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

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

Answer: C) Transduction. Rationale: Transduction occurs when a bacteriophage transfers genetic material from one bacterium to another, which can include genes for antibiotic resistance or virulence factors.

5. How does the process of transformation contribute to genetic variation in bacteria? A) By the creation of new genes through mutation B) By the uptake and incorporation of foreign DNA from the environment C) By the exchange of plasmids during conjugation D) By the rearrangement of genes within the chromosome Answer: B) By the uptake and incorporation of foreign DNA from the environment. Rationale: Transformation allows bacteria to take up free DNA from their surroundings and incorporate it into their genome, leading to genetic diversity.
6. In bacterial genetics, what is the significance of the F factor (fertility factor)? A) It is a gene that codes for flagellar motion. B) It is a plasmid that carries genes for antibiotic resistance. C) It is a segment of DNA that controls the synthesis of toxins. D) It is a plasmid that enables the process of conjugation. Answer: D) It is a plasmid that enables the process of conjugation. Rationale: The F factor is a plasmid that contains genes necessary for the formation of a pilus and the initiation of conjugation, allowing for the transfer of genetic material between bacteria.
7. Which term describes the phenomenon where genes are transferred from a mother cell to its daughter cells? A) Vertical gene transfer B) Horizontal gene transfer C) Lateral gene transfer D) Diagonal gene transfer Answer: A) Vertical gene transfer. Rationale: Vertical gene transfer refers to the inheritance of genetic material from parent organisms to their offspring, which is the primary method of genetic propagation in most organisms.
8. What is the primary function of ribosomal RNA (rRNA) in the process

of protein synthesis? A) It carries amino acids to the ribosome. B) It serves as the site of protein assembly. C) It reads the mRNA codons. D) It assists in DNA replication. Answer: B) It serves as the site of protein assembly. Rationale: rRNA, along with proteins, makes up the ribosome, which is the cellular machinery where proteins are synthesized.

9. In the lac operon model, what is the role of the repressor protein? A) It binds to the operator to enhance transcription. B) It binds to the promoter to initiate transcription. C) It binds to the operator to prevent transcription. D) It binds to the lactose to break it down. Answer: C) It binds to the operator to prevent transcription. Rationale: The repressor protein binds to the operator region of the lac operon, blocking RNA polymerase and preventing transcription of the genes needed for lactose metabolism until lactose is present.
10. What is the significance of the 'start codon' in mRNA? A) It signals the end of translation. B) It adds a methyl group to the mRNA. C) It signals the beginning of translation. D) It removes introns from the pre-mRNA. Answer: C) It signals the beginning of translation. Rationale: The start codon (AUG) on mRNA signals the ribosome to begin translating the mRNA into a protein, marking the start of the coding sequence.
11. Which enzyme is responsible for the synthesis of mRNA from a DNA template? A) DNA ligase B) RNA polymerase C) Reverse transcriptase D) Helicase Answer: B) RNA polymerase. Rationale: RNA polymerase synthesizes mRNA by reading the DNA template strand and assembling the corresponding RNA nucleotides.

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-Cas 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

complementary RNA strand B. RNA polymerase synthesizes a complementary DNA strand from a DNA template C. DNA polymerase synthesizes a complementary DNA strand from a DNA template D. RNA polymerase synthesizes a complementary RNA strand from an RNA template Answer: C. DNA polymerase synthesizes a complementary DNA strand from a DNA template Rationale: DNA replication is the process by which a DNA molecule is copied to create two identical DNA molecules, and it is carried out by DNA polymerase.

8. Which of the following terms refers to the genetic material found in bacteria outside of the main chromosomal DNA? A. Allele B. Plasmid C. Transposon D. Vector Answer: B. Plasmid Rationale: Plasmids are small, circular DNA molecules found in bacteria that can replicate independently of the main chromosomal DNA.
9. Which of the following best describes the function of restriction enzymes in genetic engineering? A. Adding nucleotides to a DNA strand B. Cutting DNA at specific sequences C. Ligating DNA fragments together D. Amplifying DNA through PCR Answer: B. Cutting DNA at specific sequences Rationale: Restriction enzymes are enzymes that cut DNA at specific sequences, allowing for the manipulation and modification of DNA molecules in genetic engineering.
10. Which of the following terms refers to the process by which a bacterial

cell takes up DNA from its environment and incorporates it into its genome? A. Transformation B. Conjugation C. Transduction D. Transcription Answer: A. Transformation Rationale: Transformation is the process by which a bacterial cell takes up DNA from its environment and incorporates it into its genome, leading to genetic changes in the recipient cell.

11. Which of the following best describes a frameshift mutation in a gene sequence? A. A single nucleotide is substituted for another B. A single nucleotide is inserted into the sequence C. A single nucleotide is deleted from the sequence D. A silent mutation occurs with no change in the amino acid sequence Answer: B. A single nucleotide is inserted into the sequence Rationale: A frameshift mutation occurs when a single nucleotide is inserted or deleted from a gene sequence, causing a shift in the reading frame and potentially altering the entire amino acid sequence of the protein.
12. Which of the following terms refers to the process of making complementary RNA strands from a DNA template? A. Translation B. Transcription C. Replication D. Recombination Answer: B. Transcription Rationale: Transcription is the process of synthesizing complementary RNA strands from a DNA template, which is a key step in gene expression and protein synthesis.
13. Which of the following processes involves the use of reverse

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. 1 7. 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

D. Ligation of DNA fragments Answer: A. Recognition of specific DNA sequences Rationale: CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a bacterial defense mechanism that can target and cleave specific DNA sequences, making it a powerful tool for genome editing.

