RNA Synthesis Flashcards
Which types of RNA are used to support protein synthesis?
tRNA, rRNA
What type of RNA carries the DNA information for protein synthesis?
mRNA
Where is the majority of RNA synthesis found in mammalian cells?
Nucleus
3 general steps of transcription
Initiation, elongation, termination
What role does RNA polymerase play in transcription?
“start protein” Looks for promotor sites and binds to them
What direction does RNA synthesis proceed in?
5’ to 3’
What does the promotor region consist of?
TATA and consensus sequences
What subunit is necessary for RNA polymerase to recognize the promotor?
sigma subunit
What replaces the sigma subunit in RNA polymerase on prokaryotes?
Nus A Protein
What type of DNA sequence causes termination?
Palindromes
Rho factor
Termination factor for prokaryotes. Binds to 5’ end of messages and causes termination when it catches up to the stalled ribosome
RNA polymerase II
found in the nucleoplasm, does the majority of the transcription
RNA polymerase I
found in the nucleolus. Produces rRNA
RNA polymerase III
found in the nucleoplasm. Produces small RNA
What is the Deadhead mushroom’s effect on the body that makes it so deadly?
Inhibits RNA polymerase II
What is the structure of a eukaryotic promotor?
TATA, CAAT (frequency of initiation), and enhancer/silencer elements (can be up or down stream)
What is mRNA’s function in prokaryotes?
Polycistronic message, short-lived, immediately translated
What is mRNA’s function in eukaryotes?
Monocistronic, introns and eons, mRNA must be processed, long-lived
What protects the 5’ end of mRNA from being degraded?
Caps made of methylated guanine and methylated riboses
What are poly A tails’ function?
Maintains message stability
What mRNAs do NOT contain poly a tails?
Those coding for histones
Introns
Only found in eukaryotes. Are removed during RNA processing.
RNA splicing precursors
GU on 5’ end, AG on 3’ end
What mediates the splicing of RNA?
Spliceosome
SNRNPs
individual parts that form a spliceosome
Alternative splicing
Exons can be spliced so they are expressed in different ways
Wobble position of Codon
the third position that has less specificity when coding for an amino acid
What are the two exceptions to the DNA codon language?
Mitochondria and chloroplasts
Transition mutation
Purine is replaced by purine, Pyrimidine is replaced by pyrimidine
Transversion mutation
Purine is changed to a pyrimidine, and vice versa
Silent mutation
Codon is changes, but the amino acid is not
Missense mutation
Inactive or partially active protein
Nonsense mutation
nonfunctional protein
Sickle cell anemia is caused by what mutation?
Missense mutation
Frameshift mutations
Insertions/deletions. only have a shift if 1 or 2 bases are affected
