Biology • Year 12 • Module 5 • Lesson 17
DNA Sequencing and DNA Profiling
Lock in the core distinction: sequencing reads the base order itself, profiling compares selected marker patterns. Build the vocabulary needed for the population-inheritance applications that follow.
1. Cloze — the two technologies in one paragraph
Fill each blank with a term from the word bank. Each term is used once. 10 marks (1 per blank)
Word bank: base order · marker · sequencing · profiling · inheritance · variation · mutation · nucleotide · sample · pattern
DNA __________ (1.1) determines the exact order of __________ (1.2) bases in a DNA region or whole genome. Because it reveals the actual __________ (1.3), it can directly identify a specific __________ (1.4) linked to an inherited disorder.
DNA __________ (1.5), by contrast, does not normally read the whole genome. Instead it compares the __________ (1.6) of selected __________ (1.7) regions between samples. This is useful for deciding whether two __________ (1.8) sources are likely to share an __________ (1.9) link, but the inference depends on the amount of __________ (1.10) at the chosen markers.
2. Term–definition match
The definitions below are shuffled. In the right-hand column write the matching term from this list: DNA sequencing, DNA profiling, base order, marker region, relatedness, population structure, nucleotide, SNP, allele, variant. 10 marks
| # | Definition (shuffled) | Matching term |
|---|---|---|
| 2.1 | The exact order of A, T, C and G in a length of DNA. | |
| 2.2 | The technology that determines the order of nucleotide bases in DNA. | |
| 2.3 | The technology that compares patterns at selected DNA regions to distinguish or relate samples. | |
| 2.4 | A selected DNA region used in comparison rather than full genome reading. | |
| 2.5 | The degree of genetic similarity between individuals or groups, which can suggest inheritance links. | |
| 2.6 | Patterns of genetic similarity and difference within and between populations. | |
| 2.7 | The basic chemical unit of DNA, consisting of a sugar, a phosphate and one of four bases. | |
| 2.8 | A single base position in DNA at which different individuals carry different bases. | |
| 2.9 | One of two or more alternative forms of a gene found at the same locus. | |
| 2.10 | A specific change in the DNA sequence, which may or may not affect phenotype. |
3. True or false — with correction
For each statement, circle T or F. If the statement is false, write the corrected version on the line. 10 marks (1 T/F, 1 correction where needed)
3.1 DNA sequencing and DNA profiling answer exactly the same biological question. T / F
3.2 DNA sequencing determines the exact order of nucleotide bases in a DNA region. T / F
3.3 A DNA profile gives the full genome base order of an individual. T / F
3.4 Whole-genome sequencing reads a chromosome end-to-end in a single uninterrupted pass. T / F
3.5 DNA profiling can support inferences about relatedness and inheritance links between samples. T / F
4. Function recall
Answer each in 1–2 sentences using precise terms from the lesson. 10 marks (2 each)
4.1 What is the function of DNA sequencing as a technology?
4.2 What is the function of DNA profiling as a technology?
4.3 What is the function of a marker region in a DNA profile?
4.4 What is the function of these two technologies in studying inheritance patterns in populations?
4.5 Why is identifying a specific inherited variant linked to a disease usually a job for sequencing, not profiling?
5. Label the sequencing-vs-profiling diagram
The diagram below contrasts what each technology produces from the same starting DNA sample. Write the missing labels into boxes A–H. 8 marks
- A — technology name (left panel) _______________________
- B — type of output (left panel: ordered string of …?) _______________________
- C — what the left output can identify directly (e.g. a specific ___ ) _______________________
- D — example inheritance use of left output (population inherited ___ study) _______________________
- E — technology name (right panel) _______________________
- F — type of output (right panel: pattern at selected ___ regions) _______________________
- G — what the right output supports (inference about ___ between samples) _______________________
- H — example inheritance use of right output (comparing related ___) _______________________
| Box | Your label |
|---|---|
| A | |
| B | |
| C | |
| D | |
| E | |
| F | |
| G | |
| H |
Q1 — Cloze (10 marks)
1.1 sequencing • 1.2 nucleotide • 1.3 base order • 1.4 mutation • 1.5 profiling • 1.6 pattern • 1.7 marker • 1.8 sample • 1.9 inheritance • 1.10 variation.
Marking: 1 mark per correctly placed term. Spelling tolerated if unambiguous.
Q2 — Term–definition matches (10 marks)
2.1 base order • 2.2 DNA sequencing • 2.3 DNA profiling • 2.4 marker region • 2.5 relatedness • 2.6 population structure • 2.7 nucleotide • 2.8 SNP • 2.9 allele • 2.10 variant.
Marking: 1 mark per correct match.
Q3 — True / false with correction (10 marks)
3.1 False. Correction: they are related technologies but answer different questions — sequencing determines the actual base order, while profiling compares patterns at selected DNA regions.
3.2 True.
3.3 False. Correction: a DNA profile is a pattern at selected marker regions; it does not give the full genome base order.
3.4 False. Correction: whole-genome sequencing fragments the DNA, sequences millions of short reads, and computationally reassembles them — chromosomes are not read end-to-end in one pass.
3.5 True.
Marking: 1 mark for correct T/F; 1 mark for an accurate correction where the statement is false.
Q4 — Function recall (10 marks)
4.1 DNA sequencing determines the exact order of nucleotide bases in a DNA region or whole genome, allowing specific variants and mutations to be identified directly. [2]
4.2 DNA profiling compares patterns at selected DNA regions between samples, supporting inferences about whether the samples match, differ or share inheritance links. [2]
4.3 A marker region is a short, variable region of DNA chosen because it differs reliably between unrelated individuals; comparing patterns at the same markers across samples is what allows a profile to distinguish or relate them. [2]
4.4 Both technologies generate data about how DNA varies within and between groups; sequencing pinpoints specific inherited variants while profiling tracks similarity at chosen markers, and together they reveal inheritance patterns, relatedness and disease-variant frequencies in populations. [2]
4.5 Identifying a specific inherited base change requires knowing the actual base order at that position — only sequencing reads base order directly. Profiling looks at pattern similarity at selected markers and usually does not show the exact base change responsible for the disease. [2]
Q5 — Labelled comparison diagram (8 marks)
A: DNA sequencing. B: ordered string of nucleotide bases (A, T, C, G) — the actual base order. C: a specific mutation / SNP / inherited variant. D: identifying inherited disease-linked variants in a population (or a comparable example, e.g. tracking allele frequencies). E: DNA profiling. F: pattern at selected marker regions (not the full genome sequence). G: inference about similarity, difference or relatedness between samples. H: comparing related individuals or families to infer inheritance links / lineage.
Marking: 1 mark per correct label A–H. Synonyms accepted (e.g. "SNP" or "specific base change" for C; "STR markers" or "selected loci" for F).