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How Cells Read the Genome: From DNA to Protein

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Questions

Question 1

What is the name of the principle that describes the flow of genetic information from DNA to RNA (transcription) and from RNA to protein (translation) in all living cells?

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Question 2

What are the two principal chemical differences between RNA and DNA molecules?

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Question 3

According to the text, what is the approximate error rate for RNA polymerase during transcription?

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Question 4

In bacterial transcription, what is the primary function of the sigma (σ) factor?

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Question 5

Which eukaryotic RNA polymerase is responsible for transcribing the genes for transfer RNA (tRNA), 5S rRNA, and some small RNAs?

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Question 6

What is the first modification that occurs on a eukaryotic pre-mRNA molecule as it is being synthesized by RNA polymerase II?

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Question 7

During the process of pre-mRNA splicing, what is the name of the looped structure formed by the excised intron?

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Question 8

What is the primary catalytic component of the spliceosome, responsible for carrying out the chemical reactions of splicing?

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Question 9

The process by which a single gene can produce a set of different but related proteins by splicing the RNA transcript in multiple ways is known as what?

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Question 10

Approximately how many adenine (A) nucleotides are added to the 3' end of a eukaryotic mRNA by poly-A polymerase to form the poly-A tail?

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Question 11

What is the primary site of ribosome synthesis and assembly in a eukaryotic cell?

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Question 12

What is the term for a group of three consecutive nucleotides in an mRNA molecule that specifies either an amino acid or a stop to translation?

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Question 13

What is the function of transfer RNA (tRNA) molecules in protein synthesis?

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Question 14

The phenomenon where a tRNA molecule can base-pair with more than one codon, typically due to a mismatch being tolerated at the third position of the codon, is known as what?

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Question 15

What is the function of aminoacyl-tRNA synthetase enzymes?

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Question 16

The ribosome is a large complex primarily composed of what two types of macromolecules?

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Question 17

What are the names of the three binding sites for tRNA molecules within a ribosome?

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Question 18

The central reaction of protein synthesis, the formation of a peptide bond, is catalyzed by what component of the ribosome?

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Question 19

In eukaryotic translation initiation, what molecule is always carried by the special initiator tRNA?

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Question 20

What signals the termination of translation when it appears in the A site of the ribosome?

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Question 21

What is the name for the large cytoplasmic assemblies made up of several ribosomes that simultaneously translate a single mRNA molecule?

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Question 22

The quality-control mechanism that detects and degrades mRNAs containing a premature stop codon, often as a result of a splicing error, is called what?

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Question 23

What is the primary signal that molecular chaperones, such as hsp70, recognize on a misfolded or incompletely folded protein?

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Question 24

What type of molecular chaperone, sometimes called a chaperonin, forms a large, barrel-shaped 'isolation chamber' for the protein folding process?

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Question 25

What small protein is attached in a chain to aberrant proteins to mark them for destruction by the proteasome?

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Question 26

What is the name of the central, hollow cylinder of the proteasome that contains the active sites for proteolysis?

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Question 27

According to the RNA world hypothesis, what dual role did RNA molecules play in primitive cells?

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Question 28

What is the key structural feature of eukaryotic RNA polymerase II that is absent in RNA polymerases I and III, and which is crucial for coordinating capping, splicing, and 3' end processing?

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Question 29

How many total possible combinations of three nucleotides (codons) are there in the genetic code, and how many different amino acids are commonly found in proteins?

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Question 30

During the elongation cycle of translation, how many high-energy phosphate bonds are consumed for each amino acid added to a polypeptide chain?

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Question 31

What is the role of guide RNAs, such as snoRNAs, in the processing of precursor ribosomal RNA (rRNA)?

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Question 32

How does the ribosome-associated quality control (RQC) system typically handle a ribosome that has stalled at the end of a broken mRNA molecule?

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Question 33

In bacteria, what is the role of the Shine-Dalgarno sequence?

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Question 34

How many tandem repeats of a seven-amino-acid sequence does the C-terminal domain (CTD) of human RNA polymerase II consist of?

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Question 35

In the process of regulated destruction, what is the role of the 19S cap of the proteasome?

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Question 36

What is the approximate rate of translation in a eukaryotic ribosome versus a bacterial ribosome?

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Question 37

When a human cell is not actively dividing, what percentage of its RNA is ribosomal RNA (rRNA)?

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Question 38

Which type of noncoding RNA directs the splicing of pre-mRNA to form mRNA?

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Question 39

What does the TATA-binding protein (TBP), a subunit of the general transcription factor TFIID, do upon binding to the TATA box sequence in DNA?

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Question 40

Why is the genetic code described as being redundant?

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Question 41

What is the typical length of a tRNA molecule?

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Question 42

Which process is NOT a recognized quality-control mechanism used by cells to prevent the translation of damaged or aberrant mRNAs?

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Question 43

What is the primary energy source that drives the conformational changes in elongation factors like EF-Tu and EF-G, and also powers the threading of proteins into the proteasome by AAA proteins?

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Question 44

What is a 'ribozyme'?

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Question 45

What are the key consensus sequences that signal the beginning and end of most introns in human pre-mRNAs?

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Question 46

In the four-step elongation cycle of translation, what immediately follows the formation of a new peptide bond in step 2?

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Question 47

How do many antibiotics, such as tetracycline and chloramphenicol, function to combat bacterial infections?

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Question 48

Why did the existence of introns in eukaryotic genes come as a surprise to scientists in 1977?

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Question 49

What is the primary reason that DNA is a more stable molecule for storing genetic information than RNA?

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Question 50

Approximately what percentage of the total proteins in a cell do proteasomes constitute?

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