Biol 301 Exam #2 Review

Transcription in bacteria differs from transcription in a eukaryotic cell because RNA polymerase (along with its sigma subunit) can initiate transcription on its own. (a) True (b) False

(a)

Which of the following molecules of RNA would you predict to be the most likely to fold into a specific structure as a result of intramolecular base-pairing?​ (a) 5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′​ (b) 5′-UGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUG-3′​ (c) 5′-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-3′​ (d) 5′-GGAAAAGGAGAUGGGCAAGGGGAAAAGGAGAUGGGCAAGG-3′​

(a) 5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′​

How does cholesterol in animal cell membranes affect the fluidity of the bilayer? (a) Cholesterol tends to stiffen the bilayer. (b) Cholesterol tends to make the bilayer more fluid. (c) Cholesterol has little effect on membrane fluidity.

(a) Cholesterol tends to stiffen the bilayer

Bacteria have no telomeres because the bacterial "chromosome" is a covalently closed circle. (a) TRUE (b) FALSE

(a) TRUE

Some genes are transcribed using one DNA strand as a template, whereas other genes may be transcribed using the other DNA strand. (a) TRUE (b) FALSE

(a) TRUE

Either/Or: (a) The DNA-binding motifs of transcriptional regulators usually bind in the major groove of the DNA helix. OR (b) The binding of transcriptional regulators generally disrupts the hydrogen bonds that holds the double helix together.

(a) The DNA-binding motifs of transcriptional regulators usually bind in the major groove of the DNA helix.

Regarding the genetic code...... (a) The genetic code is redundant. OR (b) Most amino acids have only one codon.

(a) The genetic code is redundant.

Either/Or ......about the proteasome ......... (a) Ubiquitin is a small protein that is covalently attached to proteins to mark them for delivery to the proteasome. OR (b) Misfolded proteins are delivered to the proteasome, where they are sequestered from the cytoplasm and can attempt to refold.

(a) Ubiquitin is a small protein that is covalently attached to proteins to mark them for delivery to the proteasome.

At a replication fork, the leading strand is synthesized: (a) continuously. (b) discontinuously. (c) first. (d) when the lagging strand is complete.

(a) continuously

Plasma membranes are extremely thin and fragile, requiring an extensive support network of fibrous proteins. This network is called the ____________. (a) cortex (b) attachment complex (c) cytoskeleton (d) spectrin

(a) cortex

DNA synthesis proceeds: (a) in 5' to the 3' direction. (b) in the 3' to 5' direction. (c) from the telomeres to the centromeres (d) from the centromeres to the telomeres

(a) in 5' to the 3' direction.

In DNA replication, DNA polymerases might fall off the template strands but for _______________ (a) sliding clamp (s) (b) Okazaki fragments (c) primers (d) DNA helicase

(a) sliding clamp (s)

Although all of the steps involved in expressing a gene can in principle be regulated, for most genes the most important point of control is: (a) transcription initiation. (b) RNA processing. (c) RNA transport and localization.

(a) transcription initiation.

The proofreading activity of DNA polymerase occurs in which direction? (a) 5' to 3' (b) 3' to 5'

(b) 3' to 5'

Which of the following describes a primer used in DNA replication? (a) A short segment (about 10 nucleotides) of DNA (b) A short segment (about 10 nucleotides) of RNA (c) A short segment (about 10 amino acids) of a polypeptide (d) none of the above

(b) A short segment (about 10 nucleotides) of RNA

Either/Or. (a) The large and small subunits of an individual ribosome always stay together and never exchange partners. OR (b) After a ribosome is released from a mRNA, its two subunits enter a pool.

(b) After a ribosome is released from a mRNA, its two subunits enter a pool.

Which is not involved in post-transcriptional control? (a) Riboswitch (b) DNA methylation (c) microRNA (d) RNA interference

(b) DNA methylation

On what side of the membrane are the carbohydrate chains of glycoproteins, proteoglycans, and glycolipids located? (a) Cytosolic side (b) External (noncytosolic) side

(b) External (noncytosolic) side

An individual ribosome can make only one type of protein. (a) True (b) False

(b) False

Eukaryotic replication origins are rich in C and G nucleotides. (a) True (b) False

(b) False

True/False. Okazaki fragments are removed by a nuclease that degrades RNA. (a) True (b) False

(b) False

____________ is needed to initiate DNA replication on both the leading strand and the lagging strand. (a) Telomerase (b) Primase (c) DNA Polymerase I (d) Replicase

(b) Primase

Either/Or. (a) An individual ribosome can make only one type of protein. OR (b) Ribosomes can make any protein that is specified by the particular mRNA that they are translating.

