The Secrets of Life (1) - Chromosomes, DNA and Genes

Our bodies are made up of millions of cells. Inside the nucleus of each cell, there are chromosomes (染色體). An ordinary human has 46 chromosomes in each cell made up of 23 pairs. The first 44 chromosomes (called autosomes - 常染色體) are numbered 1 to 22 according to size from the largest to smallest. The last 2 chromosomes (called sex chromosomes - 性染色體) could only be either X or Y chromosomes. A female has 2 X chromosomes whereas a male has one X and one Y chromosomes. Hence, a ordinary female's chromosomes are described as 46,XX and male as 46,XY. Usually, a mother passes 23 chromosomes (one from each pair) to her child through her egg and a father likewise passes 23 chromosomes through his sperm. When the egg and the sperm join together at the time of conception, they form the first cell of the child which now has 46 chromosomes as the parents. Hence, one half of the chromosomes are inherited from the mother and the other half from the father. The cell continues to multiply (duplicated from the first cell) as the child continues to grow, resulting in exactly 46 chromosomes in every cell of the body.

Chromosomes, when stretched out, can be as long as 12 centimetres. All of the 46 chromosomes together is about 2 metres long, yet coiled and fit into a single cell nucleus which is about 2 micrometres (0.00002 metres). Each chromosome has a short (p) arm and a long (q) arm separated by a narrow constriction called centromere. Under the microscope and with special stains, the chromosome can be seen as a series of alternate light and dark bands. The bands are labeled p1, p2, p3, q1, q2, q3, etc., counting from the centromere out toward the ends. At higher resolutions, sub-bands (also numbered from the centromere out towards the end) can be seen within the bands. At even higher resolutions, sub-sub-bands can also be seen. The first digit in the band label refers to the band, the second digit the sub-band and the digit after the period the sub-sub-band. For example, a band labelled 16 p13.1 refers to chromosome 16, p-arm, band 1, sub-band 3 and sub-sub-band 1 accordingly.

Chromosomes are made up of material called deoxyribonucleic acid (DNA-脫氧核糖核酸). Thus, each chromosome is a DNA molecule. The DNA molecule is made up of 2 very long chains of 4 chemical units: Adenine (A), Guanine (G), Thymine (T) and Cytosine (C). These 4 chemical units form the bases (as 'letters') of the genetic codes which contain all the information for human growth and development. The bases are arranged in pairs such that A is only paired with T, and G only with C. The bases are further grouped into triplets (e.g. TGA, CTG, ACT etc.) to form '3-lettered words'. Each triplet gives instruction for the cell to produce a particular type of amino acid. A sequence of triplets (e.g. TGACTGACTGTCATG ..... ) enables the cell to assemble the amino acids in the correct order for the cell to function. A complete sequence of triplets that contains particular instructions to perform a particular function is called a gene (基因). Hence, a gene is a basic unit that carries the genetic information for a particular function for human growth and development. Some genes may be responsible for producing certain type of cells like blood, hair or lung etc. Others may be responsible for producing materials with personal characteristics like colour of eye and skin, height or shape of the nose etc. Genes are labelled by their functions. (e.g. gene HBA1, haemoglobin alpha 1 located in chromosome 16, is responsible for producing a protein necessary for red blood cells.)

There are hundreds and thousands of genes in a chromosome, and it is estimated that there are about 25,000 - 35,000 genes in a single human cell. The number of chemical bases (letters A, T, G or C) in a gene varies as dependent on the function of the gene, but may range from 1, 000 to several hundred thousand. In total, there are about 3.1 billion bases (letters) in a single human cell. The arrangement of these 3.1 billion bases is very specific and unique for each individual, and hence the DNA sequence in the cell can be used like a fingerprint for individual identification. When there are changes in the chromosomes or genes (e.g. due errors during the conception of the egg and sperm or external factors like radiation etc.), the normal sequence of genetic codes in the genes (and thus the chromosomes) will be disturbed. Hence, the normal function to produce the necessary materials for the cell to develop will be affected. As result, problems in health and development may occur.

As of today, our knowledge in genes is still quite incomplete (including the exact number of genes and functions of all the genes). But with our increasing knowledge in the secrets of the genetic codes in the genes (and hence the DNA sequence), we can understand more and more about life including how we inherit our personal characteristics from the our parents, the process of aging and deceases and what problems we could expect on health and development. These can well be determined even before birth of the child by appropriate prenatal testings .....................

