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Science lesson plan · 10th grade (Year 11 in England) · 30 minutes

Write complementary DNA and mRNA base sequences

Cells, genetics and evolution

CCSS NGSS.HS-LS1-1CCSS NGSS.HS-LS3-1England: GCSE Biology: Inheritance, variation and evolution (DNA structure)

Objective and success criteria

Students will: Write complementary DNA and mRNA base sequences.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: DNA, genes and chromosomes

Leads to: Substitution, insertion and deletion mutations; Calculate DNA base percentages (A = T, C = G)

Materials: Microscope images or slides, Cell diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 4 min

  • Quick retrieval from earlier learning (DNA, genes and chromosomes). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. What is a gene? (a disease / a section of DNA that codes for a protein / a type of cell / a whole chromosome) → a section of DNA that codes for a proteinPrompt: Genes are found along chromosomes.
  2. Human body cells have 23 pairs of chromosomes. How many chromosomes are in a sperm cell? → 23Prompt: Is this a gamete (sex cell) or a body cell?
  3. How many chromosomes are in a normal human body cell? (12 / 46 (23 pairs) / 92 / 23) → 46 (23 pairs)Prompt: They come in pairs, one of each pair from each parent.

Hook · 3 min

  • Show a microscope image of cells and ask what students think they are looking at.
  • Share the objective: Write complementary DNA and mRNA base sequences. Read the success criteria together.

I do: model it · 7 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: One strand of DNA reads TGT TCT CTA. Write the complementary DNA strand (letters only).
  • Step 1: TGTTCTCTA → ACAAGAGAT
  • Step 2: So the answer is: ACAAGAGAT
  • Answer: ACAAGAGAT
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 6 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. One strand of DNA reads GCG ATC CGC. Write the complementary DNA strand (letters only). → CGCTAGGCGPrompt: A always pairs with T in DNA.
  2. A DNA template strand reads TTT GAT. Write the mRNA sequence transcribed from it (letters only). → AAACUAPrompt: RNA has uracil (U) instead of thymine (T).

You do: independent practice · 7 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. One strand of DNA reads CTA TCC ATT. Write the complementary DNA strand (letters only). → GATAGGTAAPrompt: A always pairs with T in DNA.
  2. DNA is described as a double helix. What forms the "backbone" of each strand? (pairs of bases / fatty acids / amino acids / alternating sugar and phosphate groups) → alternating sugar and phosphate groupsPrompt: The bases point inwards like the rungs of a ladder.

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: DNA, genes and chromosomes.
  • Use concrete materials: microscope images or slides.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Move on to: Substitution, insertion and deletion mutations; Calculate DNA base percentages (A = T, C = G).
  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-10.

Free lesson plan from eurekami.com/lesson-plan-builder

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Write complementary DNA and mRNA base sequences

Name

Date

Score/ 6

  1. Question 1

    One strand of DNA reads AAA TAA ACT. Write the complementary DNA strand (letters only).

    Answer

  2. Question 2

    DNA is described as a double helix. What forms the "backbone" of each strand?

    • A. alternating sugar and phosphate groups
    • B. fatty acids
    • C. pairs of bases
    • D. amino acids

  3. Question 3

    A DNA template strand reads GGT TGG. Write the mRNA sequence transcribed from it (letters only).

    Answer

  4. Question 4

    One strand of DNA reads ATA CCG TCT. Write the complementary DNA strand (letters only).

    Answer

  5. Question 5

    A DNA template strand reads TCA ATT AGG. Write the mRNA sequence transcribed from it (letters only).

    Answer

  6. Question 6

    One strand of DNA reads CGG GTA. Write the complementary DNA strand (letters only).

    Answer

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Answer key: Write complementary DNA and mRNA base sequences

  1. 1. TTTATTTGA

  2. 2. A. alternating sugar and phosphate groups

  3. 3. CCAACC

  4. 4. TATGGCAGA

  5. 5. AGUUAAUCC

  6. 6. GCCCAT