50 Fun Facts About Genetics

Who traced inheritance patterns in pea plants and is called the founder of modern genetics?

Mendel presented his pea results in Brno in 1865; Darwin never read the paper.

Mendel belonged to which religious order?

He entered St Thomas's Abbey in Brno on his physics teacher's advice and later became its abbot.

Roughly how many plants did Mendel cultivate and test between 1856 and 1863?

Most were pea plants, Pisum sativum, chosen because their traits came in clear either/or forms.

In which year was Mendel's work rediscovered by de Vries, Correns and von Tschermak?

Three botanists independently reached the same conclusions and then found Mendel had beaten them by 35 years.

Who coined the word 'genetics' in 1905?

He took it from the Greek genetikos and popularized it at a plant hybridization conference in London the next year.

Who introduced the term 'gene' in 1909?

Johannsen also drew the distinction between genotype and phenotype that biology still uses.

What idealized phenotype ratio did Mendel find in monohybrid crosses?

Three dominant to one recessive among the F2 generation; the two-trait dihybrid cross gives 9:3:3:1.

Which Mendelian law says alleles for separate traits are passed on independently?

It holds for genes on different chromosomes; linked genes on the same chromosome break the rule.

The Punnett square is named after a geneticist from which country?

Reginald Punnett co-founded the Journal of Genetics with Bateson and also played cricket with the mathematician G. H. Hardy.

The word 'allele' is a short form of which older term?

Bateson and Edith Rebecca Saunders coined it in the early 1900s to mean 'other form' of a gene.

What is it called when both alleles are expressed at once, as in AB blood type?

Incomplete dominance instead gives an intermediate phenotype, like pink flowers from red and white parents.

What term describes one gene masking the effect of another?

A classic example is the gene for albinism hiding whatever coat colour genes an animal carries.

Who argued in 1911 that genes sit on chromosomes, based on white-eyed fruit flies?

His Columbia 'Fly Room' went on to produce the first chromosome maps and a 1933 Nobel Prize.

Which of Morgan's students showed in 1913 that genes are arranged linearly on a chromosome?

He built the first genetic map overnight as an undergraduate, using linkage frequencies to order the genes.

Which insect is the model organism known by the name Drosophila melanogaster?

Cheap, fast-breeding and with giant salivary chromosomes, it has been a genetics workhorse for over a century.

Who coined the term 'chromosome' in 1888?

It means 'coloured body' — chromosomes are only visible once stained, which is why Flemming's 'chromatin' came first.

How many chromosomes does a typical human cell contain?

That is 22 pairs of autosomes plus one pair of sex chromosomes.

In which year was the correct human chromosome number finally established?

Textbooks had said 48 for three decades, repeating Theophilus Painter's error, until Joe Hin Tjio counted 46.

Duplicated copies of a chromosome joined at the centromere are called what?

They form the familiar X shape seen in karyotypes, which only exists briefly before cell division.

Who discovered bacterial 'transformation' in 1928?

Dead pneumococci passed something to live ones; Avery, MacLeod and McCarty showed in 1944 that something was DNA.

Who actually took the famous X-ray image 'Photo 51' in Rosalind Franklin's lab?

Gosling was Franklin's PhD student; Wilkins later showed the image to Watson without her permission.

Rosalind Franklin died in 1958 at what age?

Ovarian cancer killed her four years before Watson, Crick and Wilkins shared the Nobel Prize.

A group of three nucleotides that specifies one amino acid is called what?

Four bases read three at a time give 64 combinations to cover just 20 amino acids plus stop signals.

Which codon is the most common start signal, read as methionine?

In bacteria and mitochondria it is read as formylmethionine instead.

Two of the three stop codons were given which colour-themed names?

The first, 'amber', was a pun on discoverer Harris Bernstein's surname, so the others kept the colour theme.

Khorana, Holley and Nirenberg shared a Nobel Prize in which year for deciphering the genetic code?

Nirenberg and Leder had shown the triplet nature of the code; Khorana filled in the remaining codons.

Which enzyme, from a hot-spring bacterium, made PCR practical?

Thermus aquaticus thrives at 50-80 °C, so its polymerase survives the heating cycles that denature DNA.

Who invented PCR in 1983?

He shared the 1993 Nobel Prize in Chemistry with Michael Smith, seven years after Cetus first made PCR work.

Chain-termination DNA sequencing was developed in 1977 by whom?

It earned Sanger his second Nobel Prize in Chemistry; the first was for sequencing insulin.

In which year was the Human Genome Project officially launched?

Planned from 1984, it ran 13 years and was declared complete in 2003 — 50 years after the double helix.

Which company launched a rival private human genome effort in 1998?

Craig Venter's $300 million shotgun approach pushed the $3 billion public project to speed up.

Which two leaders jointly announced the rough draft of the human genome in June 2000?

Months earlier they had jointly urged that all researchers get 'unencumbered access' to the sequence.

About how many protein-coding genes does the human reference genome contain?

Early guesses ran to 100,000; the real number is barely more than a fruit fly's.

Human chromosome 2 is equivalent to a fusion of which two chimpanzee chromosomes?

It explains why humans have 23 chromosome pairs while chimpanzees have 24.

Which consortium published the first truly complete human sequence in 2022?

It filled in the roughly 8% of the genome the Human Genome Project never managed to read.

Who created the term 'genome' in 1920?

Winkler was a botany professor at Hamburg and blended 'gene' with 'chromosome'.

A mutation caused by inserting or deleting bases not divisible by three is called what?

Every codon downstream is then read in the wrong register, usually wrecking the protein.

Who coined the term 'epigenetics' in 1942?

He also drew the 'epigenetic landscape' of a ball rolling down valleys to picture how cells choose a fate.

Barbara McClintock won the 1983 Nobel Prize for discovering what in maize?

Her 'jumping genes' were largely ignored for decades; she remains the only woman with an unshared Nobel in that category.

Dolly the sheep was cloned from a cell taken from which organ?

Hence the name — Ian Wilmut said they could not think of a more impressive pair of glands than Dolly Parton's.

Doudna and Charpentier won the Nobel Prize in Chemistry for CRISPR in which year?

Their 2012 paper showed Cas9 could be programmed with a guide RNA to cut DNA at a chosen spot.

The widely used Cas9 enzyme comes from which bacterium?

The same species causes strep throat; in its native role CRISPR is an immune memory of past viral attacks.

Casgevy, the first approved CRISPR medicine, treats sickle-cell disease and which other condition?

The UK approved it in 2023 and Bahrain followed weeks later; it edits a patient's own blood stem cells.

Down syndrome is caused by an extra copy of which chromosome?

Jérôme Lejeune reported the extra chromosome in 1959, though colleague Marthe Gautier's role was later recognized.

The gene behind Huntington's disease sits on the short arm of which chromosome?

It was pinpointed in 1993 after a decade-long hunt among families around Lake Maracaibo, Venezuela.

Huntington's disease is caused by an expanding repeat of which DNA triplet?

CAG codes for glutamine, so the mutant huntingtin protein carries an abnormally long polyglutamine tract.

Cystic fibrosis follows which inheritance pattern?

Two carrier parents have a one-in-four chance per child; the CFTR gene was found on chromosome 7 in 1989.

Which sex-determination system do birds use?

In birds it is the female that carries two different sex chromosomes; ants and bees use haplodiploidy instead.

In humans, which gene on the Y chromosome triggers male development?

Even an XXY individual develops as male because of it; the platypus manages without SRY entirely.

In alligators and some turtles, what determines the sex of the offspring?

The tuatara shares the trait, which makes these species unusually vulnerable to a warming climate.