Rna & Transcription Flashcards
(48 cards)
Mushroom poison
Amanita phalloides (the “death cap”).
These mushrooms contain the toxin
alpha amanitin.
sequence contains the genetic master plan. ‘ untouchable’
DNA
the “working copy” of the DNA.
RNA
by transcription
– 3 Major Types: mRNAs, rRNAs, tRNAs.
– Small RNA molecules:
• non-translated (non-coding - ncRNAs), snRNA, snoRNA, miRNA.
– Function
• protein-coding,structural,catalytic(Ribozymes), and regulatory.
Transcription Products
– Nucleotide polymer joined by phosphodiester bonds. – Considerably smaller than DNA. – Exist as single strands. – Contain ribose instead of deoxyribose. – Contain uracil instead of thymine. – They differ in size, function, and special structural shapes and modifications.
RNA characteristics
28S, 18S, 5.8S, and 5S.
Four rRNA species
which is related to the molecular weight and shape of the compound.]
“S”is the Svedberg unit
Together, rRNAs make up about
80% of the total RNA in the cell.
rRNA interacts with ribosomal proteins to form the
Ribosomes
Main function of rRNA is
mRNA Translation
The smallest of the 3 major types of RNA
tRNA
Make up about ___1___ the total RNA in the cell.
15%
tRNA contains
Modified bases
Forms secondary
and tertiary structures
tRNA
Main function of tRNA
mRNA decoding during translation.
There is at least one type of tRNA to transfer each of the
20 amino acids
Specific amino acid is covalently attached to its
3’ end
Most heterogeneous type of RNA in size and base sequence.
mRNA
It comprises about ___1___ of the total cellular RNA.
1- 3-5%
Eukaryotic mRNA is
Monocistronic
Monocistronic means that it
Carries information from just one gene.
mRNA structural characteristics
– 5’ Cap
– Untranslated regions (UTR) at its 5’- and 3’- ends.
– 3’ Poly A tail
- Chromatin structure remodeling to allow DNA access.
- Three RNA Polymerases for the synthesis of rRNA, tRNA, and mRNA.
- Transcription factors (TFs):regulatory proteins to initiate and regulate transcription.
Requirements for transcription of eukaryotic genes
