17 - Translation Flashcards
Codon
the mRNA nucleotide triplets, customarily written in the 5’ to 3’ direction
tRNA
(transfer tRNA) is a type of RNA molecule that plays a crucial role in protein synthesis. Its primary function is to transport amino acids to the ribosome, where proteins are assembled
Anticodon
the particular nucleotide triplet that base-pairs to a specific mRNA codon
Aminoacyl-tRNA synthetases
a family of related enzymes
Small and large ribosomal subunits
are a group of enzymes that play a critical role in the process of translation, which is the synthesis of proteins from messenger RNA (mRNA) templates
Start codon
is a specific sequence of three nucleotides in messenger RNA (mRNA) that signals the beginning of protein synthesis
Stop codon
is a sequence of three nucleotides in messenger RNA (mRNA) that signals the end of protein synthesis.
Polysome
A string of ribosomes that can be seen with an electron microscope, they can be either free or bound
Signal peptide
is a short sequence of amino acids at the beginning of a newly synthesized protein that directs the protein to its proper location within or outside the cell.
SRP (signal recognition peptide)
a protein-RNA complex, escorts the ribosome to a receptor protein built into the ER membrane
SRP receptor protein
SRP receptor is a protein located on the membrane of the endoplasmic reticulum (ER) that helps guide proteins to the ER during translation.
Translocation complex
is a group of proteins in the membrane of the endoplasmic reticulum (ER) that helps move newly made proteins into or across the ER membrane during translation
Silent substitution
refers to a type of genetic mutation at the DNA level where a change in a nucleotide sequence does not alter the amino acid sequence of the protein that is produced.
NO EFFECT ON THE AMINO ACID SEQUENCE
Missense substitution
is a type of genetic mutation where a change in a single nucleotide in the DNA sequence results in the replacement of one amino acid with another in the protein.
A range of effects depending on the location within the
protein and the identity of the new amino acid
Nonsense substitution
is a type of genetic mutation where a change in a single nucleotide in the DNA sequence creates a premature stop codon in the mRNA
Effect depends on how close the new stop codon is to the
beginning of the coding sequence
Frameshift
is a type of genetic mutation that occurs when nucleotides are inserted into or deleted from the DNA sequence in numbers not divisible by three. This shifts the “reading frame” of the genetic code.
causing immediate nonsense (1-nucleotide-pair insertion)
causing extensive missense (1-nucleotide-pair deletion)
codon addition or deletion
refers to the insertion or removal of a set of three nucleotides (a codon) in the mRNA sequence. Since each codon corresponds to one amino acid, adding or deleting a codon changes the number of amino acids in the resulting protein but does not shift the reading frame.
no frameshift, but one amino acid is missing. A 3 nucleotide pair insertion would lead to an extra amino acid