射鵰英雄傳

最近翻看一部少時喜愛的武俠小說 - 金庸之（射鵰英雄傳）.此書除有吸引人的武俠情節外, 更可看到金庸之文學修養, 及其深湛文筆之功力. 其中一段描寫郭靖, 黃蓉求見當代五大高手（東邪, 西毒, 南帝, 北丐, 中神通）之南帝段皇爺. 南帝當時己歸於佛法, 化名一燈大師, 隱居深山, 不聞世事. 南帝昔日之四大弟子: 漁(漁人), 樵（樵子）, 耕(農夫）, 讀（書生）,為保一燈大師免受滋擾, 各以每人所長, 力阻二人求見. 郭, 黃幾經辛苦, 終於去到最後書生的一關. 書生以其文才, 開出一度難度極高之絕句, 要求二人對出工整之下聯. 能者可繼續上山, 不能者便得知難而退. 其上聯如下：

琴瑟琵琶 八大王一般頭面

黃蓉冰雪聰明, 不消一刻, 己對出非常工整之下聯, 並乘勢嘲諷漁樵耕讀一下. 然後順利過關上山:

魑魅魍魎 四小鬼各自肚腸

其後, 不少文人雅士, 爭相嘗試對岀下聯. 現搜集了一些出色的摘錄如下:

鼴鼮鼫鼬 四賊鼠各踩尾巴 : 鋼鐵銅鋁 四千金不同心腸
烤燴炒炸 四把火旁敲側擊 : 栗桑欒檗 四巨木不同枝葉
駙駿駒馳 四小馬各奔前程 : 猙獰獐狡 四小犬各有面容
閨閣闈閫 四內門各有風光 : 簫筑箏篁 四翠竹各懷清音
懼怕懾憚 四顆心同樣畏縮 : 盯眺盼瞻 四雙目各有看頭
齮齦齟齬 四利齒不一唇舌 : 囚囡囝因 四巨囗各吞一人
珍瑾玲珊 四美玉各領風騷 : 妻妾婆嬰 四嬌女十分麻煩
雷電雪雹 四方雨同等天氣 : 蛇蟺螻蛄 四小虫一般蠢動
挑撥按撚 四纖手別有風姿 : 嫵媚婉妙 四仙女別有風情
倜儻俊俏 四才人別款燦華 : 孫孺孩孤 四男子同等裝扮
飴餃飩餅 四麵食不同餡兒 : 舫舲舴艇 四小舟不同風帆
鵲鴿鴉鵑 四小鳥各自飛翔 : 峭嶇崆峒 四壯山各有形態
貂貉貆獾 四獸豸不盡相同 : 癰疔疽癤 四惡瘡相同爛皮
囚困囹圄 四監牢各關重犯 : 癡癖癲瘋 四狂者各有心疾
雞鴨鵝鴿 四肥鳥各自享用 : 峨嵋崆峒 兩名山譽滿天下

一部武俠小說, 除開故事情節不談, 能夠引起如此的文學迴響, 實不愧為一部不可多得的名著.

至此, 在下亦不禁一時技癢, 附庸風雅一番:

Barry, Benny, Billy, Bobby 四小B同一性別
Ancient History, Business Accounting, Modern Algebra, Visual Arts
四科A一剎光華
John, Vickie, Veronica, Johnson four smart MAN 各有千秋

When In Arabia, Do As The Arabs Do

A disappointed sales manager of Coca-Cola returned from his assignment to Saudi Arabia.
A friend asked, "Why weren't you successful with the Saudis?" The sales manager explained, "When I got posted, I was very confident that I would make a good sales pitch. But I had a problem. I didn't know how to speak Arabic. So I planned to convey the message through three posters."

First poster: A man is lying in the hot desert sand totally exhausted and fainted.
Second poster: A man is drinking Coca-Cola.
Third poster: A man is totally refreshed and lively.
And then these posters were posted all over the place.

"Terrific! That should have worked!" said the friend.
"The hell it should have!" said the sales manager. "But no one told me they read from right to left!"

