Molecular basis of inheritance - DNA structure replication transcription translation genetic code - Question Bank

1. What is the function of aminoacyl-tRNA synthetase?
A) To synthesize mRNA
B) To link amino acids to their corresponding tRNA molecules
C) To unwind DNA
D) To terminate translation
2. Which of the following is NOT a characteristic of the genetic code?
A) Universal
B) Ambiguous
C) Degenerate
D) Non-overlapping
3. The process of DNA replication is essential for:
A) Protein synthesis
B) Cell division
C) Energy production
D) Waste removal
4. What is the 'wobble' hypothesis in translation?
A) The third base of the codon can sometimes mismatch with the anticodon.
B) The first base of the anticodon can pair with more than one base on the mRNA.
C) The ribosome can move backwards along the mRNA.
D) Amino acids can be added in reverse order.
5. Which enzyme seals the nicks in the sugar-phosphate backbone of DNA during replication?
A) Helicase
B) Primase
C) DNA polymerase
D) DNA ligase
6. The genetic code specifies the sequence of:
A) Nucleotides in DNA
B) Amino acids in proteins
C) Bases in RNA
D) Sugars in DNA
7. What is the process called when DNA is transcribed into RNA?
A) Translation
B) Replication
C) Transcription
D) Reverse transcription
8. Which RNA molecule is involved in protein synthesis and has an anticodon loop?
A) mRNA
B) rRNA
C) tRNA
D) snRNA
9. What is the primary function of DNA?
A) Protein synthesis
B) Energy storage
C) Carrying genetic information
D) Catalyzing biochemical reactions
10. The antiparallel nature of DNA strands refers to:
A) The bases pairing in opposite directions
B) The sugar-phosphate backbones running in opposite directions (5' to 3' and 3' to 5')
C) The helical twist of the molecule
D) The presence of hydrogen bonds
11. Which of the following is a pyrimidine base found in DNA?
A) Adenine
B) Guanine
C) Cytosine
D) Adenine and Guanine
12. The structure of DNA described by Watson and Crick was:
A) Single-stranded helix
B) Double-stranded helix
C) Triple-stranded helix
D) Linear double strand
13. What is the role of a sigma factor in bacterial transcription?
A) To unwind the DNA double helix
B) To terminate transcription
C) To recognize and bind to the promoter region
D) To ligate DNA fragments
14. In prokaryotes, where does transcription and translation occur?
A) Transcription in nucleus, translation in cytoplasm
B) Transcription and translation in nucleus
C) Transcription and translation in cytoplasm
D) Transcription in cytoplasm, translation in nucleus
15. What is the term for the region of DNA where replication begins?
A) Origin of replication
B) Terminator sequence
C) Promoter
D) Enhancer
16. Which enzyme is responsible for adding nucleotides to the 3' end of a growing DNA strand?
A) Helicase
B) Ligase
C) DNA polymerase
D) Primase
17. What is the function of telomeres in eukaryotic chromosomes?
A) To initiate DNA replication
B) To protect the ends of chromosomes from degradation
C) To bind transcription factors
D) To form the centromere
18. The genetic code is nearly universal. Which of the following is an exception?
A) Mitochondrial DNA
B) Bacterial DNA
C) Viral DNA
D) Plant DNA
19. How many different types of amino acids are commonly found in proteins?
A) 10
B) 20
C) 30
D) 40
20. The anticodon on tRNA is complementary to the:
A) DNA template strand
B) DNA coding strand
C) mRNA codon
D) Antigen
21. Ribosomes are composed of:
A) DNA and proteins
B) RNA and proteins
C) Only DNA
D) Only proteins
22. Which molecule carries the genetic code from the nucleus to the cytoplasm in eukaryotes?
A) DNA
B) tRNA
C) rRNA
D) mRNA
23. What is the term for a coding sequence within a gene that is retained in the mature mRNA?
A) Intron
B) Exon
C) Anticodon
D) Terminator
24. What is the term for a non-coding sequence within a gene that is removed during RNA processing?
A) Exon
B) Intron
C) Codon
D) Promoter
25. What is the function of the promoter region in a gene?
A) It signals the termination of transcription.
B) It is the binding site for RNA polymerase.
C) It codes for the protein product.
D) It is involved in DNA replication.
