biotechnology 30

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What is the purpose of supplementing the medium with 1-2% FCS if CHO cells are not doubling every 14-17 hours?

To enhance cell growth and division

Which element in the CMV vectors is responsible for replication in bacterial cells?

β-lactamase gene

What does the SV40 replication origin contribute to in SV40 replication permissive cells?

Enhancement of DNA replication

Which component directs the secretion of fusion proteins into the culture medium for purification?

<p>pre-pro-trypsin leader (PPT) sequence</p> Signup and view all the answers

What is the function of the hCMV promoter regulatory region in the mammalian expression system?

<p>Drives constitutive protein expression in mammalian cells</p> Signup and view all the answers

Why are CMV vectors favorable for expressing proteins in mammalian cells?

<p>They drive high levels of constitutive protein expression</p> Signup and view all the answers

In the context of heterologous protein expression, what is the function of the lacI binding site in the lac operon control elements?

<p>Inhibit T7 polymerase gene expression</p> Signup and view all the answers

What cellular component is crucial for the production of large, complex glycosylated polypeptides in mammalian cell expression systems?

<p>Proline</p> Signup and view all the answers

What modification is necessary to induce constitutive expression in an un-induced state using the lac operon control elements?

<p>Dissociation of lacI from the operator site</p> Signup and view all the answers

Which component is responsible for the stabilization of plasmids used in bacterial cells for heterologous protein expression?

<p>Lac Repressor (lacI)</p> Signup and view all the answers

What characteristic makes Chinese Hamster Overy (CHO) cells a preferred host cell for mammalian expression systems?

<p>They can be grown as a suspension in bioreactors</p> Signup and view all the answers

Which element of the lac operon control system directly affects the expression of the gene of interest in bacterial cells?

<p>Lac Repressor (lacI)</p> Signup and view all the answers

What is the primary control point of the CMV promoter?

<p>Enhancer Sequence</p> Signup and view all the answers

Which cell type shows a relatively high level of gene expression with the CMV promoter?

<p>CHO cells</p> Signup and view all the answers

What factor is crucial for the tight control of growth conditions when using the CMV enhancer sequence?

<p>Cellular Differentiation</p> Signup and view all the answers

Which transcription factor has a strong preference for the CMV enhancer sequence?

<p>CREB</p> Signup and view all the answers

What type of cells show low levels of gene expression with the CMV promoter?

<p>Stem cells</p> Signup and view all the answers

What is one disadvantage associated with the CMV enhancer sequence?

<p>Tight control of growth conditions required</p> Signup and view all the answers

What is one potential issue with using the lac operon control elements for heterologous protein expression?

<p>Leaky expression leading to plasmid instability</p> Signup and view all the answers

What is a characteristic of the T7 RNA Polymerase in the context of heterologous protein expression?

<p>Under full induction, it can result in the desired protein being over 50% of total cell protein</p> Signup and view all the answers

What is the main role of the lac repressor in the lac operon system?

<p>To bind to the operator and prevent transcription in the absence of inducers</p> Signup and view all the answers

Why is it important to remove the lacZYA genes when using the lac operon for heterologous protein expression?

<p>To prevent interference with translation of the gene of interest</p> Signup and view all the answers

Which statement accurately describes the role of Galactoside permease (lacY) in the lac operon system?

<p>Allows lactose uptake from media into bacterial cells</p> Signup and view all the answers

Why is a more tightly controlled promoter-expression-cassette needed when using the lac operon for heterologous protein expression?

<p>To prevent target gene overexpression and cellular damage</p> Signup and view all the answers

What is the main purpose of using different restriction enzymes to cut the donor and receiver DNA when cloning a gene?

<p>To prevent re-ligation of DNA fragments.</p> Signup and view all the answers

In the context of biotechnology, what is the role of T7 lysozyme in host cells like E. coli?

<p>Breaks down T7 Polymerase before induction.</p> Signup and view all the answers

Which type of promoter is commonly used in eukaryotic expression vectors for strong gene expression?

<p>CMV promoter</p> Signup and view all the answers

Why is orientation important when cloning genes using different restriction enzymes?

<p>To ensure correct expression of the gene.</p> Signup and view all the answers

What is one advantage of using mammalian cells as an expression host over bacterial or yeast cells?

<p>Easier post-transcriptional modifications.</p> Signup and view all the answers

Why is it necessary to choose the appropriate expression format at the beginning of cloning work in biotechnology?

<p>To ensure proper folding and modification of proteins.</p> Signup and view all the answers

What are the major disadvantages of using inducible expression systems in biotechnology?

<p>off-target effects and high basal expression level</p> Signup and view all the answers

Why are stable inducible mammalian expression vectors considered the 'holy grail' for industrial recombinant protein expression?

<p>They allow for humanized product from a stable cell line that can be controllably induced without inducing pleiotropic effects.</p> Signup and view all the answers

What is a concern associated with stable integration of genes into the genome in biotechnology?

<p>Down-regulation of the promoter through methylation/de-acetylation</p> Signup and view all the answers

What are some examples of inducible systems used in biotechnology and their respective inducers?

<p>Temperature shift (37-42°C), heavy metals (zinc, copper, cadmium), and steroids (glucocorticoids)</p> Signup and view all the answers

Why is serum batch-to-batch variability a concern in modulating enhancers in biotechnology?

<p>It can lead to unpredictable changes in enhancer activity and affect the overall expression of the target gene.</p> Signup and view all the answers

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