🧫 Molecular Biology
DNA replication, transcription, translation and gene regulation.
Molecular Biology has 52 topics on LearnViz, graded from Beginner to Advanced. Pick a topic below to read its explanation, examples, FAQs and related links.
What is Molecular Biology?
Molecular biology studies how genetic information is stored, copied, transcribed and translated, and how cells regulate these processes. It links the structure of DNA to the behaviour of cells.
Beginner topics (11)
Central Dogma
The flow of genetic information from DNA to RNA to protein.
🧫 Molecular BiologyDNA Replication
The copying of DNA before cell division so each daughter cell receives a full set of genes.
🧫 Molecular BiologyBase Pairing
Adenine pairs with thymine and cytosine with guanine through hydrogen bonds.
🧫 Molecular BiologyTranscription
The process of making an RNA copy of a gene using DNA as a template.
🧫 Molecular BiologyTranslation
Ribosomes read the mRNA codons to assemble amino acids into a protein.
🧫 Molecular BiologyGenetic Code
The set of three-base codons that specify amino acids; it is nearly universal across life.
🧫 Molecular BiologyCodon
A triplet of mRNA bases that codes for one amino acid or a stop signal.
🧫 Molecular BiologyMessenger RNA
A single-stranded RNA copy of a gene that carries instructions to the ribosome.
🧫 Molecular BiologyTransfer RNA
Small RNA adaptors with an anticodon that bring the correct amino acid to the ribosome.
🧫 Molecular BiologyGene Expression
The process by which information in a gene is used to make a functional product.
🧫 Molecular BiologyDNA Packaging
DNA wraps around histone proteins to form nucleosomes that coil into compact chromatin.
🧫 Molecular BiologyIntermediate topics (23)
Semi-Conservative Replication
Each new DNA molecule contains one original strand and one newly built strand, shown by Meselson and Stahl.
🧫 Molecular BiologyDNA Polymerase
The enzyme that adds nucleotides to a growing DNA strand in the 5 prime to 3 prime direction.
🧫 Molecular BiologyHelicase and Topoisomerase
Helicase unwinds the double helix at the fork while topoisomerase relieves the supercoiling strain ahead of it.
🧫 Molecular BiologyLeading and Lagging Strands
The leading strand is made continuously, while the lagging strand is made in short Okazaki fragments.
🧫 Molecular BiologyOkazaki Fragments
Short DNA segments synthesised discontinuously on the lagging strand and joined by DNA ligase.
🧫 Molecular BiologyPrimase and RNA Primer
Primase lays down a short RNA primer that gives DNA polymerase a starting 3 prime end.
🧫 Molecular BiologyDNA Repair
Mechanisms such as mismatch, excision and double-strand break repair that fix errors and damage in DNA.
🧫 Molecular BiologyRNA Polymerase
The enzyme that builds an RNA strand complementary to the template DNA during transcription.
🧫 Molecular BiologyPromoter
A DNA sequence where RNA polymerase and transcription factors bind to start transcription of a gene.
🧫 Molecular BiologyRNA Processing
In eukaryotes, pre-mRNA gets a 5 prime cap, a poly-A tail and has introns spliced out.
🧫 Molecular BiologySplicing
The removal of introns and joining of exons by the spliceosome to produce mature mRNA.
🧫 Molecular BiologyAlternative Splicing
Different exon combinations from one gene yield several protein variants.
🧫 Molecular BiologyRibosome Structure
A large and small subunit with A, P and E sites that coordinate tRNA binding and peptide bond formation.
🧫 Molecular BiologyInitiation, Elongation, Termination
The three stages of translation: assembly at the start codon, chain growth, and release at a stop codon.
🧫 Molecular BiologyStart and Stop Codons
AUG begins translation and codes methionine; UAA, UAG and UGA end it.
🧫 Molecular BiologyOperon
A cluster of bacterial genes under one promoter and operator, regulated together.
🧫 Molecular BiologyLac Operon
An inducible bacterial operon switched on when lactose is present and glucose is scarce.
🧫 Molecular BiologyTrp Operon
A repressible operon turned off when tryptophan accumulates and activates the repressor.
🧫 Molecular BiologyTranscription Factors
Proteins that bind specific DNA sequences to turn genes on or off.
🧫 Molecular BiologyEnhancers and Silencers
Distant regulatory DNA elements that increase or decrease transcription via looping to the promoter.
🧫 Molecular BiologyDNA Methylation
Addition of methyl groups to cytosine, usually silencing gene expression.
