Molecular Biology: DNA, RNA, Protein Synthesis, and Genetic Engineering, Exams of Microbiology

Download Molecular Biology: DNA, RNA, Protein Synthesis, and Genetic Engineering and more Exams Microbiology in PDF only on Docsity! BIO 221 MICROBIOLOGY Genetics Review Exam Q & A 2024 1. Which of the following genetic mechanisms is primarily responsible for bacterial resistance to antibiotics? A) Mutation B) Conjugation C) Transduction D) Transformation Answer: B) Conjugation. Rationale: Conjugation involves the transfer of genetic material between bacteria through direct contact, often transferring genes that confer antibiotic resistance. 2. In the context of microbial genetics, what is a plasmid? A) A segment of DNA within the bacterial chromosome B) A mobile genetic element that can integrate into the chromosome C) A self-replicating genetic element independent of the chromosome D) A viral genome integrated into the bacterial DNA Answer: C) A self-replicating genetic element independent of the chromosome. Rationale: Plasmids are extrachromosomal DNA that can replicate independently and often carry genes that can be beneficial to the bacterium, such as antibiotic resistance genes. 3. What is the role of transposons in microbial genetics? A) They are involved in the regulation of gene expression. B) They facilitate the repair of damaged DNA. C) They assist in the attachment of bacteria to host cells. D) They can move from one DNA molecule to another, causing genetic variation. Answer: D) They can move from one DNA molecule to another, causing genetic variation. Rationale: Transposons, also known as jumping genes, can move within and between genomes, creating mutations and genetic diversity. 4. Which process describes the transfer of genetic material from one bacterium to another through a bacteriophage? A) Mutation B) Conjugation C) Transduction D) Transformation 12. What is the primary role of tRNA in protein synthesis? A) It helps in the replication of DNA. B) It carries specific amino acids to the ribosome. C) It unwinds the double helix of DNA. D) It splices exons during mRNA processing. Answer: B) It carries specific amino acids to the ribosome. Rationale: tRNA molecules transport the appropriate amino acids to the ribosome based on the codon sequence of the mRNA, facilitating the assembly of the protein. 13. In the context of microbial genetics, what is a 'silent mutation'? A) A mutation that results in a premature stop codon. B) A mutation that changes the amino acid sequence of a protein. C) A mutation that does not change the amino acid sequence of a protein. D) A mutation that increases the expression of a gene. Answer: C) A mutation that does not change the amino acid sequence of a protein. Rationale: Silent mutations occur when a change in the DNA sequence does not affect the amino acid sequence due to the redundancy of the genetic code. 14. What is the process called when a segment of DNA is excised and reinserted in the opposite orientation? A) Inversion B) Duplication C) Deletion D) Insertion Answer: A) Inversion. Rationale: Inversion involves the removal of a DNA segment and its reintegration in the reverse direction, which can lead to changes in gene expression and function. 15. Which of the following best describes the term 'phenotype'? A) The genetic makeup of an organism. B) The physical and functional traits expressed by an organism. C) The sequence of nucleotides in DNA. D) The total number of genes in an organism. Answer: B) The physical and functional traits expressed by an organism. Rationale: Phenotype refers to the observable characteristics of an organism, which are the result of the interaction between its genotype and the environment. 1. Which of the following best describes the central dogma of molecular biology? A. DNA to protein to RNA B. RNA to DNA to protein C. DNA to RNA to protein D. Protein to RNA to DNA Answer: C. DNA to RNA to protein Rationale: The central dogma of molecular biology states that genetic information flows from DNA to RNA to protein. 2. Which of the following mutations results in the substitution of one nucleotide for another? A. Insertion B. Deletion C. Silent D. Missense Answer: D. Missense Rationale: A missense mutation is a type of point mutation that results in the substitution of one nucleotide for another, leading to a different amino acid being incorporated into the protein. 3. Which of the following terms refers to a segment of DNA that can move from one location to another within the genome? A. Plasmid B. Transposon C. Vector D. Allele Answer: B. Transposon Rationale: Transposons are segments of DNA that can move from one location to another within the genome, causing genetic mutations. 