Biology 300 Chapter 7

Topoisomerase function?

Binds ahead of the replication fork and breaks covalent bonds in DNA backbone.

Helicase function?

Binds at the replication fork and breaks H-bonds between bases.

What can be inferred from the Beadle ad Tatum experiments?

For a mutation resulting in the production of a defective enzyme involved in a biosynthetic pathway, the compound preceding the corresponding step will accumulate.

In a DNA nucleotide, to which carbon on deoxyribose is the nitrogenous base attached? A) 1′ B) 2′ C) 3′ D) 5′

1'

Adenine complementarily binds with thymine and forms ___ ___ bonds.

2 hydrogen.

Guanine complementarily binds with cytosine and forms ____ ____ bonds.

3 hydrogen.

Deoxyribonucleotides bind together to form polynucleotides. This bond occurs between the phosphate group of one nucleotide and the C ___' position of a ____ of another nucleotide. The type of bond formed in this interaction is called a _____ bond.

3, sugar, phosphodiester.

A standard PCR cycle includes three steps: denaturation (95°C), annealing (55°C), and elongation (65°C). Drag each ingredients of a PCR reaction into the bin labeled with the step in the PCR cycle in which it is first used. Denaturation (95C) uses what? Annealing? Elongation?

Denaturation: DNA Template Annealing: Primers Elongation: Taq polymerase and dNTPs During the denaturation step of a PCR cycle, the template DNA strands are separated or denatured. Next, during the annealing step, the single-stranded primers hybridize to the denatured DNA template. Finally, during the elongation step, Taq polymerase synthesizes a new strand of DNA from the DNA template in a 5' to 3' direction, starting at the 3' end of the primers, by adding dNTPs to the 3' end of the new DNA strand.

In the first round of screening, Beadle and Tatum plated spores on minimal medium. The purpose of this screen was to ____.

Determine whether any auxotrophic mutants had been generated.

Statements about the basic structural feature of DNA.

In a DNA macromolecule, the two strands are complementary and antiparallel. The twisting of the DNA double helix is attributed to the tight packing of DNA bases and base-stacking.

What would results from a third round of replication using the methods of Meselson and Stahl?

One light band and one intermediate band.

Single-strand binding protein function?

Prevents H-bonds between bases and binds after the replication fork.

The results of the Meselson-Stahl experiments relied on all of the following except____.

The fact that DNA is the genetic material

What is a true statement about DNA?

The nucleic acid strands in a DNA molecule are oriented antiparallel to each other, meaning they run in opposite directions.

What determines which DNA strand is the template strand, and therefore in which direction RNA polymerase II moves along the DNA?

The specific sequence of bases along the DNA strands.

True/False. Guanine and adenine are purines found in DNA.

True.

The Beadle and Tatum experiments were based on all of the following assumptions except that ____.

Two strains of auxotrophic Neurospora that grow on minimal medium supplemented with biotin have mutations in the same gene.

After observing the results of one round of replication, the scientists obtained results from a second round. The purpose of one additional round of replication was to ____.

distinguish betweenness-conservative and dispersive replication.

The nitrogenous bases of each nucleotide project ____ the double helix. Therefrom complementary base pairs through the formation of _____ bonds with bases on the opposite DNA strand.

into, hydrogen.

Adenine, guanine, cytosine, and thymine are _____.

nitrogenous bases.

Dna is composed of 4 different types of ___. Each one is made up of a pentose ___, a ____ group, and one of 4 _____.

nucleotides, sugar, phosphate, nitrogenous bases.

Adenine and guanine, which have nine-member double-ring, are called ___.

purines

Cytosine and thymine, which have a six-member single-ring, are called ____.

pyrimidines.