Ribosomes and Protein Synthesis

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polypeptide Noun

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[pol-ee-pep-tahyd]

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polypeptide

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A long, unbranched chain of amino acids linked together by peptide bonds, which forms the primary structure of a protein.

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Example: This image shows that a polypeptide (represented as a 'Protein') is a long chain made by linking many smaller units called amino acids together.

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amino acid Noun

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[uh-mee-noh as-id]

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amino acid

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An organic molecule that serves as the fundamental building block, or monomer, for constructing proteins and polypeptide chains.

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Example: This diagram shows that individual molecules called amino acids (represented as dots) link together in a chain to form a larger molecule called a protein.

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genetic code Noun

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[juh-net-ik kohd]

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genetic code

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The set of rules by which information encoded in genetic material is translated into proteins by living cells.

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Example: This chart shows how a sequence of three nucleotide bases (a codon) in mRNA is translated into a specific amino acid to build a protein.

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codon Noun

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[koh-don]

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codon

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A sequence of three consecutive nucleotide bases in an mRNA molecule that specifies a particular amino acid or a stop signal.

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Example: This diagram shows that an mRNA sequence is read in groups of three bases, called codons, which determine the order of amino acids in a protein.

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start codon Noun

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[stahrt koh-don]

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start codon

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The specific codon, typically AUG, that signals the ribosome to begin the process of protein synthesis or translation.

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Example: This diagram shows an mRNA strand where the 'start codon' (AUG) signals the beginning of protein creation, resulting in the first amino acid (Met).

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stop codon Noun

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[stop koh-don]

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stop codon

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One of three specific codons that signals the termination of translation, causing the release of the completed polypeptide chain.

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Example: An mRNA sequence is read in three-letter codons to build a protein, but when a stop codon is reached, the process terminates and the protein is complete.

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transcription Noun

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[tran-skrip-shun]

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transcription

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The process of synthesizing a complementary messenger RNA (mRNA) molecule from a specific gene sequence on a DNA template.

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Example: An enzyme (RNA polymerase) reads a DNA strand and builds a matching messenger RNA (mRNA) copy, which is the first step in making a protein.

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translation Noun

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[trans-ley-shun]

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translation

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The cellular process where the genetic information coded in messenger RNA directs the synthesis of a specific protein.

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Example: A ribosome moves along an mRNA strand, reading its code to link amino acids (brought by tRNA) into a growing protein chain.

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anticodon Noun

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[an-tee-koh-don]

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anticodon

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A sequence of three nucleotides on a transfer RNA (tRNA) molecule that is complementary to a corresponding codon on mRNA.

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Example: This diagram shows how a tRNA molecule's anticodon (UAC) pairs with a matching codon (AUG) on an mRNA strand to deliver the correct amino acid.

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ribosome Noun

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[rahy-buh-sohm]

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ribosome

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A complex cell organelle, composed of rRNA and protein, that serves as the site for protein synthesis (translation).

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Example: This diagram shows a ribosome reading an mRNA strand to link amino acids together, forming a growing protein chain.