&Answers
Questions
20Francis Crick and James Watson are
most often associated with the famous
genetic molecule, but their work in
the 1950s came over 80 years after
the identification of DNA by a Swiss
physician searching for the ‘building
blocks’ of life. Friedrich Miescher
had focused on proteins in cells, but,
in 1869, he discovered a strange
substance also lurking in the nuclei of
the cells. He named it ‘nuclein’, and
suspected it would prove at least as
vital to cells as proteins. Crick and
Watson were not the first to show
he was right, either. Their celebrated
discovery of DNA’s double helix
structure was prompted by key
experiments by a team led by
the American biochemist Oswald
Avery. In 1944, working at the
Rockefeller University in New York,
they published the results of
painstaking studies using bacteria
that revealed that DNA passed genetic
information from one organism to
another. This went against the
accepted wisdom that proteins must
be the carriers of genetic information,
as DNA was ‘obviously’ too simple
a molecule to perform so complex
a role. Crick and Watson agreed with
Avery – but his own claim to a Nobel
was blocked by sceptics until the
1960s, by which time he was dead. RMWHO REALLY DISCOVERED?DNA
Friedrich Miescher Oswald AveryOzone depletion occurs when ozone
molecules in the upper atmosphere are
destroyed by chemical reactions with
halogen gases, such as chlorine.
Cold conditions above Antarctica in
the winter months encourage the formation
of extremely cold, high-altitude clouds.
These clouds provide the ideal conditions
for chlorine that was previously trappedin stable molecules to be transformed
into highly reactive chlorine gas,
which accumulates over the long polar
night. As winter ends, sunlight breaks
apart the chlorine gas molecules,
freeing billions of chlorine atoms,
which go on to react with ozone molecules,
causing a sharp dip in ozone levels:
the ozone ‘hole’. ACWHY IS OZONE DEPLETION WORSE
OVER ANTARCTICA?Francis Crick (left) and James WatsonYes. Too many calories of any kind will lead
to obesity, which increases your chance of
developing diabetes. But a 2013 study at
Stanford University found that adding
150 calories of sugar per day to your diet
increases your diabetes risk by 1 per cent, even after
accounting for obesity, physical activity and total calorie
intake. So sugar calories are particularly harmful. LVCAN EATING A LOT
OF SUGAR REALLY
LEAD TO DIABETES?WHY DOES DEPRESSION
MAKE YOU DREAM MORE?People suffering from depression
may experience unusual patterns of sleep.
Typically, they move into REM sleep (the stage in
which we are most likely to dream) more quickly,
and there may be a greater number of eye
movements per unit of time during this stage of
sleep. People who are depressed may wake up
more frequently during the night, and are,
therefore, more likely to remember their dreams.
Finally, there is some evidence that certain
medications for depression can increase
the frequency of nightmares. Other medications
appear to do the opposite, but nightmares can
occur during withdrawal from these drugs. AGrPHOTOS: SCIENCE PHOTO LIBRARY, GETTY X4, CATERS NEWS1979 1987 2006 2011