26. In eukaryotes, transcription occurs in the:
A) Cytoplasm
B) Ribosomes
C) Nucleus
D) Mitochondria
27. What does the term 'semi-conservative replication' mean?
A) Each new DNA molecule consists of two completely new strands.
B) Each new DNA molecule consists of one original strand and one newly synthesized strand.
C) The original DNA molecule is completely broken down and rebuilt.
D) Replication occurs only once per cell cycle.
28. Erwin Chargaff's rules state that in DNA, the amount of Adenine is equal to the amount of Thymine, and the amount of Guanine is equal to the amount of Cytosine. This is known as:
A) Central dogma
B) Semi-conservative replication
C) Base pairing rules
D) Chargaff's rules
29. The start codon, which also codes for Methionine, is typically:
A) UAA
B) UAG
C) AUG
D) UGA
30. Which of the following is a 'stop' codon in the genetic code?
A) AUG
B) UAA
C) GGC
D) CUU
31. The genetic code is said to be degenerate because:
A) It is universal
B) Multiple codons can specify the same amino acid
C) It contains stop codons
D) It reads in triplets
32. A sequence of three nucleotides on mRNA that specifies an amino acid is called a:
A) Gene
B) Codon
C) Anticodon
D) Intron
33. What is the role of messenger RNA (mRNA) in translation?
A) Carries amino acids to the ribosome
B) Provides the genetic code for protein synthesis
C) Forms the ribosomal structure
D) Catalyzes peptide bond formation
34. What is the function of transfer RNA (tRNA) in translation?
A) Carries genetic information from DNA
B) Carries amino acids to the ribosome
C) Forms the structural component of ribosomes
D) Catalyzes peptide bond formation
35. Where does translation primarily occur in eukaryotic cells?
A) Nucleus
B) Ribosomes
C) Golgi apparatus
D) Endoplasmic reticulum
36. The process of synthesizing proteins from an mRNA template is called:
A) Transcription
B) Replication
C) Translation
D) Mutation
37. What is the sequence of events in gene expression?
A) Replication -> Transcription -> Translation
B) Transcription -> Translation -> Replication
C) Translation -> Transcription -> Replication
D) Transcription -> Replication -> Translation
38. In RNA, which base replaces Thymine (T) when pairing with Adenine (A)?
A) Guanine (G)
B) Cytosine (C)
C) Uracil (U)
D) Adenine (A)
39. During transcription, which DNA strand serves as the template for RNA synthesis?
A) Coding strand
B) Non-coding strand
C) Template strand
D) Sense strand
40. Which enzyme is responsible for catalyzing transcription?
A) DNA polymerase
B) RNA polymerase
C) Ribosome
D) Peptidyl transferase
41. The process of synthesizing RNA from a DNA template is called:
A) Replication
B) Translation
C) Transcription
D) Reverse transcription
42. What is the role of DNA ligase in DNA replication?
A) To unwind the DNA helix
B) To synthesize new DNA strands
C) To join Okazaki fragments
D) To remove RNA primers
43. Okazaki fragments are short segments of DNA synthesized on which strand during replication?
A) Leading strand
B) Lagging strand
C) Template strand
D) Coding strand
44. Which enzyme synthesizes new DNA strands during replication?
A) RNA polymerase
B) DNA polymerase
C) Reverse transcriptase
D) Telomerase
45. During DNA replication, which enzyme is primarily responsible for unwinding the DNA double helix?
A) DNA ligase
B) Primase
C) Helicase
D) Topoisomerase
46. What is the process by which DNA makes a copy of itself called?
A) Transcription
B) Translation
C) Replication
D) Mutation
47. The two strands of DNA are held together by which type of bonds?
A) Covalent bonds
B) Peptide bonds
C) Hydrogen bonds
D) Ionic bonds
48. Which of the following is a purine base found in DNA?
A) Thymine
B) Cytosine
C) Adenine
D) Uracil
49. In the DNA double helix, which base pairs with Adenine (A)?
A) Guanine (G)
B) Cytosine (C)
C) Thymine (T)
D) Uracil (U)
50. Which scientist is credited with discovering the double helix structure of DNA?
A) Rosalind Franklin
B) Maurice Wilkins
C) James Watson and Francis Crick
D) Erwin Chargaff
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