(b) Ribosomes can make any protein that is specified by the particular mRNA that they are translating.

Phospholipids with which of the following hydrocarbon tails will produce the most fluid bilayer? (a) Tails with 18 carbon atoms, fully saturated (b) Tails with 18 carbon atoms and two double bonds (c) Tails with 20 carbon atoms, fully saturated (d) Tails with 20 carbon atoms and two double bonds

(b) Tails with 18 carbon atoms and two double bonds

Which is NOT an example of epigenetic inheritance? (a) The inheritance of methylation patterns in DNA (b) The inheritance of a single nucleotide mutation in a gene (c) The inheritance of patterns of chromosome condensation (d) The inheritance of a regulatory protein that activates its own transcription

(b) The inheritance of a single nucleotide mutation in a gene

(a) The level of a protein depends on its rate of synthesis and its catalytic activity. OR (b) The level of a protein depends on its rate of synthesis and degradation.

(b) The level of a protein depends on its rate of synthesis and degradation.

Either/Or. (a) A bacterial replication fork is asymmetrical because it contains two DNA polymerase molecules that are structurally distinct. OR (b) The replication fork is asymmetrical because the lagging strand is synthesized in pieces that are then stitched together.

(b) The replication fork is asymmetrical because the lagging strand is synthesized in pieces that are then stitched together.

___________________ is an integral part of the telomerase enzyme. (a) a DNA template (b) an RNA template (c) GGGGTTA (d) lagging strand sequences

(b) an RNA template

Regarding ribosomes........ (a) Ribosomes are large RNA structures composed solely of rRNA. OR (b) rRNA contains the catalytic activity that joins amino acids together.

(b) rRNA contains the catalytic activity that joins amino acids together.

The error rate of DNA replication is reduced both by proof reading by DNA polymerase and by DNA mismatch repair to 1/10E? (1/10?) (a) 6 (b) 8 (c) 9 (d) 12

(c) 9

In eukaryotes, where do transcription regulators bind? (a) Upstream from a gene (b) Downstream from a gene (c) Either upstream or downstream from a gene (d) The TATA box

(c) Either upstream or downstream from a gene

How often does DNA polymerase make an error during DNA replication? (a) One error in every 100 nucleotide pairs (b) One error in every 1,000 nucleotide pairs (c) One error in every 10,000,000 nucleotide pairs

(c) One error in every 10,000,000 nucleotide pairs

Ribozymes catalyze which of the following reactions? (a) DNA synthesis (b) transcription (c) RNA splicing (d) protein hydrolysis

(c) RNA splicing

What provides the energy for DNA polymerization? (a) The hydrolysis of ATP (releasing Pi) (b) The hydrolysis of GTP (releasing Pi) (c) The hydrolysis of incoming nucleoside triphosphates (releasing PPi) (d) NADH oxidation

(c) The hydrolysis of incoming nucleoside triphosphates (releasing PPi)

What is the ultimate fate of an mRNA that is targeted by a microRNA (miRNA) based on their complementary nucleotide sequences? (a) The mRNA will be translated more efficiently by ribosomes. (b) The mRNA will be transported to the nucleus. (c) The mRNA will be destroyed by a nuclease. (d) The mRNA will be excreted from the cell

(c) The mRNA will be destroyed by a nuclease.

In RNA, which base pairs with the base A? (a) C (b) G (c) U (d) T

(c) U

The entire phospholipid molecule is: (a) hydrophobic. (b) hydrophilic. (c) amphipathic.

(c) amphipathic

DNA replication is considered semiconservative because ____________________________. (a) after many rounds of DNA replication, the original DNA double helix is still intact (b) each daughter DNA molecule consists of two new strands copied from the parent DNA molecule (c) each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand (d) two DNA polyermases are involved

(c) each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand

In the bacterial cell, the tryptophan operon encodes the genes needed to synthesize tryptophan. When the concentration of tryptophan inside the cell is high: (a) it inactivates the tryptophan repressor allowing transcription of the tryptophan operon. (b) it inactivates the tryptophan repressor, which shuts down the tryptophan operon. (c) it activates the tryptophan repressor, which shuts down the tryptophan operon.

