簡介Introduction
在本活動中，你會使用自選的物料製作DNA模型。你需要應用關於DNA結構的知識。你還有機會展示你在工程學上的技能、創意、團隊合作性和溝通技巧。
In this activity, you will use materials of your own choice to make a DNA model. You will need to apply your knowledge about the structure of DNA. You will also have a chance to demonstrate your engineering skills, creativity, team work and communication skills.
背景知識：DNA的結構Background knowledge about the structure of DNA
細閱圖1以重温DNA的雙螺旋結構和互補鹼基配對：
- DNA分子由兩條多核苷酸鏈（即兩條DNA鏈）組成，這兩條鏈方向相反，互相纏繞，形成雙螺旋結構。一般來說，DNA都是右手螺旋的（圖2）。
- DNA分子的骨架由核苷酸的糖（脫氧核糖）和磷酸鹽基組成。
- 每個核苷酸的糖與一個含氮鹼基相連；含氮鹼基有四種，分別是腺嘌呤 (A)、胸腺嘧啶(T)、鳥嘌呤 (G) 和胞嘧啶 (C)。一條多核苷酸鏈上的鹼基以氫鏈與另一條多核苷酸鏈上的鹼基配對。A只與T配對，而G只與C配對。這稱為互補鹼基配對。
Study Figure 1 below to revise the double helix structure of DNA and the rule of complementary base pairing:
- A DNA molecule consists of two polynucleotide chains (i.e. two DNA strands). The two strands run in opposite directions and are twisted together to form a double helix. In general, it is a right-handed helix (Figure 2).
- The backbone of the DNA molecule is made up of the sugar (deoxyribose) and phosphate groups of nucleotides.
- Attached to the sugar of each nucleotide is one of four nitrogenous bases: adenine (A), thymine (T), guanine (G) and cytosine (C). The bases on one strand pair up with those on the other strand through hydrogen bonds. A always pairs with T, and G pairs with C. This is called complementary base pairing.
活動Task
老師會把同學為成三至五人的小組。與組員合作設計和製作DNA模型。設計DNA模型時，要注意以下各項︰
Your teacher will divide the class into groups of three to five. Collaborate with your group members to design and make a DNA model. Remember that the model:
- 模型應合乎比例。
- 模型應能表示DNA的右手螺旋結構。
- 模型應能表示互補鹼基配對。
- should be to scale.
- should represent the right-handed double helix structure of DNA.
- should illustrate complementary base pairing.
設計DNA模型Design the DNA model
1.
老師會提供不同的物料供你製作DNA模型，你可自由組合不同的物料，也可以自備物料。列出你的設計所需的物料。
Your teacher will give you a variety of materials to build the DNA model. You may choose materials in any combination or even bring your own materials. List the materials your group will use.
2.
在以下的空格內繪畫並標示你的設計。扼要地描述製作模型的步驟。
Draw and label your design below. Briefly describe your steps in making the model.
3.
寫出設計模型時，所參考的資料來源。
Write the source(s) of any reference you used when designing your model.
製作及展示模型Make the model and communicate results
1.
經老師准許後，你和組員便可收集所需物料和製作模型。
3.
老師會根據以下評核準則來評核你的表現。
| 評核準則 |
水平 |
| 優異 |
良好 |
平平 |
差劣 |
生物學知識的應用
- 模型合乎比例
- 模型展示了DNA結構的主要特徵︰右手螺旋、互補鹼基配對
|
4 | 3 | 2 | 1 |
|
解難能力
|
4 | 3 | 2 | 1 |
創新的設計
- 能發揮創意，運用不同的物料來代表DNA雙螺旋的不同成分
|
4 | 3 | 2 | 1 |
|
報告及演示
|
4 | 3 | 2 | 1 |
|
引用參考資料
|
4 | 3 | 2 | 1 |
|
整體水平
|
4 | 3 | 2 | 1 |
1.
After getting your teacher’s approval, you can collect your materials and make the DNA model.
2.
Present and display your model to the class.
3.
Your teacher will evaluate your work based on the following grading rubric.
| Assessment criteria |
Quality of work |
| Excellent |
Good |
Fair |
Poor |
Application of biological knowledge
- Model in scale.
- Model illustrates the key features of the DNA structure: right-handed double helix, complementary base pairing.
|
4 | 3 | 2 | 1 |
Practical solution
- Good use of materials to build a firm, sturdy model.
|
4 | 3 | 2 | 1 |
Innovative design
- Innovative use of different materials to represent the different components of the DNA double helix.
|
4 | 3 | 2 | 1 |
Presentation
- Clear and well-organized oral presentation, proper use of scientific language.
|
4 | 3 | 2 | 1 |
Reference acknowledgement
- Any references used are properly acknowledged.
|
4 | 3 | 2 | 1 |
|
Overall quality of work
|
4 | 3 | 2 | 1 |
4.
What modifications can you make to improve your DNA model?
問題Questions
1.
DNA的哪些特性使它成為儲存遺傳信息的理想物質？
What property of DNA makes it an ideal material for the storage of genetic information?
2.
DNA的分子結構通過哪些鍵來固定？描述這些鍵的功用。
What types of bonds holds the DNA molecule together? Describe how the bonds keep the DNA structure stable.
3.
就DNA複製和細胞分裂的過程，解釋互補鹼基配對的重要性。
What is the significance of complementary base paring? Explain in terms of the processes of DNA replication and cell division.
延展部分Extension
如果學校有3D打印機，你可在本社的網站下載可供3D打印的DNA模型。如果你會使用3D製圖軟件（例如Blender），更可以設計和製作自己的3D打印模型。
If 3D printers are available at school, you can download DNA models for 3D printing from the website shown below. You can also use 3D graphic tools (e.g. Blender) to design your own 3D-printed DNA model.