MMBio Chap 12 – Flashcards
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| insertion sequence |
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| 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) |
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| inverted repeat |
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| is a sequence of nucleotides that is the reversed complement of another sequence further downstream. |
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| mobile genetic element |
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| are a type of DNA that can move around within the genome- they include -transposons -retrotransposons -Plasmids -bacteriophage elements (Mu) -Group II introns |
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| replicative transposition |
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| 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 |
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| resolvase |
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| any group of enzymes that repress transposases |
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| transposable element |
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| the things that can move inside a cell |
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| transpoase |
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| 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. |
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| tranposition |
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| the process of transposons moving themselves to new positions within the genome. |
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| transposon |
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| are sequences of DNA that can move or transpose themselves to new positions within the genome of a single cell. |
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| What are the two ways transposons can move? |
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| 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.) |
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| How are transposons used in molecular genetics? |
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| 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. |
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| What are the simplest transposons? |
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| Insertion sequences |
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| Insertion sequences contain what (simplest transposons)? |
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| A transposase gene and inverted repeat sequences that include transposase binding sites and cleavage sites |
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| Transposons have ___ _______ ______elements flanking intervening DNA that contains additional genes. |
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| two insertion sequences |
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| In _____ and _____ transposition, the element is directly moved to a new location and a copy is left at the original location. |
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| cut and paste |
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| In ______ transposition, a copy of the element is left at the donor site. |
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| replicative |
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| ________ elements tend to target certain sequences and may target certain biological processes. |
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| Transposable elements |
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| _____ can be used for mutagenesis and offer the advantage that the insertions can be easily mapped genetically or by PCR. |
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| Transposons |
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| Transpsons have been engineered to enhance their utility as a genetic tool by incorporating ____ genes and reporter genes |
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| drug resistant |
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| What are transposons |
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| Elements of DNA which can move within the genome. |
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| Many transposons code for ____, an enzyme which allow them to cut and paste themselves. |
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| Transposase |
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| ______ worked in the area of chromosome biology using maize and suggested segments of the chromosome could jump to another location. |
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| Barbara McClintock |
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| How can cut and past transposons create multiple copies of themselves? |
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| 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 |
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| What is one way in which transposons may be harmful to an organism. |
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| transposons can insert themselves in the middle of genes and disable them |
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| The simplest mobile elements in bacteria are called |
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| insertion sequences |
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| Why might transposons be beneficial to the host organisms? |
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| They may pass on phenotypic characteristics that are preferred in natural selection, such as antibiotic resistance in bacteria. |
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| Transposons and other mobile elements are valuable to genetic researchers because |
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| They maybe be used to insert genes into a n organism and thus can serve as tools for gene therapy |
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| In conservative site-specific recombination, |
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| two DNA segments n homologous chromosomes exchange places at a specific recognition site. |
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| 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 |
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| Transposase |
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| True or False. coordinated breakage and joining events occur during transposition. |
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| true |
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| T or F- Transposons are found at various levels of complexity in bacteria |
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| True |
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| Transposases that use extensive DNA replication to leave one copy of the element behind in a process called |
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| replicative transposition |
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| True or False- Transposons in eukaryotes are mechanistically different from bacterial transposons |
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| False |
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| T or F- when transposons move to reproduce and to distribute to new hosts, the process of transposition inevitably jeopardizes the host organism |
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| Can be both but probably false |
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| T or F- transposons are known as selfish DNA because their only apparent purpose is to replicate themselves. |
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| True |
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| T or F- Transposons always require an RNA intermdiate |
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| False |
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| T or F- Ligase is required to seal the nicks caused by transposition |
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| true |
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| What DNA sequence feature is diagnostic for the presence of transposons and how is this feature produced? |
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| Short repeats on both ends of the strand |
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| The presence of mobile genetic elements can not easily be detected by |
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| gel filtration chromatography |
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| The general term for sequences that can change location within the genome is |
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| mobile genetic elements |
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| Bacterial elements that have inverted terminal repeats and do not contain coding sequences are called |
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| insertion sequences |
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| SINEs are |
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| (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 |
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| What are retrotransposons? |
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| are genetic elements that can amplify themselves in a genome and are ubiquitous components of the DNA of many eukaryotic organisms. |
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| What is the general process of retrotransposons? |
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| 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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