R4 regulation of gene expression in eukaryotes Flashcards
How many types of polymerases are there in eukaryotes ?
pol I and pol III are structural RNA for tRNA, pol II is responsible for the protein-coding genes.
How do promoters compare in eukaryotes to prokaryotes ?
promoters are much larger in eukaryotes, may be further away from the transcription site, TATA box is further away in the -30 position, repressor binds to a region called the silencer, activators bind to the enhancer regions, polymerase always binds wether transcription is on or off, regulatory proteins decide wether transcription goes ahead.
What does the banding of light grey and black mean on the karyotype ?
The alternating euchromatin (grey) and heterochromatin (black)
What are the 3 mRNA processing procedures that occur in eukaryotes ?
5’ end capping - the nuclease enzyme binds to the 3’ end and makes their way to the cap
3’ end polyadenylation - multiple adenines added, the polyA binding protein binds to the 3’ protecting it from nuclease, slowing down degradation
slicing - introns removed, exons leave the nucleus
Describe the process of slicing ?
spliceosome is a ribonucleoprotein complex consisting RNA and proteins that recognise the 5’ and 3’ end of exons, bringing them together then excising the introns, splicing is coupled to transcription, each intron varies but is recognisable to the spliceosome
exons can be spliced leading to alternative splicing - multiple different proteins from one gene
What are the uses of post-translational modification ?
allows for a quick response to signals (the protein does not need to be remade it can just be activated or inhibited)
they are reversible allowing for adaptability to a response, this is energy saving as synthesis does not need to keep reoccurring
What is protein phosphorylation ?
kinase adds a phosphate onto the protein, this is reversed by phosphotase
phosphate binds to serine, threonine and tyrosone as it requires an OH group acceptor
brings a negative charge increasing its affinity to positive substrates but decreasing it to negative substrates
What are CDKs ?
Cell cycle dependent kinases, activate cyclin proteins at each stage needed for the cell cycle, they are then degraded by phosphatase.
what is ubiquitin-dependent degradation ?
ubiquitin is a short peptide that binds to lysine, it marks cyclin proteins (cell cycle proteins) for degradation, this is done by proteasome
Bacteria use proteolysis without ubiquitination, how ?
adaptor recognises a short peptide on the substrate and binds to it, allowing for protease to bind and degrade.
What are some features of a good model organism ?
easy to maintain, short generation time, large number of offspring, well studied genome, easily manipulated genome, can share strains, few ethical concerns, decreased complexity compared to humans
What are the 2 haploid cells in yeast ?
a and alpha - fuse to make the diploid offspring, they undergo sporulation (meiosis) to continue the budding process
a cells secrete a factors, receptors for alpha cells
vica verse for alpha
They both share haploid specific genes.
What is a scaffold protein ?
no catalytic properties but allows other proteins to bind and react on it
What is schmooing ?
The membrane projection towards their mating partner
Why is mating during G1 and G2 a problem ?
G1 arrest is a protective mechanism to make sure the cell have met the conditions before the S phase (DNA replication)
G1 is before DNA replication whereas G2 is after, mating would create a triploid cell
triploid cells do not undergo meiosis creating seedless plants
