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Molecular Genetics Essentials
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1
Question
What is the "one-gene, one-enzyme" hypothesis?
Page 1
Answer
The hypothesis that each gene directs the synthesis of one enzyme.
2
Question
What is the genetic code?
Page 1
Answer
The set of rules by which nucleotide triplet sequences (codons) in DNA or RNA specify amino acid sequences in proteins.
3
Question
How does the genetic code differ between DNA and RNA?
Page 1
Answer
DNA uses thymine (T) in codons, while RNA uses uracil (U) instead of thymine; the codon sequences are otherwise equivalent.
4
Question
How does the Central Dogma relate genotype to phenotype?
Page 1
Answer
The Central Dogma describes information flow from DNA (genotype) to RNA to protein, linking genetic sequence to observable traits (phenotype).
5
Question
What is transcription?
Page 1
Answer
The process of synthesizing RNA from a DNA template.
6
Question
What is the structure and origin of mRNA?
Page 1
Answer
mRNA is single-stranded RNA transcribed from the template strand of DNA; it carries the genetic code from nucleus to ribosome.
7
Question
What is the structure and origin of tRNA?
Page 1
Answer
tRNA is a cloverleaf-shaped RNA transcribed from DNA; it has an anticodon and carries specific amino acids.
8
Question
What is the structure and origin of rRNA?
Page 1
Answer
rRNA is a component of ribosomes, transcribed from DNA in the nucleolus; it provides structural and catalytic framework for protein synthesis.
9
Question
What is the role of RNA polymerase in transcription?
Page 1
Answer
RNA polymerase binds to promoter, unwinds DNA, and synthesizes RNA complementary to the template strand.
10
Question
What is pre-mRNA?
Page 1
Answer
The initial, unprocessed transcript of eukaryotic protein-coding genes, containing introns and exons.
11
Question
What are start signals in transcription?
Page 1
Answer
Promoter sequences, such as TATA box, where RNA polymerase binds to initiate transcription.
12
Question
What are termination signals in transcription?
Page 1
Answer
Sequences like polyadenylation signals (AAUAAA) that signal the end of transcription and RNA release.
13
Question
What is the 5' cap on eukaryotic mRNA?
Page 1
Answer
A modified guanine nucleotide added to the 5' end of pre-mRNA for stability and translation initiation.
14
Question
What is the poly-A tail on eukaryotic mRNA?
Page 1
Answer
A string of adenine nucleotides added to the 3' end of pre-mRNA for stability and export.
15
Question
What are introns?
Page 1
Answer
Non-coding sequences in eukaryotic pre-mRNA that are spliced out before translation.
16
Question
What are exons?
Page 1
Answer
Coding sequences in eukaryotic pre-mRNA that are retained and joined to form mature mRNA.
17
Question
What is a mutation?
Page 1
Answer
A permanent change in the DNA sequence.
18
Question
Name three kinds of mutations.
Page 1
Answer
• Point mutations (substitutions) • Insertions • Deletions
19
Question
What is translation?
Page 1
Answer
The process of synthesizing proteins from mRNA at the ribosome.
20
Question
What are the stages of translation?
Page 1
Answer
• Initiation: ribosome assembles on mRNA • Elongation: amino acids added • Termination: stop codon reached
21
Question
What is the P site on the ribosome?
Page 1
Answer
Peptidyl site where the tRNA holding the growing polypeptide is located.
22
Question
What is the A site on the ribosome?
Page 1
Answer
Aminoacyl site where incoming charged tRNA binds.
23
Question
What is the catalytic site on the ribosome?
Page 1
Answer
The peptidyl transferase center where peptide bond formation occurs.
24
Question
What is the lac operon?
Page 1
Answer
A genetic regulatory system in E. coli controlling lactose metabolism genes.
25
Question
What is the operator in the lac operon?
Page 1
Answer
DNA sequence where repressor binds to block transcription.
26
Question
What is negative control in lac operon regulation?
Page 1
Answer
Repressor protein binds operator to prevent transcription unless lactose present.
27
Question
What is the role of CAP in lac operon?
Page 1
Answer
CAP-cAMP binds upstream of promoter to activate transcription when glucose is low.
28
Question
What is genetic engineering?
Page 2
Answer
The direct manipulation of genes using biotechnology.
29
Question
What is recombinant DNA?
Page 2
Answer
DNA molecules formed by combining DNA from different sources.
30
Question
How is reverse transcriptase used to produce cDNA?
Page 2
Answer
Reverse transcriptase synthesizes complementary DNA from an mRNA template.