(c) it activates the tryptophan repressor, which shuts down the tryptophan operon.

Which of the following is not involved in post-transcriptional control? (a) the spliceosome (b) dicer (c) mediator (d) RISC

(c) mediator

In addition to the repair of DNA double-strand breaks, homologous recombination is a mechanism for generating genetic diversity by swapping segments of parental chromosomes. During which process does swapping occur? (a) DNA replication (b) DNA repair (c) meiosis (d) transposition

(c) meiosis

Compared to the error rate of DNA polymerase, the error rate of RNA polymerases is: (a) much less. (b) about the same. (c) much greater.

(c) much greater

DNA polymerase has an " E site" for ___________________. (a) DNA synthesis (b) primer extension (c) proofreading (d) lagging strand extension

(c) proofreading

In the final phase of protein synthesis, the binding of _________________ to an A-site bearing a stop codon terminates translation. (a) ATP (b) TBP (c) release factor (d) Met tRNA

(c) release factor

In DNA replication, the DNA double helix is opened at its ____________ which is usually about 100 np long. (a) 5' end (b) 3' OH end (c) replication origin (d) telomeres

(c) replication origin

Eukaryotic DNA synthesis begins at.... (a) the telomeres. (b) the centromere. (c) the replication origins. (d) the CpG islands.

(c) the replication origins

If the genome of the bacterium E. coli requires about 20 minutes to replicate itself, how can the genome of the fruit fly Drosophila be replicated in only 3 minutes? (a) The Drosophila genome is smaller than the E. coli genome. (b) Eucaryotic DNA polymerase synthesizes DNA at a much faster rate than procaryotic DNA polymerase. (c) The nuclear membrane keeps the Drosophila DNA concentrated in one place in the cell, which increases the rate of polymerization. (d) Drosophila DNA contains more origins of replication than E. coli DNA.

(d) Drosophila DNA contains more origins of replication than E. coli DNA.

You have discovered an "Exo-" mutant form of DNA polymerase in which the 3′-to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged. Which of the following properties do you expect the mutant polymerase to have? (a) It will polymerize in both the 5′-to-3′ direction and the 3′-to-5′ direction. (b) It will polymerize more slowly than the normal Exo+ polymerase. (c) It will fall off the template more frequently than the normal Exo+ polymerase. (d) It will be more likely to generate mismatched base pairs.

(d) It will be more likely to generate mismatched base pairs.

Which of the following methods is not used by cells to regulate the amount of a protein in the cell? (a) Genes can be transcribed into mRNA with different efficiencies. (b) Many ribosomes can bind to a single mRNA molecule. (c) Proteins can be tagged with ubiquitin, marking them for degradation. (d) Nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm.

(d) Nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm.

Which of the following is (are) a general mechanism that cells use to maintain stable patterns of gene expression as cells divide? (a) a positive feedback loop, mediated by a transcriptional regulator that activates transcription of its own gene in addition to other cell-type specific genes (b) faithful propagation of condensed chromatin structures as cells divide (c) inheritance of DNA methylation patterns when cells divide (d) all of the above

(d) all of the above

What part of the DNA replication process would be most directly affected if a strain of bacteria lacking DNA ligase were used to make the cell extracts? (a) initiation of DNA synthesis (b) Okazaki fragment synthesis (c) leading-strand elongation (d) lagging-strand completion

(d) lagging strand completion

In eukaryotic cells, general transcription factors are required for the activity of all promoters transcribed by RNA polymerase II. The assembly of the general transcription factors begins with the binding of the factor ______20____________ to DNA, causing a marked local distortion in the DNA. This factor binds at the DNA sequence called the ________21__________ box, which is typically located 25 nucleotides upstream from the transcription start site. Once RNA polymerase II has been brought to the promoter DNA, it must be released to begin making transcripts. This release process is facilitated by the addition of phosphate groups to the tail of RNA polymerase by the factor _______22___________. It must be remembered that the general transcription factors and RNA polymerase are not sufficient to initiate transcription in the cell and are affected by proteins bound thousands of nucleotides away from the promoter. Proteins that link the distantly bound transcription regulators to RNA polymerase and the general transcription factors include the large complex of proteins called the _______23_________ The packing of DNA into chromatin also affects transcriptional initiation, and histone deacetylase is an enzyme that can render the DNA less accessible to the general transcription factors.