🧫 Molecular BiologyHistone Modification
Acetylation, methylation and phosphorylation of histone tails alter chromatin openness and gene activity.
🧫 Molecular BiologyMutation and Repair Link
Unrepaired DNA damage becomes permanent mutation after replication, driving cancer and ageing.
🧫 Molecular BiologyAdvanced topics (18)
Telomerase
A ribonucleoprotein enzyme that extends telomeres in stem and cancer cells using an RNA template.
🧫 Molecular BiologyChromatin Remodelling
ATP-dependent complexes slide or evict nucleosomes to control access to DNA.
🧫 Molecular BiologyRNA Interference
Small interfering RNAs guide the RISC complex to degrade matching mRNA and silence genes.
🧫 Molecular BiologymicroRNA
About 22-nucleotide RNAs that fine-tune gene expression by blocking translation or promoting mRNA decay.
🧫 Molecular BiologyLong Non-Coding RNA
RNAs longer than 200 nucleotides that regulate chromatin and gene expression, such as XIST.
🧫 Molecular BiologyReverse Transcription
Synthesis of DNA from an RNA template by reverse transcriptase, used by retroviruses and retrotransposons.
🧫 Molecular BiologyMediator Complex
A large multi-protein assembly that links enhancer-bound transcription factors to RNA polymerase II.
🧫 Molecular BiologyNonsense-Mediated Decay
A quality-control pathway that destroys mRNAs with premature stop codons.
🧫 Molecular BiologyUbiquitin-Proteasome System
Ubiquitin tagging marks proteins for destruction by the proteasome to control protein levels.
🧫 Molecular BiologyWobble Hypothesis
Flexible pairing at the third codon position lets fewer tRNAs read all 61 sense codons.
🧫 Molecular BiologyTranslational Control
Regulation of protein synthesis rate through initiation factors, upstream open reading frames and mRNA stability.
🧫 Molecular BiologyRiboswitches
RNA elements that bind small metabolites and change structure to regulate gene expression directly.
🧫 Molecular BiologyHomologous Recombination
An accurate repair pathway and meiotic mechanism exchanging DNA between similar sequences using RAD51.
🧫 Molecular BiologyNon-Homologous End Joining
An error-prone repair pathway that directly ligates broken DNA ends.
🧫 Molecular BiologyOrigin of Replication
Specific sites where replication begins, singular in bacteria and multiple in eukaryotic chromosomes.
🧫 Molecular BiologyChromosome Territories
Individual chromosomes occupy distinct regions of the nucleus, influencing genome organisation and expression.
🧫 Molecular BiologySingle-Molecule Biology
Techniques that track individual enzymes or DNA molecules to reveal dynamics hidden in bulk experiments.
🧫 Molecular BiologyCRISPR-Cas9 Mechanism
A guide RNA directs the Cas9 nuclease to a matching DNA site to cut it, enabling precise editing.
🧫 Molecular BiologyUse cases
- Research: Techniques such as PCR, cloning and sequencing are used in nearly every molecular laboratory.
- Diagnosis: Gene expression profiles and mutation tests guide cancer and infection diagnosis.
- Drug design: Knowing a drug's molecular target helps design more selective treatments.
- Biotechnology: Engineered plasmids and vectors are used to produce proteins and vaccines.
Frequently asked questions
How many topics are covered in Molecular Biology?
Molecular Biology has 52 topics on LearnViz: 11 Beginner, 23 Intermediate and 18 Advanced. Each one has its own page with an explanation, use cases, FAQs and related topics.
Where should a beginner start in Molecular Biology?
Start with the Beginner topics, such as Central Dogma, DNA Replication, Base Pairing. Once those terms feel familiar, move on to the Intermediate topics.
What are the most advanced topics in Molecular Biology?
The Advanced level includes Telomerase, Chromatin Remodelling, RNA Interference, microRNA, Long Non-Coding RNA. Read the Beginner and Intermediate topics first, because the Advanced ones build on them.
Can I test my knowledge of Molecular Biology?
Yes. The Molecular Biology quiz asks questions generated from the topic explanations, and the timed tests on LearnViz cover the same material.
What is the central dogma?
DNA is transcribed into RNA, and RNA is translated into protein. Information normally flows in that direction. Reverse transcription in retroviruses is an important exception.
What is the difference between transcription and translation?
Transcription copies a DNA sequence into messenger RNA. Translation reads that mRNA on ribosomes to assemble a polypeptide.
Why do cells need gene regulation?
Almost every cell contains the same DNA but expresses different genes. Regulation decides which proteins are made, when and how much, which is why a neuron and a liver cell differ.