Chapter 17 MB

The anticodon of a particular tRNA molecule is complementary to the _________________

corresponding mRNA codon

Translation occurs in the ___________

cytoplasm

If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred?

deletion

The RNA segments joined to one another by spliceosomes are ___________.

exons

True or false? A codon is a group of three bases that can specify more than one amino acid.

false

Once a peptide bond has been formed between the amino acid attached to the tRNA in the P site and the amino acid associated with the tRNA in the A site, what process occurs next?

translocation

The direction of synthesis of an RNA transcript is __________.

5 --> 3

______________ is a change in a nucleotide pair transforms on codon into another that is translated into the same amino acid

silent mutation

Spliceosomes are composed of ______________.

small RNAs and proteins

What component is not directly involved in translation?

DNA

In bacteria, there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. Which of the following statements explains this fact? a.) the rules for base pairing between the third base of a codon and tRNA are flexible b.) some tRNAs have anticodons that recognize 4 or more different codons c.)the DNA codes for all 61 tRNAs, but some are then destroyed

a

Which of the following statements about mutations is FALSE? a.)A knock-out mutation results in a total absence of the mutated protein. b.)Addition and deletion mutations disrupt the primary structure of proteins. c.)An addition mutation results in an added base in the DNA sequence.

a

Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product? a.) a deletion of 2 nucleotides b.) a substitution of the 1st nucleotide of a GGG codon c.) a substitution of the 3rd in an ACC codon d.) deletion of a codon

a

During RNA processing an ______________________ is added to the 3' end of the RNA

a long string of adenine nucleotides

Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene? a.) a base substitution at the end of the gene b.) a frameshift deletion at the beginning of the gene c.) a frameshift deletion at the end of the gene

b

Post-translational modifications of proteins may include which of the following processes? a.) addition of poly-A tail b.) addition of carbohydrates to form a glycoprotein c.) removal of introns d.) addition of a 5 cap

b

Which of the following processes correctly describes alternative RNA splicing? a.) it is a mechanism for increasing the rate of translation b.) it can allow the production of proteins of different sizes and functions from a single mRNA c.) it increases the rate of transcription

b

Which of the following statements CORRECTLY describes a ribozyme? a.)It is a catalyst that uses RNA as a substrate. b.)It is an RNA with catalytic activity. c.)It is an enzyme that catalyzes the association between the large and small ribosomal subunits. d.)It is an enzyme that synthesizes RNA as part of the transcription process.

b

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?

both addition and deletion mutation

The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. What is the result of this type of mutation? a.) nonsense mutation b.)frameshift mutation c.)a polypeptide missing an amino acid

c

What is a ribozyme? a.) a biological catalyst consisting of DNA b.) a DNA sequence near the promoter that assists in the binding of RNA polymerase c.) a biological catalyst made of RNA

c

Which of the following is NOT true of RNA processing? a.)A primary transcript is often much longer than the final RNA molecule that leaves the nucleus. b.)Ribozymes may function in RNA splicing. c.)Exons are cut out before mRNA leaves the nucleus.

c

Which of the following is NOT true of a codon? a.)It consists of three nucleotides. b.)It never codes for more than one amino acid. c.)It extends from one end of a tRNA molecule.

c

What molecular structures contain condons?

mRNA

________________ is a change from one amino acid for another with little effect on protein function

missense mutation

During RNA processing a(n) ______________ is added to the 5' end of the RNA.

modified guanine nucleotide

_________________ is a change of an amino acid codon into a stop codon, causing premature termination of translation and nearly always leading to nonfunctional protein

nonsense mutation

Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)?

one addition and one deletion mutation