20) Which of the following mutations is most likely to cause a phenotypic change? A) a large inversion whose ends are each in intergenic regions B) a nucleotide substitution in an exon coding for a transmembrane domain C) a frameshift mutation one codon away from the end of the nontemplate strand D) a single nucleotide deletion in an exon coding for an active site E) a duplication of all or most introns 21) Which small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein? A) one base substitution B) deletion of three bases near the start of the coding sequence, but not in the initiator codon C) one base deletion near the end of the coding sequence, but not in the terminator codon D) one base deletion near the start of a gene E) one base insertion near the end of the coding sequence, but not in the terminator codon 22) What is the effect of a nonsense mutation in a gene? A) It has no effect on the amino acid sequence of the encoded protein. B) It prevents introns from being excised. C) It alters the reading frame of the mRNA. D) It introduces a premature stop codon into the mRNA. E) It changes an amino acid in the encoded protein. 23) When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by A) a specific characteristic of the ribosome itself, which distinguishes free ribosomes from bound ribosomes. B) moving through a specialized channel of the nucleus. C) a signal sequence of RNA that precedes the start codon of the message. D) a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane. E) a chemical signal given off by the ER. 24) Which of the following is a useful feature of introns in eukaryotic cells? A) Introns allow exon shuffling. B) They are translated into small polypeptides. C) Introns protect exon structure. D) They become parts of snRNPs. E) Each intron has enzymatic properties. 25) Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression? A) Transcription can begin as soon as translation has begun even a little. B) RNA polymerase requires a primer to elongate the molecule. C) RNA polymerase binds to the promoter. D) mRNA, tRNA, and rRNA are transcribed. E) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end. 26) What is the source of the extra chromosome 21 in an individual with Down syndrome? A) nondisjunction in the mother only B) nondisjunction or translocation in either parent C) nondisjunction in the father only D) duplication of the chromosome E) It is impossible to detect with current technology.
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2) DNA is transcribed into RNA. 3) RNA is translated into protein. 4) Proteins are the functional molecules of the cell. 5) Mutations can occur in the DNA sequence, which can affect the RNA and protein sequences and, therefore, their function. 6) Mutations can be Show more…
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20) Which of the following mutations is most likely to cause a phenotypic change? 21) Which small-scale mutation would most likely have a catastrophic effect on the functioning of a protein? 22) What is the effect of a nonsense mutation in a gene? 23) When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by 24) Which of the following is a useful feature of introns in eukaryotic cells? 25) Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression? 26) What is the source of the extra chromosome 21 in an individual with Down syndrome?
Sri K.
Transcription & Translation A ________ is a segment of DNA that contains information for or "codes" for a particular RNA molecule or protein. In the process of ________, the information contained in the base sequence of a gene is copied in the form of ________. Genes contain three regions: ________, ________, and ________ regions. In prokaryotes, the promoter contains ________ & ________ boxes that are required for initiation of transcription. ________ binds to these regions of the promoter, recruiting RNA polymerase to the gene. In eukaryotes, the basal transcription machinery binds to the ________ box within the promoter. The formation of mRNA, a single stranded/double stranded (circle one) molecule, is catalyzed by ________. Transcription of a eukaryotic gene is terminated when the ________ signal is transcribed. In prokaryotes, transcription and translation (the production of ________) is simultaneous whereas in eukaryotes, the mRNA is first ________. In eukaryotic mRNA, ________ are removed and a 5' ________ is added for ________ recognition. Multiple proteins may be produced from a single eukaryotic pre-mRNA due to ________. In the process of translation, protein is produced by ________ found in the cytoplasm or associated with the ________. ________s bring the correct amino acids to the ribosomes by complimentary bonding between this molecule's ________ and the codon of mRNA. The same tRNA can bind to multiple codons by "wobbling" at the ________ base position. The process of protein production is catalyzed by ________. In translation initiation, the ________ ribosomal subunit the mRNA and binds. A tRNA with the amino acid ________ "sticks" to the ________ codon. The large ribosomal subunit then assembles with the starter tRNA in the A/P/E site (circle one). Another tRNA enters the A/P/E site (circle one), bringing with it the correct amino acid. A ________ bond is formed between the amino acid that just entered the ribosome and the amino acid held by the starter tRNA in the process of ________. The ribosome then ________ and the tRNA now without an amino acid enters the A/P/E site (circle one). With the next translocation, a new tRNA enters the A/P/E site (circle one), the growing polypeptide chain attached to the tRNA in the A/P/E site (circle one) is transferred the new tRNA and the tRNA without an amino acid in the A/P/E (circle one) leaves the ribosome. This process is repeated until a ________ codon is reached which causes a ________ factor to bind to the A site. The newly made protein and ribosomal subunits are then released/disassemble. In the process of translation, single/multiple (circle one) molecules of a particular protein can be made from an mRNA molecule. Cells look/act differently from other cell types within an organism due to ________ expression. Expression of particular genes is influenced by multiple factors. One of which is ________ remodeling. If a gene is in a region that is condensed/de-condensed (circle one) it has the potential to be transcriptionally active. The enzyme ________ adds ________ to histone groups to loosen the chromatin structure, making that region be active/inactive (circle one) transcriptionally. ________ removes the histone
During transcription the DNA base sequence is transcribed into a complementary mRNA sequence. A codon table like the one shown below lists the amino acids coded for by particular triads of mRNA bases. A segment of DNA has undergone a mutation in which one nucleotide has been changed. The original sequence was ACG and the new sequence is ACA. Use the codon table to determine whether or not this mutation will cause a change in the phenotype of the organism. a. It is impossible to determine if a change in phenotype will occur using only the DNA sequence. b. No, even though the DNA sequence changed, the sequence still codes for the same amino acid, so no change in phenotype will occur. c. Yes, the phenotype of the organism would change because any change in the DNA sequence will cause a change in phenotype. d. Yes, the phenotype of the organism would change because a new amino acid will be coded for.
Madhur L.
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