Podcast
Questions and Answers
During DNA replication, which enzymatic activity is responsible for excising misincorporated bases and replacing them with the correct ones?
During DNA replication, which enzymatic activity is responsible for excising misincorporated bases and replacing them with the correct ones?
- 3' -> 5' exonuclease activity (correct)
- Ligase activity
- 5' -> 3' polymerase activity
- 5' -> 3' exonuclease activity
In eukaryotic cells, pre-mRNA undergoes processing before translation. Which of the following modifications is essential for creating a translatable mRNA molecule?
In eukaryotic cells, pre-mRNA undergoes processing before translation. Which of the following modifications is essential for creating a translatable mRNA molecule?
- The addition of amino acids
- The removal of introns and splicing together of exons (correct)
- The removal of exons
- Replication
What is the crucial role of aminoacyl-tRNA synthetases in the process of translation?
What is the crucial role of aminoacyl-tRNA synthetases in the process of translation?
- To ensure each tRNA molecule is paired with the appropriate mRNA codon within the ribosome.
- To initiate the process of transcription by binding to a promoter sequence on the DNA.
- To catalyze the formation of peptide bonds between amino acids.
- To attach the correct amino acid to its corresponding tRNA molecule based on the tRNA's anticodon. (correct)
Which of the following is true regarding the directionality of DNA polymerase activity during replication?
Which of the following is true regarding the directionality of DNA polymerase activity during replication?
If a mutation occurs such that a stop codon is introduced prematurely in an mRNA sequence, what is the most likely consequence?
If a mutation occurs such that a stop codon is introduced prematurely in an mRNA sequence, what is the most likely consequence?
Considering the semiconservative nature of DNA replication, what would be the composition of two new DNA molecules after one round of replication, starting from one double-stranded DNA molecule?
Considering the semiconservative nature of DNA replication, what would be the composition of two new DNA molecules after one round of replication, starting from one double-stranded DNA molecule?
What determines the sequence of amino acids in a protein?
What determines the sequence of amino acids in a protein?
Where does translation take place?
Where does translation take place?
What is the role of DNA ligase during DNA replication?
What is the role of DNA ligase during DNA replication?
What is the start codon that signals the beginning of translation, and which amino acid does it code for in eukaryotes?
What is the start codon that signals the beginning of translation, and which amino acid does it code for in eukaryotes?
During transcription, what region of a gene does RNA polymerase bind to, to initiate the creation of RNA?
During transcription, what region of a gene does RNA polymerase bind to, to initiate the creation of RNA?
What is the name given to three consecutive bases in RNA that specify one amino acid in protein synthesis?
What is the name given to three consecutive bases in RNA that specify one amino acid in protein synthesis?
According to the central dogma, what is the correct sequence of information flow in a cell?
According to the central dogma, what is the correct sequence of information flow in a cell?
What is the function of a reading frame?
What is the function of a reading frame?
In the context of transcription, what is the role of the template strand?
In the context of transcription, what is the role of the template strand?
Flashcards
Semiconservative replication
Semiconservative replication
DNA replication where each new DNA molecule consists of one original strand and one newly synthesized strand.
Origin of replication
Origin of replication
Specific DNA sequence where the double helix is pulled apart and replication begins.
Replication fork
Replication fork
The point where DNA strands separate during replication, creating a Y-shaped structure.
DNA polymerase
DNA polymerase
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5' to 3' strand extension
5' to 3' strand extension
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Proofreading function
Proofreading function
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DNA ligase
DNA ligase
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Central Dogma
Central Dogma
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Genetic code
Genetic code
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Triplet code
Triplet code
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Codon
Codon
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Transcription
Transcription
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Template strand
Template strand
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Promoter
Promoter
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Pre-mRNA
Pre-mRNA
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Study Notes
- RNA and DNA are polymers of nucleotides
- DNA exists as a double-stranded helix
- DNA replication depends on specific base pairing
- DNA replication proceeds in two directions at many sites simultaneously
- Genes control phenotypic traits through protein expression
- Genetic information in codons translates into amino acid sequences
- The genetic code dictates how codons translate into amino acids
- Transcription produces genetic messages in the form of RNA
- Eukaryotic RNA is processed into mRNA before leaving the nucleus
- Transfer RNA molecules serve as interpreters during translation
- Ribosomes build polypeptides
- An initiation codon marks the start of an mRNA message
- Elongation adds amino acids to the polypeptide chain until a stop codon terminates translation
- Genetic information flows from DNA to RNA to protein
DNA Replication
- DNA replication is semiconservative
- DNA replication's specificity and fidelity arise from complementary base pairing in a DNA double helix
- DNA double helix is pulled apart at the origin of replication, where replication reactions begin
- The replication origin has two replication forks moving in opposite directions
- DNA polymerase adds nucleotides only to the 3' end of a strand, working in the 5' -> 3' direction
- DNA polymerase corrects mispairing mistakes via a proofreading function, excising the misincorporated base (3' -> 5' exonuclease activity)
Gene Expression - Overview
- The Central Dogma is: DNA -> RNA -> protein
- The genetic code links the base sequence in a gene (or RNA) and the amino acid sequence in the encoded protein
- The genetic code is a triplet code where three consecutive RNA bases specify one amino acid in protein synthesis
- Each meaningful triplet is a codon
- There are 64 (4x4x4) base triplets
Gene Expression - Transcription and RNA Processing
- Transcription synthesizes an RNA molecule from a DNA template
- In eukaryotes, transcription occurs in the nucleus, mitochondria, and chloroplast
- RNA synthesis uses one DNA strand as a template
- The promoter is a special DNA sequence near the transcription start site
- RNA polymerase binds to the exposed DNA template strand at the promoter
- Transcription terminates at a special DNA sequence downstream of the coding portion of the RNA producing pre-mRNA
- Pre-mRNA undergoes modifications to become mature, processed mRNA for translation
Gene Expression - Translation
- Translation occurs on ribosomes in the cytoplasm
- Two ribosome subunits assemble on an mRNA molecule exported from the nucleus
- Transfer RNA (tRNA) molecules each carry a specific amino acid and anticodon
- Codons have no punctuation or spaces
- After incorporating an amino acid, the ribosome moves 3 bases to the next mRNA codon
- A reading frame divides a DNA or RNA sequence into triplets
- Translation stops when the ribosome encounters a STOP codon (UAA, UAG, UGA)
- The ribosome, mRNA, and polypeptide detach from each other after reaching the stop codon
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