Test 2 quiz questions

(Q025) DNA is a better molecule for long-term storage of genetic information than RNA because

the deoxyribose sugar stabilizes DNA chains.

(Q021) Heterochromatin can spread along a chromosome until it encounters a

barrier DNA sequence

(Q014) Which of the following specialized DNA sequences provides an attachment point for the segregation of duplicated chromosomes?

centromeres

(Q018) MicroRNAs block the expression of a specific gene product by binding to the ___________ and inhibiting ___________.

mRNA; translation

(Q013) Which of the following is true about "junk DNA"?

Portions of junk sequence are conserved between species and thus may be functional.

(Q004) Which of the following is a difference between the mechanisms of DNA polymerase and RNA polymerase?

DNA polymerase needs a base-paired 3′ −OH for a polymerization reaction to occur; RNA polymerase can polymerize two nucleotides without a base-paired 3′ −OH.

(Q022) Protein concentration can be regulated by all of the steps listed EXCEPT

DNA replication.

(Q011) ___________ is a sequence of DNA that contains the information required for making a particular functional RNA or protein.

a gene

(Q001) Transplanting the nucleus of an epithelial cell into an egg cell lacking genetic information leads to the formation of

a normally developing embryo.

(Q016) When are chromosomes in their most compacted form?

during mitosis

(Q018) What types of bonds are formed between histone proteins and DNA to form nucleosome core particles?

electrostatic interactions

(Q020) Shown below is a schematic of an interphase chromosome. Which region is most likely to contain the highest density of genes?

euchromatin between telomere and centromere

(Q009) What performs the function of bacterial sigma factor in eukaryotes?

general transcription factors

(Q007) If lactose and glucose are both available to a bacterial cell, which carbon source(s) will be used?

glucose

(Q007) The bonds that link two DNA strands together are

hydrogen bonds.

(Q005) If one end of a DNA strand has a phosphate group on it, the chemical group on the other end must be

hydroxyl.

(Q013) What is the name of the protein that binds the two separated DNA strands to keep them from base pairing again before they can be replicated?

single-strand binding protein

(Q016) Which of the following is NOT a common source of DNA damage for cells in our bodies?

soap

Q008) Which of the following is found only in eukaryotic genomes, and NOT in prokaryotic genomes?

telomeres

(Q002) At which step of gene expression can cells amplify the number of copies of a protein made from a single gene?

both transcription and translation

(Q011) Many transcriptional regulators function together to decide the expression level of a particular gene. This describes the concept of

combinatorial control.

(Q007) The structural feature of DNA that hints at the mechanism for its replication is the

complementary base pairing

(Q002) Meselson and Stahl performed a classic experiment to explore three models for the mechanism of DNA replication. Which of the models held that the two parental strands would remain associated after replication?

conservative

(Q003) Using the technique shown below, Meselson and Stahl did an experiment where they grew cells in heavy medium for many generations, then after a single generation in light medium, they observed a single band of intermediate weight after centrifugation. This experiment ruled out which model of DNA replication?

conservative

(Q002) A housekeeping gene is a gene whose cellular function is

important for processes found in all cell types.

(Q006) In which direction, and on which strands does DNA replication proceed from a replication origin on a chromosome?

in both directions, on both strands

(Q009) The technique whereby human chromosomes are stained and identified is called a

karyotype

(Q017) The catalytic sites for peptide bond formation during translation is found in which part of the ribosome?

large subunit RNAs

(Q013) The reading frame to use for translating an mRNA into functional protein is determined by the

location of an AUG.

(Q010) In the cell, enhancer sequence functions are limited in their range of action by the formation of ___________ that hold specific genes and enhancers in close proximity.

loops

(Q007) Which type of RNA is converted into protein for performing its cellular function?

mRNA

(Q017) Noncoding RNAs include all of the following EXCEPT

mRNA.

(Q020) Which double-strand break repair mechanism is a simple ligation mechanism?

non homologous end joining

(Q003) The type of bond that holds together neighboring subunits in a single strand of DNA is a

phosphodiester bond.

(Q016) The control of a gene product's levels or activity after transcription has taken place is called

post-transcriptional control.

(Q008) Eukaryotic repressor proteins can decrease transcription using which of the following mechanisms?

preventing the assembly of the transcription initiation complex

(Q004) Mutations in which of the following elements would abrogate RNA polymerase's ability to activate gene expression?

promoter

(Q020) What is the name of the complex that degrades proteins that have reached the end of their lifespan, are damaged, or are misfolded?

proteasome

(Q020) Long noncoding RNA (lncRNA) can function as a(n)

protein scaffold.

(Q009) Which of the following mechanisms describes how eukaryotic activator proteins can regulate chromatin packaging to enhance transcription?

recruiting chromatin-remodeling complexes to eject or slide nearby nucleosomes

(Q023) Which of the following properties could help RNA be both an information storage unit and a self-replicating molecule?

RNA can act as a template for making copies of itself.