23. Which of the following terms refers to the process by which a DNA molecule is copied to create two identical DNA molecules? A. Translation B. Transcription C. Replication D. Recombination Answer: C. Replication Rationale: DNA replication is the process by which a DNA molecule is copied to create two identical DNA molecules, necessary for cell division and the inheritance of genetic information.
24. Which of the following best describes the role of primase in DNA replication? A. Unwinding the DNA double helix B. Synthesizing the RNA primer C. Joining Okazaki fragments D. Proofreading the DNA sequence Answer: B. Synthesizing the RNA primer Rationale Which of the following best describes a plasmid? A) A type of virus B) Circular DNA found in bacteria C) Double-stranded RNA molecule D) Protein synthesis site in a cell Answer: B) Circular DNA found in bacteria Rationale: Plasmids are small, circular DNA molecules found in bacteria that can replicate independently of the chromosomal DNA.

What is the function of DNA ligase in genetic engineering? A) Transcription of DNA B) Replication of DNA C) Joining DNA fragments D) Reading mRNA Answer: C) Joining DNA fragments Rationale: DNA ligase is an enzyme that is used to join DNA fragments together during genetic engineering processes like cloning. Which of the following is an example of a genetic mutation? A) DNA replication B) Translation C) Substitution of a nucleotide base D) Protein folding Answer: C) Substitution of a nucleotide base Rationale: Genetic mutations involve changes in the DNA sequence, such as substitutions, insertions, or deletions of nucleotide bases. What is the purpose of PCR (Polymerase Chain Reaction) in microbiology? A) Amplification of DNA B) Protein synthesis C) RNA splicing D) DNA sequencing Answer: A) Amplification of DNA Rationale: PCR is a technique used to amplify a specific segment of DNA, making multiple copies for analysis. Which process involves the transfer of genetic material from one bacterial cell to another through direct cell-to-cell contact? A) Transformation B) Transduction C) Conjugation D) Replication Answer: C) Conjugation Rationale: Conjugation is the transfer of genetic material between bacterial cells through direct contact, often mediated by a plasmid.

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

D) DNA repair Answer: B) Transcription Rationale: Transcription is the process by which RNA is synthesized from a DNA template, resulting in the production of an RNA molecule. Which genetic disorder results from the inability to properly metabolize phenylalanine? A) Tay-Sachs disease B) Sickle cell anemia C) Phenylketonuria (PKU) D) Hemophilia Answer: C) Phenylketonuria (PKU) Rationale: Phenylketonuria (PKU) is a genetic disorder caused by the inability to metabolize phenylalanine, leading to an accumulation of this amino acid in the body. In which process does the ribosome read the mRNA codons and assemble the corresponding amino acids into a polypeptide chain? A) Transcription B) Translation C) Replication D) Protein synthesis Answer: B) Translation Rationale: Translation is the process where the ribosome interprets the mRNA codons and links the corresponding amino acids to form a polypeptide chain. Which of the following is an example of a point mutation? A) Deletion of a nucleotide base B) Addition of a nucleotide base C) Substitution of a nucleotide base D) Inversion of a gene sequence Answer: C) Substitution of a nucleotide base Rationale: Point mutations involve the substitution of a single nucleotide base with another, potentially leading to changes in the protein sequence. What is the term for the complete set of proteins produced by an

organism? A) Genome B) Proteome C) Transcriptome D) Metabolome Answer: B) Proteome Rationale: The proteome refers to the entire set of proteins produced by an organism, reflecting the dynamic state of cellular activities. Which enzyme is responsible for synthesizing a new DNA strand complementary to a template DNA strand during replication? A) DNA polymerase B) Helicase C) Ligase D) Topoisomerase Answer: A) DNA polymerase Rationale: DNA polymerase is the enzyme that catalyzes the synthesis of a new DNA strand by adding nucleotides complementary to the template strand during replication. What is the term for the specific location of a gene on a chromosome? A) Locus B) Allele C) Exon D) Intron Answer: A) Locus Rationale: Locus refers to the precise location of a gene on a chromosome, representing a specific position where a particular gene is located. Which type of mutation results in the insertion or deletion of nucleotide bases, shifting the reading frame of the genetic code? A) Silent mutation B) Frameshift mutation C) Missense mutation D) Nonsense mutation Answer: B) Frameshift mutation Rationale: Frameshift mutations occur when nucleotide bases are

inserted or deleted, causing a shift in the reading frame of the genetic code and potentially altering the entire protein sequence. What is the term for the process by which foreign DNA is introduced into a host cell to produce specific proteins? A) Cloning B) Transduction C) Transformation D) Conjugation Answer: A) Cloning Rationale: Cloning involves the introduction of foreign DNA into a host cell to produce multiple copies of a specific gene or protein for various applications in research and biotechnology.