In a eukaryotic cell, the _____ ______ separates transcription from translation
what is a primary transcript?
the initial RNA transcript from any gene
What is RNA processing?
Eukaryotic RNA transcripts are modified through RNA processing to yield finished mRNA
what type of nucleotide base code is used for the instructions for assembling amino acids into proteins?
the flow of information from gene to protein is based on a triplet code: a series of nonoverlapping, three-nucleotide words. These triplets are the smallest units of uniform length that can code for all the amino acids. the mRNA base triplets are called codons.
For example, AGT at a particular position on a DNA strand results in the placement of amino acid serine at the corresponding position of the polypeptide to be produced
during translation codons are read how?
they are read in the 5' to 3' direction
how many codons are there and what do they code for?
there are 64 triplets. 61 code for amino acids; 3 triplets are "stop" signals to end translation
what is the reading frame?
how the translational machinery of the cell reads the mRNA strand
does RNA polymerase require single-strand binding proteins and topoisomerases?
no, it pries open short sequences of the DNA strands as it moves along the DNA strands. The strands then rebind after the RNA polymerase has passed
what are the terminator and the promoter?
the DNA sequence where RNA polymerase attaches is called the promoter; in bacteria, the sequence signaling the end of transcription is called the terminator
what is the transcription unit?
the stretch of DNA that is transcribed is called a transcription unit
what are the three stages of transcription?
initiation, elongation, and termination
_____ ______ mediate the binding of RNA polymerase and initiation of the transcription. when _____ ______ combine with ____ _______ __ bound to a promoter, the structure formed is called a ________ ______ _____
transcription factors, transcription factors, RNA polymerase II, transcription initiation complex
what is a TATA box?
a promoter called a TATA box is crucial in forming the initiation complex in eukaryotes
describe the mechanisms for termination in bacteria and eukaryotes
in bacteria, the polymerase stops transcription at the end of the terminator.
In eukaryotes, the polymerase continues transcription after the pre-mRNA is cleaved from the growing RNA chain; the polymerase eventually falls of the DNA
where does RNA processing occur?
in the nucleus
what happens to the end of the pre-RNA during RNA processing?
the 5' end receives a modified nucleotide 5' cap. The 3' end gets a poly-A tail
what is the purpose of modifying the ends of the pre-mRNA