Term
| during transcription which direction is mRNA made in? |
|
Definition
5" to 3"
remember transcription is the synthesis of mRNA |
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Term
| during translation which direction is mRNA translated? |
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Definition
mRNA is also translated in the 5" to 3" direction
translation is when mRNA is used to make a polypeptide chain |
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Term
| during translation which direction is the polypeptide chain made? |
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Definition
| N terminal to the C terminal |
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Term
| in preparation for translation which 4 things are needed? |
|
Definition
adaptor molecules -tRNA
specific activating enzymes
amino acids
ribosomes |
|
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Term
| which 3 ways can a tRNA molecule be depicted? |
|
Definition
as 2d clover leaf
as 3d l shaped
as a simplified dynamite stick |
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|
Term
| how many codons are there? |
|
Definition
| 64 but 61 are amino acid codons and there are 3 stop codons |
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Term
| what is the difference between the activating enzymes and the tRNA for the amino acids? |
|
Definition
| there are one activating enzyme for each amino acid but on 40 different tRNA for the 61 amino acids |
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|
Term
| how is the issue with 40 tRNA molecules per 61 amino acids solved? |
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Definition
| most amino acids are specified by more than one codon, differing in the 3rd position. this enables the use of fewer tRNAs than the number of codons |
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|
Term
| what is the name of the unusual base pairing interaction between codon and anticodon called? |
|
Definition
|
|
Term
wobble rules
which position does the wobble rule affect on the codon and the anti codon? |
|
Definition
third 3" position on the codon
first 5" position on the anti codon |
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|
Term
Wobble rules
U Can Go
explan |
|
Definition
3" codon U or C
5" anti codon G |
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|
Term
wobble rules
Giving Care
explain |
|
Definition
3" codon G
5" anticodon C |
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|
Term
wobble rules
U Ass
explain |
|
Definition
3" codon U
5" anti codon A |
|
|
Term
wobble rules
A Girl Unicorn
explain |
|
Definition
3" codon A or G
5" anti codon U |
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|
Term
wobble rules
U C Anything Interesting?
explain |
|
Definition
3" codon U, C or A
5" codon I
tRNA contains Inosine |
|
|
Term
| which unique base does tRNA contain? |
|
Definition
Inosine
pairs with a U, C or A 3" codon |
|
|
Term
| what is the process of charging a tRNA with its cognate amino acid called? |
|
Definition
|
|
Term
| which enzyme is involved in tRNA charging? |
|
Definition
| Aminoacyl-tRNA synthetase |
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|
Term
| what also happens in the first step when an amino acid binds to the tRNA synthetase? |
|
Definition
| ATP also binds. it loses two Pi and binds as AMP adenosine monophosphate. |
|
|
Term
| what happens during the covalent bonding of tRNA to the amino acid? |
|
Definition
| the AMP gets displaced. the enzyme then releases the activated aminoacyl tRNA. |
|
|
Term
| what type of bond forms between the tRNA and the amino acid? |
|
Definition
|
|
Term
| during polypeptide synthesis which organelle helps in the formation of peptide bonds? |
|
Definition
|
|
Term
| which 2 components are ribosomes composed of? |
|
Definition
| proteins and rRNA (ribosomal RNA) |
|
|
Term
| how many subunits does an active ribosome contain? |
|
Definition
| 2 , a large and a small one |
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|
Term
| which subunit of an rRNA would you find the binding site for mRNA? |
|
Definition
|
|
Term
| how many binding sites does the large ribosomal subunit have? and what binds to these? |
|
Definition
it has 3 binding sites. from left to right these are EPA and tRNA binds to these.
