Protein Synthesis and Protein Functions Flashcards
What is the process of creating custom treatment based on the genetic basis of condition?
precision medicine
What is translation?
the process of making a peptide chain using mRNA that is read 5’-3’
-codons are 3 nucleotides in a row that are read by the anticodons on tRNA
which RNA contains all anticodons?
tRNA
Where is translation completed?
in the ribosomes
What is the structure of ribosomes?
2 subunits (40s and 60s)
-33 proteins in the 40s subunit
-46 proteins in the 60s subunit
-there are 4 rRNAs that make up the ribosomes: 18S, 28S, 5.8S, and 5S rRNA
What is the most abundant RNA in the cell?
rRNA
How is 18S, 28S, and 5.8S rRNA made?
transcribed by RNA polymerase I
-further processed in the nucleolus
How is 5S rRNA made?
transcribed by RNA polymerase III outside the nucleolus
What transcribes mRNA?
RNA polymerase II
What are the functions of rRNA in the ribosomes?
- structural- framework that hold ribosomal proteins together
- facilitate chemical reactions involved in peptide elongation
- binding sites for tRNA
- conformational changes- allow ribosome to move along the mRNA
- subunit coordination- aid proper alignment of 40S and 60S subunit
What do RNA modifications allow?
- Ribosome assembly
- ribosome stability
- tRNA recognition
- codon-anticodon interactions
- peptide bond formation
What are some possible modifications of rRNA?
-methylation of 2-OH position on the nucleotide ribose sugar
-isomerization of uridine nucleotides to pseudouridine
-acetylation
What guides rRNA modification?
snoRNA
Where does a majority of ribosome assembly occur?
in the nucleolus
What are the two types of ribosomes?
membrane bound and free
What are membrane bound ribosomes?
the most abundant type
-located on the surface of ER
What are free ribosomes?
move anywhere in the cytosol
-make proteins in the cytoplasm
Where do proteins made in membrane bound proteins go?
exported out of the cell or to the plasma membrane
What allows for mRNAs to be translated? (as opposed to other RNAs)
the have a poly A tail that allows them to exit the nucleus
-allows for formation of mRNA activation complex
What are the two components of the translation initiation complex?
- mRNA activation complex
- pre-initiation complex
-40s subunit
-multiple initiation factors
initiator methionine tRNA
What is an anti-codon?
three nucleotides that associate with the codon on mRNA through base pairing
What allows for a decrease in the number of tRNAs required?
redundancy in the genetic code
-inosines in the first position allow for binding of any nucleotide in the third position of codon
What are the roles of charged tRNAs?
-use anticodons to read codons
-become charged when amino acids bind
What are the steps of translation?
-initation
-elongation
-terminatioin
Process of translation:
-first methionine codon in P site
-next aminoacyl-tRNA binds in the A site
-methionine released form tRNA
-peptide bond formed between it and the amino acid on the tRNA in the A site
-ribosomes moves 5’ to 3’ along the mRNA discharging the empty tRNA and shift peptide into the P site
-process is repeated over until a stop codon
-termination of polypeptide chain involves hydrolysis of the ester bond, releasing the protein
What is the primary structure of a protein?
the amino acid sequence in a chain
What is the secondary structure of a protein?
stretches of polypeptides that form alpha helices and beta sheets
-held in shape by hydrogen bonds
What is the tertiary structure of a protein?
refers to the 3D structure of the protein
-formed due to interactions between R groups
What is the quaternary structure of a protein?
designation for proteins that are made of more than one polypeptide chain
-complete structure of all polypeptides
What are motifs of proteins?
shared sequences of amino acids that can be used to identify potential members of a protein family
What are domains of proteins?
structural entities that function independently within a protein and can be built from a specific motif or set of motifs
What are examples of protein sequence motifs?
-proteolytic enzyme cleavage sites
-phosphorylation sites
-binding motifs
-transmembrane spanning sequences
-protein secretion leader sequences
-transcription factor DNA recognition sequences
How do mutations affect protein function?
removing or changing amino acids that define a motif or domain can have an affect on secondary, tertiary, and even quaternary structure
-this will affect the way that proteins can function
What does amelogenin do?
stabilize the amorphous Ca-P phase
-control apatite crystal morphology and organization, control of enamel thickness
-ability to self assemble into nanospheres and guide HAP crystal formation/growth
What does ameloblastin do?
cell adhesion protein, controls cell differentiation, maintains rod integrity
What does enamelin do?
cooperates with amelogenin to control mineral nucleation and elongated growth
What does Kallikrin 4 do?
digests enamel proteins during maturation stage facilitating their removal and hardening the final layer of enamel
What does Mmp-20 do?
cleaves amelogenin, ameloblastin, and enamelin at the secretory stage to produce stable intermediates with defined functions
As apatite crystals grow, what happens to amelogenin?
it is removed
What is the amelogenin dependent on?
hydrophilic C terminal
What is the structure of amelogenin?
double-ring barrel (six dimers) and assemble into structured nanospheres
Mutations in amelogenin cause…
amelogenesis imperfecta
