protein synthesis mastering bio
aminoacyl-tRNA synthetase
. Amino acids are attached to tRNA by enzymes called
trna
4. The RNA that has an amino acid attached to it, and that binds to the codon on the mRNA, is called a
5
A codon consists of _____ bases and specifies which _____ will be inserted into the polypeptide chain. See Concept 17.1 ( page 339) 1. four ... amino acid 2. three ... nucleotide 3. four ... fatty acid 4. two ... nucleotide 5. three ... amino acid
2
A particular triplet of bases in the coding strand of DNA is AAA. The anticodon on the tRNA that binds this mRNA codon is _____. 1. AAA 2. UUU 3. TTT 4. UUA
3
A particular triplet of bases in the template strand of DNA is 5-AGT-3. What would be the corresponding codon for the mRNA that is transcribed? 1. 3-ACU-5 2. 5-TCA-3 3. 3-UCA-5 4. 3-UGA-5
1
A single base substitution mutation is likely to have a less deleterious effect when the base change exhibits which of the following results? 1. a codon that specifies the same amino acid as the original codon 2. an amino acid substitution at the active site of an enzyme 3. a stop codon 4. an amino acid substitution that alters the tertiary structure of the protein
3
According to the central dogma, what is the intermediate molecule involved in the flow of information in a cell that should go in the blank? DNA → ________ → Proteins 1. rRNA 2. mtDNA 3. mRNA 4. tRNA
4
Accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the _____. 1. attachment of amino acids to rRNAs 2. binding of ribosomes to mRNA 3. binding of the anticodon to small subunit of the ribosome 4. binding of the anticodon to the codon and the attachment of amino acids to tRNAs
3
After an RNA molecule is transcribed from a eukaryotic gene, what are removed and what are spliced together to produce an mRNA molecule with a continuous coding sequence? 1. silencers ... enhancers 2. exons ... introns 3. introns ... exons 4. operators ... promoters 5. promoters ... operators
3
As a result of its involvement in a chemical reaction, an enzyme 1. donates electrons to its reactants, turning them into products. 2. receives functional groups from reactants, allowing them to become products. 3. is unchanged by the reactants or products. 4. donates amino acid R groups to its reactants, turning them into products.
3
Codons are three-base sequences in mRNA that specify the addition of a single amino acid to the growing protein chain during translation. How do eukaryotic codons and prokaryotic codons compare? 1. Prokaryotic codons usually specify different amino acids than those of eukaryotes. 2. The translation of codons is mediated by tRNAs in eukaryotes, but translation requires no intermediate molecules such as tRNAs in prokaryotes. 3. Codons are a nearly universal language among all organisms. 4. Prokaryotic codons usually contain different bases than those of eukaryotes.
4
DNA does not store the information to synthesize which of the following? 1. Messenger RNA 2. Proteins 3. DNA 4. Organelles
2
During RNA processing a(n) _____ is added to the 3' end of the RNA. 1. 3' untranslated region 2. a long string of adenine nucleotides 3. 5' untranslated region 4. coding segment 5. modified guanine nucleotide
5
During RNA processing a(n) _____ is added to the 5' end of the RNA. 1. 3' untranslated region 2. a long string of adenine nucleotides 3. 5' untranslated region 4. coding segment 5. modified guanine nucleotide
4
During _____, the cell grows and replicates both its organelles and its chromosomes. 1. prophase 2. mitosis 3. cytokinesis 4. interphase
2
During the elongation phase of translation, which site in the ribosome represents the location where a codon is being read? 1. E site 2. A site 3. P site 4. the large ribosomal subunit
4
Given a DNA molecule with the sequence of bases 5'-ATTGCA-3', what would be the sequence of the complementary strand? (It will be helpful to draw the DNA molecule when answering the question.) 1. 3'-UGCAAU-5' 2. 3'-UAACGU-5' 3. 3'-TGCAAT-5' 4. 3'-TAACGT-5'
3
How does the primary transcript in the nucleus of a eukaryotic cell compare to the functional mRNA? 1. the primary transcript is smaller than the mRNA 2. the primary transcript is the same size as the mRNA 3. the primary transcript is larger than the mRNA 4. both the primary transcript and mRNA contain introns
5
How is translation initiated? 1. subunit binds to the mRNA. 2. The tRNA bearing methionine binds to the start codon. 3. The large ribosomal subunit binds to the small one. 4. The start codon signals the start of translation. 5. All of the above.
