bio dna

Which element of the nucleotide sugar is attached to which carbon atom?

1' - nitrogenous base 3' - OH group 5' - phosphate group

Describe the density of bacterial DNA after the second round of replication in MS experiments

2 density classes- intermediate and 14N

What is the partial opening of a DNA helix to form two single strands?

A replication fork

In a DNA double helix, where do two hydrogen bonds form? Three?

Between A and T, C and G

Which DNA enzyme covalently links nucleotides?

Polymerase

Which enzymes did A & M & M use in their experiments? What did they remove?

RNA digesting, protein digesting, DNA digesting. They removed protein.

Which types of Strep p did Griffith inject into mice?

Smooth, rough, heat killed, live

What is the coiling of DNA strands that leads to torsional strain?

Supercoiling

What are different forms of bases called?

Tautomers

Which enzyme contains a small internal piece of RNA used to extend the end of a linear DNA molecule?

Telomerase

_________ are short protective repeats of DNA on the ends of eukaryotic chromosomes which are generated by the enzyme __________.

Telomeres, telomerase

What do the problems in replicating the ends of the chromosomes deal with?

The need for a primer and the directionality of polymerases

Why do eukaryotic cells have multiple origins of replication?

To ensure timely replication of multiple relatively large chromosomes.

Which enzyme relieves coiling in DNA strands ahead of the replication fork?

Topoisomerase

What is involved in the unwinding of DNA?

Topoisomerase, helicase, single-strand binding proteins

What does gyrase do?

Unlinks two daughter DNA molecules

M & S used two isotopes of ________ in their DNA replication.

nitrogen

The DNA controlled by an origin is called a ________.

replicon

The _________ is a macromolecular assembly of enzymes involved in DNA replication.

replisome

DNA replication that leads to the production of double helices with one parental strand and one newly synthesized strand is consistent with...

semiconservative replication

Short, repeated sequences of DNA are characteristic of...

telomeres.

During DNA replication, new strands are synthesized from ________ strands on the original molecule.

template

DNA replication in E. coli ends at a site called the...

terminus.

Phages are a type of _____ that infect _________ cells, causing them to lyse.

virus, bacterial

The density of bacterial DNA following the first round of DNA replication in the MS experiment can be best described as...

an intermediate between 14 N and 15 N.

The main eukaryotic DNA polymerases that extend DNA are...

delta and epsilon

Steps of semiconservative DNA replication

1. Double helix separates 2. Nucleotides hydrogen bond to template strand 3. Covalent bonds form between sugars and phosphates 4. Daughter strands are produced for each template strand

Steps of Hershey and Chase's experiment to demonstrate that DNA was genetic material of T2

1. Labeled substances were added to E. coli 2. Blender was used to shear off phage coats 3. Sample was centrifuged 4. Radioactivity was measured

Steps of lagging strand synthesis

1. Synthesize primers with primase 2. Synthesize DNA 3. Replace RNA primers with DNA 4. Stitch fragments together

What are telomeres related to?

Cellular aging

Differences in prokaryotic and eukaryotic replication

Complexity of enzymology, number of origins of replication, structure of chromosome

Which model for DNA replication suggests both strands of the double helix remain intact and the new DNA double helix consists of two new DNA strands?

Conservative

Which enzyme seals the nicks to join Okazaki fragments?

DNA ligase

As one strand is synthesized continuously, replication is what on the other strand?

Discontinuous

What cuts DNA internally and what cuts at the end of DNA?

Endonuclease, exonuclease.

What do components of a virus include?

Genetic material and protein coats

Contributions of Hershey and Chase, Griffith, Avery and MacLeod and McCarty, and Meselson and Stahl

H & C determined DNA was genetic material by studying T2 bacteriophage, Griffith showed that there was a transforming principle that could be passed between bacterial cells, A & M & M determined DNA was genetic material by studying transforming principle, M & S determined a method for replication of genetic material.

Which enzyme uses ATP to unwind the DNA template?

Helicase

Functions of DNA replication enzymes

Helicase causes DNA strand separation at origin of replication, topoisomerase relieves coiling in DNA strands ahead of replication fork, primase makes a 10-12 complimentary primer to the DNA, polymerase attaches a nucleotide to the 3' end of the DNA strand.

Who's experiments showed that DNA was the genetic material?

Hershey and Chase

Who performed microbiological experiments that helped identify genetic material?

Hershey and Chase, Avery and MacLeod and McCarty, and Griffith

Functions of each DNA polymerase

I acts on the lagging strand to remove primers and replace them with DNA, II is not involved in replication but used for DNA repair, III is the main replication enzyme

Leading strand synthesis in E. coli occurs via the action of which DNA polymerase?

III

An Okazaki fragment is a short fragment of DNA created on what strand of DNA?

Lagging

What complicates DNA replication in eukaryotic cells?

Linear chromosomes

What cells contain high levels of telomerase despite their age?

Lymphocytes

What does DNA primase do?

Makes a primer 10-20 nucleotides in length and makes a primer of RNA complimentary to DNA

Who performed the experiments used to distinguish between the three potential DNA replication mechanisms?

Meselson and Stahl

Do RNA polymers require primers to begin synthesis?

No

Which 3 items are required for DNA replication?

Nucleotides, template, polymerase

What did Wilkins do? Franklin?

Wilkins performs uniformly oriented DNA fibers, Franklin determined x-ray diffraction patterns of DNA structure