bio101 14

How many hydrogen bonds are formed between adenine and thymine in the double DNA helix?

2

Which of these best describes the density of the bacterial DNA after the second round of replication in the Meselson-Stahl experiments?

2 density classes - one intermediate and one 14N

Guanine forms ________ hydrogen bonds with cytosine.

3

How many hydrogen bonds form between cytosine and guanine in the DNA double helix?

3

Which of these describes the expected experimental results after two rounds if the dispersive model for DNA replication is correct?

3/4 of DNA molecule would be light and 1/4 of DNA molecule would be heavy

Which of the following occurs during mismatch repair?

An incorrectly incorporated base is replaced with the correct one.

Why is the diameter of a DNA double helix 2 nm?

Because each base-pair contains one purine and one pyrimidine

The sequence of DNA bases is written in the _________' to_______ ' direction.

Blank 1: 5 or five Blank 2: 3 or three

The continuously synthesized DNA strand is called the_____ strand, while the discontinuously synthesized strand is called the_____ strand

Blank 1: leading Blank 2: lagging

In the Hershey Chase experiments, the isotope 35S was used to label_______ and the isotope 32P was used to label________

Blank 1: proteins, protein, or T2 coat proteins Blank 2: DNA

Which of the following facilitates the reversal of damage to our hereditary material before a permanent mutation can occur?

DNA repair systems

On which strand does the removal of the last primer leave a gap that cannot be primed at the ends of the chromosome.

Lagging

Which of these is not required for DNA replication?

Lipids

The experiments used to distinguish between the three potential DNA replication mechanisms were performed by

Meselson and Stahl.

The discovery of a substance called nuclein, later to be named nucleic acid, was accomplished by

Miescher.

Short fragments of DNA created on the lagging strand of DNA during replication are called

Okazaki fragments.

Adjacent nucleotides in the same DNA strand are held together by covalent bonds known as_______ bonds

Phosphodiester

When trying to discover the substance responsible for transformation, Avery, MacLeod and McCarty removed from their preparation and found that the transforming activity persisted.

Protein

Which of these is not involved in the unwinding of DNA during replication?

RNA polymerase (makes primers)

Chargaff's rule indicates that the amount of A in a sample is equal to the amount of________ and the amount of C in a sample is equal to the amount of______.

T:G

In the Meselson-Stahl experiment, what was the expected composition of DNA molecules after two rounds of replication, if the conservative model was correct?

The DNA strands would be all heavy or all light

Discontinuous replication occurs on one strand during DNA replication. Which of these are reasons for discontinuous replication?

The antiparallel nature of the DNA strands The 5' to 3' synthesis activity of polymerase

Which protein periodically attaches the β-subunit of DNA polymerase III to the lagging strand?

The clamp loader

The appearance of colonies of Streptococcus pneumoniae is related to the presence or absence of ______.

a capsule

Bacterial replication (for example in E. coli) begins at

a single origin

Cells have several non-specific repair pathways. Indicate which of the following are two general categories of non-specific repair mechanisms

error-prone error-free

In E. coli, the SOS response is part of the

error-prone repair pathway.

Cancer cells contain

higher levels of telomerase than normal, non-cancer cells.

The sliding clamp of a DNA polymerase ____.

holds the polymerase to the DNA template

The primary purpose of the Meselson and Stahl experiments was to determine

how dna replicates

The topological state of DNA refers to

how the DNA coils

DNA______ is an enzyme that joins to adjacent Okazaki fragments during the synthesis of the lagging DNA strand.

ligase

Which of the following types of Streptococcus pneumoniae bacteria did Griffith inject into mice?

live rough heat killed smooth

Of the following choices, which type of Streptococcus pneumoniae would lead to death if injected into a mouse?

live smooth

The level of telomerase stays high in ______, despite their age.

lymphocytes

The polarity of a DNA or RNA strands refers to the orientation of which of the following?

phosphate group to hydroxyl group

Many thousands of nucleotides can be joined together to form a polymer of nucleic acids via which type of bond?

phosphodiester

Repeating sugar and phosphate units in a single DNA strand make up the

phosphodiester backbone.

