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CAIE A-Level Biology A2 19.1.10 Microarrays in Genome Analysis Questions

Use real genome and expression studies to prepare labelled samples, explain probe hybridisation and interpret fluorescent microarray signals as alleles, deletions or expression…

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Prepare fluorescently labelled single-stranded genomic DNA or make labelled cDNA from extracted mRNA for microarray analysis of genomes or gene expression.
  • Hybridise labelled sample DNA or cDNA to complementary known probes on a microarray, wash away unbound sample and detect fluorescent spots with UV or a laser scanner.
  • Interpret fluorescence position, presence and intensity to identify alleles, estimate deleted genome regions and compare which genes are expressed or their expression levels between samples.

CAIE A-Level Biology A2 19.1.10 Microarrays in Genome Analysis Questions question 1

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Question (a)

(a)

Researchers wanted to know if changes in gene expression were important in the inability of the AD mice to learn.

Groups of normal mice and AD mice either received training to allow them to learn how to swim a water maze, or they received no training. The mice in the four groups then had mRNA extracted from the memory-forming areas of their brains.

Reverse transcription of the mRNA of individuals in each group was carried out and the resulting cDNA was labelled with fluorescent nucleotides. This was then used for DNA microarray analysis using slides containing DNA sequences from 3 3 6 9 6 mouse genes.

Explain the principles of this type of DNA microarray analysis.

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Question (b)

(b)

Table 5.1 summarises the microarray analysis of differences in gene expression for:
- an untrained AD mouse compared to an untrained normal mouse
- a trained AD mouse compared to a trained normal mouse.

Table 5.1

Table 5.1

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Question (i)

(i)

State what the results in Table 5.1 show about the effect of training and learning on gene expression in brain cells.

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