Questions and Answers
A codon is a group of three bases that can specify more than one amino acid.
False
Which of the following statements about mutations is false?
If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?
Deletion
Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?
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If the sequence ATGCATGTCAATTGA were mutated such that a base were inserted after the first G and the third T were deleted, how many amino acids would be changed in the mutant protein?
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If a mutated DNA sequence produces a protein that differs in one central amino acid from the normal protein, which of the following kinds of mutations could have occurred?
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According to Beadle and Tatum's hypothesis, how many genes are necessary for this pathway (A→B→C)?
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The flow of information in a cell proceeds in what sequence?
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A codon consists of __________ bases and specifies which __________ will be inserted into the polypeptide chain.
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The corresponding codon for the mRNA transcribed from the DNA template strand 5' AGT 3' is?
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A gene from an organism can theoretically be expressed by any other organism.
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The direction of synthesis of an RNA transcript is _____?
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In which direction does the RNA polymerase move?
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Where does RNA polymerase begin transcribing a gene into mRNA?
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What is the function of RNA polymerase?
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Which of the following does not occur in prokaryotic gene expression, but does occur in eukaryotic gene expression?
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Which of the following best describes the significance of the TATA box in eukaryotic promoters?
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During RNA processing a(n) _____ is added to the 5' end of the RNA.
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During RNA processing a(n) _____ is added to the 3' end of the RNA.
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Spliceosomes are composed of _____.
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The RNA segments joined to one another by spliceosomes are _____.
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Study Notes
Codons and Mutations
- A codon is a triplet of nucleotide bases that specifies a single amino acid.
- Knock-out mutation causes a loss of protein function, not necessarily a complete absence of the protein.
- A deletion mutation occurs when one base is lost from a DNA sequence, altering the original sequence.
- A combination of one addition mutation and one deletion can restore the reading frame of a gene.
Protein Changes from Mutations
- Inserting a base and deleting another can lead to changes in two amino acids in the protein produced.
- Mutations may cause a protein to differ by one central amino acid if the change occurs in the same codon.
Gene Function and Expression
- According to Beadle and Tatum's hypothesis, two genes are necessary for a simple metabolic pathway involving two enzymes.
- The flow of genetic information in cells follows the sequence: DNA → RNA → Protein.
- Genes are universally translatable across organisms due to the conservation of the genetic code.
Transcription and RNA Synthesis
- RNA transcripts are synthesized in the 5' to 3' direction, with nucleotides being added to the 3' end.
- RNA polymerase moves along the DNA template strand in the 3' to 5' direction.
- Transcription begins at a promoter region, and in eukaryotes, this requires transcription factors for RNA polymerase binding.
RNA Processing
- RNA polymerase unwinds DNA and synthesizes RNA strands during transcription.
- Eukaryotic gene expression includes the addition of a poly-A tail to the 3' end of mRNA and a 5' cap composed of a modified guanine nucleotide.
- The TATA box in eukaryotic promoters serves as a recognition site for specific transcription factors.
Splicing
- Spliceosomes, consisting of small RNAs and proteins, facilitate the joining of RNA segments.
- The segments that are retained and joined by spliceosomes are known as exons, which contain the expressed regions of the gene.
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Test your knowledge on key concepts from Biology Chapter 14 with these flashcards. This quiz covers fundamental topics such as codons and mutations, providing an excellent review tool for mastering the material.