Sub-strand 2.2 - Protein structure, function and synthesis - Lesson 1 - Protein synthesis

Aug 31, 2026

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Instructional content for Sub-strand 2.2 on protein structure, function and synthesis within Strand 2 (gene expression). Lesson 1 focuses on protein synthesis by explaining transcription and translation, including roles of DNA, mRNA, tRNA and ribosomes. Learners extend Form 6 concepts to DNA triplets, mRNA codons, and tRNA anticodons, practice using a codon dictionary to identify amino acids, and analyze the redundant nature of the genetic code. Notes compare DNA, mRNA and tRNA and outline transcription stages, RNA processing, and translation steps leading to polypeptide and folded proteins. The genetic code is summarized as 64 codon arrangements mapping to 20 amino acids.

LanguageEnglish

CategoryGeneral

FormatDOCX

Pages19

Reading Time7 min

AccessFree to download

Protein synthesis

Key learning outcomes

Key terms and learning checklist

Comparison of DNA, mRNA and tRNA

Protein synthesis stages: transcription

RNA processing/splicing

Protein synthesis stages: translation

Genetic code and reading the codon chart

STRAND 2: GENE EXPRESSION Sub-strand 2.2 Protein structure, function and synthesis LESSON 1: PROTEIN SYNTHESIS Key Learning outcome: Students are able to demonstrate understanding of protein synthesis and how it contributes to forms and functions: transcription and translation; ribosomes revision and extension of form 6 to include role of DNA (triplets), mRNA (codons), tRNA (anticodons) use of codon dictionary to identify amino acids; redundant nature of the genetic code The specific learning outcomes targeted in this lesson are provided below: Tick the last column when you have achieved each outcome. Key Terms: Tick if you are able to define and use the following terms correctly. Recommended Readings: LESSON NOTES Comparison of DNA, tRNA and mRNA DNA (Deoxyribose Nucleic Aicd) Is double stranded, helical in shape and very long since it is composed of many genes. One of its strands acts as a template (anti-sense, non-coding strand or template strand) which is copied by mRNA to make a protein. The other strand (sense) conserves the genetic instruction. Its sugar group is called deoxyribose. It has the bases: A (adenine), T (thymine), C (cytosine) and G (Guaninie) Every 3 bases along the strand is called a Triplet (1 triplet codes for 1 amino acid). mRNA (messenger Ribonucleic Acid) Single-stranded, thread-like and smaller than DNA but larger than tRNA. It is a copy (transcript) of a gene in the DNA strand. It has a start codon (AUG) on one end and a stop codon (any of UAA, UAG or UGA) on its other end). Its sugar group is called Ribose. It has the bases: A, C, G and U (uracil) instead of thymine. Every 3 bases along it is called a codon. Each codon codes for an amino acid. The codon is a copy of the triplets on the anti-sense strand of DNA. Therefore, each codon should be the same as the triplets found on the DNA sense strand. tRNA (transfer Ribonucleic Acid) Single-stranded; smaller than mRNA and shaped like a clover-leaf. It is involved in the translation of mRNA into a polypeptide chain. It does this by carrying the correct amino acid to its corresponding mRNA codon within the ribosome. Its sugar group is the same as mRNA. It has a specific 3 base sequence called a triplet which corresponds to its complementary codon on mRNA. PROTEIN SYNTHESIS Protein synthesis is a process in cells which involves the decoding of the instruction held within a gene, to produce a protein. Stages of protein synthesis There are two stages of protein synthesis: transcription and translation. Transcription DNA unwinds at a specific gene sequence. Initiation: RNA polymerase enzyme attaches to the start of the gene sequence and adds on free nucleotides along the DNA template strand. The first triplet to be transcribed on the gene sequence would be TAC. This will be transcribed as AUG on the mRNA strand. This is the start codon on mRNA. Elongation: RNA polymerase starts adding on new nucleotides to the already existing chain of nucleotides. The addition of nucleotides follows the base – pairing rule A-U, C-G. mRNA mRNA Termination: RNA polymerase enzyme stops adding more nucleotides to the growing mRNA strand. This is because it has reached the last triplet on the DNA template strand. This triplet should read either ATT, ATC or ACT. So the last codon on the mRNA strand should either be UAA, UAG or UGA. HYPERLINK "http://1.bp.blogspot.com/-hu2juyywUxs/TYi3t74Xa6I/AAAAAAAAADM/FGBZC-p1FxU/s1600/sense-antisense.JPG" http://1.bp.blogspot.com/-hu2juyywUxs/TYi3t74Xa6I/AAAAAAAAADM/FGBZC-p1FxU/s1600/sense-antisense.JPG Editing or RNA Processing/Splicing: mRNA detaches from the DNA template. The mRNA strand would have copied ALL of the bases along the specific gene sequence on DNA. Some of the base sequences (codons) do not code for amino acids and therefore must be removed before mRNA undergoes the next stage. These non-coding regions are called introns. The base sequences (codons) which do code for amino acids are called exons. The introns are removed by

FAQs

What are the two main stages of protein synthesis taught in this lesson?

Protein synthesis includes transcription and translation. Transcription produces an mRNA copy from a DNA template, and translation uses mRNA codons to build a polypeptide chain.

How do DNA triplets relate to mRNA codons and tRNA anticodons?

DNA triplets form the basis for mRNA codons, and each mRNA codon corresponds to a complementary tRNA anticodon. During translation, tRNA brings the correct amino acid matching the codon within the ribosome.

What is RNA processing (splicing) and why is it needed?

After transcription, introns are removed and exons are reconnected to form the final mRNA transcript. This produces an mRNA that is shorter than the original transcript and ready for translation.

Aug 31, 2026

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