Present experimental evidence related to Griffith's experiment and the identification of the cell's genetic material.
When experimenting with Streptococcus pneumoniae in the 1920's, Griffith noticed that some colonies were shiny and smooth and some were rough in appearance. He called the shiny colonies, the ‘S strain' and the rough colonies, the ‘R' strain. When Griffith injected mice with the S strain, which he discovered were encapsulated, they died. When he injected them with the R strain, they did not die. In trying to determine what factor was responsible for the S strain's virulence, Griffith heat-killed the S bacteria to destroy the capsule. When he injected mice with the normally fatal S strain bacteria that had been heat-killed, they did not die. However, if the heat-killed S strain bacteria were mixed with harmless live R strain bacteria of the same species and injected, the mice did die. Surprisingly, living S strain bacteria were recovered from the bodies of the mice. Griffith concluded that some substance from the dead S strain bacteria passed to the R strain bacteria, imparting virulence and the ability to form a capsule. Avery and others continued the search for the substance that "transformed" the R strain into the S strain.
Hypothesis I: Genetic material or "transforming substance" is protein.
Hypothesis II: Genetic material or "transforming substance" is RNA.
Hypothesis III: Genetic material or "transforming substance" is DNA.

An experiment was performed that demonstrated that DNA extracted from the S strain bacteria transformed R strain bacteria. This finding:
A. Supports Hypothesis I
B. Supports Hypothesis II
C. Supports Hypothesis III
D. Rejects Hypothesis I only.
E. Rejects Hypothesis II only.
F Rejects Hypothesis III only.
G. Does not support any of these hypotheses.

C

Which of the following statements is NOT true about the debate over the nature of genetic material?
A. Many scientists believed that DNA was not the genetic material because, with only four types of nucleotides, DNA did not have enough variability to store information.
B. Scientists focused on carbohydrate and protein in their studies of possible genetic material since they knew that genes were on chromosomes and that chromosomes were made of carbohydrate and protein.
C. Many scientists thought that proteins had a greater capacity for storing information because proteins contain 20 amino acids that could be sequenced differently.
D. Some scientists thought that RNA was likely to be the genetic material.

B

Transformation of bacteria was shown to occur when _______ bacteria were injected into mice and the mice _______.
A. live S strain; died
B. live R strain; didn't die
C. live S and R strain; died
D. live R strain and dead S strain; died
E. live S strain and dead R strain; didn't die

D

DNA was shown to be the transforming substance when only the ______ enzymes could inhibit transformation.
A. proteinase
B. RNAase
C. DNAase
D. lipase

C

If a DNA sample contains 13% adenine, what percentage of the sample contains cytosine?
A. 13%
B. 37%
C. 26%
D. 74%

B

One of Chargaff's rules states that
A. A + G = T + C.
B. A = C, T = G.
C. A = G, T = C.
D. A + T = G + C.

A

The X-ray diffraction photography of Rosalind Franklin and Maurice Wilkins was critical evidence in the study of DNA,
A. indicating that DNA has a double helix structure.
B. showing equal numbers of purines and pyrimidines.
C. showing the bases of DNA were held together by hydrogen bonds.
D. revealing the structure of the deoxyribose sugar.
E. of the location of each adenine, guanine, cytosine, and thymine.

A

In the Watson and Crick model of DNA, the "steps" of the ladder are composed of
A. sugars.
B. a purine and a pyrimidine.
C. two purines.
D. two pyrimidines.
E. a sugar and a phosphate molecule.

B

Before Watson and Crick described DNA structure, Linus Pauling proposed a possible model with three strands of support running down the middle and the bases extending out the sides. How did Pauling's model differ from Watson and Crick's?
A. He missed the number of support strands which was two rather than three.
B. The support strands ran along the outside rather than down the center.
C. The bases were paired in the middle rather than sticking out the sides.
D. All of the choices describe how Pauling's model was different than Watson and Crick's model.

