Flashcards in Amino acid and protein synthesis test 3 Deck (42):
AA biosynthesis from alpha ketogluterate
AA biosynthesis from 3-phosphoglycerate?
AA biosynthesis from oxaloacetate
AA biosynthesis from pyruvate
AA biosynthesis from phosphenolpyruvate and erythrose 4-phosphate
AA biosynthesis from ribose-5-phosphate
T/F DNA is primarily in the nucleosome form?
what is an intron and exon?
introns are non-coding
exons are coding for AAs
All the DNA in mammals codes for proteins T/F?
false only 1.5% codes for proteins
25,000 human genes
what is the regulatory/silencer region of DNA?
binding of proteins that promote or inhibit transcription
what is the promoter region of DNA?
transcription factor and RNA polymerase binding site
what is the open reading frame?
AA encoding region containing introns and exons
what is the UTR?
untranslated regions necessary for RNA processing
RNA polymerase I
synthesizes ribosomal RNA or rRNA
RNA polymerase II
synthesis messenger RNA or mRNA
RNA polymerase III
synthesis of transfer RNA tRNA
how is DNA read by the RNA polymerase?
made 5'-3' (same as non template DNA)
what initiates DNA binding of RNA polymerase?
transcription factor complexes
Negative regulation of DNA transcription
-molecular signal causes repressor to move from operator region
-molecular signal binds with free repressor which then binds to operator region to inhibit transcription
positive regulation of DNA transcription
-enhancement can occur with the removal of an activator(allow binding of RNA polymerase)
-or the binding of an activator(stabilize RNA polymerase)
what are the Three RNA processing steps?
addition of 5' cap
addition of poly A tail
**this is in order of how this happens
what is the purpose of the 5' cap?
-binds to ribosomes to initiate transcription
-tethers mRNA until translation is complete
-four classes of introns
-two are self splicing
-most introns are not self splicing and require a spliceosomes.
-introns are released into nuclear space and degraded
how does splicing lead to more protein diversity?
because splicing happens at different places depending on where it is produced
-thus 1 gene=more than one protein
Termination and Poly A tail
AAUAAA upstream sequence
G and U rich residues downstream
protects mRNA tail
Anchors mRNA during translation
**occurs independent of RNA polymerase
how does mRNA get out of the nucleus?
binding of protein factors bring the mRNA to nuclear pore and then go off to translation
where are the two domains of translation
in the cytosol
and in RER membrane
what is the importance of inosinate?
it is very promiscuous and allows for variance in the 3rd codon and allows for resistance to mutation.
what are the five steps in translation?
activation of AAs
what occurs in activation
aminoacylating tRNAs (putting the AA on the tRNA)
what occurs in initiation
-initiation factors bind to 5'
-recruit 40s ribosome complex, which scans mRNA for start codon and the anticodon binds.
-poly A tail and 5' keep mRNA in place
-then the large 60s ribosome binds
**ATP/GTP hydrolysis drives initiation
elongation at the ribosome
-mRNA is read 5'-3' (opposite of RNA polym)
-aminoacyl, peptidyl, and exit sites of large ribosome subunit (APE)
-poly pep chain is made N->C terminus
termination factor causes release
proteins made at the endoplasmic reticulum are what kind?
integral membrane proteins
-primary site of protein modification
what is the Signal Recognition Particle cycle?
the SRP on the ER causes the ribosome to associate and make the protein into that site at the RER.
post-translational modifications that occur within the ER
proteins made at the ER are what kind. (3) of them
integral membrane proteins
proteins made in the cytoplasmic space are what kind (3) types
structurally associated proteins
how do proteins get into the nucleus?
because they have a nuclear localization sequence on them that recruits other proteins that bring that protein into the nucleus
what targets a protein for degradation?
polyubiquitination tags a protein for destruction
proteosome degrade what kind of proteins?
degrades cytoplasmic proteins