Bacterial DNA is primarily compacted by supercoiling and folding. Briefly describe each mechanism
What will be an ideal response?
Supercoiling refers to twisting of double-helical DNA such that the helix is twisted on itself. Supercoiling in the counterclockwise direction, opposite to the right-handed turn of DNA, is negative supercoiling, whereas twisting in the same direction as the helix is positive supercoiling. Negative supercoiling promotes unwinding of dsDNA, whereas positive supercoiling is thought to promote stability of dsDNA.
DNA is folded by small nucleoid-associated and structural maintenance of chromosomes (SMC) family proteins. Folding serves to condense the chromosome, which reduces the space within the cell that is taken up by the chromosome. Essentially, this compaction mechanism allows for a lot of DNA to be stored in a tiny cell!
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a. microtubules b. actin c. cyclins d. cyclin-dependent kinases e. histones
Cancers of nerve tissues in the brain are called ____
a. sarcomas b. leukemia c. gliomas d. lymphomas e. adenocarcinomas
In a series of cotransformation experiments, DNA fragments from x+y+z+ donor bacteria were used to transform xyz recipient bacteria
The following transformation phenotypes were observed in the recipient cells: xy+z xyz+ x+y+z x+yz+ What does this imply about the gene order of x, y, and z?
Which of the following substances can easily diffuse across the lipid bilayer of the cell membrane? (Circle ALL that apply.)