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IGCSE · Cambridge (CIE) · 0610

Define a protein-coding gene as a length of DNA

Core definition: a gene is a DNA length coding for a protein. It carries information; the DNA does not turn into amino acids. This pathway states the protein-coding syllabus scope explicitly.

Chromosomes, genes and proteins pathway · 17.1

Core and Extended; Biology 0610, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked

Before you begin

  • Recall the nucleus, DNA base pairing, gametes, fertilisation, enzymes, membrane carriers and chemical synapses.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

Which gives the required gene definition?

What you will learn

  • Use the syllabus gene definition precisely
  • Distinguish coding information from a finished protein

Original teaching model. Counts and records are stipulated; drawings are schematic.

Define a protein-coding gene as a length of DNACore definition: a gene is a DNA length coding for a protein. It carries information; the DNA does not turn into amino acids. This pathway states the protein-coding syllabus scope explicitly.Nucleus · selected chromosomeEnlarged DNA viewMarked gene region · not to scaleCoding informationUsed in protein productionDNA does not become amino acids
Core definition: a gene is a DNA length coding for a protein. It carries information; the DNA does not turn into amino acids. This pathway states the protein-coding syllabus scope explicitly.
Information, material and count key
FeatureMeaning
MaterialA length of DNA
RoleCodes for a protein
Product distinctionGene is not the protein
ScopeProtein-coding syllabus definition

Use the syllabus gene definition precisely

For this syllabus, define a gene as a length of DNA that codes for a protein. The definition gives both the material and its information role. A gene is not a protein, an amino acid or the whole nucleus. Saying only a gene controls a characteristic misses the DNA region and protein-coding link that this requirement asks learners to state.

The phrase codes for means the DNA carries information used in making the protein; it does not mean DNA physically becomes the protein. DNA bases and the amino acids assembled into a protein are different kinds of building blocks. The Extended sequence later explains the messenger RNA and ribosome links, but those details are not required to give this Core definition.

Distinguish coding information from a finished protein

The syllabus uses a protein-coding gene definition. Wider biology also recognises genes whose products are functional RNA molecules rather than proteins. This broader meaning does not change the requested answer in this pathway, and learners are not asked to memorise a full catalogue of RNA genes. Keep the defined scope rather than claim every DNA region must code for a protein.

The original definition model places a bracket on a DNA length and points to an information role for protein production. The arrow is not a material-conversion arrow. When a question asks for a definition, give the complete concise relationship first, then use an example only if requested. An imagined protein shape cannot by itself reveal an exact gene base sequence.

Pause and explain

What does codes for mean here?

Put the idea to work

Worked example

What is missing from a gene is a thing controlling a feature?

Show the worked solution
  1. Name the DNA material.
  2. Name the protein-coding role.

Answer For this syllabus, a gene is a length of DNA that codes for a protein.

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From guided practice to a new situation

Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.

1 · Guided

Give the syllabus definition of a gene.

Give me a hint

Include DNA length and protein coding.

Compare my reasoning
  1. Name a length of DNA.
  2. State that it codes for a protein.

A gene is a length of DNA that codes for a protein.

Look for these in your work

  • Give the material
  • Give the coding role
2 · Independent

Correct the statement a gene is a protein stored in the nucleus.

Give me a hint

Distinguish information from product.

Compare my reasoning
  1. Identify a gene as DNA.
  2. Identify protein as a product made using information.

A protein-coding gene is a length of DNA, not a stored protein; its information is used to make a protein.

Look for these in your work

  • Correct the material
  • Retain information use
3 · Transfer

A diagram says a DNA gene is used up and converted into amino acids. Evaluate.

Give me a hint

Information use is not material conversion.

Compare my reasoning
  1. Retain the gene as DNA.
  2. Identify amino acids as different building blocks.

The claim is wrong: the gene provides information and remains DNA; amino acids are assembled into a protein rather than being converted from the gene.

Look for these in your work

  • Reject DNA consumption
  • Distinguish the protein material

Common mistakes

  • DNA is not converted into amino acids.
  • Use the specified protein-coding scope.
Recall without your notes

What can you explain now?

What does codes for mean here?

Compare with the explanation

Carries information used to make a protein

It is an information relationship.

After trying it yourself, choose your next review. This is your self-assessment.

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Make it stick

Explain use the syllabus gene definition precisely and distinguish coding information from a finished protein. Use the stated cell, chromosome sets and information pathway before opening the solutions.

If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.

Keep learning Biology

Course scope and assessment

780 sequenced lessons provide 2340 guided, independent and application problems in characteristics, classification, cells, organisation, specimen size, membrane transport, biological molecules, enzymes, plant and human nutrition, plant transport, circulatory systems, the heart, blood vessels, blood, disease transmission, body defences, immunity, gas exchange in humans, respiration energy uses and investigations, aerobic respiration, anaerobic respiration and recovery, excretion in humans, coordination and response, sense organs, hormones, homeostasis, tropic responses, drugs, asexual reproduction, sexual reproduction, sexual reproduction in plants, sexual reproduction in humans, sex hormones in humans, sexually transmitted infections, chromosomes, genes and proteins, mitosis, meiosis, monohybrid inheritance, variation, adaptive features, selection, energy flow, food chains and webs, nutrient cycles, population, community, ecosystem, population-growth phases, food supply, habitat destruction, pollution, conservation, biotechnology and genetic modification. 61 of 61 syllabus sections have linked teaching and staged practice. The earlier inheritance overview remains introductory, and the monohybrid pathway develops the relevant Core and Supplement requirements. This is not full programme completion or guaranteed exam readiness. Written practice is self-checked.

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