Lecture 8 Flashcards
What is a set of rules that covert the nucleotide sequence of a gene inot the amino acid sequence of protein
genetic code
A protein is synthesized in the
amino to carboxyl direction by the sequential addition of amino acids to the carboxyl end of the growing peptide chain
What is teh genetic code intermediary?
mNA
How is the sequence of nucleotides in the mRNA molecule read?
consecutively in groups of three
What is each group of 3 consecutive nucleotides in RNA called?
a codon
What does a codon specify?
Either one amino acid or a stop to the translation process
How many total codons?
61 triplet codons code for the 20 known amino acids, thus the cod is degenerate
What does degenerate mean?
More than one codon per amino acid
How does an amino acid recognize a codon?
tRNA
How can the codons in mRNA be translated into a protein?
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What is the adaptor hypothesis?
It postulates that the genetic code is read by molecules that can recognize a codon and carry the corresponding amino acide
What does transfer RNA or tRNA do?
serves as an adaptor that binds to a specific codon and brings iwth it an amino acid for incorporation into the polypeptide chain
What is the secondary structure of tRNA?
cloverleaf… tRNA fold up into a defined 3D strucutre an contains 4 short double helical segments
What are two regions of of tRNA?
two regions of unpaired nucleotides are curitcial to the function
What is the anticodon loop of tRna?
a set of 3 consecutive nuclellotides that pair with a compelnetary….
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Are there more than one tRNA for most amino acids?
yes
Some tRNAs require accurate base pairing only at?
the first two positions of the codon and can tolerate a mismatch?
What is it called when it can tolerate a mismatch?
wobble hypthesis
What does the wobble base pairing explain/
Why so many of the alternative….
Amino acid reacts with? for the activation of adenylated amino acid?
ATP looses 2 phosphates…
adenylated amino acid is?
amino acid-AMP
What is the recognition and attachment of the correct amino acid to the corresponding tRNA catalyzed by?
aminoacyl-tRNA synthestases
What does aminoacyl-tRNA synthatase do?
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at tRNA level there is a bonding site for the?
anti codon
Editing (hydrolytic) site cleaves …. speicies that are …. than the correct one
activated, smaller
What raises the overal accuracy of tRNA chargin to approximately on mistake in 40,000 coupling
hydrolytic editing…. this is on the snythatase
What is the genetic code translated by?
two adaptors
What are the two adaptors?
tRNA and the tRNA synthetase
What contains highly discriminating amino acid
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Prokaryotic ribosome
70s… small subunit
eukaryotic ribosome
80s and small subunit
What is a ribosome?
A complex catalytic machine, consiting of two subuits
What does each ribosome subunit consist of?
Different ribosomal proteins and several ribosomeal RNAs (rRNAs)
What determin the overall shape of the ribosome?
rRNAs
-its ability to postition tRNAs on the mRNA, adn it scatalytic activity in forming peptide bonds
small subunit?
provides…
large subunit
…
Protein synthesis is performed on?
the ribosome
- it ensures accuracy and maintains correct reading frame
What are separate when not snythesizing proteins?
the 2 ribosomes su
How are the ribosomes subunits joined/
join together at the 5’ end of mRNA and initaed protien snythesis
What direction is teh ribosoem pulled through?
5-3 direction
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Where does the ribosome making occur?
cytosol
What is a polyribosome?
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What contains 4 binding sites for RNA
ribosomes
what are the three tRNA sites?
A(aminoacyl)
P(peptidyl)
E(exit)
What is the 4ths bieing site for?
mRNA
The A, P and E site
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What is teh fundamental reaction of protein snythesis?
The formation of peptide bond btw amino acids
Where does the reaction of protein snythsis occur?
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