Cell Biology: Transcription and Gene Expression
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What is the primary purpose of transcription in cells?

  • To copy DNA into RNA. (correct)
  • To replicate genetic material for cell division.
  • To assemble proteins from amino acids.
  • To synthesize DNA from RNA.

    • Which component is unique to eukaryotic chromosome structure compared to bacterial chromosomes?

  • Linear arrangement
  • Presence of histones (correct)
  • Circular structure
  • Cytoplasmic location

    • In which location does transcription occur in eukaryotic cells?

  • Plasma membrane
  • Cytoplasm
  • Ribosome
  • Nucleus (correct)

    • What is the role of a promoter in gene expression?

    <p>To bind RNA polymerase and signal for transcription.</p> Signup and view all the answers

    Which sequence is typically found in bacterial promoters?

    <p>-35 box and -10 box</p> Signup and view all the answers

    During protein synthesis, what is the correct process that follows transcription?

    <p>Translation of mRNA into protein</p> Signup and view all the answers

    Which factor assists in the process of transcription in eukaryotic cells?

    <p>General transcription factors</p> Signup and view all the answers

    What is a key difference between DNA replication and protein synthesis?

    <p>Replication copies entire genomes, while protein synthesis uses specific genes.</p> Signup and view all the answers

    What is the role of exons in mRNA transcripts?

    <p>They may be spliced out or kept in a mRNA transcript.</p> Signup and view all the answers

    Which statement correctly describes the non-template or coding strand?

    <p>It contains the same sequence as mRNA, except with T's instead of U's.</p> Signup and view all the answers

    What function does the poly A tail serve in eukaryotic mRNA?

    <p>It prevents degradation of the mRNA molecule.</p> Signup and view all the answers

    Which of the following statements is true regarding ribosomal binding sites?

    <p>They do not function during transcription; only during translation.</p> Signup and view all the answers

    What is the consequence of splicing out exons during mRNA processing?

    <p>It can lead to the production of different protein isoforms.</p> Signup and view all the answers

    How does the structure of mRNA differ from that of its non-template or coding strand?

    <p>mRNA contains uracil in place of thymine.</p> Signup and view all the answers

    Why is it important that exons can be spliced together in various combinations?

    <p>To create diverse proteins through alternative splicing.</p> Signup and view all the answers

    In what primary cellular process is the ribosomal binding site involved?

    <p>Translation.</p> Signup and view all the answers

    Which of the following correctly describes a feature of eukaryotic RNA processing?

    <p>Eukaryotic RNA undergoes splicing.</p> Signup and view all the answers

    What distinguishes the promoter structure in bacteria from that in eukaryotes?

    <p>Bacteria use -35 and -10 boxes.</p> Signup and view all the answers

    Which of the following statements is true regarding bacterial RNA?

    <p>Bacterial RNA does not typically undergo modifications.</p> Signup and view all the answers

    What is the result of splicing in eukaryotic cells?

    <p>Introns are removed and exons are joined.</p> Signup and view all the answers

    Which of the following correctly describes transcription termination in eukaryotes compared to bacteria?

    <p>Eukaryotes use a specific terminator sequence.</p> Signup and view all the answers

    How does the presence of a 5' cap affect eukaryotic mRNA?

    <p>It aids in ribosome binding for translation.</p> Signup and view all the answers

    Which statement about the transcription process is accurate for bacteria?

    <p>They initiate transcription with a promoter recognized by RNA polymerase.</p> Signup and view all the answers

    What is a key difference in the way eukaryotic and bacterial ribosomes initiate translation?

    <p>Eukaryotic ribosomes bind to the 5' cap of the mRNA.</p> Signup and view all the answers

    What is the mRNA codon corresponding to a tRNA anticodon of 5'-ACU-3'?

    <p>5'-AGU-3'</p> Signup and view all the answers

    Which amino acid is carried by the tRNA with the anticodon 5'-ACU-3'?

    <p>Ser</p> Signup and view all the answers

    What is the sequence of the template strand DNA corresponding to the tRNA anticodon of 5'-ACU-3'?

    <p>5'-ACT-3'</p> Signup and view all the answers

    If the template strand of DNA is 3'-TCA-5', what would be the corresponding mRNA sequence?

    <p>5'-AGU-3'</p> Signup and view all the answers

    Which of the following best explains the significance of the wobble hypothesis?

    <p>It explains the redundancy in the genetic code.</p> Signup and view all the answers

    What does the concept of a 'stop codon' signify in mRNA?

    <p>It marks the end of protein synthesis.</p> Signup and view all the answers

    Which statement about aminoacyl-tRNA synthetases is accurate?

    <p>They catalyze the attachment of the correct amino acid to its corresponding tRNA.</p> Signup and view all the answers

    Why might cells prefer a two-step process of transcription and translation over direct translation of DNA into proteins?

    <p>It allows for higher fidelity in protein synthesis.</p> Signup and view all the answers

    Which nitrogenous base is present in RNA instead of thymine?

    <p>Uracil</p> Signup and view all the answers

    What is the main function of ribosomes in protein synthesis?

    <p>Translate RNA into proteins</p> Signup and view all the answers

    What is the likely outcome if an antibiotic like streptomycin distorts ribosome structure?

    <p>Disruption of correct codon-anticodon pairing</p> Signup and view all the answers

    What is a potential consequence of an increased rate of mismatched bases during DNA replication?

    <p>Increased likelihood of mutations</p> Signup and view all the answers

    Which of the following terms describes a mutation that does not cause a change in phenotype?

    <p>Silent mutation</p> Signup and view all the answers

    In the context of the mal operon, MalT acts as which type of regulator?

    <p>Positive regulator</p> Signup and view all the answers

    What differentiates an error in DNA replication from a mutation?

