Textbook Questions Unit 2 Flashcards
Which of the following types of RNA molecule is/are part of the “machinery” of translation of the genetic code?
tRNA, rRNA
Genes are _______ present in a cell, but _______ present in viruses.
Always
Always
Ribosomes are ________ present in a cell, but _______ present in viruses.
Always, Never
RNA polymerase is _______ present in a cell, but ________ present in viruses.
Always, Sometimes
tRNA is _______ present in a cell, but _______ present in viruses.
Always, Never
How are viruses different from eukaryotic cells?
They require a host in order to reproduce
What is the function of the structural elements of a virus?
To package and protect the viral genome
Which of the following represents the flow of information within a cell?
DNA > RNA > protein
mRNA acts as a messenger that carries information encoded by DNA to ribosomes, where proteins are synthesized.
Which of the following is NOT a rationale for using mRNA intermediates in gene expression?
DNA lacks the necessary information for protein production.
DNA contains the information for protein production in its coding strand, which is acquired by mRNA during the process of transcription.
Which of the following act(s) as a decoder, reading mRNA codons and bringing the correct amino acid to the ribosome?
tRNA
tRNA possesses an anticodon, which uses complementary base-pairing to bind the mRNA codon and provide the correct amino acid to the growing chain.
What is the role of the A-site in translation?
to accept the next tRNA and its accompanying amino acid to the ribosome
The A-site contains the next mRNA codon, which is recognized by the appropriate amino-acylated tRNA. After accepting this tRNA, the peptide chain is transferred to the A-site momentarily before the ribosome translocates along the mRNA.
You have designed a drug that irreversibly binds to the P-site of the ribosome. What is the outcome for a growing bacterial cell?
Protein translation would fail to initiate because of the inability of the initiator tRNA to bind within the ribosome.
If the P-site is occupied by the antibiotic, the initiator tRNA will no longer be able to bind the start codon, halting translation initiation.
Which of the following statements best describes transcription?
the production of RNA from a DNA template
The template strand of DNA is read 3′ to 5′ by RNA polymerase using complementary base-pairing rules. This results in the synthesis of a single-stranded transcript that may be used in a variety of ways.
What is the name of the DNA sequence to which RNA polymerase attaches to a gene and assists in transcription initiation?
the promoter
The promoter sequence is located upstream of the transcription start site. These sequences are recognized by RNA polymerase, promoting the binding of the enzyme upstream of the gene sequence itself.
Which enzyme breaks the hydrogen bonds during replication?
DNA helicase
How do stabilizing proteins work on the DNA?
They bind to the single-stranded DNA.
In which direction does the replication fork move?
It moves ahead of the newly synthesized DNA.
What ensures that the single strands of DNA do not come back together?
Stabilizing proteins
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.
Why is DNA replication essential for a cell?
An organism must copy its DNA to pass genetic information to its offspring.
What is the function of the parental DNA in replication?
It serves as the template for DNA replication.
What is the inducer molecule in the lac operon?
Allolactose
With which genetic region does the repressor protein interact?
The operator region
When the cell is not in the presence of lactose,
the repressor proteins bind to the operator.
What is the basic function of the lac operon?
To code for enzymes involved in catabolizing lactose.
According to the animation, to what genetic element does the RNA polymerase bind?
The promoter
Transcription produces which of the following?
mRNA, tRNA, and rRNA are all produced by transcription.
According to the animation, which of the following makes mRNA from the information stored in a DNA template?
RNA polymerase
Ribosomes contain which of the following?
rRNA
Which of the following is involved in bringing amino acids to the ribosomes
tRNA
Which of the following can be translated into protein?
mRNA
With which nucleotide does adenine base-pair in a folded RNA molecule?
U
There are two hydrogen bonds formed between adenine and uracil in a folded RNA molecule. These interactions, as well as the hydrogen bonds between G and C, help stabilize the three-dimensional fold within an RNA molecule, which contributes to its function. It is important to note that thymine is only found in DNA—not RNA.
What would be the sequence of the complementary DNA strand 5’ATCGGCTACG3’?
Based on the rules of complementary base pairing, the amount of guanine in a molecule of DNA will always be equal to the amount of cytosine. The same rule applies to adenine and thymine.
3’TAGCCGATGC’5
The base-pairing rules are A pairs with T and G with C. In order to hydrogen bond, the strands must run antiparallel, in opposite directions.
Which molecule demonstrates the widest range of functions due to its ability to adopt multiple conformations?