20. TFIID 21. TATA 22. TFIIH 23. mediator

At what site do all charged tRNAs (with the exception of the initiator tRNA) first bind to the ribosome?

A site

Indicate whether the following statements are true or false. If a statement is false, explain why it is false.​ A. When DNA is being replicated inside a cell, local heating occurs, allowing the two strands to separate.​ B. DNA replication origins are typically rich in G-C base pairs.​ C. Meselson and Stahl ruled out the dispersive model for DNA replication.​ D. DNA replication is a bidirectional process that is initiated at multiple locations along chromosomes in eukaryotic cells.​

A. False B. False C. True D. True

The large and small suunits of an individual ribosome always stay together and never exchange partners - T/F

F - Ribosomal subunits exchange partners after each round of translation. After a ribosome is released from an mRNA, its two subunits dissociate and enter a pool of free small and large subunits from which new ribosomes assemble.

Ribosomes are cytoplasmic oganelles that are encapsulated by a single membrane - T/F

F - Ribosomes are cytoplasmic organelles but they are not individually enclosed in a membrane.

An individual ribosome can make only one type of protein - T/F

F - Ribosomes can make any protein that is specified by the particular mRNA that they are translating. After translation, ribosomes are released from the mRNA and can then start translating a different mRNA.

The amount of a proteins present in the cell depends on its rate of synthesis, its catalytic activity, and its rate of degradation - T/F

F - The level of a protein depends on its rate of synthesis and degradation but not on its catalytic activity.

All mRNAs fold into particular three-dimensional structures that are required for their translation - T/F

F - mRNAs are translated as linear polymers; there is no requirement that they have a particular folded structure. In fact, such structures that are formed by mRNA can inhiit translation because the ribosome has to unfold the mRNA in order to read the message.

Because the two strands of DNA are complementary, the mRNA of a given gene can be synthesized using either strand as a template - T/F

F - the position of the promoter determines the direction in which transcription proceeds and which DNA strand is used as the template. Transcription in the opposite direction would produce an mRNA with a completely different (and probably meaningless) sequence.

An mRNA may contain the sequence ATTGACCCCGGTCAA

F- RNA contains uracil but not thymine.

All proteins are fully functional upon leaving a ribosome. True or False.

False.

What type of enzyme moves phospholipids from one monolayer to the other in a biological membrane?

Flippase

In eukaryotes, what must assemble at a promoter before RNA polymerase can transcribe a gene?

General transcription factors

To begin transcription, RNA polymerase recognizes nucleotide sequences in what region of the DNA?

Promoter region

What is the term for an RNA molecule that possesses catalytic activity?

Ribozyme

Copying errors not caught by the replication machinery can be corrected by:

The DNA mismatch repair system

The assembly of general transcription factors to a eukaryotic promoter begins at what site in a promoter?

The TATA box

Even though control of eukaryotic gene expression is combinatorial, the effect of a single gene regulatory protein can still be decisive in switching any particular gene on or off. True or False

True

Most cancers arise from cells that have accumulated multiple mutations. True or False.

True

RNA polymerases can start an RNA chain without a primer. True or False.

True

True or False. In bacteria, but not eukaryotes, many mRNAs contain the coding region for more than one gene

True

Proteasomes act primarily on proteins that have been marked for destruction by the covalent attachment of which small protein?

Ubiquitin

What part of the DNA replication process would be most directly affected if a strain of bacteria lacking helicase were used to make the cell extracts?​ (a) initiation of DNA synthesis​ (b) Okazaki fragment synthesis​ (c) leading-strand elongation​ (d) lagging-strand completion​

a. initiation of DNA synthesis

What part of the DNA replication process would be most directly affected if a strain of bacteria lacking primase were used to make the cell extracts?​ (a) initiation of DNA synthesis​ (b) Okazaki fragment synthesis​ (c) leading-strand elongation​ (d) lagging-strand completion​

a. initiation of DNA synthesis

Which type of lipids are the most abundant in the plasma membrane?​ (a) phospholipids​ (b) glycolipids​ (c) sterols​ (d) triacylglycerides​

