micro hw 5

The sequence of the DNA "backbone is -base-phosphate-sugar-base- -phosphate-base-phosphate-base- -phosphate-sugar-phosphate-sugar- -base-sugar-base-sugar- -base-sugar-phosphate-base-

-phosphate-sugar-phosphate-sugar-

The structure of DNA explains both its ability to encode genetic information and the way in which it is copied during cell reproduction. True False

true

Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine? 24 31 38 12 It cannot be determined from the information provided.

12

A DNA strand with the sequence 3' GTGAACTGC 5' is complementary to the sequence 5' GTGAACTGC 3' 3' GCAGTTCAC 5' 5' GCACTTCAC 3' 3' GACGTTACA 5'

5' GCACTTCAC 3'

An Okazaki fragment has which of the following arrangements? 3' RNA nucleotides, DNA nucleotides 5' DNA polymerase I, DNA polymerase III primase, polymerase, ligase 5' DNA to 3' 5' RNA nucleotide, DNA nucleotide 3'

5' RNA nucleotide, DNA nucleotide 3'

In an analysis of the nucleotide composition of DNA, which of the following will be found? G + C = T + A A = G and C = T A = C A + C = G + T

A + C = G + T

Which of the following best describes the addition of nucleotides to a growing DNA chain? A nucleoside diphosphate is added to the 3' end of the DNA, releasing a molecule of phosphate. A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate. A nucleoside triphosphate is added to the 5' end of the DNA, releasing a molecule of pyrophosphate. A nucleoside monophosphate is added to the 5' end of the DNA. A nucleoside diphosphate is added to the 5' end of the DNA, releasing a molecule of phosphate.

A nucleoside triphosphate is added to the 3' end of the DNA, releasing a molecule of pyrophosphate.

Which of the following is true of DNA replication? The preexisting strand is read in the 5' _ 3' direction. The new strand is made in the 3' _ 5' direction. An RNA primer is needed to begin DNA synthesis. All of the above are true of DNA replication. More than one, but not all, are true of DNA replication.

An RNA primer is needed to begin DNA synthesis.

Why is DNA replication essential for a cell? It allows the organism to repair any mistakes. An organism must copy its DNA to pass genetic information to its offspring. Because DNA is double-stranded. All organisms require two copies of DNA. Submit

An organism must copy its DNA to pass genetic information to its offspring.

______________________ is the overall direction of two ____________________ strands of DNA relative to one another so that the _________________ run opposite of each other. Antiparallel; complementary; 5' to 3' orientations Perpendicular; complementary; nucleotides Clockwise; circular; coding regions Antiparallel; supplementary; phosphate backbones

Antiparallel; complementary; 5' to 3' orientations

Which enzyme breaks the hydrogen bonds during replication? DNA helicase ATP Stabilizing proteins Replication fork

DNA helicase

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base? Radioactive thymine would pair with nonradioactive guanine. One of the daughter cells, but not the other, would have radioactive DNA. DNA in both daughter cells would be radioactive. Neither of the two daughter cells would be radioactive. All four bases of the DNA would be radioactive.

DNA in both daughter cells would be radioactive.

What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands? DNA has a helical shape. DNA is double-stranded. DNA is antiparallel. DNA is flexible.

DNA is flexible

The molecule that seals the gaps between the pieces of DNA in the lagging strand is RNA. the replication fork. DNA ligase. DNA polymerase. the leading strand

DNA ligase

Which statement about DNA replication is FALSE? DNA polymerase builds a new strand by adding DNA nucleotides one at a time. The two strands of parental DNA are separated during DNA replication. DNA ligase adds nucleotides to the lagging strand. Because the two strands of parental DNA run in opposite directions, the new strands must be made in different ways. The lagging strand is made of a series of pieces that must be joined together to make a continuous strand.

DNA ligase adds nucleotides to the lagging strand.

Which of the following build(s) new strands of DNA? The leading strand The origins of replication The lagging strand Parental DNA DNA polymerases

DNA polymerase

Which of the following removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments? ligase DNA polymerase I primase DNA polymerase III helicase

DNA polymerase I

Which enzyme catalyzes the elongation of a DNA strand in the 5' →♦ 3' direction? DNA ligase DNA polymerase III topoisomerase primase helicase

DNA polymerase III

A new DNA strand elongates only in the 5' to 3' direction because replication must progress toward the replication fork. DNA polymerase begins adding nucleotides at the 5' end of the template. DNA polymerase can only add nucleotides to the free 3' end. Okazaki fragments prevent elongation in the 3' to 5' direction. the polarity of the DNA molecule prevents addition of nucleotides at the 3' end.

DNA polymerase can only add nucleotides to the free 3' end.