2
If a DNA sequence is altered from TAGCTGA to TAGTGA, what kind of mutation has occurred? 1. Both addition and deletion. 2. Deletion. 3. Addition. 4. None.
3
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? 1. An addition mutation 2. A deletion mutation. 3. An addition mutation and a deletion mutation. 4. None.
2
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? 1. One. 2. Two. 3. Three. 4. None.
3
In an experimental situation, a student researcher inserts an mRNA molecule into a eukaryotic cell after she has removed its 5 cap and poly-A tail. Which of the following processes would you expect her to find to have occurred? 1. The mRNA is quickly converted into a ribosomal subunit. 2. The mRNA attaches to a ribosome and is translated, but more slowly. 3. The molecule is digested by enzymes because it is not protected at the 5 end. 4. The cell adds a new poly-A tail to the mRNA.
4
Once researchers identified DNA as the molecule responsible for transmitting heritable traits, they asked how information was transferred from the DNA in the nucleus to the site of protein synthesis in the cytoplasm. Which of the following statements correctly describes the mechanism of information transfer in eukaryotes that accomplishes this task? 1. Transfer RNA takes information from DNA directly to a ribosome, where protein synthesis takes place. 2. DNA from a single gene is replicated and transferred to the cytoplasm, where it serves as a template for protein synthesis. 3. Histone proteins in the chromosomes transfer information from the nucleus to the ribosome, where protein synthesis takes place. 4. Messenger RNA is transcribed from a single gene and transfers information from the DNA in the nucleus to the cytoplasm, where protein synthesis takes place.
5
Polypeptides are assembled from _____. 1. hexoses 2. glycerol 3. nucleotides 4. proteins 5. amino acids
3
Post-translational modifications of proteins may include which of the following processes? 1. addition of a poly-A tail 2. addition of a 5 cap 3. addition of carbohydrates to form a glycoprotein 4. removal of introns
4
RNA processing converts the RNA transcript into _____. 1. a protein 2. DNA 3. a eukaryotic cell 4. mRNA 5. a polypeptide
2
Rank the following one-base point mutations with respect to their likelihood of affecting the structure of the corresponding polypeptide (from most likely to least likely). 1. insertion mutation deep within an intron 2. substitution mutation at the third position of a codon in an exon 3. substitution mutation at the second position of a codon in an exon 4. deletion mutation within the first exon of the gene 1. 2, 1, 4, 3 2. 4, 3, 2, 1 3. 1, 2, 3, 4 4. 3, 1, 4, 2
1
Spliceosomes are composed of _____. 1. snRNPs and other proteins 2. polymerases and ligases 3. introns and exons 4. the RNA transcript and protein 5. snRNPs and snurps
2
The RNA segments joined to one another by spliceosomes are _____. 1. caps 2. exons 3. snRNPs 4. tails 5. introns
4
The anticodon of a particular tRNA molecule is 1. complementary to the corresponding triplet in rRNA. 2. the part of tRNA that bonds to a specific amino acid. 3. changeable, depending on the amino acid that attaches to the tRNA. 4. complementary to the corresponding mRNA codon. 5. catalytic, making the tRNA a ribozyme.
3
The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact? 1. Each amino acid in a protein is encoded by a triplet of nucleotides. 2. Many genes are subject to alternative RNA splicing. 3. Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated
2
The direction of synthesis of an RNA transcript is _____. 1. 1' —> 5' 2. 5' —> 3' 3. 1' —> 3' 4. 3' —> 5' 5. 2' —> 4'
2
The genetic code is essentially the same for all organisms. From this, one can logically assume which of the following statements to be true? 1. Different organisms have different types of amino acids. 2. A gene from an organism can theoretically be expressed by any other organism. 3. DNA was the first genetic material. 4. The same codons in different organisms translate into different amino acids.
3
The genetic code is redundant. What is meant by this statement? 1. The genetic code is universal (the same for all organisms). 2. A single codon can specify the addition of more than one amino acid. 3. More than one codon can specify the addition of the same amino acid. 4. The genetic code is different for different domains of organisms.
