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Glycosidic bonds are between nucleic acid _____ and _____. | nitrogen, ribose |
Pyrimidines are always ____ conformation while purines are only sometimes. | anti |
T or F: Purines are more sensitive to acidic pH and hydrolysis than pyrimidines. | True |
The linkages in nucleotide polymers are _____. | phosphodiester linkages |
How is DNA stabilized? | hydrogen bonds and base pair stacking, charge-charge interactions |
T or F: The less GC pairs in a DNA molecules, the harder it is to melt. | False |
What is the importance of the major groove in B-DNA? | Many DNA binding proteins interact with bases here. |
Supercoiling | Segments of DNA are over or underwound. |
_____ is the most adundant type of RNA in the cell. | rRNA |
What doesmRNA last such a short time in the cell? | Single strands are degraded quickly; acts as a method to control protein production |
Spliceosome | Clips out introns and sews together exons |
rRNA has _____ and _____ properties. | catalytic, scaffholding |
Which type of RNA binds to mRNA for degradation? | siRNA (silencing) |
Which type of RNA is used to build unusual bases? | snRNA |
Explain why RNA is more easily degraded than DNA. | RNA is more chemically unstable - at a high pH, the phosphate bond in RNA is readily cleaved, forming a cyclic intermediate in which water can attack and degrade. DNA does not have a free hydroxyl, so this does not occur in DNA. |
Restriction endonucleoases | A mechanism used by bacteria which restrict incorporation of foreign DNA into the genome. |
Restriction endonucleases bind to ______ sequences. | palindromic |
How does the bacterial cell keep its own DNA from being degraded? | The DNA of the bacteria is methylated. |
How are restriction endonucleases used for human use? | Used to insert desired DNA sequences into bacterial plasmids. |
Intercalating agent | An aromatic compound which is inserted in between DNA bases, altering the structure. |
How can DNA be renatured? | By cooling denatured DNA or by re-association and zippering |
______ and ______ can remove or reintroduce supercoils into DNA | toposomerases, gyrases |
Name the steps in synthesizing polymers of DNA. | 1. dimethoxytrityl group blocks the 5'-OH of the first nucleotide
2. Coupling reaction adds the second base
3. Capped with acetic anhydride
4. Phosphate linkage added between N1 and N2 |