Exam 10: DNA Replication and Recombination

In general, DNA replicates semiconservatively and bidirectionally.

DNA replicates conservatively, which means that one of the two daughter double helices is "old" and the other is "new."

Below is a diagram of DNA replication as currently believed to occur in E. coli. Arrows start from numbers and end at specific points. Answer the questions relating to the locations specified by the numbers. 1() Which end (5' or 3') of the molecule is here? 2() Which enzyme is probably functioning here to deal with supercoils in the DNA? 3() Which enzyme is probably functioning here to unwind the DNA? 4() Which nucleic acid is probably depicted here? 5() What are these short DNA fragments usually called? 6() Which enzyme probably functions here to couple these two newly synthesized fragments of DNA? 7() Is this strand the leading or lagging strand? 8() Which end (5' or 3') of the molecule is here?

Assume that you are microscopically examining mitotic metaphase cells of an organism with a 2n chromosome number of 4 (one pair metacentric and one pair telocentric). Assume also that the cell passed through one S phase labeling (innermost phosphate of dTTP radioactive) just prior to the period of observation. Assuming that the circle below represents a cell, draw its chromosomes and the autoradiographic pattern you would expect to see.

What is the name of the replication unit in prokaryotes, and how does it differ in eukaryotes?

As unwinding of the helix occurs during DNA replication, tension is created ahead of the replication fork. Describe the nature of this tension and state the manner in which it is resolved.

During DNA replication, what is the function of RNA primase?

Briefly describe what is meant by the term autoradiography and identify a classic experiment that used autoradiography to determine the replicative nature of DNA in eukaryotes.

Which cluster of terms accurately reflects the nature of DNA replication in prokaryotes?

Structures located at the ends of eukaryotic chromosomes are called A) recessive inversions B) centromeres C) telomerases D) telomeres E) permissive mutations

The discontinuous aspect of replication of DNA in vivo is caused by

Chromatin assembly factors (CAFs) move along with the replication fork and assemble new nucleosomes.

Which terms accurately reflect the nature of replication of the chromosome in E. coli?

Compare the rate of DNA replication in prokaryotes and eukaryotes.

Bacteria are dependent on telomerase to complete synthesis of their chromosome ends.

DNA polymerase I is thought to add nucleotides _.

The complex of proteins that is involved in the replication of DNA is called a(n) ________.

What three possible models were suggested to originally describe the nature of DNA replication?

The Meselson and Stahl experiment provided conclusive evidence for the semiconservative replication of DNA in E. coli. What pattern of bands would occur in a CsCl gradient for conservative replication?

Which protein is responsible for the initial step in unwinding the DNA helix during replication of the bacterial chromosome?