Genetics
遺傳學
Why do you look like your parents? In this lesson you will learn about genetics, how traits are passed down through DNA and genes, and the difference between dominant and recessive traits.
為甚麼你長得像你的父母？在這一課，你會學習遺傳學、特徵怎樣透過DNA 和基因遺傳，以及顯性和隱性特徵的分別。
1 · What is genetics?
甚麼是遺傳學？
Genetics is the study of how traits are passed from parents to their children. Traits are features such as eye colour, hair colour and height. The passing down of traits is called heredity.
遺傳學是研究特徵怎樣由父母遺傳給子女的科學。特徵是指眼睛顏色、頭髮顏色和身高等。這種特徵的傳承稱為遺傳。
2 · DNA and chromosomes
DNA 和染色體
Your traits are controlled by genes, which are made of a chemical called DNA. DNA is shaped like a twisted ladder. Genes are found on chromosomes inside the nucleus of every cell.
你的特徵由基因控制，基因由一種稱為 DNA 的化學物質組成。DNA 的形狀像一條扭轉的梯子。基因位於每個細胞細胞核內的染色體上。
Cell → nucleus → chromosomes → DNA → genes. Genes are the instructions for your traits.
細胞 → 細胞核 → 染色體 → DNA → 基因。基因就是你特徵的說明書。
3 · Dominant and recessive
顯性與隱性
Some traits are dominant and some are recessive:
有些特徵是顯性的，有些是隱性的：
- A dominant trait shows up even if you have only one copy.即使你只有一個顯性基因，顯性特徵也會表現出來。
- A recessive trait only shows up if you have two copies.隱性特徵只有在你有兩個基因時才會表現。
- Brown eyes are dominant over blue eyes.棕色眼睛比藍色眼睛顯性。
4 · Inherited traits
遺傳的特徵
Some traits are inherited, such as eye colour and blood type. Other things, such as your haircut or the language you speak, are learned and are not inherited.
有些特徵是遺傳的，例如眼睛顏色和血型。其他事物，如你的髮型或語言，是後天學習的，不是遺傳的。
5 · Quick check
小測驗