism or a replicative transposition mechanism.
Term
tranposition
Definition
the process of transposons moving themselves to new positions within the genome.
Term
transposon
Definition
are sequences of DNA that can move or transpose themselves to new positions within the genome of a single cell.
Term
What are the two ways transposons can move?
Definition
Cut and past transposition (in which the element is directly moved to a new location.) or by replicative transposition (copy and paste- a copy of the transposon is left at the donor site.)
Term
How are transposons used in molecular genetics?
Definition
They allow the position of the insertion to be determined genetically or by PCR. They can also be engineered in a number of ways to make them a powerful tool for mutagenesis and for studying gene regulation.
Term
What are the simplest transposons?
Definition
Insertion sequences
Term
Insertion sequences contain what (simplest transposons)?
Definition
A transposase gene and inverted repeat sequences that include transposase binding sites and cleavage sites
Term
Transposons have ___ _______ ______elements flanking intervening DNA that contains additional genes.
Definition
two insertion sequences
Term
In _____ and _____ transposition, the element is directly moved to a new location and a copy is left at the original location.
Definition
cut and paste
Term
In ______ transposition, a copy of the element is left at the donor site.
Definition
replicative
Term
________ elements tend to target certain sequences and may target certain biological processes.
Definition
Transposable elements
Term
_____ can be used for mutagenesis and offer the advantage that the insertions can be easily mapped genetically or by PCR.
Definition
Transposons
Term
Transpsons have been engineered to enhance their utility as a genetic tool by incorporating ____ genes and reporter genes
Definition
drug resistant
Term
What are transposons
Definition
Elements of DNA which can move within the genome.
Term
Many transposons code for ____, an enzyme which allow them to cut and paste themselves.
Definition
Transposase
Term
______ worked in the area of chromosome biology using maize and suggested segments of the chromosome could jump to another location.
Definition
Barbara McClintock
Term
How can cut and past transposons create multiple copies of themselves?
Definition
During DNA replication, the transposon removes itself from a chromosome that has already been replicated and inserts into a chromosome that has not yet been replicated
Term
What is one way in which transposons may be harmful to an organism.
Definition
transposons can insert themselves in the middle of genes and disable them
Term
The simplest mobile elements in bacteria are called
Definition
insertion sequences
Term
Why might transposons be beneficial to the host organisms?
Definition
They may pass on phenotypic characteristics that are preferred in natural selection, such as antibiotic resistance in bacteria.
Term
Transposons and other mobile elements are valuable to genetic researchers because
Definition
They maybe be used to insert genes into a n organism and thus can serve as tools for gene therapy
Term
In conservative site-specific recombination,
Definition
two DNA segments n homologous chromosomes exchange places at a specific recognition site.
Term
Transposition is a process in which a discrete DNA entity can move between DNA sites that lack homology using a self encoded protein called a
Definition
Transposase
Term
True or False. coordinated breakage and joining events occur during transposition.
Definition
true
Term
T or F- Transposons are found at various levels of complexity in bacteria
Definition
True
Term
Transposases that use extensive DNA replication to leave one copy of the element behind in a process called
Definition
replicative transposition
Term
True or False- Transposons in eukaryotes are mechanistically different from bacterial transposons
Definition
False
Term
T or F- when transposons move to reproduce and to distribute to new hosts, the process of transposition inevitably jeopardizes the host organism
Definition
Can be both but probably false
Term
T or F- transposons are known as selfish DNA because their only apparent purpose is to replicate themselves.
Definition
True
Term
T or F- Transposons always require an RNA intermdiate
Definition
False
Term
T or F- Ligase is required to seal the nicks caused by transposition
Definition
true
Term
What DNA sequence feature is diagnostic for the presence of transposons and how is this feature produced?
Definition
Short repeats on both ends of the strand
Term
The presence of mobile genetic elements can not easily be detected by
Definition
gel filtration chromatography
Term
The general term for sequences that can change location within the genome is
Definition
mobile genetic elements
Term
Bacterial elements that have inverted terminal repeats and do not contain coding sequences are called
Definition
insertion sequences
Term
SINEs are
Definition
(Short interspersed elements)-short DNA sequences that represent reverse transcribed RNA molecules originally transcribed by RNA polymerase III- rely on other mobile elements for transposition
Term
What are retrotransposons?
Definition
are genetic elements that can amplify themselves in a genome and are ubiquitous components of the DNA of many eukaryotic organisms.
Term
What is the general process of retrotransposons?
Definition
They copy themselves in two stages. First from DNA to RNA by transcription, then from RNA back to DNA by reverse transcription. The DNA copy is then inserted into the genome in a new position.
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