E = exit site
P = Peptidyl site
A = aminoacyl site |
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|
Term
| name the 3 steps in translation of mRNA |
|
Definition
Initiation
Elongation/translocation
Termination |
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|
Term
eukaryotic mRNA has a unique 3" end. what is this called?
what cap would you find at the 5" end? |
|
Definition
the Poly A tail is found at the 3" end
the 5" end has a methylated cap |
|
|
Term
| when does initiation begin? |
|
Definition
| when the small unit of the ribosome attaches to the methylated cap and moves to the translation initiation site. |
|
|
Term
| what is typically the first mRNA codon? |
|
Definition
AUG - codes for methionine, a start codon
the anti codon would be UAC |
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|
Term
| during elongation which binding site on the large unit of the ribosome does the charged tRNA molecule bind to? |
|
Definition
| it binds to the aminoacyl binding site. the polypeptide chain it then peptide bonded to the incoming charged tRNA. this then moves to the P site and the one that was in the P site has now moved to the E (exit) site and been relased |
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|
Term
| what codon is needed for a relase factor to enter the A site of the large ribosomal subunit and what does this do? |
|
Definition
| a stop codon is needed for a release factor to enter the A site. This terminates translation |
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|
Term
| which two stages in tanslation require energy and how is this derived? |
|
Definition
| code recognition (elongation) and translocation need energy. this is derived from GTP to GDP |
|
|
Term
| between which functional groups is a peptide bond formed? is anything produced during peptide bond formation? |
|
Definition
between the carboxyl group of one amino acid and the amino group of the following one.
a molecule of h20 is formed during the formation of a peptide bond |
|
|
Term
|
Definition
Stop codons
AUG is aka a start codon |
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|
Term
| a mRNA is generally translated simultaneously by several ribosomes in clusters. what is this known as? |
|
Definition
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|
Term
| the major differences in translation between eukaryotic and prokaryotic arise from what feauture in eukaryotic cells? |
|
Definition
| compartmental organisation in eukaryotic cells |
|
|
Term
which kingdom of cell can transcribe and translate the same gene simultaneously?
|
|
Definition
| Prokaryotes. New protein diffuses to its operating site. |
|
|
Term
| which part of a cell segregates transcription from translation and whats happens during this time? |
|
Definition
| the nuclear envelope segregates transcription from translation and during this time RNA processing takes place. |
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|
Term
| eukaryotic cells have to lots of ribosomes. what are they and where are they found? |
|
Definition
| free and bound. free ones found in cytosol and the bound ones found attached to cytosolic side of the endoplasmic reticulum |
|
|
Term
| which side of the ER are bound ribosomes found? |
|
Definition
|
|
Term
| where does translation begin? |
|
Definition
|
|
Term
| a polypeptide destined for the ER or export will have a signal peptide. what is this and where is it found on the polypeptide? |
|
Definition
| it is a chain of about 20 amino acids long and found near the N terminus. helps direct signal recognition particle (SRP) to take the polypeptide to its destination |
|
|
Term
| what happens when a SRP binds to the specific signal peptide? |
|
Definition
| takes the polypeptide and its ribosomes and attaches it to a signal receptor protein in the ER membrane. the signal peptide is then cleaved |
|
|
Term
| do signal peptides only go to the ER? |
|
Definition
| no. specific signal peptides target polypeptides to mitochondria, chloroplast, nucleus and other organelles not part of the endomembrane system. |
|
|
Term
| where is the signal cleaving enzyme that removes the signal peptide found? |
|
Definition
| in the signal receptor protein bound to the ER. it also has a membrane pore that allows the polypeptide chain through into the ER |
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|
Term
| which antibiotic inhibits the formation of peptide bonds? |
|
Definition
|
|
Term
| which antibiotic inhibits the translocation of mRNA along the ribosome? |
|
Definition
|
|
Term
| which antibiotic inhibits interactions between tRNA and mRNA? |
|
Definition
|
|
Term
| which antibiotic inhibits initiation of translation? |
|
Definition
|
|
Term
| which antibiotic inhibits binding of tRNA to ribosome? |
|
Definition
|
|
Term
| what does peptidyl transferase do? |
|
Definition
| catalyse the formation of peptide bonds |
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