The overall conclusion of the Hershey-Chase experiment was that DNA was responsible for heredity proteins and DNA were responsible for heredity the ratio of Adenine to thymine was always the same phage DNA was similar to bacterial DNA

DNA was responsible for heredity

What was the significance of Frederick Griffith's experiments with Streptococcus pneumoniae? He showed that the DNA from strain S cells could transform strain R cells. He showed that strain R cells could easily take up capsules released by dead S cells. He showed that the DNA from strain R cells could transform strain S cells. He showed that strain R and strain S cells could be killed by heat.

He showed that the DNA from strain S cells could transform strain R cells.

What is the function of the parental DNA in replication? It gives the cell two complete copies of the DNA. It serves as the template for DNA replication. It allows for the DNA to be circular. It is passed into the offspring of the parent.

It serves as the template for DNA replication.

Which of the following are terms associated with Okazaki fragments? DNA ligase Lagging strand Discontinuous Lagging strand, DNA ligase, and discontinuous

Lagging strand, DNA ligase, and discontinuous

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation? No proofreading will occur. Replication will require a DNA template from another source. The DNA will supercoil. Replication will occur via RNA polymerase alone. No replication fork will be formed.

No replication fork will be formed

Replication in prokaryotes differs from replication in eukaryotes for which of these reasons? The prokaryotic chromosome has histones, whereas eukaryotic chromosomes do not. Prokaryotes have telomeres, and eukaryotes do not. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many. The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes.

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

For a couple of decades, biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. What was the basis of this thinking? Proteins have two different levels of structural organization; DNA has four. Proteins have a greater variety of three-dimensional forms than does DNA. Proteins are made of 40 amino acids and DNA is made of four nucleotides. Some viruses only transmit proteins. A and B are correct.

Proteins have a greater variety of three-dimensional forms than does DNA

During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA? U C A T G Submit

T

What is meant by the description "antiparallel" regarding the strands that make up DNA? The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. One strand contains only purines and the other contains only pyrimidines. One strand is positively charged and the other is negatively charged. Base pairings create unequal spacing between the two DNA strands. The twisting nature of DNA creates nonparallel strands.

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

Which statement about DNA replication is CORRECT? The lagging strand is built continuously. The leading strand is built continuously, and the lagging strand is built in pieces. DNA ligase helps assemble the leading strand. The leading strand is one of the strands of parental DNA. The lagging strand is one of the strands of parental DNA.

The leading strand is built continuously, and the lagging strand is built in pieces.

Why is the DNA synthesis of the lagging strand considered discontinuous? The synthesis is moving in the opposite direction from the replication fork. DNA synthesis on the lagging strand occurs 3' to 5'. The lagging strand only produces single-stranded DNA molecules. The lagging strand only requires one primer instead of multiple primers.

The synthesis is moving in the opposite direction from the replication fork.

How do stabilizing proteins work on the DNA? They use ATP to break the hydrogen bonds. They bind to the single-stranded DNA. They form the replication fork. They bind to the double-stranded DNA.

They bind to the single-stranded DNA

What is the function of the connector proteins? They enable one parental DNA strand and one newly synthesized DNA strand to be held together. They link the leading strand DNA polymerase and the lagging strand DNA polymerase together. They produce the Okazaki fragments. They allow DNA synthesis to occur in the 3' to 5' direction.

They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.

What are the products of semiconservative replication for a double-stranded DNA molecule? Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand. One double-stranded DNA molecule consisting of one parental strand and one daughter strand. One double-stranded DNA molecule, consisting of two daughter strands. Two double-stranded DNA molecules, one consisting of two parental strands and the other consisting of two daughter strands.

Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.

Which of the following is found at the 5 end of a DNA strand? a hydroxyl group histones a phosphate group a hydrogen bond a methyl group

a phosphate group

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method? causing specific double strand DNA breaks that result in blunt ends on both strands adding a single 5' cap structure that resists degradation by nucleases causing linear ends of the newly replicated DNA to circularize adding numerous GC pairs which resist hydrolysis and maintain chromosome integrity adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn

adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn

The higher order structure of DNA shows symmetry, whereas the higher order structures of most proteins do not. Why isn't protein shape more regular like DNA? DNA has one main function in cells whereas proteins have many. The many different amino acid R groups on proteins confer many different shapes. Some S amino acids cause proteins to bend; others cause protein to flatten. All of the above

all of the above

Part complete The Ames test involves exposure of a histidine requiring strain of Salmonella typhimurium. After the test, mutants grow on a medium that is histidine-free. These mutants are an example of pyrimidine dimer formation point mutation site-direct mutagenesis back mutation

back mutation

Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication? nucleosome loosening, 4 dNTPs, 4 rNTPs topoisomerases, telomerase, polymerases ligase, primers, nucleases double-stranded DNA, 4 kinds of dNTPs, primers, origins G-C rich regions, polymerases, chromosome nicks

double-stranded DNA, 4 kinds of dNTPs, primers, origins

Bacteria typically contain multiple chromosomes. True False

false

Which of the following separates the DNA strands during replication? helicase primase DNA polymerase I DNA polymerase III ligase

helicase

What kind of chemical bond is found between paired bases of the DNA double helix? hydrogen covalent phosphate ionic sulfhydryl

hydrogen

All of the following are associated with nucleic acid structure EXCEPT phosphate. uracil. ribose. hydrogen bonds. ionic bonds.