Damage caused by UV light leading to thymine dimers is corrected during photorepair by the enzyme

photolyase

The bacterium Streptococcus pneumoniae causes the disease_________ , which can be fatal.

pneumonia

Of the following list, which 3 items are required for DNA replication?

polymerase, nucleotides, & template

The ability of a polymerase to remain attached to a template is called

processivity

The carbon atoms in a sugar ring are numbered in a clockwise direction starting with the carbon atom to the ______ of the oxygen atom.

right

Which of the following is an enzyme that prevents chromosomal shortening by attaching a repeat sequence to the ends of a chromosome?

telomerase

Which of the following is a region at the ends of eukaryotic chromosomes?

telomere

In nucleic acids, the prime symbol is used to indicate

the carbon in a sugar rather than the atoms in the bases attached to the sugars

The stability of DNA molecules is due to

the sum of the hydrogen bonds between base pairs

X-ray diffraction is used to determine ____.

the three dimensional shape of a molecule

DNA repair mechanisms have evolved because

there is no way for cells to avoid exposure to mutagens

Which DNA polymerase acts on the lagging strand to remove primers and replace them with DNA?

1

A DNA strand runs 3' to 5'. The complementary strand runs

5' to 3'

A segment of DNA has the sequence 5'-ATGCCC-3'. The complementary sequence would be

5'-GGGCAT-3'

A new DNA strand can only be synthesized in a_____ to_______ direction

5;3

Which of these are used in RNA?

Adenine Guanine Uracil Cytosine

In each base-pair of a DNA double helix, a two-ringed________ nitrogenous base is interacting with a three-ringed________ nitrogenous base, which makes the diameter of the double helix 2 nm.

Blank 1: pyrimidine Blank 2: purine

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

Blank 1: replication Blank 2: fork

Bacteriophages are a type of_______ that infect_______ cells, causing them to lyse.

Blank 1: viruses or virus Blank 2: bacterial or bacteria

How are the origins of replication adjusted in eukaryotic cells, so that early in the embryonic development of eukaryotic organisms DNA can be replicated faster?

Cells can increase the number of origins used in early development.

The evidence from the Avery, MacLeod, and McCarty experiments suggested that_______ is the transforming substance.

DNA

The purpose of the Hershey Chase experiments was to determine whether a bacteriophage injected which of these two items into a cell?

DNA protein

A bacteriophage is composed of

DNA proteins

The basic design of the Meselson-Stahl experiment was to label

DNA and follow it through 2 rounds of replication

Which enzymes did Avery, MacLeod, and McCarty use in order to identify the genetic material?

DNA digesting enzymes RNA digesting enzymes protein digesting enzymes

Which enzyme unlinks the two new intertwined molecules at the end of replication in E. coli?

DNA gyrase

During the synthesis of the lagging DNA strand, Okazaki fragments are joined by the enzyme

DNA ligase.

Even with the proofreading abilities of ____, mutations still occur.

DNA polymerase

Mutations occur despite the proofreading efforts of ______, therefore, repair mechanisms are necessary to prevent the accumulation of errors.

DNA polymerase

Which enzyme covalently links nucleotides together during DNA replication?

DNA polymerase

The tetranucleotide hypothesis suggested that

DNA was a repeat of a four base sequence that never varied

Franklin used a technique called x-ray______ to suggest that DNA has a helical structure.

Diffraction

In which type of repair mechanism is a damaged region of DNA removed and then replaced by DNA synthesis?

Excision repair

Which of the following was not a piece of evidence provided by the Avery, MacLeod, and McCarty experiments to suggest that DNA is the transforming substance?

Extracting proteins and lipids reduced transforming activity

The enzyme DNA________ is the topoisomerase involved in DNA replication.

GR

The description of transformation as the transfer of virulence from one cell to another was proposed by

Griffith.

The amount of which nitrogenous base in a double helix will always be the same as the amount of cytosine?

Guanine

In the Meselson-Stahl experiment, what was the expected composition of DNA molecules after two rounds of replication, if the semiconservative model was correct?

Half of the molecules would have 2 light strands and half would have a heavy and light strand.

The experiments with radioactively labeled phage that showed that DNA was the genetic material were performed by

Hershey and Chase

Which DNA polymerase uses its 5'-to-3' exonuclease activity to remove primer segments and its 5'-to-3' polymerase activity to replace them.

