2.7 DNA replication, transcription and translation Flashcards
What enzyme unwinds the double helix during DNA replication?
Helicase.
What is the role of DNA polymerase in DNA replication?
DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template.
What was the main finding of the Meselson and Stahl experiments?
They demonstrated that DNA replication is semi-conservative.
What enzyme synthesizes mRNA from DNA base sequences?
RNA polymerase.
How does uracil replace thymine in RNA?
In RNA, uracil (U) replaces thymine (T), so adenine (A) pairs with uracil (U) instead of thymine (T).
What is the role of mRNA in translation?
mRNA serves as the template for protein synthesis on ribosomes.
What does a codon on mRNA correspond to?
Each codon on mRNA corresponds to one amino acid in a polypeptide.
What is PCR used for?
To amplify small fragments of DNA rapidly.
What enzyme is crucial for PCR, and why?
Taq DNA polymerase, because it is thermostable and can withstand the high temperatures used in PCR.
How is human insulin produced in bacteria?
By transferring the human insulin gene into E. coli, utilizing the universality of the genetic code.
Why is producing insulin in bacteria advantageous over extracting it from animals?
It’s more efficient and reduces the risk of allergic reactions to animal insulin.
How can you deduce the DNA base sequence from an mRNA sequence?
By using the RNA to DNA base pairing rules. For example, mRNA sequence AGCUUA would correspond to DNA sequence TCGAAT.
Describe the detailed process of translation.
Translation involves initiation, reading mRNA codons, each specifying an amino acid, until a stop codon is reached.
How does the genetic code ensure the accurate translation of mRNA into a protein’s amino acid sequence?
The genetic code consists of codons on mRNA, each specifying a particular amino acid, ensuring accurate protein synthesis.
Give an example of how to use a genetic code table to determine an amino acid from a codon.
Codon AUG codes for Methionine (Met), according to the genetic code table.
