Reading 6 Flashcards
What is the nucleotide substrate for RNA polymerase?
ribonucleotide triphosphates
Where within a eukaryotic cell does the process of transcription occur?
nucleus
What does the enzyme RNA polymerase do?
adds ribonucleoside triphosphates to the growing new pre-mRNA
Define the term polycistronic RNA?
where a single terminator is present at the end of a group of several genes that are transcribed together
What is the function of the Shine-Dalgarno sequence?
sequence on the 5` untranslated region that serves as the ribosome binding site during translation
What is the function of the Kozak sequence?
sequence that plays a role in initiation of the translation process
Eukaryotes have many types of RNA polymerases. How do they differ from each other?
-1: synthesizes pre-rRNA
-2: synthesizes precursors of microRNA, snRNA, and mRNA
-3: synthesizes tRNA
What is a promoter, and what does it do?
gives ribosome somewhere to bind
What is an intron?
non coding, intervening sequences
What is an exon?
coding region
Describe how the 5’ and 3’ ends of most eukaryotic pre-mRNAs modified.
-5 cap: extra modified nucleotide as well as methyl groups, increases stability
-3 poly A tail: lots of adenine, stability
Describe the two-step process of splicing.
-pre-mRNA is cut at the 5 splice site, intron folds back forming a lariat
-cut at 3 splice site, exons attach, intron lariat leaves
What is alternative splicing?
a single pre-mRNA is processed in different ways to produce different proteins from same DNA