a. phospholipids

You are studying a set of mouse genes whose expression increases when cells are exposed to the hormone cortisol, and you believe that the same cortisol-responsive transcriptional activator regulates all of these genes. Which of the following statements below should be true if your hypothesis is correct?​ (a) The cortisol-responsive genes share a DNA sequence in their regulatory regions that binds the cortisol-responsive transcriptional activator.​ (b) The cortisol-responsive genes must all be in an operon.​ (c) The transcriptional regulators that bind to the regulatory regions of the cortisol-responsive genes must all be the same.​ (d) The cortisol-responsive genes must not be transcribed in response to other hormones.​

a. the cortisol-responsive genes share a DNA sequence in their regulatory regions that binds the cortisol-responsive transcriptional activator

Amino acids are attached to their tRNA molecules by:

aminoacyl-tRNA synthetase

Which of the following statements is NOT true? a. The different lifetimes of eukaryotic mRNAs are controlled in part by nucleotide sequences in the mRNA itself. b. In a eukaryotic mRNA, the poly-A tail promotes degradation of the molecule. c. Many eukaryotic mRNAs have a longer lifetime than bacterial mRNAs. d. The longer the lifetime of an mRNA, the more protein can be produced from it.

b. In a eukaryotic mRNA, the poly-A tail promotes degradation of the molecule.

You have a bacterial strain with a mutation that removes the transcription termination signal from the Abd operon. Which of the following statements describes the most likely effect of this mutation on Abd transcription? ​ (a) The Abd RNA will not be produced in the mutant strain.​ (b) The Abd RNA from the mutant strain will be longer than normal.​ (c) Sigma factor will not dissociate from RNA polymerase when the Abd operon is being transcribed in the mutant strain.​ (d) RNA polymerase will move in a backward fashion at the Abd operon in the mutant strain.​

b. The Abd RNA from the mutant strain will be longer than normal.

The DNA duplex consists of two long covalent polymers wrapped around each other many times over their entire length. The separation of the DNA strands for replication causes the strands to be "overwound" in front of the replication fork. How does the cell relieve the torsional stress created along the DNA duplex during replication?​ (a) Nothing needs to be done because the two strands will be separated after replication is complete.​ (b) Topoisomerases break the covalent bonds of the backbone allowing the local unwinding of DNA ahead of the replication fork.​ (c) Helicase unwinds the DNA and rewinds it after replication is complete.​ (d) DNA repair enzymes remove torsional stress as they replace incorrectly paired bases.​

b. Topoismerases break the covalent bonds of the backbone allowing the local unwinding of DNA ahead of the replication fork

How are most eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter?​ (a) by binding to their binding site and sliding to the site of RNA polymerase assembly​ (b) by looping out the intervening DNA between their binding site and the promoter​ (c) by unwinding the DNA between their binding site and the promoter​ (d) by attracting RNA polymerase and modifying it before it can bind to the promoter​

b. by looping out of the intervening DNA between their binding site and the promoter

The plasma membrane serves many functions, many of which depend on the presence of specialized membrane proteins. Which of the following roles of the plasma membrane could still occur if the bilayer were lacking these proteins?​ (a) intercellular communication​ (b) selective permeability ​ (c) cellular movement​ (d) import/export of molecules​

b. selective permeability

Which of the following statements about sequence proofreading during DNA replication is false?​ (a) The exonuclease activity is in a different domain of the DNA polymerase.​ (b) The exonuclease activity cleaves DNA in the 5′-to-3′ direction.​ (c) The DNA proofreading activity occurs concomitantly with strand elongation.​ (d) If an incorrect base is added, it is "unpaired" before removal.​

b. the exonuclease activity cleaves DNA in the 5'-to-3' direction

The distinct characteristics of different cell types in a multicellular organism result mainly from the differential regulation of the _________________.​ (a) replication of specific genes.​ (b) transcription of genes transcribed by RNA polymerase II.​ (c) transcription of housekeeping genes.​ (d) proteins that directly bind the TATA box of eukaryotic genes.​

b. transcription of genes transcribe by RNA polymerase II

Many activator proteins must do what before they can interact with DNA?

