translation Flashcards
how many types of bases in nucleic acid
4
how many types of bases in nucleic acid
4
how many amino acids
20
how many possible codes
64
DNA is…
universal, non-overlapping and degenerate
degerate
same amino acid coded for by a number of codes
translation directn
5’ to 3’
three roles of RNA in translation
1) mRNA–> transporting DNA info from nucleus 2) ribosomal RNA- makes up the ribosome where translation occurs 3)tRNA–> deciphers the codons on the mRNA
where does translation occur
in the nucleus’ ribosome
ribozyme
an RNA molecule capable of acting as an enzyme.
tRNA is responsible for the catalysis of..
peptide bond formation
tRNA
-clover shaped molecule with is produced in the nucleus and resides in the cytoplasm -it has anticodons and an acceptor stem which attaches to specific amino acids
where is tRNA produced
the nucleus
what couples tRNA with specific amino acids
specific enzymes- diff for all tRNA
the anti-codons pair with..
codons on the mRNA, delivering its amino cid in the correct sequence
how is the amino acid sequence perfected
due to the compatibility of anti-codons on tRNA and codons on mRNA
a ribosome is..
a large complex of 4 RNAs and more than 82 proteins
ribosomal unit structure
on the ribosomal subunit there are 3 sites 1: A site- aminoacyl-tRNA site 2: P site= peptidyl- tRNA site 3: E site- exit site Made up of a large ribsookmoal sub unit and small subunit
the ribosome is made up of…
a large ribosomal subunit- 49 proteins and 3 RNA a small ribosome subunit-33 proteins and 1 RNA and various sites
the ribosome is made up of…
a large ribosomal subunit a small ribosome subunit and various sites
how many amino acids
20
how many possible codes
64
DNA is…
universal, non-overlapping and degenerate
degerate
same amino acid coded for by a number of codes
translation directn
5’ to 3’
three roles of RNA in translation
1) mRNA–> transporting DNA info from nucleus 2) ribosomal RNA- makes up the ribosome where translation occurs 3)tRNA–> deciphers the codons on the mRNA
where does translation occur
in the nucleus’ ribosome
translation ends with
mRNA and ribosomal subunits dissembling an the release of a newly synthesised protein
tRNA is responsible for the catalysis of..
peptide bond formation
tRNA
-clover shaped molecule with is produced in the nucleus and resides in the cytoplasm -it has anticodons and an acceptor stem which attaches to specific amino acids
where is tRNA produced
the nucleus
what couples tRNA with specific amino acids
specific enzymes- diff for all tRNA
the anti-codons pair with..
codons on the mRNA, delivering its amino cid in the correct sequence
how is the amino acid sequence perfected
due to the compatibility of anti-codons on tRNA and codons on mRNA
rRNA
RNA component of the the ribosomes
a ribosome is..
a large complex of four RNAs and more than 80 proteins
tRNA in the E site will not have
an amino acid- it is released after a peptide bond is formed between tRNA molecules in the P and A site
the ribosome is made up of…
a large ribosomal subunit a small ribosome subunit and various sites
there are no tRNA that match the..
stop codon sequence
3 steps of translation
1) initiation 2)elongation 3)termination
1) initiation
- initiates at the first (5’) AUG codon - when the small unit of ribosome is in place, it will delineate (indicate the exact position) where the two sites of translation will be -AUG codon is bound to the initiator tRNA- therefore the first amino acid in the polypeptide chain will always be METHIONINE -this allows the large subunit to bind and the ribosome to assemble -p site is filled with initiator tRNa but the A-site is empty
first codon of translation is always
AUG
AUG codes for
methionine
experiment that crick and brenner did to crack the eugenic code
used bacteriophage T4(virus’ which infect and replicates inside bacteria) which infects E-coli -by generating mutants in the RII gene of bacteriophage T4 using proflavin -causing a ‘rapid lysis’ phenotype of larger plaques
proflavin
a planar molecule, intercalates between base paris in DNA -causes ‘frameshift’ mutations -insertion of an extra base of deletion of a base
stop codons ar bound by
termination factors
translation ends with
mRNA and ribosomal subunits dissembling an the release of a newly synthesised protein
amino acids on the tRNA are selected by..
their codons on the mRNA
initiator amino acid carried on the initiator tRNA
methionine
what scans for the start codon
the initiator tRNA and the bottom part of the ribosomal subunit- the top part of the ribosomal subunit only joins after AUG has been found
where is the initiator tRNA’s site on the ribosomal rna
p-site
e-site
exist site for tRNA after it is done delivering the amino acid
new (non initiator tRNA) enter the
A site
what happens to adjacent amino acids in the ribosome
a peptide bond is formed
when peptide bond is formed
the amino cid in the p site will release its amino cid and move into the E site- the tRNA in the A site will move into the P site and now the A site is empty for a new tRNA with an amino acid on it to enter
there are no tRNA that match the..
stop codon sequence
who tried to crack the genetic code
crick and brenner
how many bases correspond to one amino acid
3
cricks hypothesis with triple mutations which proved that the genetic code was triplet (+++)
THE XBI GYR EDZ FOX ATE THE EGG makes sense
evidence for the code not being overlapping – simple
because single base mutations only ever affect one amino acid
experiment that crick and brenner did to crack the eugenic code
used bacteriophage T4(virus’ which infect and relicate inside bacteria) which infects E-coli -by generating mutants in the RII gene using proflavin -cuasing a ‘rapid lysis’ phenotype of larger plaques
proflavin
a planar molecule, intercalates between base paris in DNA -causes ‘frameshift’ mutations -insertion of an extra base of deletion of a base
the proflavin and (+) and (-)
the proflavin caused base inseriont (+) and base deletions (-) –> these causes bacteriophages which were different to their wild types
wild type
a strain, gene, or characteristic which prevails among individuals in natural conditions, as distinct from an atypical mutant type.
double mutants- (+-)
wild type
double mutants - (++)
RII mutation
double mutants (–)
RII mutation
double frameshift mutants of the same type will still have..
mutant phenotypes
triple mutants (+++)
wild type
triple mutants (—)
wild type
triple mutants (+-+)
RII
wild type message- CRICKS HYPOTHESIS
THE BIG RED FOX ATE THE GG
cricks hypothesis with single (+)
causes a frame shift so the message now reads THE XBI GRE DFO XAT ETH EEG G -this makes no sense
cricks hypothesis with double mutation (++)
THE XBI EDF OXA TET HEE GG -makes no sense
cricks hypothesis with double WT mutation (+-)
THE XBI GRD FOX ATE THE EGG -psuedo wild type
some tRNAs can tolerate a mismatch at the third codon position- this is called a
wobble
three codons that do not code for an amino acid
stop codon