D

Scientists have created genetically modified organisms (GMOs) by isolating and then transferring the jellyfish gene for green fluorescent protein into pigs, bacteria, plants and mice. The result was bioluminescent organisms! These experiments demonstrate that:
A. jellyfish genes may be transferred into other aquatic ectotherms, but not mammals
B. genes have no difficulty crossing the species barrier
C. animal genes will not function if transferred into animals
D. genes can only be transferred to other organisms within the same species

B

Which of the following statements about DNA replication is NOT correct?
A. Unwinding of the DNA molecule occurs as hydrogen bonds break.
B. Replication occurs as each base is paired with another exactly like it.
C. The process is known as semiconservative replication because one old strand is conserved in the new molecule.
D. The enzyme that catalyzes DNA replication is DNA polymerase.
E. Complementary base pairs are held together with hydrogen bonds.

B

Nucleotides contain all of the following except:
A. a phosphate group
B. a 5 - carbon sugar
C. a nitrogen base
D. histones
E. a phosphate and a nitrogen base

D

During DNA replication, the enzyme ___________, catalyzes the elongation of new DNA by adding, to the 3' end of the previous nucleotide, new nucleotides that are complementary to a DNA template.
A. helicase
B. DNA polymerase
C. DNA ligase
D. ATP synthase

B

Which statement is NOT true about DNA replication?
A. It proceeds in a 5'-to-3' direction only.
B. One strand of new DNA is replicated faster than the other strand at the replication fork.
C. DNA can only replicate at one point on a chromosome at one time.
D. It occurs more rapidly in bacteria than in eukaryotes.
E. Replication can only begin at a special origin of replication.

C

Which statement is NOT true about DNA replication in prokaryotes?
A. Replication begins at a single origin of replication.
B. Replication is bidirectional from the origin(s).
C. Replication occurs at about 1 million base pairs per minute.
D. Since bacterial cells replicate so rapidly, a second round of replication may begin before the first has been completed.
E. There are many bacterial chromosomes, with replication occurring in each at the same time.

E

Which statement is NOT true about DNA replication in eukaryotes?
A. Replication of the entire genome takes about ten minutes.
B. A replication fork occurs at each growing point of the replicating chromosome(s).
C. Eukaryotes have many different chromosomes, with replication occurring in each at the same time.
D. Replication occurs at the rate of about 500-5000 base pairs per minute.
E. Multiple sites of replication are present on each chromosome.

A

DNA replication is considered semiconservative because:
A. it will create three new, identical strands when finished.
B. it uses the original strand as a template for replication.
C. it always replicates in the 3 to 5 prime direction.
D. it never replicates in the 5 to 3 prime direction.

B

Before the DNA repair enzyme complex has completed its function, approximately how many base-pairs are still improperly matched?
A. 1 in 10,000
B. 1 in 100,000
C. 1 in 1,000,000
D. 1 in 10,000,000
E. 1 in a billion

B

After the DNA repair enzymes complex has completed its function, approximately how many base-pairs are still improperly matched?
A. 1 in 10,000
B. 1 in 100,000
C. 1 in 1,000,000
D. 1 in 100,000,000
E. 1 in a billion

D

Which is NOT true about the genetic code?
A. Most amino acids have only one codon.
B. It is composed of a triplet code of three bases per codon.
C. It produces 64 different possibilities of base sequences.
D. It was cracked through the use of a cell-free system of enzymes.
E. It contains start and stop codons as instructions.

A

The correct sequence of events in translation is:
A. initiation, termination, elongation.
B. elongation, termination, initiation.
C. termination, elongation, initiation.
D. elongation, initiation, termination.
E. initiation, elongation, termination.

E

An unknown chemical is analyzed and found to contain the bases thymine and guanine. This chemical is most likely
A. tRNA.
B. mRNA.
C. DNA.
D. rRNA.

C

Codons:
A. are triplets coding for a single amino acid.
B. are the alphabet of the genetic language.
C. each have only one meaning.
D. All of the choices are correct.
E. Only two of the choices are true.

D

The first codon to be deciphered was ______, which codes for ________.
A. AAA, proline
B. GGG, alanine
C. UUU, phenylalanine
D. TTT, arginine
E CCC, glycine

C

Transcription of a part of a DNA molecule with a nucleotide sequence of A-A-A-C-A-A-C-T-T results in a mRNA molecule with the complementary sequence of
A. G-G-G-A-G-A-A-C-C.
B. U-U-U-C-U-U-C-A-A
C. U-U-U-G-U-U-G-A-A.
D. T-T-T-G-A-A-G-C-C.
E. C-C-C-A-C-C-T-C-C.
F. none of the choices are correct.