4. Which of the following processes involves the transfer of genetic material between bacteria through direct cell-to-cell contact? A. Transformation B. Conjugation C. Transduction D. Replication Answer: B. Conjugation Rationale: Conjugation is the process by which genetic material is transferred between bacteria through direct cell-to-cell contact, typically mediated by a plasmid. 5. Which of the following best describes the function of CRISPR-Cas9 technology in genome editing? A. Creating transgenic organisms B. Removing entire genes from a genome C. Introducing specific mutations into a genome D. Amplifying DNA samples for analysis Answer: C. Introducing specific mutations into a genome Rationale: CRISPR-Cas9 technology is a powerful tool for genome editing that allows for the precise introduction of specific mutations into a genome. 6. Which of the following terms refers to a form of horizontal gene transfer in bacteria mediated by bacteriophages? A. Transformation B. Conjugation C. Transduction D. Transposition Answer: C. Transduction Rationale: Transduction is a form of horizontal gene transfer in bacteria in which genetic material is transferred by bacteriophages. 7. Which of the following best describes the process of DNA replication? A. One strand of DNA serves as a template for the creation of a transcriptase to convert RNA into DNA? A. Replication B. Transcription C. Reverse transcription D. Translation Answer: C. Reverse transcription Rationale: Reverse transcription is the process by which an RNA molecule is converted into a DNA molecule, typically by the enzyme reverse transcriptase. 14. Which of the following best describes the function of ligase in genetic engineering? A. Cutting DNA at specific sequences B. Amplifying DNA through PCR C. Joining DNA fragments together D. Adding nucleotides to a DNA strand Answer: C. Joining DNA fragments together Rationale: Ligase is an enzyme that joins DNA fragments together by catalyzing the formation of phosphodiester bonds between the sugar- phosphate backbones of the fragments. 15. Which of the following terms refers to a form of genetic recombination in bacteria that involves the exchange of genetic material between homologous DNA sequences? A. Transformation B. Conjugation C. Transduction D. Recombination Answer: D. Recombination Rationale: Genetic recombination is the process by which genetic material is exchanged between homologous DNA sequences, leading to genetic variation within a population. 16. Which of the following best describes the role of RNA polymerase in gene expression? A. Synthesizing RNA from a DNA template B. Synthesizing DNA from an RNA template C. Transcribing DNA into protein D. Replicating DNA strands Answer: A. Synthesizing RNA from a DNA template Rationale: RNA polymerase is an enzyme that catalyzes the synthesis of RNA from a DNA template during the process of transcription. 17. Which of the following terms refers to a type of DNA mutation in which one or more nucleotides are added to or deleted from a gene sequence? A. Point mutation B. Frameshift mutation C. Silent mutation D. Missense mutation Answer: B. Frameshift mutation Rationale: A frameshift mutation is a type of DNA mutation in which one or more nucleotides are added to or deleted from a gene sequence, causing a shift in the reading frame and potentially altering the protein product. 18. Which of the following best describes the function of reverse transcriptase in gene expression? A. Synthesizing DNA from an RNA template B. Synthesizing RNA from a DNA template C. Transcribing RNA into protein D. Replicating RNA strands Answer: A. Synthesizing DNA from an RNA template Rationale: Reverse transcriptase is an enzyme that catalyzes the synthesis of DNA from an RNA template, typically used by retroviruses to replicate their genomes. 19. Which of the following terms refers to the process of making a protein from an mRNA template? A. Translation B. Transcription C. Replication D. Recombination Answer: A. Translation Rationale: Translation is the process by which a protein is synthesized from an mRNA template, involving the decoding of the mRNA sequence to assemble the corresponding amino acid sequence. 20. Which of the following best describes the role of tRNA in protein synthesis? A. Carrying amino acids to the ribosome B. Synthesizing RNA from a DNA template C. Catalyzing the formation of peptide bonds D. Transcribing DNA into RNA Answer: A. Carrying amino acids to the ribosome Rationale: tRNA (transfer RNA) molecules are responsible for carrying amino acids to the ribosome during protein synthesis, where they are added to the growing polypeptide chain. 