4
The initiator tRNA attaches at the ribosome's _____ site. 1. A 2. translocation 3. E 4. P 5. Q
1
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? 1. a polypeptide missing an amino acid 2. a nonsense mutation 3. a frameshift mutation 4 .a base-pair substitution
translation
The process, performed by the ribosome, of reading mRNA and synthesizing a protein is ____
4
The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____. 1. CAG 2. CTG 3. GAC 4. CUG 5. TCG
3
The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases. 1. disulfide (S−S) bonds 2. covalent bonds 3. hydrogen bonds 4. ionic bonds
2
Transcription begins at a promoter. What is a promoter? 1. The same as a start codon 2. A site in DNA that recruits the RNA Polymerase 3. Part of the RNA molecule itself 4. A site found on the RNA polymerase
4
Transcription in eukaryotes requires which of the following molecules in addition to RNA polymerase? 1. aminoacyl-tRNA synthetase 2. anticodons 3. ribosomes and tRNA 4. several transcription factors
1
Translation occurs in the _____. 1. cytoplasm 2. lysosome 3. nucleus 4. Golgi apparatus 5. nucleoplasm
2
True or false? A codon is a group of three bases that can specify more than one amino acid. 1. True 2. False
2
Use this model of a eukaryotic transcript to answer the following question. E = exon and I = intron 5' UTR E1 I1 E2 I2 E3 I3 E4 UTR 3' Which components of the previous molecule will also be found in mRNA in the cytosol? 1. 5' E1 E2 E3 E4 3' 2. 5' UTR E1 E2 E3 E4 UTR 3' 3. 5' UTR I1 I2 I3 UTR 3' 4. 5' E1 I1 E2 I2 E3 I3 E4 3'
2
What determines which base is to be added to an RNA strand during transcription? 1. Base pairing between the two DNA strands 2. Base pairing between the DNA template strand and the RNA nucleotides 3. The order of the chemical groups in the backbone of the RNA molecule 4. The previous base
3
What does a mutagen cause? See Concept 17.5 ( page 360) Hints 1. problems with mitosis 2. decreased permeability of the nuclear envelope 3. a change in the sequence of DNA 4. a reduction in the number of tRNA molecules available for protein synthesis decreased enzyme activity throughout the cell
1
What enzyme catalyzes the attachment of an amino acid to tRNA? 1. aminoacyl-tRNA synthetase 2. rubisco 3. dextrinase 4. argininosuccinate lyase 5. nuclease
4
What happens to RNA polymerase II after it has completed transcription of a gene? 1. It joins with another RNA polymerase to carry out transcription. 2. It begins transcribing the next gene on the chromosome. 3. It is degraded. 4. It is free to bind to another promoter and begin transcription.
4
What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA? 1. RNA processing 2. gene expression 3. polypeptide formation 4. transcription 5. translation
1
What name is given to the process in which pre-mRNA is edited into mRNA? 1. RNA processing 2. gene expression 3. polypeptide formation 4. transcription 5. translation
5
What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein? 1. RNA processing 2. gene expression 3. polypeptide formation 4. transcription 5. translation
3
Where does RNA polymerase begin transcribing a gene into mRNA? See Concept 17.2 ( page 342) 1. It looks for the AUG start codon. 2. The ribosome directs it to the correct portion of the DNA molecule. 3. It starts after a certain nucleotide sequence called a promoter. 4. It starts at one end of the chromosome. 5Transfer RNA acts to translate the message to RNA polymerase
4
Which mutation(s) would not change the remainder of the reading frame of a gene sequence that follows the mutation(s)? 1. One deletion mutation. 2. One addition and two deletion mutations. 3. One addition mutation. 4. One addition and one deletion mutation.
2
Which of the following DNA mutations is most likely to damage the protein it specifies? 1. a substitution in the last base of a codon 2. a base-pair deletion 3. an addition of three nucleotides 4. a codon deletion
4
Which of the following characteristics is directly related to the coding of a single amino acid during the process of translation? 1. the amino acetyl tRNA synthase 2. the base sequence of the tRNA 3. the complementarity of DNA and RNA 4. the three-base sequence of mRNA
4
Which of the following clues would tell you if a cell is prokaryotic or eukaryotic? 1. the presence or absence of a rigid cell wall 2. the presence or absence of ribosomes 3. whether the cell contains DNA or RNA 4. whether or not the cell is compartmentalized by internal membranes
4
Which of the following molecular structures contain codons? 1. rRNA 2. a protein 3. tRNA 4. mRNA
2
Which of the following mutations would likely be most dangerous to a cell? 1. Substitution of one nucleotide for another 2. Deletion of one nucleotide 3. Deletion of three nucleotides
1
Which of the following processes correctly describes alternative RNA splicing? 1. It can allow the production of proteins of different sizes and functions from a single mRNA. 2. It is a mechanism for increasing the rate of translation. 3. It can allow the production of similar proteins from different RNAs. 4. It increases the rate of transcription.
