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Science lesson plan · 10th grade (Year 11 in England) · 45 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 · 5 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. How many chromosomes are in a normal human body cell? (46 (23 pairs) / 92 / 23 / 12) → 46 (23 pairs)Prompt: They come in pairs, one of each pair from each parent.
  2. Human body cells have 23 pairs of chromosomes. How many chromosomes are in a skin cell? → 46Prompt: Is this a gamete (sex cell) or a body cell?
  3. What shape is a DNA molecule? (a ring of six atoms / a cube / a double helix / a single straight line) → a double helixPrompt: It looks like a twisted ladder.

Hook · 5 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 · 10 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 · 10 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 CCA GAA GGG. Write the complementary DNA strand (letters only). → GGTCTTCCCPrompt: A always pairs with T in DNA.
  2. A DNA template strand reads AGC TTG AAC. Write the mRNA sequence transcribed from it (letters only). → UCGAACUUGPrompt: RNA has uracil (U) instead of thymine (T).

You do: independent practice · 10 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 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A DNA template strand reads GTC CAT. Write the mRNA sequence transcribed from it (letters only). → CAGGUAPrompt: RNA has uracil (U) instead of thymine (T).
  2. Which base is found in RNA but not in DNA? (guanine (G) / thymine (T) / adenine (A) / uracil (U)) → uracil (U)Prompt: It replaces one of the DNA bases.

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/ 8

  1. Question 1

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

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

  2. Question 2

    A DNA template strand reads CAT GTG ACG. Write the mRNA sequence transcribed from it (letters only).

    Answer

  3. Question 3

    One strand of DNA reads TGG TGA GCG. Write the complementary DNA strand (letters only).

    Answer

  4. Question 4

    Which scientists' X-ray image helped show DNA is a double helix?

    • A. Alexander Fleming's
    • B. Rosalind Franklin's (with Maurice Wilkins's lab)
    • C. Gregor Mendel's
    • D. Louis Pasteur's

  5. Question 5

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

    Answer

  6. Question 6

    One strand of DNA reads GTC AAG. Write the complementary DNA strand (letters only).

    Answer

  7. Question 7

    Which base is found in RNA but not in DNA?

    • A. guanine (G)
    • B. thymine (T)
    • C. uracil (U)
    • D. adenine (A)

  8. Question 8

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

    Answer

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Answer key: Write complementary DNA and mRNA base sequences

  1. 1. C. alternating sugar and phosphate groups

  2. 2. GUACACUGC

  3. 3. ACCACTCGC

  4. 4. B. Rosalind Franklin's (with Maurice Wilkins's lab)

  5. 5. UAAGCG

  6. 6. CAGTTC

  7. 7. C. uracil (U)

  8. 8. GUGAAG