簡介Introduction
在本活動中，你會探究如何以DNA作為數據儲存的媒介。你需要把文字訊息轉換成DNA密碼，並嘗試破解由其他同學設計的密碼。你還有機會展示團隊合作性、溝通技巧和解難能力。
In this activity, you will explore the use of DNA as a data storage medium. You will translate text messages into the DNA code and decode messages written by others. You will have a chance to demonstrate your team work, communication and problem-solving skills.
背景知識Background knowledge
1.
DNA的特性使它適合作為儲存遺傳信息的物質。
- DNA是由大量核苷酸組成的大分子，能攜帶大量遺傳信息。
- DNA四種不同的核苷酸由四種含氮鹼基──腺嘌呤 (A)、胸腺嘧啶 (T)、胞嘧啶 (C) 和鳥嘌呤 (G) 形成。不同的鹼基序列可編碼無限多種不同的蛋白質。
- DNA的分子穩定。兩條多核苷酸鏈通過互補鹼基之間的氫鍵連結，形成雙螺旋結構。鹼基朝向雙螺旋的內部，能保護遺傳信息，免受破壞。
1.
DNA is well suited to its function as a store of genetic information.
- DNA is a large molecule made up of a huge number of nucleotides. This allows DNA to carry a large amount of genetic information.
- There are four types of DNA nucleotides, each specified by one of four nitrogenous bases: adenine (A), thymine (T), cytosine (C) and guanine (G). Different sequences of bases code for a potentially infinite number of different protein molecules.
- DNA is a stable molecule which exists as a double helix, with two polynucleotide chains held together by hydrogen bonds between complementary bases. The bases project towards the centre of the double helix. This protects the genetic information from damage.
2.
DNA能編碼並保存大量信息，啟發科學家研究以DNA作為數據儲存媒介。
DNA can encode and store a lot of information, which has inspired scientists to investigate its potential use as a data storage medium.
背景
在大數據時代，我們對數據儲存空間的需求急速增長。在不久的將來，傳統數碼儲存媒介，例如：硬碟、磁碟、光碟、可攜式硬碟及USB儲存裝置，或不足以滿足我們的需求。再者，這些媒介的壽命亦有限。以DNA作為數據儲存媒介是一個可能的解決方法。
Background information
In this era of big data, the demand for data storage capacity keeps growing rapidly. Traditional digital storage media, such as HDD (hard disk drive), floppy disks, CDs, DVDs, portable hard drives and USB streak drives, may soon not be able to meet the demand. Meanwhile, these media have limited span of life. DNA as a data storage medium may be a solution to these problems.
DNA儲存數據的原理
下圖顯示如何用DNA存取數據：
How DNA data storage works
The flow chart below outlines how to store data in DNA and how to retrieve it:
由數據編碼成DNA
Encoding data in DNA
- 電腦和其他數碼電子設備用二進制數系統（只有「0」和「1」的數字系統）來儲存和處理數據。音訊檔案、文字、影片或圖像會在電腦系統中轉換成二進制代碼。
- 把二進制代碼會轉換成由四種鹼基 (A, T, C, G) 組合而成的DNA序列。
- 確定鹼基序列後，便可以合成DNA並儲存起來。一克的DNA能夠儲存高達2.15億GB的數據。
- Computers and other digital electronic devices store and process data with the binary number system that uses only two digital numbers ‘0’ and ‘1’. Audio files, text, videos or images are converted to binary codes in computer systems.
- These binary codes are converted to DNA sequences made up of combinations of four bases, A, T, C and G.
- Once the base sequence is determined, the DNA can be chemically synthesized and stored. One gram of DNA can store up to 215 million gigabytes (GB) of data.
從DNA取回數據
Retrieving data from DNA
- 要從DNA取回數據，需要進行DNA序列測定。
- 把DNA鹼基序列復原為二進制代碼。
- 電腦系統能夠處理二進制代碼並顯示原來的檔案。
- To retrieve the data, DNA sequencing is carried out.
- The DNA base sequence is converted back to binary codes.
- The computer interprets the binary codes as the original digital file.
有關科學本質的觀念
以DNA儲存數據的起源可以追溯至1988年，當時的科學家把圖像編碼到一個只有28個鹼基對的DNA片段。在2019年，科學家成功把16 GB的維基百科資料編碼到人工合成DNA上。DNA儲存容量之大，使它有着龐大的潛力作為儲存媒介（一克的DNA能夠儲存高達2.15億GB的數據），但是相關技術成本高，以及緩慢的讀取和寫入過程，導致現時的實際用途非常有限。由此可見，科學發展受當時的技術和設備所影響。
NOS ideas
One of the earliest uses of DNA data storage dates back to 1988 when scientists encoded graphic information in a DNA fragment consisting of 28 base pairs. In 2019, scientists reported that 16 GB of Wikipedia have been encoded into synthetic DNA. While DNA as a storage medium has enormous potential because of its high storage capacity—one gram of DNA can store up to 215 million GB of data, its practical use is currently severely limited because of its high cost and the slow processes of reading and writing data. This demonstrates that progress in science is influenced by the technology and the types of equipment available at the time.
