Bio Test 4 Flashcards
What is gene expression?
The process by which DNA directs the synthesis of proteins. The expression of genes that code for proteins includes two stages: transcription and translation
What is transcription?
The synthesis of RNA using a DNA template; Double helix, in the nucleus
What is translation?
The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of “language” from nucleotides to amino acids; mRNA sequence in the cytoplasm
In eukaryotes, what is the pre-mRNA called?
Primary transcript
How many nucleotide bases are there?
4
How many amino acid bases are there?
20
How many unique triplet codes exist?
64
What is the start codon?
AUG
Why is genetic code said to be redundant but not ambiguous?
Under normal circumstances, a given codon encodes one and only amino acid
Name the enzyme that uses the DNA template strand to transcribe a new mRNA strand:
Messenger RNA
Why is the promoter area important in beginning transcription?
A specific nucleotide sequence in the DNA of a gene that binds RNA polymerase, positioning it to start transcribing RNA at the appropriate place
What region signals the end of transcription?
Terminator
What is a transcription unit?
A region of DNA being transcribed into an RNA molecule
What is the TATA box?
A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
In the elongation of the RNA strand how is the DNA unwound? What happens to the growing strain?
Histones, the growing RNA chain is extended by one nucleotide at a time in the 5’-3’ direction