ionic bonds

Which of the following characteristics of a chromosome would identify it as a prokaryotic chromosome rather than a eukaryotic chromosome? View Available Hint(s) It contains histones. It contains double-stranded DNA. It contains A, C, G, and T. It is a circular molecule.

it is a circular molecule

In which direction does the replication fork move? It moves ahead of the unzipped DNA. It moves from the double-stranded DNA to the single-stranded DNA. It moves ahead of the newly synthesized DNA. It moves towards the stabilizing proteins.

it moves ahead of the newly synthesized DNA

Which DNA strand is synthesized continuously? Lagging strand Neither the leading nor the lagging strand is synthesized continuously. The leading and lagging strands are both synthesized continuously. Leading strand

leading strand

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). These two classes of DNA probably represent leading strands and RNA primers. RNA primers and mitochondrial DNA. leading strands and Okazaki fragments. Okazaki fragments and RNA primers. lagging strands and Okazaki fragments.

leading strands and Okazaki fragments.

Which of the following covalently connects segments of DNA? helicase DNA polymerase III DNA polymerase I primase ligase

ligase

The Ames test proves that a chemical is carcinogenic. carcinogenic in humans. carcinogenic in Salmonella. mutagenic in Salmonella. mutagenic in humans

mutagenic in Salmonella.

Which is the largest among the followings? Nucleotide Nitrogenous base Phosphate Carbon

nucleotide

Which of the following synthesizes short segments of RNA? DNA polymerase III ligase DNA polymerase I primase helicase

primase

What is the function of topoisomerase? the addition of methyl groups to bases of DNA relieving strain in the DNA ahead of the replication fork stabilizing single-stranded DNA at the replication fork elongation of new DNA at a replication fork by addition of nucleotides to the existing chain unwinding of the double helix

relieving strain in the DNA ahead of the replication fork

DNA is synthesized through a process known as _____. translation conservative replication transcription semiconservative replication

semiconservative replication

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following? side groups of nitrogenous bases sequence of bases different five-carbon sugars phosphate-sugar backbones complementary pairing of bases

sequence of bases

Which of the following help to hold the DNA strands apart while they are being replicated? single-strand binding proteins primase exonuclease ligase DNA polymerase

single-strand binding proteins

What ensures that the single strands of DNA do not come back together? DNA helicase ATP The replication fork Stabilizing proteins

stabilizing proteins

Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that the relative proportion of each of the four bases differs within individuals of a species. the amount of ribose is always equivalent to deoxyribose. the amount of A is always equivalent to T, and C to G. the human genome is more complex than that of other species. transformation causes protein to be brought into the cell.

the amount of A is always equivalent to T, and C to G.

In a healthy cell, the rate of DNA repair is equal to the rate of DNA mutation. When the rate of repair lags behind the rate of mutation, what is a possible fate of the cell? DNA synthesis will continue in an attempt to repair itself. The cell can be transformed to a cancerous cell. It will become embryonic. RNA may be used instead of DNA as inheritance material.

the cell can be transformed to a cancerous cell

Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA? the rate of replication the frequency of A vs. T nucleotides the bond angles of the subunits the sequence of nucleotides the diameter of the helix

the diameter of the helix

The leading and the lagging strands differ in that the leading strand is synthesized at twice the rate of the lagging strand. the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end. the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together. the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.

The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose. triphosphate monomers are active in the nucleoside triphosphates, but not in ATP. ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells. the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups. ATP contains three high-energy bonds; the nucleoside triphosphates have two.

the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.

What determines the nucleotide sequence of the newly synthesized strand during DNA replication? the arrangement of histones in the sugar phosphate backbone the nucleotide sequence of the template strand the relative amounts of the four nucleoside triphosphates in the cell the primase used in the reaction the particular DNA polymerase catalyzing the reaction

the nucleotide sequence of the template strand

What is the function of DNA polymerase III? to add nucleotides to the end of a growing DNA strand to rejoin the two DNA strands (one new and one old) after replication to seal together the broken ends of DNA strands to unwind the DNA helix during replication to degrade damaged DNA molecules

to add nucleotides to the end of a growing DNA strand