bind to a metabolite or other small molecule

New membrane phospholipids are synthesized by enzymes bound to the _____________ side of the _________________ membrane.​ (a) cytosolic, mitochondrial​ (b) luminal, Golgi​ (c) cytosolic, endoplasmic reticulum​ (d) extracellular, plasma​

c. cytostolic, endoplasmic reticulum

Several members of the same family were diagnosed with the same kind of cancer when they were unusually young. Which one of the following is the most likely explanation for this phenomenon? It is possible that the individuals with the cancer have _______________________.​ (a) inherited a cancer-causing gene that suffered a mutation in an ancestor's somatic cells.​ (b) inherited a mutation in a gene required for DNA synthesis.​ (c) inherited a mutation in a gene required for mismatch repair.​ (d) inherited a mutation in a gene required for the synthesis of purine nucleotides.

c. inherited a mutation in a gene required for mismatch repair.

The tryptophan operator ___________________________.​ (a) is an allosteric protein.​ (b) binds to the tryptophan repressor when the repressor is bound to tryptophan.​ (c) is required for production of the mRNA encoded by the tryptophan operon.​ (d) is important for the production of the tryptophan repressor.

c. is required for production of the mRNA encoded by the tryptophan operon

Which of the following statements about miRNAs is false?​ (a) One miRNA can regulate the expression of many genes.​ (b) miRNAs are transcribed in the nucleus from genomic DNA.​ (c) miRNAs are produced from rRNAs.​ (d) miRNAs are made by RNA polymerase.​

c. miRNAs are produced from rRNAs

Which of the following cell types, when fully differentiated, does NOT divide to form new cells? a. fibroblasts b. liver cells c. neurons d. smooth muscle cells

c. neurons

Which one of the following is the main reason that a typical eukaryotic gene is able to respond to a far greater variety of regulatory signals than a typical prokaryotic gene or operon?​ (a) Eukaryotes have three types of RNA polymerase.​ (b) Eukaryotic RNA polymerases require general transcription factors.​ (c) The transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter.​ (d) Prokaryotic genes are packaged into nucleosomes.

c. the transcription of a eukaryotic gene can be influenced by proteins that bind far from the promoter.

Unlike DNA, which typically forms a helical structure, different molecules of RNA can fold into a variety of three-dimensional shapes. This is largely because ___________________.​ (a) RNA contains uracil and uses ribose as the sugar.​ (b) RNA bases cannot form hydrogen bonds with each other. ​ (c) RNA nucleotides use a different chemical linkage between nucleotides compared to DNA.​ (d) RNA is single-stranded.​

d. RNA is single-stranded

snRNAs ___________________.​ (a) are translated into snRNPs.​ (b) are important for producing mature mRNA transcripts in bacteria. ​ (c) are removed by the spliceosome during RNA splicing.​ (d) can bind to specific sequences at intron-exon boundaries through complementary base-pairing.​

d. can bind to specific sequences at intron-exon boundaries through complementary base-pairing.

A molecule of bacterial DNA introduced into a yeast cell is imported into the nucleus but fails to replicate with the yeast DNA. Where do you think the block to replication arises? Choose the protein or protein complex below that is most probably responsible for the failure to replicate bacterial DNA. Give an explanation for your answer.​ (a) primase​ (b) helicase​ (c) DNA polymerase​ (d) initiator proteins​

d. initiator proteins

You are examining the DNA sequences that code for the enzyme phosphofructokinase in skinks and Komodo dragons. You notice that the coding sequence that actually directs the sequence of amino acids in the enzyme is very similar in the two organisms but that the surrounding sequences vary quite a bit. What is the most likely explanation for this?​ (a) Coding sequences are repaired more efficiently.​ (b) Coding sequences are replicated more accurately.​ (c) Coding sequences are packaged more tightly in the chromosomes to protect them from DNA damage.​ (d) Mutations in coding sequences are more likely to be deleterious to the organism than mutations in noncoding sequences.​

d. mutations in coding sequences are more likely to be deleterious to the organism than mutations in noncoding sequences

An RNA molecule can fold into complex three-dimensional shapes because:

it is single stranded

Two types of noncoding (regulatory) RNAs are:

small interfering RNAs and microRNAs

Double strand breaks can be repaired flawlessly by:

the homologous recombination

In the /alpha helices of transmembrane proteins, the hydrophobic side chains are facing:

the outside of the membrane-spanning helix