Ch 14 bio

RNA polymerase

Which enzyme synthesizes tRNA? aminoacyl-tRNA synthetase DNA polymerase reverse transcriptase ribosomal RNA RNA polymerase

CAU

If the 5′ → 3′ nucleotide sequence on the nontemplate DNA strand is CAT, what is the corresponding codon on mRNA? GTA GUA CAT UAC CAU

Small RNAs in spliceosome

Which of the following would not be found in a bacterial cell? -RNA polymerase -rRNA -simultaneous transcription and translation -small RNAs in spliceosome -mRNA

Moves along the template strand of DNA, elongating an RNA molecule in a 5’> 3′ direction

RNA polymerase: -is a ribozyme. -moves along the template strand of DNA, elongating an RNA molecule in a 5′ → 3′ direction. -is the enzyme that transcribes exons but does not transcribe introns. -is the enzyme that creates hydrogen bonds between nucleotides on the DNA template strand and their complementary RNA nucleotides. -is the protein responsible for the production of ribonucleotides.

DNA to RNA

Transcription involves the transfer of information from: -RNA to DNA. -DNA to RNA. -the nucleus to the cytoplasm -mRNA to an amino acid sequence. -DNA to an amino acid sequence.

A gene for a transcription factor

Which of the following is transcribed and then translated to form a protein product? -a gene for a transcription factor -5′ and 3′ UTRs -a gene for tRNA -an intron -a gene for rRNA

Citrulline

A series of studies on mutants ofNeurospora identified three classes of mutants that needed arginine added to minimal media in order to grow. The production of arginine includes the following steps: precursor → ornithine → citrulline → arginine. What nutrient(s) have to be supplied to the mutants that had a defective enzyme for the ornithine → citrulline step in order for them to grow? -either ornithine or citrulline -the precursor, ornithine, and citrulline -ornithine -citrulline -the precursor

It is established by the promoter

How is the template strand for a particular gene determined? -It is established by the promoter. -It is the DNA strand that runs from the 3′ → 5′ direction -It doesn’t matter which strand is the template because they are complementary and will produce the same mRNA. -It is the DNA strand that runs from the 5′ → 3′ direction. -It is signaled by a polyadenylation signal sequence.

Assemblies of protein and small RNAs, called spliceosomes, may catalyze splicing

Which of the following is true of RNA processing? -Large quantities of rRNA are assembled into ribosomes. -Signal peptides are added to the 5′ end of the transcript. -Assemblies of protein and small RNAs, called spliceosomes, may catalyze splicing. -Exons are excised before the mRNA is translated. -The RNA transcript that leaves the nucleus may be much longer than the original transcript.

Small RNA molecules

Which of the following is not involved in the formation of a eukaryotic transcription initiation complex? -small RNA molecules -RNA polymerase II -TATA box -promoter -transcription factors

Both a point mutation and a nucleotide-pair substitution

The type of mutation responsible for sickle-cell anemia is: -both a point mutation and a nucleotide-pair substitution. -a point mutation. -a nucleotide-pair insertion. -a silent mutation. -a nucleotide-pair substitution

Promoter

All of the following are transcribed from DNA except: -3′ and 5′ UTRs. -exons. -tRNA. -promoter. -introns.

All of these choices are correct

A nucleotide deletion early in the coding sequence of a gene would most likely result in: -a nonfunctional protein. -a nonsense mutation. -multiple missense mutations. -all of these choices are correct. -a frameshift mutation.

Introns … Exons

After an RNA molecule is transcribed from a eukaryotic gene, what are removed and what are spliced together to produce an mRNA molecule with a continuous coding sequence? operators … promoters silencers … enhancers promoters … operators exons … introns introns … exons

A biological catalyst made of RNA

What is a ribozyme? -a DNA sequence near the promoter that assists in the binding of RNA polymerase -a mutated ribosome -a biological catalyst made of RNA -an enzyme that holds open the DNA double helix while RNA polymerase adds nucleotides -a biological catalyst consisting of DNA

A change in the sequence of DNA

What does a mutagen cause? -decreased permeability of the nuclear envelope -a reduction in the number of tRNA molecules available for protein synthesis -decreased enzyme activity throughout the cell -problems with mitosis -a change in the sequence of DNA

Three … Amino acid

A codon consists of _____ bases and specifies which _____ will be inserted into the polypeptide chain. four … fatty acid three … amino acid three … nucleotide four … amino acid two … nucleotide

All of the above

How is translation initiated? -The small ribosomal subunit binds to the mRNA. -The tRNA bearing methionine binds to the start codon. -The large ribosomal subunit binds to the small one. -The start codon signals the start of translation -All of the above.

Each tRNA binds a particular amino acid

Which one of the following is true of tRNAs? -tRNAs carry special sequences known as codons. -There are four types of tRNA. -Each tRNA binds a particular amino acid. -tRNAs are double-stranded. -All of the above.

RNA polymerase

Aminoacyl-tRNA synthetase

Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis. Select all that apply. -The amino acid glycine -RNA polymerase -Aminoacyl-tRNA synthetase

A gene codes for either a polypeptide or an RNA molecule

Which of these is currently considered the best definition of a gene? -A gene codes for either a polypeptide or an RNA molecule. -A gene codes for a single protein. -A gene codes for a particular ribozyme. -A gene codes for a single enzyme. -A gene codes for a single polypeptide.

It unwinds the double helix and adds nucleotides to a growing strand of RNA

What is the function of RNA polymerase? -It relies on other enzymes to unwind the double helix. -It adds nucleotides to the 5′ end of the growing mRNA molecule. -It unwinds the double helix and adds nucleotides to a growing strand of RNA. -It proceeds slowly along the DNA strand, requiring about a minute to add two nucleotides to the growing mRNA molecule. -All of the above.

All are correct

Which of the following statements about ribozymes is/are correct? Select all that apply. -A ribosome can be regarded as one large ribozyme. -Ribozymes are RNA molecules that function as enzymes. -In some genes, intron RNA functions as a ribozyme and catalyzes its own excision.

Ribozymes
Messenger RNA

Which of the following molecules are produced by transcription? Select all that apply. Ribozymes Messenger RNA Ribosomal proteins

Deletion of one nucleotide

Which of the following mutations would likely be most dangerous to a cell? -Substitution of one nucleotide for another -Deletion of one nucleotide -Deletion of three nucleotides

It starts after a certain nucleotide sequence called a promoter

Where does RNA polymerase begin transcribing a gene into mRNA? -It looks for the AUG start codon. -Transfer RNA acts to translate the message to RNA polymerase. -The ribosome directs it to the correct portion of the DNA molecule -It starts after a certain nucleotide sequence called a promoter. -It starts at one end of the chromosome.

From DNA to RNA to protein

The flow of information in a cell proceeds in what sequence? -from RNA to protein to DNA -from protein to RNA to DNA -from RNA to DNA to protein -from DNA to RNA to protein -from DNA to protein to RNA

Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated

The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact? -Each amino acid in a protein is encoded by a triplet of nucleotides. -Many genes are subject to alternative RNA splicing. -Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated.