Q2-F12/Translation and dynamic regulation of proteins Flashcards
what are the 5 key components for translation?
What are the characteristics of genetic code?
What is sickle cell anemia cuased by?
a missense mutation in the beta-globin gene
a single nucleotide subsitution (A to T) in the codon for aa 6
it converts a glutamic acid codon (GAG) to a valine codon (GTG)
What does sickle cell anemia do do hemoglobin molecules?
the change in the aa seq causes the hemoglobin molecules to crystallize when O2 levels in the blood are low. this causes the RBC’s to sickle and get stuck in small vessels
What structure is tRNA?
secondary
what is the Wobble exception to base pairing?
some tRNA anticodons can pair with more than one codon, can go against watson crick base pairing
3rd position can tolerate more mispairing than the 1st or 2nd
https://www.youtube.com/watch?v=zHfiWXQIA2Q
What are the 3 sites on the ribosome?
What are the 2 parts of initiation of translation?
- assembly of components required for chain formation
- recognition of start codon by a tRNAmet molecule
What provides the required energy in translation?
GTP
What are the 3 main parts of translation?
initiation, elongation, termination
elongation in translation involved the addition of amino acids to the ______ end of the growing polypeptide chain
carboxyl (c-terminus)
what facilitates the formation of peptide bonds between adjacent amino acids in translation?
peptidyltransferase
explain elongation in translation.
what causes termination in translation?
a stop codon
What is the stop codon recognized by?
a release factor
What happens when a release factor binds to the A site?
the newly synthesized protein is released and the tRNA-ribosome-mRNA complex is disassembled
What are some ways we can regulate protein activity?
Protein turnover is a normal process. What does it ensure?
it ensures a protein fit for purpose. it can also be used as a mechanism to turn off a pathway, reduce activity in a cell, or stop a process.
What happens to proteins with key regulatory functions and why?
Proteins with key regulatory functions often rapidly turned over or degraded in order to keep them under tight regulation
Why is rapid protein turnover nessessary sometimes?
Rapid turnover of proteins is necessary to allow their levels to change quickly in response to external stimuli.
when do proteins get degraded/when does normal protein turnover occur?
what are the role of cyclins in protein degradation?
cyclins are made to help get into the cell cycle and are degraded when the cell wants to turn them off
when proteins get activated, some of them get cleaved in the process and need to be replaced
what are the 2 ways proteins are degraded?
Where do lysosomes come from?
the ER
Are lysosomes acidic or basic?
HIGHLY acidic (pH=4)
they have proton pumps that pump H+ ions into lysosomes to reduce the pH
What do lysosomes have in them?
Have degradative enzymes (acid hydrolases) that are only active at low pH – protects cytosolic proteins from activities if they leak out
What can lysosomes degrade?
what is it called when proteins are labelled or tagged for degradation?
polyubiquitination
once a protein is polyubiquinated, that protein is recognized by the __________ and degraded
proteasome
what is a proteasome
it is a multiprotein, barrel shaped complex
What does a proteasome contain in it?
protease enzymes
Where are proteasomes found?
in the nucleus or cytoplasm
What are some common post translational modifications of proteins?
explain ligand binding.
Explain proteolytic cleavage.
A zymogen is a type of pro-enzyme. When a pro-enzyme is attached to a protein, that protein is inactive. The cleavage of the pro-enzyme from this protein, turns the protein from inactive to active
Explain the reversible phosphorylation of proteins.
Phosphate is on serine, threonine, and tyrosine residues
when you add/remove (kinase/phosphatase) a phosphate, you can…
- alter the proteins function
- mark for degradation
- alter localization
- promote interactions
what is chronic myelogenous leukemia?
CLM is uncontrolled growth of myeloid cells in the bone marrow until they all spill out into the blood. this is bad because all the “normal healthy cells” get crowded out and its harder for them to survive because theres more competition for nutrients. This causes cytopenia, which is a reduction in the number of healthy cells.
What causes chromic myelogenous leukemia?
A chromosome translocation that results in a Philedelphia chromosome. A portion of Chromosome 9s long arm switches with Chromosome 22s long arm.
This obviously results in a modified Chromosome 9 and Chromosome 22 (22-is called the Philedelphia Chromosome).
What then happens is a Chromosome 22 gene called Breakpoint Cluster Region (BCR) sits right next to a Chromosome 9 gene called ABL.
When they combine, it forms a fusion gene called BCR-ABL.
The BCR-ABL gene codes for a protein also called BCR-ABL. This protein turns on enzymes called tyrosine kinase that help with cell division. This is kinda like BCR-ABL is an on/off switch and it is stuck in the on-position.
Since its always on, it forces myeloid cells to keep dividing quicker than they should, which causes them to spill out into the bloodstream.
How is Chronic Myelogneous leukemia treated?
it is treated with an tyrosine kinase inhibitor like Gleevec/Glivec/Imitinib that specifically targets BCR-ABL.
