Chapter 7 Flashcards
List three ways in which the process of eukaryotic transcription differs from the process of bacterial transcription.
Any three of the following are acceptable. 1. Bacterial cells contain a single RNA polymerase, whereas eukaryotic cells have three. 2. Bacterial RNA polymerase can initiate transcription without the help of additional proteins, whereas eukaryotic RNA polymerases need general transcription factors. 3. In eukaryotic cells, transcription regulators can influence transcriptional initiation thousands of nucleotides away from the promoter, whereas bacterial regulatory sequences are very close to the promoter. 4. Eukaryotic transcription is affected by chromatin structure and nucleosomes, whereas bacteria lack nucleosomes.
Name three covalent modifications that can be made to an RNA molecule in eukaryotic cells before the RNA molecule becomes a mature mRNA.
A poly-A tail is added. A 5′ cap is added. Introns can be spliced out.
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 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 _____.
TFIID; TATA; TFIIH
The genetic code specifies which amino acids are encoded by the codons on the mRNA. It is _________ because some amino acids have more than one codon. ____________ codons do not specify an amino acid.
redundant; STOP
- Which of the following is not a key advantage of wobble in the codon-anticodon reaction? a. It allows for fewer tRNAs in the cell. b. It allows for making more than one protein from the same coding sequence. c. It allows for a certain amount of mutation in the mRNA without affecting the protein sequence. d. All of these are advantages of wobble.
b
The _______________ in a tRNA molecule is designed to base-pair with a complementary sequence of three nucleotides, the ________________, in an mRNA molecule.
anticodon; codon
In all cells, a special_____molecule, recognizing the ___________codon AUG and carrying the amino acid ______________, provides the amino acid that begins a protein chain.
initiator tRNA; start; Met_( methionine)
- Which of the following pairs of codons might you expect to be read by the same tRNA as a result of the wobble? (a) CUU and UUU (b) GAU and GAA (c) CAC and CAU (d) AAU and AGU
c These two codons differ only in the third position and also encode the same amino acid, which is the definition of wobble.
The piece of RNA below includes the region that codes the binding site for the initiator tRNA needed in translation. 5′-GUUUCCCGUAUACAUGCGUGCCGGGGGC-3′ Which amino acid will be on the tRNA that is the first to bind to the A-site of the ribosome? (a)methionine (b)arginine (c)cysteine (d)valine
(a)methionine
Once an mRNA is produced, its message can be decoded on ribosomes. The ribosome 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 the codons of the mRNA.
large; small
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.
P; A
The _____ enzyme catalyzes the formation of a new peptide bond between the growing polypeptide chain and the newly arriving amino acid.
peptidyl transferase
The end of a protein-coding message is signaled by the presence of a stop codon, which binds the __________________ called ____.
protein; release factor.
Eventually, most proteins will be degraded by a large complex of proteolytic enzymes called the _____.
proteasome
The instructions specified by the DNA will ultimately specify the sequence of proteins. This process involves DNA, made up of ___ different nucleotides, which gets ____into RNA, which is then ________ into proteins, made up of _____ different amino acids.
4; transcribed; translated; 20
In eukaryotic cells, DNA gets made into RNA in the _______, while proteins are produced from RNA in the _____.
nucleus; cytoplasm
The segment of DNA called a ____ is the portion that is copied into RNA; this process is catalyzed by RNA _____.
gene; polymerase
Where does transcription take place?
nucleus
Where does translation take place?
cytoplasm/ribosome
Where does RNA splicing take place?
nucleus
Where does polyadenylation take place?
nucleus
Where does RNA capping take place?
nucleus
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 ___________________.
RNA is ss
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 ___ ____.
transcription
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, _________ molecules regulate gene expression, and _______other __________ molecules are important in the splicing of RNA transcripts, gene regulation, telomere maintenance, and many other processes.
mRNA; tRNA; rRNA; microRNAs; noncoding RNAs
Imagine that an RNA polymerase is transcribing a segment of DNA that contains the following sequence: 5′-AGTCTAGGCACTGA-3′ 3′-TCAGATCCGTGACT-5′ If the polymerase is transcribing from this segment of DNA from left to right, which strand (top or bottom) is the template?
bottom
Imagine that an RNA polymerase is transcribing a segment of DNA that contains the following sequence: 5′-AGTCTAGGCACTGA-3′ 3′-TCAGATCCGTGACT-5′ What will be the sequence of that RNA (be sure to label the 5′ and 3′ ends of your RNA molecule)?
5’-AGUCUAGGCACUGA-3’
Most rRNA genes are transcribed by which main polymerase?
RNA Polymerase I
tRNA genes are transcribed by which main polymerase?
RNA Polymerase III
5S rRNA genes are transcribed by which main polymerase?
RNA Polymerase III
protein-coding genes are transcribed by which main polymerase?
RNA Polymerase II
miRNA genes are transcribed by which main polymerase?
RNA Polymerase II
The genetic code specifies which amino acids are encoded by the codons on the mRNA. It is _________ because some amino acids have more than one codon. ____________ codons do not specify an amino acid.
redundant; STOP
Which of the following pairs of codons might you expect to be read by the same tRNA as a result of wobble?
- 5’-AGA-GGA-GAU-3’
- 5’-ACA-CCC-ACU-3’ (Thr- Pro-Thr)
- 5’-GGG-AAA-UUU-3’ (GLy-Lys-Phe)
- 5’-CGG-GGU-GAC-3’(Arg-Gly-Asp)
a
- Which of the following pairs of codons might you expect to be read by the same tRNA as a result of wobble?
(a) CUU and UUU
(b) GAU and GAA
(c) CAC and CAU
(d) AAU and AGU
c
These two codons differ only in the third position and also encode the same amino acid, which is the definition of wobble.
_____ produces an RNA molecule that is complementary strand of DNA.
transcription
The sequence of the coding strand is equivalent to the ______.
RNA products
_______ mediate transcription.
RNA Polymerase
The growing RNA chain is extended in the ___ to ___ direction.
5’; 3’
What is responsible for both unwinding the RNA helix and catalyzing the formation of the phosphodiester bonds between nucleotides.
RNA Polymerase
What type of RNA codes for proteins?
mRNA
What type of RNA forms the core of the ribosome’s structure and catalyze protein synthesis?
rRNA
What type of RNA regulate gene expression?
miRNA
What type of RNA serve as adaptors between mRNA and amino acids during protein synthesis?
tRNA
What type of RNA is used in RNA splicing, gene regulation, telomere maintenance, and many other processes?
Other noncoding RNAs
What is required for RNA Pol II to initiate?
General transcription factors