4
Which of the following processes occurs during transcription? 1. proteins are synthesized 2. DNA is replicated 3. mRNA attaches to ribosomes 4. RNA is synthesized
1
Which of the following shows the flow of genetic information? 1. DNA to RNA to protein 2. DNA to RNA to ribosomes 3. RNA to DNA to protein 4. protein to RNA to DNA
4
Which of the following statements about mutations is false? 1. An addition mutation results in an added base in the DNA sequence. 2. A deletion mutation results in the loss of a base in the DNA sequence. 3. Addition and deletion mutations disrupt the primary structure of proteins. 4. A knock-out mutation results in a total absence of the mutated protein.
4
Which of the following statements best describes the promoter of a protein-coding gene? 1. The promoter is part of the RNA molecule itself. 2. The promoter is a site found on RNA polymerase. 3. The promoter is a site at which only RNA polymerase will bind. 4. The promoter is a nontranscribed region of a gene.
2
Which of the following statements best describes the significance of the TATA box in the promoters of eukaryotes? 1. It is the recognition site for ribosomal binding during translation. 2. It is the recognition site for the binding of a specific transcription factor. 3. It sets the reading frame of the mRNA during translation. 4. It is the recognition site for ribosomal binding during transcription.
2
Which of the following statements best describes the termination of transcription in prokaryotes? 1. Once transcription has initiated, RNA polymerase transcribes until it reaches the end of the chromosome. 2. RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript. 3. RNA polymerase transcribes through a stop codon, causing the polymerase to stop advancing through the gene and release the mRNA. 4. RNA polymerase transcribes through the polyadenylation signal, causing proteins to associate with the transcript and cut it free from the polymerase.
4
Which of the following statements correctly describes the effect a nonsense mutation would have on a gene? 1. It changes an amino acid in the encoded protein. 2. It alters the reading frame of the mRNA. 3. It has no effect on the amino acid sequence of the encoded protein. 4. It introduces a premature stop codon into the mRNA.
4
Which of the following statements is the most current description of a gene? 1. a unit of heredity that causes formation of a phenotypic characteristic 2. a discrete unit of hereditary information that consists of a sequence of amino acids 3. a DNA subunit that codes for a single complete protein 4. a DNA sequence that is expressed to form a functional product: either RNA or polypeptide
1
Which of the following statements supports the one gene-one enzyme hypothesis? 1. A mutation in a single gene can result in a defective protein. 2. Multiple antibody genes can code for different related proteins, depending on the splicing that takes place post-transcriptionally. 3. Alkaptonuria results when individuals lack multiple enzymes involved in the catalysis of homogentisic acid. 4. Sickle-cell anemia results in normal hemoglobin.
2
Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand? 1. Identical 2. Complementary 3. Covalently bound 4. Permanently base-paired
2
Which of these correctly illustrates the pairing of DNA and RNA nucleotides? 1. GTTACG CAATCG 2. GTTACG CAAUGC 3. GTTACG GTTACG 4. GTTACG ACCGTA 5. GTTACG UAACAU
3
Which one of the following structures, if missing, would usually prevent translation from starting? 1. poly-A tail 2. 5 cap 3. AUG codon 4. exon
1
Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure. Which of the following is an accurate statement about proteins? 1. The primary structure of a protein is the order of amino acids in a polypeptide, as coded for by the DNA of a gene. 2. Secondary structure, which includes α helices and β pleated sheets, results from interactions between R groups. 3. Tertiary structure is the combining of several polypeptide subunits to form a functional protein; tertiary structure may be stabilized by hydrophobic interactions, hydrogen bonds, ionic bonds, and peptide bonds. 4. Quaternary structure is only found in proteins that have four polypeptide subunits.
termination
______of translation happens when the ribosome hits a stop codon on the mRNA.
initiation
of translation always happens at the start codon of the mRNA.