Think Before You Speak

There were four guys, a French, a Russian, a German and an American, who found a small genie bottle. When they rubbed the bottle, a genie appeared. Thankful that the four guys had released him out of the bottle, the genie said, "I will give each of you a wish. In front of you, there are four swimming pools. When you run towards the pool and jump, you shout what you want the pool of water to become, your wish will come true."
The French started. He ran towards the pool, jumped and shouted, "WINE". There he jumped into a pool of wine.
Next the Russian followed. He ran towards the pool, jumped and shouted, "VODKA". There he jumped into a pool of vodka.
Then it was the German's turn. He ran towards the pool, jumped and shouted, "BEER". There he jumped into a pool of beer.
Lastly it was the American. He ran towards the pool but stepped on a banana peel. He slipped towards the pool and shouted, "SHIT". There he jumped into a pool of ............................

The Monty Hall Problem

You are on a TV show. You are given a choice of 3 doors. Behind one door is a car; behind the others, goats. You are to pick a door, winning whatever is behind it. So you pick one, say door 1. Since there are 2 goats behind 3 doors, whatever you choose, there is at least one goat left behind the 2 other doors. The host, Monty Hall, who knows what's behind them, opens one of these 2 other doors, say door 3, to reveal a goat. He then asks you, "Do you want to stick to your choice, or do you want to switch to door 2?" The question really is to ask, "Does switching increase your chance of winning the car?"
When you pick door 1, the chance of winning the car is 1/3 (i.e. the chance of having the car behind door 1 is 1/3 since there is 1 car in 3 possible doors). And then Monty eliminates door 3 for you by revealing a goat behind door 3. Intuitively, you think you then get a better chance of winning the car as the chance of having the car in door 1 is now 1/2 (since there is 1 car in only 2 possible doors) and likewise in door 2 is also 1/2. So you think it makes no difference whether to switch or not. So you choose to stick with door 1. Right? WRONG!

Let's go back and examine the probabilities in more details.

When you pick door 1, your chance of having the car behind door 1 is 1/3. There's no question about it. Let's now group doors 2 and 3 together. Your chance of having the car NOT behind door 1 (i.e. behind either door 2 or 3) is 2/3 since the total probability must equal to 1. By eliminating door 3 from the scene (by Monty), your chance of having the car behind door 1 is NOT increased from 1/3 to 1/2 as intuitively thought. Your chance of having the car in door 1 is still 1/3 as when you make your choice, you choose 1 out of 3 possibilities (doors 1, 2 and 3). As the saying goes, the dice has been cast. The probability will not, and cannot be altered. Only IF you are free to choose at this point, you are then to choose 1 out of 2 possibilities (doors 1 and 2), and the chance of having the car behind door 1 is indeed 1/2. So by eliminating door 3 from the scene, the effect is ONLY simply changing our group consisting of doors 2 and 3 to a group consisting of door 2 only. Hence your chance of having the car NOT behind door 1 (now behind door 2 only) is still 2/3. In other words, AT THIS POINT, the chance of having the car behind door 2 is 2/3, not 1/2 as intuitively thought. So after Monty eliminates door 3 for you by revealing a goat behind door 3, the chance of having a car in door 1 is 1/3, and in door 2 is 2/3.
Hence, YES, you WILL increase your chance of winning by switching. IN THEORY, YOU SHOULD ALWAYS SWITCH.

Behind the Shadow of The Father

It was a very hot summer day. The whole world seemed to be burning. Inside an air-conditioned clinic, a doctor was still feeling the heat outside. He raised his head and looked through the window. He saw hawkers busy selling their stuff on the street, hustling and bustling under the red hot sun. Before long, he heard very noisy sounds. Several people carried a big fellow into the clinic. The man had already fainted, with sweat all over his body. A little young girl was following and crying.
After the doctor's examination, the man was found to have gotten a sun-stroke. He was then given some water and an injection, and gradually regained his consciousness. Seeing her father recovered, the little girl was relieved despite still sobbing. She took out her purse, put all the money she got on the table and wanted to pay the doctor for the medical treatment. The doctor said, "Forget it. You may take this as a little help from me." The little girl thanked the doctor but continued crying. Trying to cheer up the little girl, the doctor said, "Don't cry, sweetheart. I know you are a strong girl. You were out in the sun all day and you are still okay. Look at your dad, he isn't as strong as you are." The girl cried even more loudly. She said, " No! It's not true! Dad asked me to sit behind his shadow all the time. It was him who stood up there, blocking the sun away from me all day. That's why I'm okay and he's not!"