活動Task
老師會把同學分成三至五人的小組。你會與其他組別比賽，模擬機器把數據編碼成DNA鹼基序列，以及從DNA鹼基序列中解碼的過程。
Your teacher will divide the class into groups of three to five. You will play a game which simulates how machines encode and decode data to and from DNA bases.
第一部分︰編碼Part I: Encoding
1.
與組員討論並寫出一個10個英文詞彙以內的信息。
Discuss with your group members to think of a message to encode. The message should be within 10 words.
2.
根據下頁的「二進制代碼表」，把信息轉換成一連串的二進制代碼。
Convert the message to a series of binary codes according to the chart on the next page.
|
字符
Character
|
二進制代碼
Binary Code
|
| A | 01000001 |
| B | 01000010 |
| C | 01000011 |
| D | 01000100 |
| E | 01000101 |
| F | 01000110 |
| G | 01000111 |
| H | 01001000 |
| I | 01001001 |
| J | 01001010 |
| K | 01001011 |
| L | 01001100 |
| M | 01001101 |
|
字符
Character
|
二進制代碼
Binary Code
|
| N | 01001110 |
| O | 01001111 |
| P | 01010000 |
| Q | 01010001 |
| R | 01010010 |
| S | 01010011 |
| T | 01010100 |
| U | 01010101 |
| V | 01010110 |
| W | 01010111 |
| X | 01011000 |
| Y | 01011001 |
| Z | 01011010 |
|
字符
Character
|
二進制代碼
Binary Code
|
| . | 00101110 |
| ? | 00111111 |
| (space) | 00100000 |
| 0 | 00110000 |
| 1 | 00110001 |
| 2 | 00110010 |
| 3 | 00110011 |
| 4 | 00110100 |
| 5 | 00110101 |
| 6 | 00110110 |
| 7 | 00110111 |
| 8 | 00111000 |
| 9 | 00111001 |
3.
為每個DNA鹼基配上一個二進制代碼。
Assign a binary code to each of the four DNA bases A, T, C and G.
A = C = T = G =
A = C = T = G =
4.
把步驟2的二進制代碼轉換成DNA鹼基序列。
Convert the series of binary codes written in step 2 to a DNA base sequence.
第一部分︰編碼Part I: Encoding
5.
編碼後，把寫有DNA鹼基序列的p.5交給老師。
Hand in p.5 of your worksheet with the encoded DNA base sequence to your teacher.
6.
你和組員會收到其他組別的DNA鹼基序列，嘗試把DNA鹼基序列轉換成二進制代碼，然後再「解碼」成原來的信息。
Your group will receive the DNA base sequence from another group. Convert the DNA base sequence to binary codes, and then to text to retrieve the message.
7.
能在最短時間內把信息「解碼」的組別便勝出。
The group that can retrieve the message in the shortest time wins the game.
討論Discussion
1.
討論以DNA儲存數據的好處及限制。
Discuss about the advantages and current limitations of using DNA to store data.
2.
填寫下頁的「自我及組員評估表」，以評估自己和組員的表現。
Evaluate your group’s performance using the Self and peer evaluation form provided on the next page.
自我及組員評估表
Self and peer evaluation form
1.
把各組員的姓名寫在1–4的空格內，並為自己及各組員的表現評分。
分數：4 = 優異 3 = 良好 2 = 平平 1 = 有待改進
Write the names of your group members in the numbered boxes. Assign yourself and each group member a score for each attribute.
Score: 4 = Excellent 3 = Good 2 = Fair 1 = Need improvement
| 表現Attribute |
組員Group member |
| 我Myself |
1. |
2. |
3. |
4. |
| 積極提出意見Participation in developing ideas |
| | | | |
| 願意聆聽組員的意見並作出回應Willingness to listen to and discuss other’s ideas |
| | | | |
| 帶領／促進討論Participation in leading/facilitating discussion |
| | | | |
| 對活動感興趣並投入其中Interest and enthusiasm in the activity |
| | | | |
| 與組員的合作Cooperation with other group members |
| | | | |
| 時間管理Time management |
| | | | |
| 整體水平Overall contribution |
| | | | |
2.
就團隊合作而言，你在這個活動中有甚麼得着？
What did you learn about working in a group from this activity?
3.
如果再有機會進行類似活動，你有哪些地方需要改進？
What would you have done differently, given the opportunity?
4.
你對這活動有甚麼評價和建議？
Do you have any other comments or suggestions about the activity?
延展部分Extension
由文字轉換成DNA序列
From text to DNA sequence
由DNA序列轉換成文字
From DNA sequence to text