Mastering Biology Ch. 17

11 September 2022
4.7 (114 reviews)
19 test answers

Unlock all answers in this set

Unlock answers (15)
question
In the diagram below, the gray unit represents _____.
In the diagram below, the gray unit represents _____.
answer
RNA polymerase. RNA polymerase untwists a portion of the DNA double helix.
question
In the diagram below, the green unit represents _____.
In the diagram below, the green unit represents _____.
answer
the promoter. The promoter is the region of DNA at which the process of transcription begins.
question
In the diagram below, the two blue strands represent _____.
In the diagram below, the two blue strands represent _____.
answer
DNA
question
Which of these correctly illustrates the pairing of DNA and RNA nucleotides?
answer
GTTACG CAAUGC
question
The direction of synthesis of an RNA transcript is _____.
answer
5' β€”> 3'. Nucleotides are added to the 3' end of RNA.
question
During RNA processing a(n) _____ is added to the 5' end of the RNA.
answer
modified guanine nucleotide. The 5' cap consists of a modified guanine nucleotide.
question
During RNA processing a(n) _____ is added to the 3' end of the RNA.
answer
a long string of adenine nucleotides. A poly-A tail is added to the 3' end of the RNA.
question
Spliceosomes are composed of _____.
answer
small RNAs and proteins. Spliceosomes are complexes composed of small RNAs and proteins.
question
The RNA segments joined to one another by spliceosomes are _____.
answer
exons. Exons are expressed regions.
question
Translation occurs in the _____.
answer
cytoplasm. Ribosomes, the sites of translation, are found in the cytoplasm.
question
Sort each description by the type of RNA it describes.
answer
tRNA: contains an anticodon, has amino acids covalently attached to it mRNA: contains exons, specifies the amino acid sequence for a protein rRNA: is a component of ribosomes, is the most abundant form of RNA
question
Indicate at which step of the replication-transcription-translation process each type of RNA first plays a role.
answer
Transcription/RNA processing: mRNA Translation: tRNA, rRNA During replication, a faithful copy of a DNA molecule is made. During transcription, the DNA "message" is copied onto a molecule of mRNA. During translation, the information carried in the mRNA is transferred to molecules of tRNA to build a protein on the ribosomes.
question
Where does translation take place?
answer
Ribosome
question
Which nucleic acid is translated to make a protein?
answer
mRNA mRNA is the message that is translated to make a protein
question
Which of the following processes is an example of a post-translational modification?
answer
Phosphorylation. Enzymes can phosphorylate proteins to alter their activity.
question
Which of the following steps occurs last in the initiation phase of translation?
answer
The large ribosomal subunit joins the complex. This step occurs after the 5' mRNA is bound by the ribosome and the start codon is bound by an aminoacyl tRNA.
question
At which site do new aminoacyl tRNAs enter the ribosome during elongation?
answer
A-site. This is the site at which new aminoacyl tRNAs that are complementary to the mRNA codon enter the ribosome.
question
What is meant by translocation?
answer
The ribosome slides one codon down the mRNA. Translocation is the process by which the ribosome slides down the mRNA so a new cycle of elongation can begin.
question
True or false. A tRNA with an anticodon complementary to the stop codon catalyzes the reaction by which translation is terminated.
answer
False. There are no tRNAs complementary to the three stop codons; termination occurs when release factors recognize the stop codon in the A-site and catalyze the release of the polypeptide from the tRNA in the P-site.