18 Questions
What is the role of the sigma factor in prokaryotic transcription initiation?
It helps RNA polymerase recognize the promoter sequence
Where in the eukaryotic cell do transcription, mRNA processing, and translation occur? What makes this different than prokaryotes?
Transcription and mRNA processing in the nucleus, translation in the cytoplasm; differs from prokaryotes where all processes occur in the cytoplasm
What do we mean when we say the genetic code is 'universal' and 'degenerate'?
Universal: The genetic code is the same for all organisms; Degenerate: Each amino acid is coded by only one codon
During mRNA synthesis, where does the energy come from to create bonds between nucleotides?
From the cleavage of ATP to AMP and pyrophosphate
What is the importance of the 2’, 3’, and 5’ carbons of RNA (and/or DNA)?
They are involved in forming the sugar-phosphate backbone of the nucleic acid.
Given that there are 20 amino acids, explain why the genetic code cannot consist of two nucleotides per codon, and why it would be overkill to use four nucleotides per codon.
Two nucleotides per codon would not provide enough combinations to code for 20 amino acids, while four nucleotides per codon would result in redundancy and inefficiency.
What is the role of tRNA? How are tRNAs 'charged'?
tRNA carries specific amino acids to the ribosome during translation; they are 'charged' through the addition of a phosphate group.
What do we mean when we say the genetic code is 'universal'?
The same genetic code is used by all living organisms on Earth.
What is the difference between DNA, gene, and chromosome?
A gene is a specific sequence of DNA that contains the information for making a particular protein, while a chromosome is a structure composed of DNA and proteins that carries many genes.
Why is it important for the initiation of transcription to be tightly controlled in both prokaryotes and eukaryotes?
Tightly controlled initiation ensures that the correct genes are expressed at the right time and in the right amounts.
Where does transcription occur in eukaryotic cells?
In the nucleus
What is the role of the 2’, 3’, and 5’ carbons of RNA (and/or DNA)?
They are involved in forming the backbone structure of the RNA or DNA molecule.
What is the role of the nontemplate strand in transcription?
It acts as the coding strand for protein synthesis.
What is the role of the sigma factor in prokaryotic transcription initiation?
It helps to unwind the DNA double helix at the initiation site.
Why is it overkill to use four nucleotides per codon in the genetic code?
It would make the genetic code too complex and error-prone.
What do we mean when we say the genetic code is 'degenerate'?
It means that the genetic code has redundancy, with some amino acids being specified by more than one codon.
How are tRNAs 'charged'?
They are activated by attaching a specific amino acid to their 3’ end.
What is the difference between a gene and a codon?
A gene is a sequence of nucleotides that encodes a specific protein, while a codon is a three-nucleotide sequence that codes for a specific amino acid.
Test your knowledge of molecular biology with this quiz. Explore the significance of the 2’, 3’, and 5’ carbons in RNA and DNA, as well as the universal and degenerate nature of the genetic code. Delve into the limitations of using two or four nucleotides per codon and differentiate between DNA, gene, codon, exon, and chromosome.
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