I

Which DNA polymerase does not seem to play a role in replication but is involved in the DNA repair process?

II

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

III

Which DNA polymerase has a sliding clamp made of two identical protein chains (beta-subunits) that form a circle that is loaded onto the DNA template?

III

On the E. coli chromosome, where is the terminus site located relative to the oriC?

The terminus is roughly opposite the oriC.

Indicate the 4 nitrogenous bases used in DNA.

Thymine Guanine Cytosine Adenine

Why do eukaryotic cells have multiple origins of replication?

To ensure timely replication of multiple, relatively large chromosomes

In order to determine the density of DNA strands, Meselson and Stahl used this technique so that DNA fragments would migrate to the area in the gradient where they had the same density.

Ultracentrifugation

In addition to its 3'-to-5' exonuclease function, E.coli's DNA polymerase I also has

a 5'-to-3' exonuclease function.

Features of the Watson and Crick model include ____.

a sugar phosphate backbone a helical structure a double stranded structure

The ends of the chromosomes shorten when telomerase is

absent

In a DNA double helix, two hydrogen bonds form between

adenine and thymine

The density of the bacterial DNA following the first round of DNA replication in the Meselson-Stahl experiment can best be described as

an intermediate between 14 N and 15 N

The term used to describe two DNA strands that run in opposite directions from each other is ____.

antiparallel

DNA's phosphodiester__________ is composed of sugars and phosphates.

backbone

Viruses that infect bacteria, causing them to lyse, are known as

bacteriophages

Telomeres are related to

cellular aging

Genes, which contain trait specifying information, are located on

chromosomes.

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

conservative

Different models for DNA replication included

conservative replication dispersive replication semiconservative replication

The major significance of the Hershey and Chase's experiments is that they

determined that DNA is the genetic material

Information about the three dimensional shape of a molecule can be determined by using x-ray

diffraction

This model of DNA replication suggests that newly synthesized strands of DNA would consist of mixtures of parental and newly synthesized strands of DNA.

dispersive

An ______ cuts DNA internally and an ______ cuts at the ends of DNA.

endonuclease; exonuclease

E. coli polymerases I, II, and III have 3' to 5'_________ ctivity, which provides them with a proofreading function, i.e. they can remove a mispaired base.

exonuclease

A bacteriophage contains (choose all that apply)

genetic material a protein coat

The enzyme ___uses ATP to unwind the DNA template.

helicase

The T2 bacteriophage was an ideal model system for the Hershey Chase experiments because ___.

it is made of only protein and DNA

While one strand is synthesized continuously, replication is __________on the other strand, because polymerases can only synthesize DNA in one direction and the two DNA strands run in opposite directions.

lagging

________repair, cells remove bases that have been incorrectly incorporated by DNA polymers and replace them with the correct base.

mismatch

Agents that cause mutation are known as

mutagens

Radiation, UV light, x-rays, and chemicals in the environment can cause mutations in DNA and are therefore referred to as

mutagens

Nucleotides contain a sugar, a phosphate, and a

nitrogenous

Select all of the following that are components of a nucleotide.

nitrogenous base sugar phosphate group

The function of telomeres is to

protect the ends of chromosomes

Chromosomes are primarily composed of DNA and

proteins

A chromosome is primarily composed of (chose all that apply)

proteins DNA

The results of the Hershey and Chase experiments suggested that DNA was the genetic material because

radioactive bacteriophage DNA was found in the cytoplasm of bacterial cells

The DNA controlled by an origin is called a

replicon

Miescher's nuclein was later termed nucleic acid because it was ____.

slightly acidic found in the nucleus

the term ____ refers to the coiling of two DNA strands leading to torsional strain.

supercoiling

Chargaff's experiments showed that the amount of adenine in a sample was always the same as the amount of ____.

thymine

In a DNA double helix with 23% adenine, you would expect to also see 23%

thymine

The enzyme that relieves DNA supercoiling ahead of the replication fork is

topoisomerase

Griffith defined______ as the transfer of virulence from one cell to another.

transformation

A heavy isotope of nitrogen was used in the Meselson-Stahl experiment so that

v