21. Which of the following terms refers to the process of amplifying a specific DNA sequence through repeated cycles of denaturation, annealing, and extension? A. Translation B. Transcription C. PCR (polymerase chain reaction) D. Transformation Answer: C. PCR (polymerase chain reaction) Rationale: PCR is a common technique used to amplify specific DNA sequences through repeated cycles of denaturation, annealing, and extension using DNA polymerase. 22. Which of the following best describes the function of CRISPR in genome editing? A. Recognition of specific DNA sequences B. Synthesis of RNA from a DNA template C. Introduction of specific mutations into a genome What is the role of a restriction enzyme in genetic engineering? A) DNA replication B) DNA splicing C) Protein synthesis D) DNA sequencing Answer: B) DNA splicing Rationale: Restriction enzymes are used to cut DNA at specific sequences, allowing for the splicing of DNA fragments in genetic engineering. Which term refers to the complete set of genes in an organism? A) Allele B) Genome C) Trait D) Chromosome Answer: B) Genome Rationale: The genome is the entire set of genes present in an organism, including both coding and non-coding regions. What is the primary function of messenger RNA (mRNA) in protein synthesis? A) Carries amino acids to the ribosome B) Carries the genetic code from DNA to the ribosome C) Forms peptide bonds between amino acids D) Initiates translation Answer: B) Carries the genetic code from DNA to the ribosome Rationale: mRNA serves as the messenger that carries the genetic information from DNA to the ribosome for protein synthesis. Which process involves the creation of a complementary RNA strand from a DNA template? A) Translation B) Transcription C) Replication D) DNA repair Answer: B) Transcription Rationale: Transcription is the process by which an RNA molecule is synthesized from a DNA template, forming a complementary RNA strand. What is the function of tRNA (transfer RNA) in protein synthesis? A) Carries amino acids to the ribosome B) Transcribes DNA into RNA C) Initiates translation D) Forms peptide bonds between amino acids Answer: A) Carries amino acids to the ribosome Rationale: tRNA molecules deliver specific amino acids to the ribosome during protein synthesis based on the mRNA codons. In bacterial genetics, what is the term for the uptake of naked DNA from the environment? A) Transformation B) Transduction C) Conjugation D) Transcription Answer: A) Transformation Rationale: Transformation is the process by which bacteria take up external naked DNA from the environment and incorporate it into their own genome. Which enzyme is responsible for unwinding the DNA double helix during replication? A) DNA polymerase B) Helicase C) Ligase D) Topoisomerase Answer: B) Helicase Rationale: Helicase is an enzyme that unwinds the DNA double helix by breaking the hydrogen bonds between the base pairs during replication. What is the term for the process by which a gene is turned on to produce a functional product? A) Repression B) Transcription C) Translation D) Gene expression Answer: D) Gene expression Rationale: Gene expression refers to the process by which information from a gene is used to produce a functional gene product like a protein. Which term describes the phenomenon where a single gene influences multiple distinct traits? A) Pleiotropy B) Codominance C) Epistasis D) Polygenic inheritance Answer: A) Pleiotropy Rationale: Pleiotropy occurs when a single gene has multiple effects on an organism's phenotype, influencing different traits. What is the function of a vector in genetic engineering? A) Carries genes into a host cell B) Transcribes mRNA C) Replicates DNA D) Synthesizes proteins Answer: A) Carries genes into a host cell Rationale: Vectors are DNA molecules used to transport foreign genetic material into a host cell during genetic engineering processes. Which of the following genetic disorders is caused by an abnormality in the number of sex chromosomes? A) Down syndrome B) Turner syndrome C) Cystic fibrosis D) Huntington's disease Answer: B) Turner syndrome Rationale: Turner syndrome is a genetic disorder caused by the complete or partial absence of one of the two X chromosomes in females. What is the term for the process by which a segment of DNA is copied to produce a complementary RNA molecule? A) Translation B) Transcription C) Replication