Molecular Biology
of Genes

IIntroduction

1. 01

   Genes are DNA

   The genome carries an organism's hereditary information; its DNA directs the production of the cell's RNAs, which in turn are used to produce its proteins: the central dogma.

   • From genome to base pairChromosomes, alleles, DNA and one base pair
   • Griffith's experimentExperiment · 10 steps
   • The Hershey–Chase experimentExperiment · 10 steps
   • TransfectionExperiment · 6 steps
   • NucleotidesScene · 8 steps
   • The double helixScene · 10 steps
   • DNA replicationScene · 6 steps
   • The Meselson–Stahl experimentScene · 6 steps
   • DNA or RNA genomesScene · 7 steps
   • Denaturation and hybridisationScene · 6 steps
   • MutationsScene · 6 steps
   • Frameshifts and reversionScene · 6 steps
   • Its moleculesLibrary · 8 molecules

IITranscription and post-transcriptional mechanisms

1. 02

   Prokaryotic transcription

   RNA polymerase binds a promoter and reads the template strand, making RNA 5′ → 3′ until it reaches a terminator.

   • The complete transcription cycleFilm · from the promoter search to termination
   • Its proteinsLibrary · 16 proteins
2. 03

   Eukaryotic transcription

   Three RNA polymerases transcribe a chromatin template, placed at the promoter by basal transcription factors and boosted by enhancers that can lie far away.

   • Three polymerases in one nucleusWhere each works
   • Three RNA polymerasesScene · 6 steps
   • Inactive, poised and active genesScene · 6 steps
   • TBP and the TATA boxScene · 6 steps
   • EnhancersScene · 7 steps
   • DNA methylationScene · 7 steps
   • Its proteinsLibrary · 19 proteins
3. 04

   RNA splicing and processing

   Introns are transcribed along with the exons and then removed by splicing, as eukaryotic RNAs are processed to become mature and functional.

   • From gene to mRNAA gene's RNA capped and spliced as it is made
   • The 5′ capScene · 8 steps
   • Splice sitesScene · 7 steps
   • Splice sites in pairsExperiment · 7 steps
   • Splicing proceeds through a lariatScene · 8 steps
   • snRNPsScene · 7 steps
   • The spliceosome cycleScene · 8 steps
   • U1 and the 5′ splice siteExperiment · 7 steps
   • The commitment complexScene · 7 steps
   • Alternative splicingExperiment · 8 steps
   • IsoformsScene · 8 steps
   • Its moleculesLibrary · 17 molecules
4. 05

   mRNA stability and localisation

   An mRNA carries regulatory information that dictates how often it is translated, how stable it is and where in the cell translation occurs.

   In preparation
5. 06

   Catalytic RNAs

   Ribozymes, from RNase P to self-splicing introns: RNAs that cleave and join phosphodiester bonds.

   In preparation
6. 07

   Translation

   The information in a gene is read in nonoverlapping triplets, codons, from a fixed starting point, to assemble a polypeptide.

   In preparation
7. 08

   Using the genetic code

   Of the 64 codons, 61 specify amino acids and 3 are stop signals; the code is degenerate and nearly universal.

   In preparation

IIIGene regulation

1. 09

   The operon

   Trans-acting factors recognise and bind cis-acting elements to switch a bacterium's genes on and off as its environment changes.

   In preparation
2. 10

   Phage strategies

   The lytic cycle and lysogeny: how a phage stages its gene expression, and chooses between the two.

   In preparation
3. 11

   Eukaryotic transcription regulation

   Chromosome structure and its modifications, and how chromatin regulates gene expression.

   In preparation
4. 12

   Epigenetic effects are inherited

   Changes in gene expression that do not change the DNA sequence itself, but are passed on.

   In preparation
5. 13

   Regulatory RNAs

   RNAs that tune gene expression quickly and selectively by base pairing, without rewriting DNA or making new proteins.

   In preparation