(Q010) The splicing of introns out of an mRNA molecule is catalyzed by

RNA molecules that base pair with the splice sites to promote intron removal.

(Q005) Why does RNA polymerase make more mistakes than DNA polymerase?

RNA polymerase does not have proofreading activity.

(Q012) The information in an mRNA molecule is converted into protein sequence using

three consecutive bases, with no overlap between triplets.

(Q015) What is a function of the nucleolus?

to assemble ribosomal RNA and proteins into ribosomes

(Q001) The process of gene expression always involves which process(es) described in the central dogma?

transcription

(Q003) Which of the following is the main point of control for regulating gene expression levels?

transcription

(Q006) Generally, bacterial promoters that are regulated by transcriptional activators bind ___________ to RNA polymerase on their own, but promoters that are regulated with transcriptional repressors bind ___________ to RNA polymerase.

weakly; strongly

(Q010) Which of the following describes the chromosomal makeup of a somatic cell of a human biological male?

22 pairs of autosomes + 1 X chromosome + 1 Y chromosome

(Q001) If a stretch of DNA on the parental strand of a replicating chromosome has the sequence 5′-AGCTCGATCGGCTA-3′, what will the sequence of the newly synthesized strand made from this stretch of template be?

3′-TCGAGCTAGCCGAT-5′

(Q011) Export of RNA from the nucleus requires the RNA to have which characteristic(s)?

5′ cap and poly-A tail

(Q005) The sequence at which DNA replication begins tends to have which characteristic?

AT-rich

(Q010) How does Polymerase help maintain the accuracy of DNA replication?

DNA polymerase can cut out improperly base-paired nucleotides and add the correct one during synthesis.

(Q012) What is the relationship between genome size and organismal complexity?

More complex organisms generally have larger genomes but there are many notable exceptions.

(Q019) How does methylation of histone tails affect the accessibility of DNA?

It can have different effects depending on the location.

(Q001) Which of the following is a function of the protein component of chromosomes?

It packages the DNA strands

(Q013) A reporter gene is an experimentally engineered regulatory DNA sequence from a gene of interest that has been fused to a gene that encodes a protein that is easily observed experimentally. Why is this approach useful?

It provides information into where and when a gene is expressed.

(Q014) What is the function of a topoisomerase in DNA replication?

It relieves the tension in DNA strands.

(Q019) What is the benefit of protein synthesis in polyribosomes?

More protein can be produced from a single RNA.

(Q019) Which protein complex mediates the RNAi silencing process by inhibiting RNA polymerase via histone methylation and heterochromatin formation?

RITS

(Q003) Which nucleic acid often base pairs with itself to fold into complex three-dimensional shapes in the cell?

RNA

(Q006) Which characteristic of a replicating RNA polymerase allows multiple transcripts to be made simultaneously from the same region of DNA?

The RNA transcript dissociates from the DNA template immediately once complete.

(Q022) What can happen if heterochromatin spreads inappropriately into an area with active genes?

The active genes can become silenced.

(Q018) What is the first step that must occur to repair damage on one strand of the double helix?

The damaged region must be removed.

(Q019) In bacteria, how does the cell recognize which strand is the newly synthesized strand and thus contains the mismatch?

The newly synthesized strand is unmethylated.

(Q011) How are the primers from which DNA synthesis starts different from the DNA itself?

The primers are made up of RNA not DNA.

(Q024) Why is RNA thought to predate DNA in evolution?

The sugar in RNA is easier to make with the organic molecules that were present on primitive Earth.

(Q015) How do tRNAs become attached to the correct amino acid?

aminoacyl-tRNA synthetases

(Q004) The consistent diameter of the DNA double helix arises because of which property?

base pairing of pyrimidines with purines

(Q021) Single nucleotide changes from unrepaired DNA damage that lead to uncontrolled cell division can lead to which of the following conditions?

cancer

(Q014) A transcriptional regulator that activates expression of additional transcriptional regulators that induce production of a particular cell type or organ is called a

master regulator.

(Q017) What is the name of the type of damage caused by an improperly paired base in the DNA?

mismatch

(Q018) What recognizes the stop codons in an mRNA?

release factor

(Q012) What is the name of the enzyme that fills the sequence gaps after primers are removed from a newly synthesized DNA strand?

repair polymerase

(Q004) What is the name of the DNA sequence where replication begins?

replication origin

(Q012) In eukaryotes, multiple genes can be expressed simultaneously by

the binding of a specific transcriptional regulator to several genes.

(Q008) The energy for the polymerization reaction in DNA synthesis is powered by

the breaking of high-energy phosphate bonds in the deoxynucleotides.

(Q002) When Griffith injected heat-killed infectious bacteria mixed with live harmless bacteria, he found that the mice died because

the live harmless bacteria were transformed into infectious bacteria.

(Q006) The part of the DNA molecule that carries the information for producing proteins is

the order of the nucleotide bases.

(Q005) Excess amounts of the amino acid tryptophan result in downregulation of the expression of the enzymes required for its synthesis due to

the repressor binding to the operator.