Lecture #10 Flashcards
What is the process on how information is transfered from DNA to protein?
DNA to RNA to Protein
What RNA is transcribed in both prokaryotes and eukaryotes?
mRNA, rRNA and tRNA
What RNA is produced only in prokaryotes?
CRISPR RNA (crRNA)
What structures makes RNA different than DNA?
contains a ribose instead of deoxyribose, has uracil instead of thymine, and is a single stranded molecule
What is the significance of the 2’ hydroxyl group in RNA compared to DNA?
the 2’ hydroxyl group makes RNA less stable and more reactive than DNA
What are the basic steps of RNA synthesis?
RNA is synthesized in a 5’ to 3’ direction, polymerase begins at to unwind the DNA at the start of the gene and begins to add complementary nucleotides to the template strand at the 3’ end, then DNA rewinds
True or False. In prokaryotes, transcription and translation occur at different times
False. In prokaryotes, transcription and translation occur simultaneously
What are the post-transcriptional modifications to mRNA
addition of a 5’ cap, 3’ cleavage and addition of a polyAtail, RNA splicing and RNA editing
What is the addition of a 5’ cap?
facilitates binding of ribosome 5’ end of mRNA
What does the 3’ cleavage and addition of a polyAtail do?
increases. stability of mRNA, facilitates binding of ribosome to mRNA
What is RNA splicing?
the removal of noncoding introns from pre-mRNA
What is RNA editing?
alters nucleotide sequence of mRNA
What is the function of the ribosome?
after transcription, the ribosome translates the mRNA sequence into the language of proteins
What is the primary structure of proteins?
amino acids joined together in a polypeptide chain
What is the secondary structure of proteins?
interactions between amino acids cause primary structure to fold into secondary structure (alpha helix)
What is the tertiary structure of proteins?
folded secondary structure
What is the quaternary structure of proteins?
two or more polypeptide chains joined
What are the stop codons in the genetic code?
UAA, UAG, UGA
What is the start codon of the genetic code?
AUG
How does translation begin in prokaryotes?
RNA sequence helps position the ribosome near the 5’ end of the coding sequence
How does translation begin in eukaryotes?
a cap-binding protein positions the ribosome at the 5’ of mRNA and a ribosome scans progressively to locate AUG
What is a consensus sequence?
compromises the most commonly encountered nucleotides at each site
What does Y mean in a consensus sequence?
the presence of a pyrimidine
What does R mean in a consensus sequence?
the presence of a purine
