what are the missing words? each gene codes for a particular combination of __________ __________ which makes a specific protein

The missing words are "amino acids". Genes contain the instructions for building proteins through DNA sequences that are transcribed into mRNA and then translated by ribosomes. Each gene codes for a particular combination of amino acids which makes a specific protein, as sequences of three nucleotides (codons) specify individual amino acids linked into polypeptide chains.

How Translation Works

• DNA to mRNA : A gene's nucleotide sequence is copied into messenger RNA (mRNA) during transcription.

• Codons in Action : Ribosomes read mRNA in groups of three nucleotides called codons; each codon matches a transfer RNA (tRNA) carrying a specific amino acid.

• Chain Building : tRNAs add amino acids one by one, forming a polypeptide that folds into a functional protein. Stop codons end the process.

This central dogma of molecular biology—DNA → RNA → protein—ensures precise protein synthesis vital for life.

Why Amino Acids Matter

Proteins' diverse functions (enzymes, structures, signals) arise from 20 standard amino acids' unique properties like polarity or charge. Imagine a gene as a recipe: codons are steps, amino acids are ingredients, yielding everything from hemoglobin to antibodies.

"Each sequence of three nucleotides, called a codon, usually codes for one particular amino acid. (Amino acids are the building blocks of proteins.)"

Real-World Example

Hemoglobin, carrying oxygen in blood, is coded by the HBB gene's amino acid sequence; a single swap (valine for glutamic acid) causes sickle cell anemia.

TL;DR : Genes code for amino acids → specific proteins via codons.

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