Slide 1
A ribosome translates a message into a protein chain
A ribosome reads a molecular message and assembles amino acids into a protein chain. This cellular process is called translation.
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The ribosome contains both proteins and ribosomal ribonucleic acid (RNA). Its RNA participates directly in catalysis, making the machine an example of a biological catalyst whose central chemistry is not performed by protein alone.
Slide 2
Three-base codons specify amino acids or stopping
The genetic code is read in three-base units called codons. Most codons specify an amino acid, while some signal stopping.
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Several codons can specify the same amino acid. This redundancy means some base substitutions leave the amino-acid sequence unchanged, although other consequences for RNA or translation can still occur.
Slide 3
Transfer RNAs connect each codon with its amino acid
Transfer ribonucleic acids, or transfer RNAs, connect codons with amino acids.
Their anticodons, matching three-base regions, pair with the message while carrying the corresponding amino acid.
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Enzymes that attach amino acids to transfer RNAs provide an essential accuracy step. The ribosome reads the adaptor’s pairing, so correct loading is needed before the message can be translated faithfully.
Slide 4
The starting position determines every group of three
Starting at the correct position establishes the groups of three. Shifting that reading frame can change every later codon until a stop is reached.
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An insertion or deletion of one base in a coding region can create a frameshift. A change of three bases instead preserves the downstream grouping, although the added or removed amino acid can still matter.
Slide 5
The new chain still needs to become functional
After synthesis, a protein often folds, joins partners or receives chemical modifications. The amino-acid sequence begins the process but is not the final assembled function.
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Some proteins are directed to membranes or specific cellular compartments by sequence signals. Where a protein arrives can be as important as whether the cell successfully produced its chain.
Sources
- Translation
National Human Genome Research Institute
- Ribosome
National Human Genome Research Institute
- Enzyme
National Human Genome Research Institute