2024年2月13日 星期二

Rosalind Franklin: a Forgotten Hero in the Unveiling of the Secret of Life

The following piece of writing focuses on the theme of outstanding women in different disciplines. It is for the school I worked at.

Rosalind Franklin played a pivotal role in unraveling the structure of DNA, a breakthrough that revolutionized our understanding of the chemistry of DNA and ultimately led to the discovery of the hereditary mechanism in all living organisms on Earth. 

Consequently, Franklin stands out as an exceptional figure in the fields of chemistry and biology, solidifying her status as a pioneering woman in these domains.

=======================================================


Left: franklin; right: "Photo 51" from the X-ray diffraction of DNA crystal

Nowadays, James Watson and Francis Crick are widely celebrated as the “discoverers of the structure of DNA”. However, in his book “The Double Helix”, Watson mentioned Rosalind Franklin, a female contributor to this discovery. Some even accuse Watson and Crick of stealing this woman’s work. Who is Rosalind Franklin? Was her DNA research stolen?

James Watson and Francis Crick

Rosalind Franklin (1920 – 1958), born in London, exhibited great interest and talent in mathematics from her young age. She eventually worked as a researcher at King’s College, London, after receiving her PhD.

Scientists already knew at the time that DNA is the substance that stores genetic information. They didn’t know HOW it does so, nor its chemical structure. DNA is so small that it is invisible even under a light microscope. Its structure must be determined indirectly using a technique called X-ray crystallography. In this method, DNA was purified and crystallized (molecules regularly arranged). An invisible beam of X-ray is fired at the DNA crystal, causing the light rays to spread (diffract) and produce an image on a photographic film. 

* We can confirm the structure of DNA by comparing the image to the patterns predicted by various models.

*: You can carry our a similar process at home, by shooting a laser pointer through a very thin slit in a piece of paper. A diffraction pattern will be seen on a wall.

Diffraction of the laser from a laser point shining through a narrow slit in a paper

The principle of X-ray crystallography

Franklin produced “Photo 51”, the clearest X-ray image of DNA at the time. She immediately recognized that the DNA molecule should be somewhat helical. But she insisted on gathering more evidence before deciding on the structure.

However, Watson and Crick, who work on DNA at the University of Cambridge, wanted to confirm its structure as soon as possible. After several failures, they discovered the correct DNA structure: two helices intertwined - a double helix. It was later discovered that their conclusion was based largely on Photo 51 of Franklin, which was passed on to them by Franklin’s former colleagues after she left King’s College.

The DNA double helix (red and blue)

Soon after, the structure was published. When Franklin discovered this, she published the same DNA structure based on Photo 51 in the same journal issue. Her manuscripts later revealed that she had calculated the correct DNA structure before Watson and Crick did, but the prediction did not reach the two men.

The double helix has a significant impact on biology. It describes how genetic information is encoded and replicated. The information determines how an organism appears, functions, and reproduces. Unsurprisingly, Watson and Crick were awarded the Nobel Prize in Chemistry for their achievement. But not Franklin, because it is against the rules to award the Nobel Prize to a deceased person, and Franklin died of ovarian cancer before that. This is how Franklin became forgotten.

Did Watson and Crick steal Franklin’s work? And, perhaps more importantly, can the current scientific community do justice to every research contributor?

======================================================

Google translate + 微調:

現在,詹姆斯·沃森(James Watson)和弗朗西斯·克里克(Francis Crick)被譽為「DNA結構的發現者」。然而,華森在他的《雙螺旋》一書中提到了這項發現的一位女性貢獻者-羅莎琳德·富蘭克林。有些人甚至指責華生和克里克竊取了這位女士的作品。富蘭克林是誰?她的DNA研究成果被偷了嗎?

羅莎琳德·富蘭克林(Rosalind Franklin,1920-1958)出生於倫敦,從小就表現出對數學的濃厚興趣和天賦。獲得博士學位後,她最終在倫敦國王學院擔任研究員。

當時科學家已經知道DNA是儲存遺傳訊息的物質。他們不知道它是如何做到這一點的,也不知道它的化學結構。DNA非常小,即使在光學顯微鏡下也看不見。當時必須使用X射線晶體學技術間接確定其結構。在此方法中,DNA被純化並結晶(分子規則地排列)。一束不可見的X射線射向DNA晶體,導致光線擴散(繞射)並在膠片上產生影像。*我們可以透過將影像與各種模型預測的模式進行比較來確認DNA的結構。

*:您可以在家中進行類似的過程,方法是將雷射筆穿過一張紙上的非常細的縫隙。在牆上可以看到繞射圖案。

富蘭克林製作了“照片51”,這是當時最清晰的DNA的X光影像。她立即意識到DNA分子應該是螺旋狀的。但她堅持在決定結構之前收集更多證據。

然而,在劍橋大學研究DNA的華生和克里克希望盡快確認其結構。經過幾次失敗後,他們發現了正確的DNA結構:兩個螺旋交織在一起 - 雙螺旋。後來發現,他們的結論很大程度上是基於富蘭克林的照片51,這張照片是富蘭克林離開國王學院後,由她的前同事傳給他們的。

不久之後,該結構就被公佈了。當富蘭克林發現這一點時,她在同一期期刊上發表了基於照片51的相同DNA結構。她的手稿後來透露,她在華生和克里克之前計算出正確的DNA結構,但這項預測並沒有傳達給這兩個人。

雙螺旋對生物學有重大影響。它協助描述遺傳訊息如何被編碼和複製。這些資訊決定了生物的外觀、它們如何作用和繁殖。毫不奇怪,沃森和克里克因其成就而獲得諾貝爾化學獎。但富蘭克林則不然,因為將諾貝爾獎授予已故的人是違反規定的,而富蘭克林在此之前就死於卵巢癌。富蘭克林就是這樣被遺忘的。

華森和克里克竊取了富蘭克林的成果嗎?也許更重要的是,當前的科學界能否公平對待每一位研究貢獻者?

2022年7月20日 星期三

拙文: 絕對空虛? 完全的「無」可能嗎?|星島教育網

 





https://stedu.stheadline.com/sec/article/27269/STEM%E7%86%B1%E8%A9%B1-%E7%B5%95%E5%B0%8D%E7%A9%BA%E8%99%9B-%E5%AE%8C%E5%85%A8%E7%9A%84-%E7%84%A1-%E5%8F%AF%E8%83%BD%E5%97%8E