Lecture 14: Transcription & Translation Flashcards
What are genes made up of?
DNA
How are genes expressed in the phenotype?
As polypeptides.
What is the central dogma of molecular biology?
DNA + RNA = Protein
True or false. RNA viruses exclude DNA altogether, going directly from RNA to Protein.
True.
in retroviruses, what is the rule for transcription?
It is reversed.
RNA to DNA to RNA to Protein
What are the two steps that express a gene?
1) DNA is transcribed to RNA
2) RNA is translated into protein
How is DNA transcribed to RNA?
Buy a DNA template after the basis of DNA are exposed by unwinding of the double helix.
True or false. In a given region of DNA, both strands can act as a template for transcription.
False. In a given region of DNA, only one of the two strands can act as a template for transcription.
How does RNA polymerase catalyze transcription?
By using the template strand of DNA.
How does initiation of transcription work?
RNA polymerase recognizes and binds tightly to promoter sequence on DNA.
True or false. RNA will elongate into a 3’ to 5’ direction, parallel to the template DNA.
False. RNA will elongate into a 5’ to 3’ direction, antiparallel to the template DNA.
How are the transcriptions terminated?
Through special sequences, and protein helpers.
What does the genetic code consist of?
Triplets of nucleotides (codons)
What is the number of the total possible codons?
64 because there there are 4 bases (4^3)
Why is the genetic code called redundant?
Because there are only 20 different amino acids and there is more than one codon for certain amino acids.
Why is the genetic code unambiguous?
Because a single code does not specify more than one amino acid.
In prokaryotes, when does translation begin?
It begins before the mRNA is completed.
In eukaryotes where does transcription and translation occur?
Transcription in the nucleus and translation in the cytoplasm.
What are the three components that translation requires?
- tRNA’s
- activating enzymes
- Ribosomes
True or false. In translation, amino acids are linked in codon-specified, order in mRNA.
True.
When is the codon-specified order in mRNA achieved?
when the transfer RNA (tRNA) binds the correct amino acid, and has an anti-codeine complementary to the mRNA codon.
How are charged tRNA’s formed?
Through the aminoacyl-tRNA synthetases that attaches a specific amino acid to its appropriate tRNA.
Where does the mRNA meet the charged tRNA?
At a ribosome.
What triggers the beginning of translation?
When an initiation complex consisting of an amino acid-charged tRNA and a small ribosomal subunit bound to mRNA.
