Numerical Typicals for Genetics and Evolution - Molecular Basis of Inheritance: Shortcut and Trick

##DNA Structure and Replication

DNA length in human cell ≈ length of ~100 billion baseball fields.
# base pairs in the human genome ≈ # base pairs in ~1 million copies of the complete works of Shakespeare.
Coding sequence in the human genome ≈ number of words in ~200 copies of the Bible.
Human genome replication time ≈ driving from New York City to Los Angeles at an average speed of 50 mph (assuming perfect weather and no traffic delays).

##Transcription

# of RNA polymerases transcribing a gene ≈ # people needed to fill a few subway trains (in rush hour).
Average mRNA length ≈ length of a small book’s chapter (in terms of nucleotides).
Speed of RNA polymerase ≈ typing 300-500 words per minute without mistakes (assuming 4-5 nucleotides per word).
# of ribosomes translating mRNA ≈ # shoppers at a medium-sized store at peak hours.

##Translation

# of codons in genetic code ≈ # of possible 3-letter words that can be formed from the letters “A”, “C”, “G”, “T”.
# of amino acids in genetic code ≈ # amino acids in the standard set of Scrabble tiles (plus one blank).
# tRNA molecules in a cell ≈ # residents in a small town.
Speed of ribosomes during translation ≈ typing ~20-40 words per minute without mistakes.

##Gene Expression

Inducible gene’s fold change upon induction ≈ fold change in population of a country during a gold rush or immigration boom.
Repressible gene’s fold change upon repression ≈ fold change in population of a country during a famine or mass exodus.
# of transcription factors required for cooperative binding ≈ like 2 or 3 friends needed for a group decision (or an intervention).
Half-life of mRNA ≈ time it takes to read a newspaper’s front page.
Half-life of proteins ≈ time it takes to wash the dishes.

##Evolution

Nucleotide substitution rates ≈ the rate at which letters would randomly change in a book.
Synonymous vs non-synonymous substitution rates ≈ rate of changes that don’t change word meanings (e.g., “dog” to “dawg”) vs. those that do (e.g., “dog” to “frog”).
Mutation rates ≈ like finding a typo in a book of 1 billion pages (if typos were random occurrences).
Effective population size ≈ number of humans if the world’s people suddenly decided to form one village (no matter how spread out).
Branch lengths in phylogenetic trees ≈ lengths of branches on a family tree that connects 2 relatives.
Natural selection coefficients ≈ the effect of an advantage or disadvantage (like a superpower) passed down the genes.
Critical effective population size (Ne) for the Drift-barrier hypothesis ≈ like a threshold number of people below which genetic diversity in a town suffers.