C

If one strand of DNA has the base sequence AAGCAA, the complementary strand has which of the following sequences?
A. UUCGUU
B. TTCGTT
C. AAGCAA
D. UTCGTU
E. TTCGTG

B

Transcription is initiated when:
A. initiation factors assemble ribosomal subunits, mRNA, and initiator tRNA.
B. RNA polymerase comes to a stop sequence.
C. RNA polymerase binds to a region of DNA called the promoter.
D. new nucleotides are added to an existing strand of nucleotides.

C

For translation to take place, which of the following would NOT be required to be present?
A. DNA.
B. mRNA.
C. tRNA-amino acid complex.
D. rRNA.
E. ribosome.

A

Which of the following processes does NOT take place during translation?
A. Growth of a polypeptide chain.
B. Attachment of a ribosome to mRNA.
C. Binding of two tRNA molecules per ribosome.
D. Liberation of polypeptide from the ribosome.
E. Production of mRNA.

E

During the elongation of a polypeptide chain, _________ occurs when the mRNA moves to the next site on the ribosome to read the next codon.
A. translocation
B. transcription
C. translation
D. transference

A

Which of the following would be transcribed into mRNA?
A. a noncoding gene
B. a protein-coding gene
C. a promoter
D. a ribozyme

B

A (an) _______ is a group of three bases on tRNA that is complementary to a specific mRNA codon.
A. codon
B. anticodon
C. poly-A tail
D. cap

B

Which of the following statements concerning ribosomes are true?
A. Several ribosomes are often attached to and translating the same mRNA.
B. Ribosomes join amino acids to form a polypeptide.
C. Ribosomes have a binding site for mRNA and three binding sites for tRNA molecules.
D. No protein synthesis within a cell would occur without ribosomes.
E. All of the above statements are true.

E

A unit of a chromosome that consists of DNA wound around a core of eight histone proteins is a transposon.

FALSE

Ribozymes are RNA molecules that function as enzymes, catalyzing reactions during RNA splicing.

TRUE

Growth at two replication forks arising from a single origin of replication produce a "bubble" as daughter DNA molecules form.

TRUE

During the replication of DNA, DNA polymerase has to synthesize the daughter strand in the 5' to 3‘ direction because DNA polymerase can only join nucleotides to the 3' end of the growing new strand.

TRUE

Telomerase is an enzyme that unwinds DNA during DNA replication.

FALSE

The poly-A tail is a modified guanine nucleotide that tells a ribosome where to attach when translation begins.

FALSE

Which of the following amino acid chains would be produced from the mRNA sequence AUACUUCCUAGUUGA
A. Isoleucine - leucine- proline- serine- stop
B. Isoleucine - leucine- stop - proline- serine
C. Glycine - glutamate - lysine - lysine - stop
D. Isoleucine - alanine- proline- serine- stop

A

Which of the following polypeptide chain would be sequenced from the mRNA code AGGGAGCCC
A. arginine - glutamate - proline
B. serine - leucine - proline
C. arginine - glutamate - alanine
D. serine - asparatate - proline

A

Which of the following statements applies to the semiconservative nature of DNA replication?
A. The old strands serve as a template for the new strand.
B. The old strand is pulled apart and reformed into the new strand.
C. The new strand serves as a template for the old strand.
D. None of these statements apply to the semiconservative nature of DNA replication.

A

Determine the number of codon sequences it would require to produce the following amino acid sequence: alanine - proline - serine - isoleucine - stop.
A. It would take 5 codon sequences.
B. It would take 3 codon sequences.
C. It would take 6 codon sequences.
D. It would take 4 codon sequences.

A

Which section of the pre-mRNA contains the protein coding regions?
A. exons
B. introns
C. The entire pre-mRNA contains protein coding regions.
D. The pre-mRNA does not code for proteins at all.

A