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1.4 DNA Sequencing & Gene Expression Data — Test 1
Q1. Sanger (dideoxy) sequencing determines a DNA sequence by:✓ Chain termination using dideoxynucleotides
Q2. In automated DNA sequencing, the four bases are distinguished by:✓ Different fluorescent dyes
Q3. Capillary array electrophoresis improved sequencing throughput mainly by:✓ Running many samples in parallel through thin capillaries
Q4. Next-generation sequencing (NGS) technologies are characterised by:✓ Massively parallel, high-throughput sequencing of many fragments at once
Q5. In genome sequencing, 'coverage' (or depth) refers to:✓ The average number of times each base is sequenced
Q6. The shotgun sequencing strategy involves:✓ Randomly fragmenting DNA, sequencing the pieces, then assembling overlaps
Q7. The output trace of an automated sequencer, showing peaks for each base, is called a:✓ Chromatogram
Q8. A Phred quality score is used to indicate the:✓ Confidence (accuracy) of a base call
Q9. Assembly in genome sequencing is the process of:✓ Joining overlapping reads into longer continuous sequences
Q10. Gene-expression data measured on a genome-wide scale are commonly generated by:✓ DNA microarrays and RNA-seq
Q11. A DNA microarray measures gene expression based on:✓ Hybridisation of labelled cDNA to immobilised probes
Q12. The Maxam-Gilbert sequencing method is based on:✓ Base-specific chemical cleavage of DNA
Q13. Pyrosequencing detects each incorporated nucleotide by measuring:✓ A light signal released during nucleotide incorporation
Q14. A 'read' in sequencing refers to:✓ A single contiguous sequence determined from one DNA fragment
Q15. SAGE (Serial Analysis of Gene Expression) quantifies expression by:✓ Counting short sequence tags representing transcripts
Q16. Higher sequencing coverage is desirable mainly because it:✓ Improves the accuracy and reliability of base calls and variant detection
Q17. The reference genome of a species is used in analysis as a:✓ Standard sequence against which new reads are compared
Q18. Compared with Sanger sequencing, NGS generally produces:✓ Far more reads at lower cost per base, but often shorter reads
Q19. Microarray and RNA-seq expression data are valuable because they reveal:✓ Which genes are active and at what levels under given conditions
Q20. Match each sequencing term/method with its description and select the correct option.✓ A-ii, B-i, C-iv, D-iii