    <p>Errors are temporary, mutations are permanent</p> Signup and view all the answers

    Which of the following statements is true regarding protein function and amino acid substitutions?

    <p>Similar types of amino acid substitutions may not affect function</p> Signup and view all the answers

    What is the outcome when LacI binds to lactose?

    <p>LacI can no longer bind to the operator effectively</p> Signup and view all the answers

    How does the presence of lactose influence the transcription of the lac operon?

    <p>It increases transcription by allowing RNA polymerase to bind to the promoter</p> Signup and view all the answers

    Which proteins are primarily responsible for lactose metabolism?

    <p>β-galactosidase and permease</p> Signup and view all the answers

    What role does MalT play in the presence of maltose?

    <p>It enhances transcription of the <em>malPQ</em> genes</p> Signup and view all the answers

    What happens to the transcription of the lac operon when lactose is absent?

    <p>LacI remains bound to the operator, blocking transcription</p> Signup and view all the answers

    Which statement is true regarding the translation of proteins in the operon?

    <p>Each protein has its unique ribosomal binding site enabling simultaneous translation</p> Signup and view all the answers

    What is required for RNA polymerase to transcribe the lac operon effectively?

    <p>LacI must not be bound to the operator</p> Signup and view all the answers

    What occurs when maltose binds to MalT?

    <p>The conformation of MalT is changed</p> Signup and view all the answers

    Study Notes

    Unit 2-1: Nucleic Acids - Structure, DNA assembly and organization

    • Study Questions: These questions focus on foundational knowledge about DNA structure and organization. They are the basic building blocks for mastering the concepts.

    • DNA Stability: Hydrogen bonds between strands (base pairing) and stacking interactions stabilize DNA in aqueous environments. These interactions exclude hydrophobic surfaces from water, increasing stability.

    • DNA Directionality: DNA is written 5' to 3'.

    • Protein Directionality: Proteins are written N to C.

    • Nucleic Acid Backbone: The backbone of a nucleic acid is formed by a sugar-phosphate linkage.

    Unit 2-1: Exam Style Questions

    • Base Proportions: In a bacterium, if 14% of DNA is Thymine, then 28% will be Adenine, 14% Cytosine and 44% Guanine. There is no way to determine Guanosine values from Thymiine values.

    • Purine-Pyrimidine Pairing: In normal double-stranded DNA, purines only pair with certain pyrimidines; A pairs with T, and G pairs with C. This is optimal for maximal hydrogen bonds, which strengthens DNA.

    Unit 2-1: DNA Strand Directionality

    • Directionality in DNA: DNA strands run in an antiparallel fashion. This means one strand runs 5' to 3' while the opposite strand runs 3' to 5'.

    • Specific Carbon Atoms: DNA directionality refers to specific carbon atoms on the ribose or deoxyribose ring within the DNA structure.

    Unit 2-2: Biological Information Flow

    • Transcription: Copying DNA to RNA.

    • Translation: Synthesis of proteins from mRNA.

    • DNA Replication vs. Protein Synthesis: DNA replication is the copying of DNA while protein synthesis is the production of proteins from DNA. DNA replication occurs at specific points in the cell cycle (S phase), while protein synthesis occurs throughout cell life.

    Unit 2-3: Transcription - Gene structure

    • Eukaryotic vs. Bacterial Transcription: Eukaryotic transcription takes place in the nucleus. Bacterial transcription takes place in the cytoplasm. Eukaryotic mRNA is processed (splicing, capping, poly-A tail) before translation, while bacterial mRNA does not. Eukaryotes use several general transcription factors to bind to the promoter, while bacteria use just one.

    • Gene Structure Components: The transcription and translation process include regions such as Promoters, Introns, Stop codons, 5’ Caps and TATA box. These regions have specific functions in gene structure as well as protein formation.

    Unit 2-4: Transcription-Mechanism of transcription

    • Comparing Eukaryotic and Bacterial Transcription: Eukaryotic and bacteria both have different sites of transcriptions and promoters. Eukaryotic transcription includes splicing, and addition of 5' cap and 3' poly-A tail. Bacterial mRNA does not involve these steps.

    Unit 2-5: Translation

    • Ribosome Binding Site (Bacteria): Initiation ribosomes bind to the specific mRNA sequence (ribosome binding site).

    • Transcription Termination and Translation Termination: These processes involve specific sequences and signals within the RNA.

    • Amino Acid Coding: Given a tRNA anticodon, the corresponding mRNA codon and DNA template sequence can be determined, enabling calculation of the carried amino acid.

    Unit 2-6: DNA Mutations

    • Point Mutations: Point mutations are changes to a single nucleotide base in a DNA sequence. Deletions (one, two or three base pairs) also have impacts on the protein, and even moving a base pair can impact the overall protein made.

    • Effects by Type of Mutation: Missense mutations result in a different amino acid. Nonsense mutations lead to a premature stop codon, and silent mutations have no effect on the amino acid sequence.

    Unit 2-7: Regulating Gene Expression

    • Operon structure: An operon is a functional unit of genetic material that has a promoter, operator and structural genes (such as structural genes that code for enzymes).

    • Lac operon: The Lac operon is negatively regulated by a repressor protein that prevents transcription when lactose levels are low and is positively regulated when lactose is high.

    • Mal operon: The Mal operon is positively regulated by an activator protein that enhances transcription when maltose levels are high, preventing the synthesis when maltose is not present. When maltose levels are low, it is transcribed at low levels.

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    BIOL 112 Unit 2 Practice Questions Spring 2024 PDF

    Description

    Test your knowledge on key concepts of transcription and gene expression in eukaryotic cells. This quiz covers the roles of various components, the location of transcription, and differences between DNA and mRNA. Prepare to explore essential topics such as promoters, splicing, and the significance of exons.

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