Biology Chapter 13

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How many DNA molecules would there be after four rounds of PCR if the initial reaction mixture contained two molecules?

cytosine, uracil, thymine

Which of these is (are) pyrimidines? Select all that apply.

DNA is usually double-stranded, whereas RNA is usually single-stranded.

Which of these is a difference between a DNA and an RNA molecule?

The crime scene sample contains DNA fragments from both the victim and Suspect 1

Why is Suspect 1 considered more likely to have committed the crime than Suspect 2?

DNA polymerase can assemble DNA only in the 5' to 3' direction

Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?

Primase

creates short RNA primers, initiating DNA synthesis on both template strands.

phosphate groups

A strand of DNA consists of a sequence of covalently linked DNA nucleotides. Match the terms to the correct description. DNA possesses many negative charges because of the presence of _____________________ which help form the backbone of each DNA strand.

each new DNA double helix consists of one old DNA strand and one new DNA strand

After DNA replication is completed ...........

labeled DNA...DNA

After allowing phages grown with bacteria in a medium that contained 32P and 35S, Hershey and Chase used a centrifuge to separate the phage ghosts from the infected cell. They then examined the infected cells and found that they contained _____, which demonstrated that _____ is the phage's genetic material.

template

An old DNA strand is used as a ____________ for the assembly of a new DNA strand.

cuts, swivels, and rejoins DNA strands ahead of the replication fork.

Correctly match the proteins with their functions in DNA Replication. 1. Topoisomerase

lagging strand

DNA ligase joins Okazaki fragments by forming phosphodiester bonds between them, thus completing DNA replication.

deoxyribose sugar

Distinguishes DNA from RNA and helps form the backbone of each DNA strand

extension

During which step in the PCR cycle are nucleotides used?

Annealing

During which step in the PCR cycle do primers form bonds with a single-stranded template?

nitrogenous bases

Examples include Adenine and Thymine, which pair with each other in the double helix

thymine and cytosine

Fill in the blanks with the correct term. Spelling counts. In a DNA double helix an adenine of one strand always pairs with a(n) ______ of the complementary strand, and a guanine of one strand always pairs with a(n) _______ of the complementary strand.

a bacteriophage or phage

Hershey and Chase did a series of classic experiments demonstrating that DNA is the genetic material and they used an organism like that shown above. What does this image represent?

proteins

Hershey and Chase used 35S to radioactively label the the T2 phage's _____________.

negative...positive

In gel electrophoresis DNA molecules migrate from _____ to _____ ends of the gel.

green, yellow, orange, red

In the accompanying image, a nucleotide is indicated by

ligase

Short segments of newly synthesized DNA are joined into a continuous strand by _____.

replication forks and replication bubbles

The action of helicase creates _____.

hydrogen bonds

The complementary DNA strands of a double helix are held together by ______________________ between their nitrogenous bases.

helicase

The first step in the replication of DNA is catalyzed by _____.

DNA

The radioactive isotope 32P labels the T2 phage's _________.

-ACGT

The sticky end of the DNA restriction fragment shown here will pair with a DNA restriction fragment with the sticky end _____.

RNA primer complementary to a preexisting DNA strand

The synthesis of a new strand begins with the synthesis of a(n) _____.

sticky ends

The unpaired nucleotides produced by the action of restriction enzymes are referred to as ________________.

nucleotide

This is an image of a(n) _____.

true

True or false? The Taq enzyme is a type of DNA polymerase that allows researchers to separate the DNA strands during the annealing step of the PCR cycle without destroying the polymerase.

A method to amplify a fragment of DNA.

What is the polymerase chain reaction (PCR)?

B, C

Which of the DNA fragments is common to both the victim and Suspect 1? Which of the DNA fragments is common to both the victim and Suspect 2?

Single-strand binding proteins

bind to the single strands of DNA, preventing them from re-forming hydrogen bonds with each other and allowing synthesis to occur on both strands.

Helicase

breaks the hydrogen bonds between the parental DNA strands and unwinds the double helix.

DNA polymerase I

removes the RNA primers and replaces them with DNA nucleotides.

DNA polymerase III

synthesizes the new strands, but it requires an existing 3′ hydroxyl (—OH) group to add nucleotides.