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AP Bio Protein Synthesis

metabolic defects
study of this provided evidence that genes specify proteins
transcription and translation
two main processes
DNA synthesizes RNA
RNA synthesizes Protein
triplet in mRNA
exported out of nucleus and be processed
in a eukaryotic cell, mRNA must be
triplet sequence of nucleotides
the smallest units of uniform length to allow translation of all 20 amino acids
three types of RNA
most closely related to DNA
3 letters, looks like this letter
eukaryotes have ____ polymerases
RNA polymerase II
responsible for mRNA synthesis
initiation, elongation, termination
transcription is divided into 3 parts including
RNA must be _____ before it can function
RNA polymerase binds to promotor region, TATA box plays critical role during this
initiation in transcription
helicase unwinds DNA and RNA polymerase adds nucleotides 10 bases long growing 5 to 3 direction
elongation on transcription
terminator sequence stops transcription
termination of transcription
stops transcription
DNA reforms double helix, RNA peels off template DNA (gene)
number of ATP needed for one amino acid
RNA processing
post transcriptional modification is also called
guanine triphosphate
during capping, a modified ____ is added to the 5 end of mRNA
Poly-A tail
20-200 adenine nucleotides added to 3' end of mRNA
also occurs during RNA processing
protects mRNA from hydrolytic degredation
5' cap first function
identifies mRNA to the small ribosomal subunit
5' cap second function
means of protection
both 5' cap and poly-a tail are
inhibit degredation of mRNA in cytosol
first function poly-a
help mrna export from nucleus
second function poly-a
trailer sequence
poly-a tail is seperated from the stop codon by a _____
noncoding sequences that are removed
coding sequences that are spliced together
identify and help bring about the splicing process
catalyzes splicing reactions
rna and protein
make snRNPs
snRNPs and other proteins
make up a splicisome
control gene activity, allow single gene to synthesize different proteins
role of introns
synthesis of proteins
interpreter between base sequence of mRNA and amino acid sequence of protein
different types of tRNA are known
tRNA is around ____ nucleotides long
anticodon base
pairs with codon of mRNA
coordinate the pairing of tRNA with mRNA
ribosomes contain ___ subunits
ribosomes are constructed in the
three sites
aminoacyl-tRNA synthase
an enzyme that catalyzes attachment of an amino acid to its cognate tRNA
number of different types of ATS
activation of amino acid with AMP
first step
attachment of amino acid to tRNA
step two
brings mrna, trna, and ribosomal subunits together
initiation of translation
three-step cycle that adds amino acids one by one to the initial amino acid, requires cooperation of several
elongation of translation
release of the polypeptide chain from the complex
termination of translation
5'cap attaches to small ribosomal subunit, trna carrying met attaches to mrna codon, large ribosomal subunit attaches
process of initiation in translation
site of mRNA codon and tRNA anticodon coupling
P site
holds the tRNA carrying the growing polypeptide chain
A site
holds the tRNA carrying the next amino acid to be added to the chain
codon recognition, translocation
two parts of elongation of translation
tRNA is directed into the A site by an elongation factor then peptide bond forms between adjacent amino acids
amino acid in A site moves to P, mRNA moves through ribosome 5 to 3
termination sequence is encountered, release factor bonds to sequence, release factor seperates polypeptide and tRNA
assemble nucleic acid chains from monomer nucleotides whos order is determined by complementary base pairing to template strand, synthesize 5 to 3 direction
DNA polymerase and RNA polymerase both
DNA polymerase requires a
uses nucleotides with deoxyribose
DNA polymerase
uses nucleotides with ribose
RNA polymerase
transcription factor would not bind to it, so neither would RNA polymerase
if sequence change occured in tata box
help mRNA leave nucleus, prevent from degredation, facilitate ribosome attachment
5 cap and poly-a tail help
gene expression
process by which DNA directs the synthesis of proteins or RNAs
beadle and tatum
one gene one enzyme hypothesis
has ribose, uracil, single strand
RNA is different from DNA in that it
location of transcription
ribosomes, cytoplasm
location of translation
primary transcript
pre mRNA is also known as
unique triplets exist
template strand
coding strand of DNA is called
end of translation
coded by UAA, UAG, UGA
start codon
different codons code same amino acid, but same codon cant code for different amino acid
why is genetic code redundant but not ambiguous
RNA polymerase
enzyme that uses DNA template strand to transcribe mRNA
transcription unit
region of DNA that is transcribed into an RNA molecule
start point
polymerase initiates RNA synthesis at the ____ ____ on template strand
determines which of the two strands of double helix is used for template
promotor extends several dozen nucleotide pairs ___ from starting point
transcription factors
in eukaryotic cells, ____ ____ mediate the initiation of transcription by RNA pol 2
TATA box
DNA sequence in eukaryotic promotors crucial in forming the transcription initiation complex
transcription factors, promotor, RNA polymerase
comprises a transcribtion initation complex
base pairs with nucleotides at specific sites along intron
cuts pre-mRNA releasing intron and at the same time splices exons together
short nucleotide sequences at end of introns
signal for splicing by snRNPs, then snRNA binds to these sites
RNA molecules functioning as enzymes which catalyze reactions during RNA splicing
all biological catalysts are proteins
idea rendered obsolete by discovery of ribozymes
single strand
allows RNA to base-pair with a complementary region in same molecule giving it a 3-D structure
functional groups
some bases in RNA contain _____ ____ that may participate in catalysis
hydrogen bonding
with other nucleic acid molecules adds specificity
single gene may code for multiple proteins
consequence of alternative splicing of mRNA
RNA synthesized from a DNA template
attaches to ribosomes in cytoplasm and specifies primary structure of a protein
shorter than mRNA, 4 base pair regions, 3 loops
gather together with proteins to make ribosomes
rRNA is formed in
nucleotide triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule
amino acid, codon
____ binds to 3' site of tRNA, ____ binds to 5' site of it
scientists expected to find one aminoacyl-tRNA synthase per codon but fewer have been discovered can be explained by the ____ concept
flexible base pairing occurs at the 3rd base in a codon at the 3 end of an mRNA codon
active site binds amino acid and atp
step one of trna-amino acid joining
atp loses 2 P groups and joins amino acid as AMP
step two of trna-amino acid joining
trna covalent bond to amino acid and displace AMP
step three of trna-amino acid joining
trna and amino acid is released
step four of trna-amino acid joining
smaller, molecular composition
prokaryotic ribosomes are ___ and have different ____
inactivate bacterial ribosomes without affecting eukaryotes
antibiotic drugs can
gives energy for initiation
first amino acid in polypeptide
catalyzes the formation of a peptide bond between the new amino acid in the A site and carbozyl end of the growing polypeptide
release factor
protein that binds directly to stop codon on A site causing addition of water molecule
mechanism termination is accomplished
group of several ribosomes attaached to and translating same messenger rna
protein folding, post-transitional modifications
will result in final form protein
attachment of sugar lipid or phosphate groups, remove amino acids from leading end, chain may be cleaved, chains come together
post translational modifications
binds to the signal peptide halting synthesis momentairly
receptor protein
SRP binds to a ____ in Er membrane which is part of a protein complex that has a membrane pore and signal cleaving enzyme
SRP, signal protein
leaves and pp synthesis resumes with simaltaneous translocation across membrane with ____ ____ remaining attached to translocation complex
signal cleaving enzyme
cuts off signal peptide