Protein Synthesis & One Gene Hypothesis

A method used to identify the order of steps in a biochemical pathway by studying mutations that block specific steps.

An organism that cannot synthesize a particular compound required for growth. In the context of the text, the mutants are unable to synthesize arginine.

Adding a specific compound to the growth medium to bypass a blocked step in a metabolic pathway. If growth resumes, it suggests that the added compound comes after the blocked step in the pathway.

A specific mutation that prevents the conversion of ornithine to citrulline in the arginine biosynthesis pathway.

A specific mutation that prevents the formation of arginine from citrulline in the arginine biosynthesis pathway.

A specific mutation that blocks a step in the biosynthesis of ornithine, a precursor to arginine.

The series of chemical reactions that produce arginine from a precursor molecule.

The process of using mutations to study the genetic basis of biochemical pathways.

The sequence of amino acids in a protein chain.

The local folding patterns within a protein chain, such as alpha-helices and beta-sheets, formed through hydrogen bonds between nearby amino acids.

The overall three-dimensional shape of a single polypeptide chain, determined by interactions between R-groups of amino acids.

The arrangement of multiple polypeptide chains (subunits) in a protein complex, stabilized by interactions between them.

A distinct functional unit within a protein, often consisting of a specific sequence of amino acids that folds into a compact structure.

The sequence of three nucleotides (a triplet) in mRNA that codes for a specific amino acid.

The set of rules that defines how a sequence of nucleotides in DNA is translated into a sequence of amino acids in a protein.

The number of nucleotides required to encode a single amino acid is three, due to the potential 64 combinations of a triplet code (4 bases x 4 bases x 4 bases = 64)

The process by which amino acids are linked together to form a polypeptide chain.

A site on the ribosome where a charged tRNA molecule carrying the next amino acid binds.

A site on the ribosome where the growing polypeptide chain is attached to a tRNA.

A site on the ribosome where the tRNA that has just released its amino acid exits.

A protein involved in delivering charged tRNA to the A site of the ribosome during elongation.

A protein involved in regenerating EF-Tu-GTP from EF-Tu-GDP after GTP hydrolysis.

The process by which a ribosome moves one codon down the mRNA during translation.

A sequence in mRNA that can be translated into a short polypeptide chain, located upstream of the main start codon.

tRNAs that recognize the same amino acid despite having different anticodons.

A phenomenon where the third base pairing between codon and anticodon isn't always strict, allowing some tRNAs to recognize multiple codons.

The sequence of codons in mRNA that specifies the order of amino acids in a polypeptide chain.

A codon that signals the start of protein synthesis, usually AUG.

A genetic code where each nucleotide is part of only one codon.

Codons that encode for the same amino acid.

A type of flexible base pairing in the third position of a codon and anticodon.

A codon that specifies an amino acid.

The initiation factor that prevents the large ribosomal subunit from binding to the small ribosomal subunit during initiation.

The initiation factor that enhances the dissociation of the large and small ribosomal subunits, preparing them for translation initiation.

The region on mRNA where the ribosome binds during initiation of translation.

Consensus sequence within the ribosome-binding site on mRNA that is complementary to a sequence in the 16S rRNA. This sequence helps guide and position the ribosome for translation.

The initiation tRNA that carries the formylmethionine (fMet) amino acid and binds to the AUG initiation codon during translation initiation.

The complex formed during translation initiation that consists of the small ribosomal subunit, mRNA, initiator tRNA (fMet-tRNA Met), GTP, and several initiation factors.

The complex formed after the large ribosomal subunit joins the 30S initiation complex, signifying completion of the initiation step of translation.

The process of translation initiation in eukaryotic cells, which involves similar steps as in prokaryotes but with some notable differences.

A specialized molecule within the ribosome, often an rRNA, that catalyzes a chemical reaction.

The movement of the ribosome along the mRNA molecule in the 5' to 3' direction, shifting the ribosome to the next codon.

A protein that assists in the elongation of the polypeptide chain during translation by facilitating the movement of the ribosome along the mRNA.

A protein that assists in the translation of proteins containing multiple proline amino acids in a row, preventing ribosome stalling.

RNAs made by polynucleotide phosphorylase are called random copolymers because they contain a random mixture of bases.

The ratio of bases in a random copolymer affects the proportion of amino acids in the protein it codes for.

Nirenberg and Leder's technique using ribosome-bound tRNAs helped determine the codons for specific amino acids.

They found that short mRNA sequences could bind to ribosomes and that the codon on the mRNA would base pair with the anticodon on a tRNA, which carried a specific amino acid.

This technique allowed them to determine the codons for specific amino acids by studying the amino acids carried by the tRNAs that bind to the ribosome.

The study of the genetic code is a crucial area in molecular biology as it helps us understand how genetic information is translated into proteins.

Nirenberg and Leder's work on the genetic code laid the foundation for modern molecular biology, leading to advancements in disease research, drug development, and genetic engineering.

A sequence of three nucleotides in mRNA that specifies a particular amino acid during protein synthesis.

The set of rules that defines how a sequence of nucleotides in DNA or RNA is translated into a sequence of amino acids in a protein.

The genetic code is considered degenerate because multiple codons can specify the same amino acid. This redundancy helps protect against mutations.

The three codons (UAA, UAG, UGA) that signal the termination of protein synthesis. They mark the end of the protein sequence.

This is how Nirenberg and Leder figured out which codons code for which amino acids by using short, synthetic mRNA molecules.

Francis Crick described the genetic code as being as important to biology as the periodic table of elements is to chemistry. This highlights its fundamental importance in understanding life.

Aminoacyl-tRNA synthetases are enzymes that attach the correct amino acid to its corresponding tRNA molecule.

Each tRNA has a unique sequence, allowing aminoacyl-tRNA synthetases to recognize and bind to the correct tRNA.

The process of attaching an amino acid to its tRNA is called tRNA charging.

The process of initiation in protein synthesis brings together all the components needed to start building a protein.

The initiation complex is formed when the small ribosomal subunit, mRNA, initiator tRNA, initiation factors, and GTP come together.

The small and large subunits of the ribosome are essential for protein synthesis.

Initiation factors are proteins that help assemble the initiation complex.

The initiator tRNA carries the first amino acid, usually N-formylmethionine, to the ribosome.

A short sequence of nucleotides in eukaryotic mRNA that surrounds the start codon, AUG, and helps the small ribosomal subunit identify the correct start site.

A complex of proteins that binds to the 5' cap on mRNA, playing a role in both mRNA export from the nucleus and initiation of translation in the cytoplasm.

A key initiation factor in eukaryotes that binds to the 5' cap of mRNA after the CBC is removed, promoting the continued translation of the mRNA.

A series of steps involving the small ribosomal subunit, initiation factors, and the initiator tRNA that recognizes the 5' cap on mRNA and scans it for the start codon.

The process of forming a peptide bond between amino acids attached to tRNAs in the ribosome's P and A sites.

The process of adding amino acids one by one to a growing polypeptide chain.

The repeating steps involved in elongation: a tRNA enters the A site, a peptide bond forms, and the ribosome translocates to the next codon.