Briefly explain how Ti plasmids induce crown gall (tumor) growth in plants parasitized by Agrobacterium tumefaciens, highlighting the specific properties that make this plasmid so useful in biotechnology
What will be an ideal response?
Ti plasmids are so named because they carry tumor-inducing genes. The plasmid enters (transforms) a host cell, and a 30-kb region called transforming- or T-DNA integrates by recombination with the host DNA. The T-DNA region carries genes for plant cell transformation, creating the crown gall where Agrobacterium flourishes under natural conditions. The T-DNA region necessary for successful excision, transfer, and integration consists of only its 25-bp terminal repeats, which means the rest of the DNA in this region can be replaced with DNA of interest and the whole plasmid engineered to vector this DNA.
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One of the reasons that pufferfish are a good species to compare to humans is because
A. it is so easy to hybridize the two and investigate the consequences. B. they are so distantly related that it's easy to distinguish mutually conserved sequences. C. the introns are often identical. D. of the rapid response time in pufferfish to artificial selection. E. they have been separated for so many millions of years and yet the gene sequence is almost identical.
Discuss some of the possible ways in which nonsense mutations can potentially be suppressed in a cell
What will be an ideal response?
Chlamydia can prevent the formation of phagolysosomes and therefore can
a. avoid being phagocytized. b. avoid destruction by complement. c. prevent adherence. d. avoid being digested. e. none of the above
To help avoid a waterborne infection, what would you recommend to a traveler going to South America?
a. vaccination b. bring chlorine with you c. only consume/use bottled water d. only consume canned foods and beverages