TRANSLATION
-
-
PROKARYOTIC A EUKARYOTIC TRANSLATION
Learning Outcomes
Understand & describe the following
[1] Properties of nucleic acids vs amino acids [6] Role of ribosomes in protein synthesis
[2] Features of the genetic code [7] Stages of translation and its features
[3] tRNA as an adaptor molecule [8] Differences between prokaryotic and eukaryotic translation
[4] tRNA binding to codons and amino acids [9] Inhibition of protein synthesis as a mechanism of drugs and toxins
[5] Role of aminoacyl-tRNAsynthases
Properties Of Nucleic Acids SAMMO acids
Nucleic acids are structurally similar = similar function
[1] Aromatic ring structure
[2] 4 nucleic acids
Chemical Structure of amino acids = hold a diverse range of functions
[1] Aromatic, Acidic, Basic, Hydrophobic, Small, etc etc
[2] 20 amino acids
Genetic code -
A Review
Nearly universal - diff cell read nucleotide & convert to same amino acids
Rules of Genetic Codes
[1] 3 nucleotides = codon = encode an amino acid
[a] 4 types of nucleotides so need at least 3 3(4*4*4 = 64 permutations) to code for 20 amino acids
[b] Non-Overlapping
[2] No punctuation
=
[3] Has directionality - 5’ to 3’
AUG CCA
not
AAG } non overlapping ✓ -
[4] Is degenerate
Gg Degenerate Genetic Code
AVG UGC GCC . .
.
} overlapping ✗
↳
64 codons (3 = STOP) = 61 codons & only 20 amino acids so most amino acids are encoded by 1+ codon
Minimises effect of genetic mutations
"
"
Redundant
Translation .
: d fidelity as
Proteins #
Error Rdtf Of Translation
Permenant
Complexity = potential for error @ each step
Balance translation accuracy w/ speed
Ex. How Accurate must it be?
[1] E.Coli average protein has 300 amino acids
[2] Some have >1000 amino acids
[3] Translational error frequency must not exceed 1 per 10,000 amino acids
, TRANSLATION
-
-
PROKARYOTIC A EUKARYOTIC TRANSLATION
Learning Outcomes
Understand & describe the following
[1] Properties of nucleic acids vs amino acids [6] Role of ribosomes in protein synthesis
[2] Features of the genetic code [7] Stages of translation and its features
[3] tRNA as an adaptor molecule [8] Differences between prokaryotic and eukaryotic translation
[4] tRNA binding to codons and amino acids [9] Inhibition of protein synthesis as a mechanism of drugs and toxins
[5] Role of aminoacyl-tRNAsynthases
Transfer RNAs = Adaptor molecules
Function
Transfer RNA (tRNA) recognise & binds to a specific codon & brings amino acid with it
[1] Min 1 tRNA for each amino acid (attached to 3’ CCA - post-transcriptional modification
to tRNA) w/ anticodon in central loop
CCA Terminus
General Features y
[1] Single-Stranded
[2] 73-93 ribonucleotides
[4] Many modified ribonucleotides (post-transcriptional modification)
[3] Internal base-paired to form an L-shaped structure
Specific to each tRNA
[1] Anticodon
[2] Structures of loops/helices
[3] Modified nucleotides
+ RNA structures
-
-
PROKARYOTIC A EUKARYOTIC TRANSLATION
Learning Outcomes
Understand & describe the following
[1] Properties of nucleic acids vs amino acids [6] Role of ribosomes in protein synthesis
[2] Features of the genetic code [7] Stages of translation and its features
[3] tRNA as an adaptor molecule [8] Differences between prokaryotic and eukaryotic translation
[4] tRNA binding to codons and amino acids [9] Inhibition of protein synthesis as a mechanism of drugs and toxins
[5] Role of aminoacyl-tRNAsynthases
Properties Of Nucleic Acids SAMMO acids
Nucleic acids are structurally similar = similar function
[1] Aromatic ring structure
[2] 4 nucleic acids
Chemical Structure of amino acids = hold a diverse range of functions
[1] Aromatic, Acidic, Basic, Hydrophobic, Small, etc etc
[2] 20 amino acids
Genetic code -
A Review
Nearly universal - diff cell read nucleotide & convert to same amino acids
Rules of Genetic Codes
[1] 3 nucleotides = codon = encode an amino acid
[a] 4 types of nucleotides so need at least 3 3(4*4*4 = 64 permutations) to code for 20 amino acids
[b] Non-Overlapping
[2] No punctuation
=
[3] Has directionality - 5’ to 3’
AUG CCA
not
AAG } non overlapping ✓ -
[4] Is degenerate
Gg Degenerate Genetic Code
AVG UGC GCC . .
.
} overlapping ✗
↳
64 codons (3 = STOP) = 61 codons & only 20 amino acids so most amino acids are encoded by 1+ codon
Minimises effect of genetic mutations
"
"
Redundant
Translation .
: d fidelity as
Proteins #
Error Rdtf Of Translation
Permenant
Complexity = potential for error @ each step
Balance translation accuracy w/ speed
Ex. How Accurate must it be?
[1] E.Coli average protein has 300 amino acids
[2] Some have >1000 amino acids
[3] Translational error frequency must not exceed 1 per 10,000 amino acids
, TRANSLATION
-
-
PROKARYOTIC A EUKARYOTIC TRANSLATION
Learning Outcomes
Understand & describe the following
[1] Properties of nucleic acids vs amino acids [6] Role of ribosomes in protein synthesis
[2] Features of the genetic code [7] Stages of translation and its features
[3] tRNA as an adaptor molecule [8] Differences between prokaryotic and eukaryotic translation
[4] tRNA binding to codons and amino acids [9] Inhibition of protein synthesis as a mechanism of drugs and toxins
[5] Role of aminoacyl-tRNAsynthases
Transfer RNAs = Adaptor molecules
Function
Transfer RNA (tRNA) recognise & binds to a specific codon & brings amino acid with it
[1] Min 1 tRNA for each amino acid (attached to 3’ CCA - post-transcriptional modification
to tRNA) w/ anticodon in central loop
CCA Terminus
General Features y
[1] Single-Stranded
[2] 73-93 ribonucleotides
[4] Many modified ribonucleotides (post-transcriptional modification)
[3] Internal base-paired to form an L-shaped structure
Specific to each tRNA
[1] Anticodon
[2] Structures of loops/helices
[3] Modified nucleotides
+ RNA structures
