Unit 9 — DNA, Protein Synthesis, Mutation, and Biotechnology
BIO.3C
Unit 9: Need to Know and Be Able to Do
9.1 - DNA, Genes, and Chromosomes
Need to know
- DNA is a polymer made of repeating units called nucleotides.
- DNA stores information in the order of its nucleotides.
- A gene is a section of DNA that codes for a product, often a protein.
- Chromosomes contain DNA; genes are sections of DNA located on chromosomes.
- Chromosomes transfer genetic information — the instructions for traits — from parents to offspring.
Be able to do
- Use a model or diagram to identify a nucleotide, a gene, and a chromosome, and explain how they fit together.
- Explain why the order of nucleotides is what lets DNA work as instructions for a specific protein.
- Explain how a trait is passed from parent to offspring through chromosomes.
9.2 - Transcription and Translation
Need to know
- Transcription is the process that produces mRNA. It occurs in the nucleus.
- Translation is the process that produces a polypeptide (protein). It occurs at the ribosome.
- During translation, the ribosome reads the mRNA information and amino acids are assembled into a polypeptide.
- In transcription, complementary bases pair: DNA A → U, T → A, G → C, C → G.
- mRNA contains uracil (U) in place of thymine (T).
- A codon is a group of three mRNA bases that codes for one amino acid. A codon chart shows which amino acid each mRNA codon codes for.
- Transcribe a DNA sequence into mRNA before using a codon chart.
Be able to do
- Label transcription, translation, their products, and their locations on a diagram.
- Transcribe a DNA template strand into an mRNA sequence.
- Sort descriptors into a Venn diagram comparing transcription and translation.
- Transcribe a DNA sequence into mRNA and use a codon chart to find the amino acids.
9.3 - Gene Mutations
Need to know
- A substitution (point) mutation changes one base to a different base; the number of bases stays the same and the reading frame is not shifted.
- A silent mutation changes a nucleotide but not the amino acid. A missense mutation changes the amino acid (for example Pro → Ala).
- Frameshift mutations are caused by an insertion or a deletion, which shifts the reading frame downstream of the change.
- A frameshift can change every amino acid after the change; a point mutation changes at most one.
- Transcribe a DNA sequence into mRNA before using a codon chart, including for a sequence with an insertion or a deletion.
- Mutation effects trace through DNA → mRNA codon → amino acid sequence → protein/trait.
- A mutation can have a positive, negative, or no effect on the resulting protein or trait.
Be able to do
- Distinguish a substitution from an insertion or a deletion by comparing an original sequence with a mutated one.
- Use the codon chart to decide whether a substitution is silent or missense.
- Use the codon chart to find the amino acids that result from a mutated sequence, and predict how a frameshift changes the protein compared with a point mutation.
- Trace a mutation’s effect from the DNA to the protein and the trait.
9.4 - DNA Technology
Need to know
- Cloning: conserving the genetics of endangered species; producing predictable traits for research and agriculture; producing patient-matched cells for tissue repair.
- Transgenic organisms: disease resistance, faster growth, or added nutrition in crops and livestock (for example insulin production, Bt corn, Golden Rice).
- Human Genome Project: earlier disease detection and diagnosis; better-matched medicine doses; support for gene therapy research.
- Gel electrophoresis: forensic identification, paternity and relatedness testing, and disaster-victim identification, by comparing DNA fragment patterns.
- Stem cell research is part of this standard too: its benefits and its ethical issues.
- Evaluate ethical issues involving cloning, transgenic organisms, stem cell research, the Human Genome Project, and gel electrophoresis. Each has benefits and risks or ethical concerns.
- The strongest ethical argument against cloning endangered species is that the process could be used on organisms for personal preference (misuse).
- A scientific argument uses a claim, evidence, and reasoning — and separates evidence from opinion.
Be able to do
- Identify how each named DNA technology benefits society, and match a technology to a scenario that describes its use.
- Read a gel: smaller fragments travel farther, and matching band patterns suggest the same source.
- Sort statements about transgenic organisms into benefits and risks.
- Pick the ethical concern that fits a technology or a cloning scenario.
- Tell evidence from opinion, evaluate whether a claim is supported, and weigh the benefits and the risks of a DNA technology.
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Practice Quiz—with feedback Unit Quiz9.1 DNA, Genes, and Chromosomes
Practice nucleotides, genes, chromosomes, and how instructions pass from parent to offspring.
Open untimed reviewTake graded quiz9.2 Transcription and Translation
Label transcription and translation, transcribe a DNA template into mRNA, and use the codon chart to find the amino acids.
Open untimed reviewTake graded quiz9.3 Gene Mutations
Tell substitutions from insertions and deletions, decide whether a substitution is silent or missense, and predict how a frameshift changes the protein.
Open untimed reviewTake graded quiz9.4 DNA Technology
What cloning, transgenic organisms, the Human Genome Project, gel electrophoresis, and stem cell research are — how each one helps society, the risks and ethical concerns each raises, and how to build a scientific argument.
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Open the BIO.3C section of the Biology Review Doc for Blooket games and Wayground reviews.
Open BIO.3C review documentExplore with NASA: GeneLab
Find out how genes in plants, mice, and microbes respond to spaceflight, and open real NASA studies.
GeneLab: Genes in Space3D Protein Viewer