RNA
The ability of RNA to fold into numerous three-dimensional conformations allows it to serve a variety of functions within the cell, including synthesizing proteins, regulating gene expression, and serving as a source of information for specific viruses.
Which of the following lists the stages of the cell cycle in correct order?
interphase, prophase, metaphase, anaphase, telophase
The cell prepares to divide during interphase, including replicating its DNA. Then through mitosis and cytokinesis, the genetic material and the cell itself is divided, producing two identical daughter cells.
Which of the following is not a correct description of a stage of mitosis?
In prophase, the DNA replicates and the cell prepares for division.
DNA replication and preparation for division takes place during interphase, which is represented by three distinct stages: G1, S, and G2.
Which of the following build(s) new strands of DNA?
Enzymes are responsible for actually making new strands.
DNA polymerases
DNA polymerases build new strands of DNA by adding DNA nucleotides one at a time.
Which statement about DNA replication is CORRECT?
The leading strand is newly sythesized DNA that can be synthesized without stopping.
The leading strand is built continuously, and the lagging strand is built in pieces.
The leading and lagging strands are the new strands of DNA made during DNA replication. The leading strand is built continuously, and the lagging strand is built in pieces.
During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA?
Remember that thymine is replaced with uricil only in RNA.
T
The molecule that seals the gaps between the pieces of DNA in the lagging strand is
Ligating the DNA ends to one another requires an enzyme (note: all enzymes end in “ase”).
DNA ligase
Which statement about DNA replication is FALSE?
It is true that DNA polymerase builds both new leading and lagging strands by adding DNA nucleotides one at a time.
DNA ligase adds nucleotides to the lagging strand.
You’re right! This statement is FALSE. DNA ligase seals the gaps between segments of DNA in the lagging strand. It does not add nucleotides to the lagging strand.
What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands?
DNA is flexible
What is the function of the connector proteins?
They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.
Which DNA strand is synthesized continuously?
Leading strand
Which of the following are terms associated with Okazaki fragments?
Lagging strand, DNA ligase, and discontinuous
Why is the DNA synthesis of the lagging strand considered discontinuous?
The synthesis is moving in the opposite direction from the replication fork.
What are the steps in which the lagging strand is synthesized?
- DNA polymerase begins synthesizing the lagging strand by adding nucleotides to a short segment of RNA
- After each piece of the lagging strand is complete, it is released from DNA polymerase
- a different DNA polymerase replaces the RNA segments with DNA
- DNA ligase seals the gaps between the pieces, and eventually forms a continuous strand
During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome?
p site
How does the ribosome know if the entering charged tRNA is correct?
The anticodon on the tRNA base pairs to the codon on the mRNA.
Where would one find an uncharged tRNA molecule in a ribosome?
in the P and E sites
What kind of bond is formed when two amino acids join together?
a peptide bond
How is translation terminated?
When a protein called a release factor enters and binds to the A site
What results from the process of translation?
a polypeptide
How is bacterial translation different from eukaryotic translation?
Bacteria can begin translation before transcription has terminated.
According to the animation, ribosomes move along the mRNA in which direction?
5’ to 3’
How can viruses be distinguished from eukaryotic and prokaryotic organisms?
Viruses are acellular
Viruses are small, acellular, obligate intracellular parasites that consist of a small amount of genetic material enclosed in a protein shell
What are the differences between DNA and RNA?
The RNA backbone is made up of ribose sugars and phosphate, while the DNA backbone is made up of deoxyribose sugars and phosphate; further, RNA uses uracil nucleotide whereas DNA uses thymine nucleotide
RNA is usually a single-stranded nucleic acid
What effects does lysozyme have on bacteria?
lysozyme digests pptidoglycan, weakening their cell walls
Where does transcription occur in eukaryotic cells?
in the nucleus
Transcription is the synthesis of RNA from a DNA template.
What type of genome do viruses have?
Depending on the virus, viral genomes can be either DNA or RNA, either of which can be single stranded or double stranded
Viruses can have ssRNA, dsRNA, ssDNA, or dsDNA as their genomes, depending on the type of virus.
What type of organisms do phages infect?
Bacteria
What is the term used to describe viral nucleic acid surrounded by a protein “shell”?
Nucleocapsid
Where does an enveloped virus get its envelope?
from a membrane of its host cell
Which characteristics are used to classify viruses?
type of nucleic acid, presence or absence of an envelope, shape, and size
What cellular structure protects bacteria from drying out?
Glycocalyx
What type of microbe has lipid A?
Gram-negative bacteria
