Ch. 1 Study Questions Flashcards
What is the function of DNA?
To store the genetic material
How do the structures of purines and pyrimidines differ?
Purines have a double ring structure and pyrimidines have a single ring structure.
Which of the ribose carbons participate in the phosphodiester bond?
The 5’ ribose C carries the P group that forms a phosphodiester bond with the OH group on the 3’ ribose C
Which of the ribose carbons carries the nitrogen base?
The 1’ C of the ribose carries the nitrogen base
Why does DNA polymerase require primase activity?
DNA polymerase cannot begin synthesis without a 3’ OH group
What is the covalent bond between nucleotides catalyzed by DNA polymerase?
Phosphodiester bond
Is DNA replication conservative or semi-conservative?
Semi-conservative
What is the lagging strand in DNA synthesis?
The lagging strand is the 5’ to 3’ strand with respect to the direction of synthesis
Requires the replication assembly to jump ahead and read 3’ to 5’ back toward the moving replication fork
The leading strand is read continuously 3’ to 5’
Synthesis proceeds 5’ to 3’ on both strands
Short pieces of DNA involved in DNA synthesis in replicating cells are called ________ fragments.
Okazaki
Name the function of the following enzymes: polymerase helicase primase exonuclease endonuclease
Polymerase - adds nucleotides; catalyzes the formation of phosphodiester bonds between nucleotides
Helicase - unwinds the double helix by breaking and reattaching phosphodiester bonds
Primase - an RNA polymerase that adds an RNA primer to start replication in the absence of the 3’ OH group on the lagging strand
Exonuclease - digests phosphodiester bonds from the ends of nucleic acid molecules
Endonuclease - breaks the phosphodiester bonds in nucleic acids within the polymer chain, rather than from the ends
Compare how DNA moves from cell to cell by:
Conjugation
Transduction
Transformation
Conjugation - physical contact
Transduction - viral or bacteriophage intermediate
Tranformation - no physical contact nor viral carriers
A plasmid that carries genes for its own transfer and propagation is called _______.
Self-transmissible
What enzymes can convert a supercoiled plasmid to a relaxed circle?
Helicases (topoisomerases) can digest the phosphodiester bond of one ds DNA, allowing the twisted strands to unwind
