4- RNA (gene regulation & protein synthesis) Flashcards
what are stem loops?
-regions where RNA fold back on itself using base pairing
-minimises energy
what is central dogma?
it’s the flow of information from DNA to protein
is RNA single or double stranded?
single stranded
what are the bases in RNA?
Adenine and Uracil (A&U)
Cytosine and guanine
(C&G)
what are the 3 main classes of RNA?
ribosomal RNA (rRNA)
transfer RNA (tRNA)
messenger RNA (mRNA)
what is rRNA?
combines with proteins to form ribosomes where protein synthesis takes place
what is tRNA?
carries amino acid to ribosome to be incorporated into protein
what is mRNA?
carries genetic info for protein synthesis (code for synthesis of proteins and are least abundant)
what are the more stable classes of RNA?
rRNA and tRNA are more stable than mRNA
*kindof random but just try think like rRNA makes ribosome and tRNA like carries amino acids = both more like stable structures with stable jobs. mRNA can be degraded or fall apart and made and then broken down etc
what is the sedimentation coefficient (S)?
- a measure used to characterize the size and shape of molecules (particularly rRNA)
- it describes how fast a molecule moves when centrifugation (separates molecules based on size & density) which somehow tells us about ribosome structure + function etc
describe role of tRNA?
= they are adapters between nucleic acid code and amino acid code
=tRNA has specific anticodon which consists of 3 nucleotides
what does tRNA look like?
= it has distinct 3D structure
= when flattened 2D is looks like clover structure
=in reality it looks very different
what is RNA made by?
RNA polymerase
how many types of RNA Polymerase do
a) prokaryotic cells
b) eukaryotic cells have?
a) 1 type
b) 3 types, pol I, pol II, pol III
what type of RNA polymerase synthesises mRNA?
pol II
what makes up a nucleoside?
- base
-sugar
what makes up a nucleotide?
- nucleoside (base&sugar)
-phosphate
what type of sugar is RNA?
ribose sugar (has oxygen)
what is RNA polymerases structure?
large multi-subunit complexes
what toxin can be used to distinguish between different RNA polymerases?
alpha-amanitin (which is derived form a fungus) is an inhibitor of RNA polymerase II (transcribes mRNA) so if in lab put in alpha amantin and transcription stops you know it’s RNA polymerase II (other examples exist)
what are the steps of transcription?
- RNA polymerase binds
- DNA chain seperates (breaking hydrogen bonds & untwisting double helix to gain access to nucleotides)
- transcription initiation (selection of 1st nucleotide of growing RNA)
- elongation (adding further nucleotides)
- termination (release of finished RNA)
what are conditions/ how does RNA polymerase bind? (in transcription)
-it needs to detect initiation sites (promoters) on DNA
-requires transcription factors
what are promoters/initiation sites?
specific sequences of DNA nucleotides that allow binding of DNA polymerase (so it can unwind DNA)
what direction is RNA synthesised?
moves along DNA from 3’ to 5’ end so RNA synthesised from 5’ to 3’ direction