A father's love is usually straightforward, pragmatic and yet mostly unspoken. Like a mother's love, it is also always dedicated, unconditional and unreserved, and is readily available when you need it. While we usually tend to praise mother's love more, do take a moment to appreciate the love from the father.

月亮代表我的心

This is a translation of the song 'The Moon Reflects All In My Heart' (月亮代表我的心) by Teresa Teng (鄧麗君) : 1953-1995. It's a very beautiful song sung by a very beautiful voice. Hope you enjoy!

You asked me how intimate my love is, how much I love you,
My passion's real, my love's real too.
The moon reflects all in my heart!

You asked me how intimate my love is, how much I love you,
My passion ne'er fades, my love ne'er dies.
The moon reflects all in my heart!

It was just a soft and tender kiss from you,
but it'd already touched the bottom of my heart.
It was such an unforgettable affair with you,
and it did make me miss you every moment till this time.

You asked me how intimate my love is, how much I love you,
You just go have a think, you just go have a look.
The moon reflects all in my heart!

你問我愛你有多深　我愛你有幾分
我的情也真　我的愛也真
月亮代表我的心

你問我愛你有多深　我愛你有幾分
我的情不移　我的愛不變
月亮代表我的心

輕輕的一個吻　已經打動我的心
深深的一段情　教我思念到如今

你問我愛你有多深　我愛你有幾分
你去想一想　你去看一看
月亮代表我的心

(extract from http://www.youtube.com/watch?v=51xS4yXbryc).

Wife : Girlfriend = TV : Mobile

Wife is like TV.
Girlfriend is like MOBILE (Phone).

At home watch TV.
Go out bring MOBILE.

No money, sell TV.
Got money change MOBILE.

Sometimes enjoy TV.
But most of the time you play with MOBILE.

TV is free for life.
For MOBILE if you don't pay, the services will be terminated.

TV is big, bulky and most of the time old.
MOBILE is cute, slim, curvy and portable at any time.

Operational cost for TV is acceptable.
Cost for MOBILE is high and often demanding.

TV has remote.
MOBILE doesn't.

With TV you MUST listen.
MOBILE is for two-way communications (you talk and listen).

TV do not have virus.
MOBILE? Definitely yes!

Wife vs Computer

I heard this from my friend (an IT guy) :

Wife can be mapped to a computer:
1. You face it everyday, and yet you still don't understand its complicated logic and difficult procedures.
2. It runs simple programs, which take you days to debug their errors.
3. It performs fast and accurate computations. It can compute how much salary to the dollar you still get left, and how much money you need in each single day in matter of nanoseconds.
4. It has superb memory and storage. Your every minor mistakes are stored securely and permanently on file, and can be recalled momentarily as and when required.
5. It organizes everything for you systematically: which restaurant to go, what tie to wear and when to see the in-law.
6. It is expensive to purchase. It is even more expensive to purchase the associated software and peripherals.
7. One minor careless mistake will cause it to crash. You need to spend a fortune and weeks to repair and restore for recovery.
8. It hangs up from time to time for no reasons, but will resume its operations automatically without your knowing.
9. It is your most precious toy and tool ever in life that you love and hate.

I Wish .........................

One day, a pair of young lovers went for a sightseeing trip on a bus, the destination of which was a famous tourist attraction. Before the bus entered the hills area, it passed by a small beautiful beach. The scenaries of the beach fully fascinated the pair. The man said to his girl friend, "Before going to the hills, why don't we go to the beach for a walk?" The girl said, " Good idea. I'd love to." So the man pressed the bell to signal to disembark. Afterwards, the bus continued to drive on slowly. The pair walked leisurely in the direction to the beach. But very shortly, they heard a sudden big "BOOM". A hugh boulder rolled down from the hill and struck right on the bus. Very unfortunately, no passengers on the bus survived.
Shocked at the scene, the man said to his girl friend very sadly, "I wish we were still on the bus." The girl was speechless with tears all over her face. She held her boyfriend's hand tight and nodded her head hard in agreement.

Under such situation, people might think about themselves first. They would feel happy and lucky to have gotten off the bus; otherwise they would be killed too. But the pair concerned more about the others and looked at the matter from a broader perspective. They thought that if they were still on the bus, the bus wouldn't have stopped but continued. When the boulder fell down, it wouldn't have hit the bus and the tragedy wouldn't have happened at all! They felt very sorry to have disembarked and not to have stayed with the other passengers!