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  • It's often said that despite humanity's many conflicts,

    常謂儘管人類之間有許多衝突

  • we all bleed the same blood.

    我們流的血都是一樣的

  • It's a nice thought but not quite accurate.

    這想法雖佳,不過不太正確

  • In fact, our blood comes in a few different varieties.

    其實,我們的血液本自有一些不同差異

  • Our red blood cells contain a protein called hemoglobin

    我們的紅血球含有一種叫做血紅蛋白的蛋白質--

  • that binds to oxygen,

    --可以和氧結合

  • allowing the cells to transport it throughout the body.

    讓紅血球能夠將之運送到全身

  • But they also have another kind of complex protein

    可是它們還有另外一種複合性蛋白質

  • on the outside of the cell membrane.

    在細胞膜的外面

  • These proteins, known as antigens, communicate with white blood cells,

    這一些蛋白質 -- 稱為抗原 -- 跟白血球溝通

  • immune cells that protect against infection.

    [白血球是] 對抗感染的免疫細胞

  • Antigens serve as identifying markers,

    抗原作為辨識標記

  • allowing the immune system to recognize your body's own cells

    讓免疫系統可以辨識你自己身體的細胞

  • without attacking them as foreign bodies.

    而不會當作異物攻擊它們

  • The two main kinds of antigens, A and B, determine your blood type.

    兩種主要的抗原 -- A 和 B -- 決定你的血型

  • But how do we get four blood types from only two antigens?

    不過我們如何只從兩種抗原而得到四種血型呢?

  • Well, the antigens are coded for by three different alleles,

    是這樣的,這些抗原是依三種不同的 “對偶基因” 來編碼

  • varieties of a particular gene.

    [對偶基因] 是一種特殊基因的種類

  • While the A and B alleles code for A and B antigens,

    A 和 B 對偶基因編碼 A 型和 B 型抗原,

  • the O allele codes for neither,

    而 O 對偶基因則沒有編碼任何一種

  • and because we inherit one copy of each gene from each parent,

    而且因為我們從父母各自遺傳一組基因,

  • every individual has two alleles determining blood type.

    每人擁有兩個決定血型的對偶基因

  • When these happen to be different,

    當這些編碼不同,

  • one overrides the other depending on their relative dominance.

    依據他們的相對顯性,一個會覆蓋另一個

  • For blood types, the A and B alleles are both dominant, while O is recessive.

    就血型來說,A 和 B 對偶基因都是顯性,而 O 是隱性

  • So A and A gives you type A blood, while B and B gives you type B.

    所以 A 和 A 結合就成為 A 型,而 B 和 B 結合就成為 B 型

  • If you inherit one of each,

    如果你遺傳了其中各一個,

  • the resulting codominance will produce both A and B antigens,

    所產生的共顯性會製造 A 與 B 抗原

  • which is type AB.

    這就是 AB 型

  • The O allele is recessive,

    O 對偶基因是隱性的

  • so either of the others will override it when they're paired,

    所以其他任何一個和它配對都會覆蓋它

  • resulting in either type A or type B.

    形成不是A 型就是 B 型

  • But if you happen to inherit two Os, instructions will be expressed

    可是如果你剛好遺傳到兩個 O,指令將下達

  • that make blood cells without the A or the B antigen.

    製造沒有 A 或 B 抗原的血球

  • Because of these interactions,

    因為這些交互作用,

  • knowing both parents' blood types

    知道雙親的血型,

  • lets us predict the relative probability of their children's blood types.

    就可以讓我們預測他們的小孩血型的相對機率

  • Why do blood types matter?

    血型為什麼重要呢?

  • For blood transfusions,

    就輸血而言,

  • finding the correct one is a matter of life and death.

    找對正確的血是攸關生死的

  • If someone with type A blood is given type B blood, or vice versa,

    如果一個 A 型的人輸了 B 型的血,反之亦然,

  • their antibodies will reject the foreign antigens and attack them,

    他們的抗體就會排斥外來的抗原並攻擊它們

  • potentially causing the transfused blood to clot.

    可能會導致所輸入的血凝固

  • But because people with type AB blood produce both A and B antigens,

    不過因為 AB 型的人會製造出 A 抗原及 B 抗原,

  • they don't make antibodies against them, so they will recognize either as safe,

    他們不會製造抗體來抵抗它們,所以將任何血型都視為安全

  • making them universal recipients.

    讓他們成為 “全適受血者”

  • On the other hand,

    反過來說,

  • people with blood type O do not produce either antigen,

    O 型的人不製造任何一種抗原

  • which makes them universal donors,

    使他們成為 “全適捐血者”

  • but will cause their immune system to make

    不過他們的免疫系統會製造

  • antibodies that reject any other blood type.

    排斥其他任何血型的抗體

  • Unfortunately, matching donors and recipients is a bit more complicated

    不幸的是,要配對捐血者和受血者不是那麼簡單的事情

  • due to additional antigen systems,

    因為還要將其他的抗原系統考慮在內

  • particular the Rh factor,

    尤其是 Rh 因子

  • named after the Rhesus monkeys in which it was first isolated.

    -- 以第一次在恆河猴身上分離出來而得名

  • Rh+ or Rh- refers to the presence or absence of the D antigen of the Rh blood group system.

    Rh 陽性或 Rh 陰性意指 Rh 血型系統裡是否存在 D 抗原

  • And in addition to impeding some blood transfusions,

    除了妨礙一些輸血之外

  • it can cause severe complications in pregnancy.

    它也可能導致懷孕時的嚴重併發症

  • If an Rh- mother is carrying an Rh+ child,

    如果一位 Rh 陰性的母親懷有 Rh 陽性的孩子

  • her body will produce Rh antibodies that may cross the placenta

    她的身體就會製造 Rh 的抗體,可能穿過胎盤

  • and attack the fetus,

    攻擊胎兒

  • a condition known as hemolytic disease of the newborn.

    這種情況叫做 “新生兒溶血症”

  • Some cultures believe blood type to be associated with personality,

    有些文化相信血型和個性是有關的

  • though this is not supported by science.

    儘管科學不支持這種說法

  • And though the proportions of different blood types

    雖然不同血型的分佈

  • vary between human populations,

    在各種人種之間是有差異的

  • scientists aren't sure why they evolved;

    科學家不確定為什麼會有如此的演化

  • perhaps as protection against blood born diseases,

    也許是為了對抗血液衍生的疾病

  • or due to random genetic drift.

    或者是因隨機的遺傳漂變

  • Finally, different species have different sets of antigens.

    最後,不同物種有不同的抗原組合

  • In fact, the four main blood types shared by us apes

    其實,我們人猿的四種主要血型

  • seem paltry in comparison to the thirteen types found in dogs.

    相較於狗類的十三種,看起來是微不足道的

It's often said that despite humanity's many conflicts,

常謂儘管人類之間有許多衝突

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B1 中級 中文 美國腔 TED-Ed 抗原 血型 基因 抗體 製造

【TED-Ed】為什麼血型很重要?- Natalie S. Hodge (【TED-Ed】Why do blood types matter? - Natalie S. Hodge)

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    Ann 發佈於 2021 年 01 月 14 日
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