Bioinformatics Lecture `1

What six core practical skills are evaluated in the BB1824 Bioinformatics MCQ assessment?

Searching PubMed for publications, identifying peptides and reading frames, interpreting raw sequence data, running BLAST searches, analyzing protein domains with InterPro and SMART, and cross-referencing sequences with disease conditions.

What are the simple and complete definitions of bioinformatics?

Simple definition: using computers to solve molecular biology problems. Complete definition: applying computational techniques for the study, management, and analysis of the flow of biological data and information.

How does modern data-driven bioscience differ from classical observational science?

Classical science relied on macro-level physical observation to test hypotheses, whereas modern bioscience analyzes massive high-throughput molecular datasets where direct visual inspection is impossible.

Why is raw genomic sequencing data alone insufficient to understand complex human diseases?

Sequencing merely yields billions of unstructured raw nucleotide fragments; bioinformatic tools and structural modeling are required to assemble fragments, identify coding genes, predict 3D protein structures, and map biological pathways.

Why are general search engines and commercial AI models unsuitable as primary data tools for biomedical research?

General search engines and AI models search unverified web content and risk hallucinating outputs, whereas specialized biological databases are expert-curated, peer-reviewed, and updated by domain scientists.

Why do exact keyword searches fail when querying biological DNA or protein sequences?

Keyword searches look for exact character string matches, whereas sequence alignment algorithms are needed to detect non-identical homologous sequences that vary due to evolutionary mutations and species variations.

Which specific biological databases are used for literature, genetic disorders, nucleotide records, protein domains, and sequence alignments?

PubMed for literature, OMIM for genetic disorders, GenBank for nucleotide records, InterPro and SMART for protein domains, and BLAST for sequence alignments.

What are the four main hierarchical sections of a standardized flat-file database record like GenBank?

Locus/Header (metadata and accession IDs), References (literature citations and PubMed IDs), Features/Annotations (gene map location, CDS coordinates, and tissue source), and ORIGIN (raw sequence block).

Why do bioinformaticians query sequence databases using raw nucleotide or amino acid sequences rather than gene names?

Gene names and text keywords vary across species and publications, whereas raw sequence alignments reveal structural, evolutionary, and functional homology directly.

What is the sequential flow of biological information from DNA to clinical phenotype?

Genomic DNA is transcribed into mRNA, mRNA is translated into a polypeptide chain, the polypeptide folds into a functional 3D protein structure, and protein activity or dysfunction produces a physiological phenotype or clinical symptoms.

How does the scope of biomedical bioinformatics differ from population-level evolutionary biology?

Biomedical bioinformatics focuses on the individual molecular level (DNA to 3D structure, function, and symptoms), whereas population-level biology studies natural selection and evolutionary dynamics across generations.

How do amino acid side-chain interactions regulate membrane transporter function?

Electrostatic interactions between specific charged residues stabilize transitions between outward-open and vertical-occluded states, while small molecules and ions bind within transmembrane pockets to modulate transport.

Why is comparative sequence and target modeling across species necessary in computational drug discovery?

Testing unvalidated compounds on humans is ethically prohibited; cross-species modeling identifies conserved protein targets in animal models to predict efficacy and toxicity before clinical trials.

What is a reading frame, and why does double-stranded DNA have exactly six potential reading frames?

A reading frame is a contiguous sequence of non-overlapping codons. Double-stranded DNA has six frames because translation can begin at base 1, 2, or 3 on both the forward sense strand (+1, +2, +3) and reverse complement strand (+4, +5, +6).

How is the mRNA sequence 5'-CUC AGC GUU ACC AU-3' translated in Frames 1, 2, and 3?

Frame 1 translates to Leu-Ser-Val-Thr, Frame 2 translates to Ser-Ala-Leu-Pro, and Frame 3 translates to Gln-Arg-Tyr-His. (Slide 37)

What is the cause-and-effect impact of a frameshift mutation on protein translation?

Inserting or deleting nucleotides not divisible by three shifts the triplet reading frame downstream, altering the amino acid sequence and frequently introducing premature stop codons that truncate the protein.

How can you determine whether a codon table or codon wheel represents DNA or RNA?

The presence of Uracil (U) indicates an RNA codon table or wheel, whereas the presence of Thymine (T) indicates a DNA codon table or wheel.

What is genetic code degeneracy, and why is back-translation from protein to DNA non-deterministic?

Degeneracy means multiple distinct codons encode the same amino acid; translation is deterministic because each codon maps to one amino acid, but back-translation is non-deterministic because one amino acid yields multiple potential codon choices.

What do IUB ambiguity codes R, Y, and N represent, and what are their complementary bases?

R represents purines (A or G) with complement Y; Y represents pyrimidines (C or T/U) with complement R; N represents any base (A, C, G, or T) with complement N.

How many potential DNA coding sequences exist for the dipeptide Threonine-Histidine (TH)?

Eight potential DNA sequences, because Threonine is encoded by 4 codons and Histidine is encoded by 2 codons (4 x 2 = 8).

Why does back-translating a 20-amino-acid peptide create over 2 billion sequence combinations?

Multiplying the codon degeneracies for each amino acid in the chain produces an exponential combinatorial expansion (over 2 x 10^9 possible sequences), making single DNA probing impractical.

What three bioinformatic and laboratory applications require an understanding of genetic code degeneracy?

Searching DNA databases with protein queries (tblastn), searching protein databases with DNA queries in 6 frames (blastx), and designing degenerate PCR primers.