Ch. 7 Practice questions

Name three covalent modifications that can be made to an RNA molecule in eukaryotic cells before the RNA molecule becomes a mature mRNA.

1) RNA cappins 2) polyadenylation 3)splicing

If you were told that this segment of RNA was part of the coding region of an MRNA for a large protein, give the amino acid sequence for the protein that is encoded by this segment of mRNA. 5'-UAGUCUAGGCACUGA-3'

3'-AUCAGAUCCGUGACU-5'

The instructions specified by the DNA will ultimately specify the sequence of proteins. This process involves DNA made up of ____ different nucleotides, which gets _____ transcribed into RNA which is then _____ into proteins make up of _____ different amino acids. In eukaryotic cells DNA gets made into RNA in the ____, while proteins are produced from RNA in the ________. The segment of DNA called a ______ is the portion that is copied into RNA; this process is catalyzed by RNA ______.

4 transcribed translated 20 nucleus cytoplasm gene polymerase

You have a piece of DNA that includes the following sequence: 5'-ATAGGCATTACATCCGGATAGCAT-3' 3'-TATCCGTAAGCTAGGCCTATCGTA-5' How should the RNA molecule look that is being transcribed?

5'-AUAGGCAUUCGAUCCGGAUAGCAU-3'

which of the following statements are true?

Gene A and gene b can be transcribed at different rates, producing different amounts of RNA within the same cell.

what molecule is likely to contain the genetic information of the virus?

RNA

which of the following molecules is thought to have arisen first during evolution

RNA

unlike DNA, which typically forms a helical structure, different molecules of RNA can fold into a variety of 3d shapes. This largely because ______.

RNA is single stranded.

Transcription in bacteria differs from transcription in a eukaryotic cell because

RNA polymerase (along with its sigma subunit) can initiate transcription on its own

Which of following might decrease the transcription of only one specific gene in a bacterial cell?

a mutation that introduced extensive sequence changes into the DNA that precedes the gene's transcription start site

Why is the old dogma "one gene - one protein" no always true for eukaryotic genes?

alternative splicing

what amino acid will be on the tRNA that is the first to bind to the A site of the ribosome?

arginine

snRNAs?

can bind to specific sequeneces at intron-exon boundaries through complementary base-pairing

which of the following statements about RNA splicing is false?

for a gene to function properly, every exon must be removed from the primary transcript in the same fashion on every mRNA molecule produced from the same gene.

genes in eukaryotic cells often have intronic sequences coded for within the DNA. These sequences are ultimately not translated into proteins why?

intronic sequences are removed from RNA molecules by the splice some, which works in the nucleus

a poison added to an in vitro translation mixture containing mRNA molecules with the sequence 5'-AUGAAAAAAAAAAAAUAA-3' has the following effect: the only product made is a MET-LYS dipeptide that remains attached to the ribosome . What is the most likely way in which the poison acts to inhibit protein synthesis?

it inhibits movement of the small subunit relative relative to the large subunit

RNA in cells differs from DA in that ________.

it is single stranded and can fold up into a variety of structures.

Which of the following statements is true?

rRNA contains the catalytic activity that joins amino acids together

the sigma subunit of bacterial RNA polymerase ______

recognizes promoter sites in the DNA

which of the following statement about prokaryotic mRNA molecules is false?

ribosomes must bind to the 5' cap before initiating transation

ribozymes catalyze which of the following reactions

rna splicing

in eukaryotes , but not in prokaryotes, ribosomes find the start site of translation by

scanning along the mRNA from the 5' end

the length of a particular gene in human DNA, measured from the start site for transcription to the end of the protein-coding region , is 10,000 nucleotides, whereas the length of the mRNA produced from this gene is 4000 nucleotides. What is most likely reason for this difference?

splicing entrons

the ribosome is important for catalyzing the formation of the peptide bonds. Which of the following statements is true?

the catalytic site of the peptide bond formation is formed primarily from an rRNA

which of the following statements about the genetic code is correct?

the genetic code is redundant

which of the following does not occur before a eukaryotic mRNA is exported from the nucleus?

the ribosome binds to the mRNA

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 that a typical prokaryotic gene or operon?

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

For a cell's genetic material to be used, the information is first copied from the DNA into the nucleotide sequence of RNA in a process called ______. Various kinds of RNA are produced, each with different functions. _____molecules code for proteins , ______ molecules act as adaptors for protein synthesis, ____ molecules are integral components of the ribosome, and ______ molecules are important in the splicing of RNA transcripts.

transcription mRNA tRNA rRNA snRNA

Which of the following statements is false?

unlike DNA, RNA uses a uracil base and a deoxyribose sugar.

which of the following pairs of codons might you expect to be read by the same tRNA as a result of wobble?

CAC and CAU

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 _____ to DNA, causing a marked local distortion in the DNA. this factor binds at the DNA sequence called the _____ box, which is typically located 25 nucleotides upstream from the transcription start site. Once RNA polymerase II has been brought to the DNA 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 ________. ......Proteins that link the distantly bound transcription regulators to RNA polymerase and the general transcription factors include the large complex of proteins called the ______. The packing of dna into chromatin also effects transcriptional initiation, and histone _______ is an enzyme that render the DNA less accessible to the general transcription factors.

TFIIA TATA TFIIH MEDIATOR DEACETYLASE

in a diploid organism, the DNA encoding one of the tRNAs for the amino acid tyrosine is mutated such that the sequence of the anticodon is now 5'- CTA-3' instead of 5'-GTA-3'. What kind of aberration in protein synthesis will this tRNA cause? Explain your answer.

protein synthesis will stop prematurely

which of following methods is not used by cells to regulate the amount of a protein in the cell

proteins can be tagged with ubiquitin, marking them for degradation

once an mRNA is produced, its messaged can be decoded on ribosomes. The ribosomes is composed of two subunits: the ______ subunit, which catalyzes the formation of the peptide bonds that link the amino acids together into a polypeptide chain, and the ______ subunit, which matches the tRNAs to to the codons of the mRNA. During the chain elongation process of translating an mRNA into protein, the growing polypeptide chain attached to a tRNA is bound to the______ site of the ribosome. An incoming aminoacyl-tRNA carrying the next amino acid in the chain will bind to the ______ site by forming base pairs with the exposed codon in the mRNA. The ________ enzyme catalyzes the formation of a new peptide bond between the growing polypeptide chain and the newly arriving amino acid . The end of the a protein-coding message is signaled by the presence of a stop codon, which binds the ______ called release factor. Eventually, most proteins will be degraded by a large complex of proteolytic enzymes called the ______.

large small p a peptidyl transferase protein proteasome

what amino acid would you expect a tRNA with the anticodon 5'-CUU-3' to carry?

lysine

which of the following statements about the proteasome is a false?

misfolded proteins are delivered to the proteasome, where they are sequestered from the cytoplasm and can attempt to refold

according to current thinking the minimum requirement for life to have originated on Earth was the formation of a _____

molecule that could catalyze it's own relication

Transcription is similar to DNA replication in that ________.

nucleotide polymerization occurs only in the 5' to 3' direction.

list three ways in which the process of eukaryotic transcription differs from the process of bacterial transcription.

occurs in the nucleus 3 RNA polymerase transcription factors

there are several reasons why the primase used to make the RNA primer for DNA replication is not suitable for gene transcription. which of the statements below is not one of those reasons?

primase can initiates RNA synthesis without the need for a base-paired primer.