BMS5021 · Introduction to Bioinformatics
DNA, the Genome & the Genetic Code
Weeks 1-2 of Monash University BMS5021 Introduction to Bioinformatics lay the molecular foundation: DNA as the hereditary molecule, how the genome is organised into chromosomes, genes and non-coding regulatory DNA, and the central dogma that connects sequence to protein. Because the unit is built for students with little biology, these ideas are taught cleanly and are exactly the kind of factual content the Topic 1 in-workshop MCQ quizzes reward. Getting the vocabulary — bases and base-pairing, the RNA types, promoters and enhancers, transcription and translation — straight here makes every later analysis chapter readable.
What this chapter covers
- 01DNA structure: four bases Adenine (A), Cytosine (C), Guanine (G), Thymine (T); base pairs A-T and C-G
- 02The central dogma: DNA -> (transcription) RNA -> (translation) protein, plus replication and reverse transcription (RNA -> DNA)
- 03Genome hierarchy: genome -> chromosomes -> genes -> non-coding regions; humans have 23 pairs = 46 chromosomes
- 04Non-coding 'junk' DNA regulates WHEN and WHERE genes are on/off; promoters, enhancers and transcription factors
- 05Three major RNAs and their proportions: rRNA (most abundant, ~75-80%), tRNA (~10%), mRNA (~5%)
- 06mRNA gains a poly-A 3' tail for stability and is converted to cDNA before sequencing (most platforms cannot read native RNA)
- 07Levels of gene-expression control: chromatin/DNA modification, transcriptional, post-transcriptional, translational/post-translational
- 08The genetic code links nucleotide sequence to amino-acid (protein) sequence (ULO1)
Base-pairing and the RNA census (Topic 1 quiz-style item)
- +1Apply the base-pairing rules A-T and C-G to each base of 5'-ATGC-3'. The complement (antiparallel) pairs A with T, T with A, G with C, C with G, and runs in the opposite direction, giving 3'-TACG-5'. Written in the conventional 5'->3' direction that is 5'-GCAT-3'.
- +1Recall the RNA proportions taught in the unit: rRNA is the most abundant at about 75-80% of total RNA, tRNA is about 10%, and mRNA is only about 5%. So the most abundant species is ribosomal RNA (rRNA).
- +1Explain the cDNA step. Most sequencing platforms cannot sequence native RNA directly, so RNA is reverse-transcribed into complementary DNA (cDNA) first; for mRNA specifically the poly-A tail is used to enrich it (and other RNAs are depleted) before library preparation.
Key terms
- DNA / bases
- Deoxyribonucleic acid, the hereditary molecule, built from four nucleotides Adenine (A), Cytosine (C), Guanine (G) and Thymine (T); the complementary base pairs are A-T and C-G.
- Central dogma
- DNA -> (transcription) RNA -> (translation) protein, with DNA replication and reverse transcription (RNA -> DNA) as additional routes. Describes how sequence information becomes a functional protein.
- Genome
- The complete set of an organism's DNA, organised as chromosomes -> genes -> non-coding regions. Humans carry 23 pairs of chromosomes (46 total), one set from each parent.
- Non-coding / regulatory DNA
- DNA that does not encode a protein (once loosely called 'junk DNA') but regulates WHEN and WHERE genes are expressed, including promoters and enhancers bound by transcription factors.
- The three RNAs
- rRNA (ribosomal, most abundant ~75-80%), tRNA (transfer, ~10%) and mRNA (messenger, ~5%). mRNA carries the protein-coding message and gains a poly-A 3' tail for stability.
- Gene expression
- The multi-step process of 'reading' a gene to build its protein, controlled at several levels: chromatin/DNA modification, transcription, RNA processing/transport/degradation, and translation/post-translation.
DNA, the Genome & the Genetic Code FAQ
How does this chapter show up in BMS5021 assessment?
The Week 1-2 biology of the gene is assessed by the Topic 1 in-workshop MCQ quizzes (30% across Weeks 1-4). Expect factual multiple-choice items on base-pairing, chromosome number, the RNA species and their proportions, promoters/enhancers and the levels of gene-expression control. There is no exam, so these quizzes are your only formal test of this material — confirm the quiz dates and format on Moodle.
Why does a bioinformatics unit start with basic molecular biology?
Because BMS5021 is built for students with little or no biology background, and every downstream analysis assumes this vocabulary. You cannot interpret an RNA-seq result without knowing what mRNA is and why it is enriched, or read an alignment without understanding bases and strands. The first two weeks give you the language the rest of the unit is written in.
What is the difference between coding genes and non-coding DNA?
Genes carry the instructions for a specific protein or functional RNA. Non-coding regions do not encode a protein but regulate gene activity — promoters and enhancers determine when and where a gene is switched on, and transcription factors bind these regions to recruit or repress the transcription machinery. Much of what was once dismissed as 'junk DNA' is regulatory.
Can AI help me learn the central dogma for the quiz?
Yes. Sia can explain DNA -> RNA -> protein step by step, drill you on base-pairing and the RNA proportions, and re-explain transcription versus translation a different way if the first explanation doesn't land. It helps you understand and rehearse the facts; it does not sit your quiz for you, and Monash University academic-integrity rules apply.
Exam move
Build a one-page fact sheet for Weeks 1-2 and self-test it until recall is automatic, because the Topic 1 quizzes reward clean facts, not derivations: the four bases and the A-T / C-G pairing, 46 chromosomes, the rRNA/tRNA/mRNA proportions (~75-80% / ~10% / ~5%), the central dogma with its extra arrows (replication, reverse transcription), and the roles of promoters, enhancers and transcription factors. Do the asynchronous mini-lectures before the workshop so the workshop time cements rather than introduces the ideas. Use active recall — cover the sheet and reproduce it — and ask Sia to quiz you and explain anything you miss. Confirm the quiz timing and rules on Moodle.
Working through DNA, the Genome & the Genetic Code in BMS5021? Sia is AskSia’s AI Biology tutor — ask any BMS5021 DNA, the Genome & the Genetic Code question and get a clear, step-by-step explanation grounded in how BMS5021 is taught and assessed. Read this chapter free, then take your hardest questions to Sia.
