出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/06/09 09:00:06」(JST)
「A」のその他の用法については「A (曖昧さ回避)」をご覧ください。 |
Aa Aa | ||||||||||||||||||||||||||||||
ラテン文字 | ||||||||||||||||||||||||||||||
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Aは、ラテン文字(アルファベット)の1番目の文字。小文字は a 。ギリシャ文字のΑ(アルファ)に由来し、キリル文字のАに相当する。
大きく分けて3つの字形が使われる。
牛の角を逆にした形に由来する。
この文字が表す音素は原則として[a](非円唇前舌広母音)もしくは[ɑ](非円唇後舌広母音)、またはその類似音である。
大文字 | Unicode | JIS X 0213 | 文字参照 | 小文字 | Unicode | JIS X 0213 | 文字参照 | 備考 |
---|---|---|---|---|---|---|---|---|
A | U+0041 |
1-3-33 | A A |
a | U+0061 |
1-3-65 | a a |
半角 |
A | U+FF21 |
1-3-33 | A A |
a | U+FF41 |
1-3-65 | a a |
全角 |
Ⓐ | U+24B6 |
‐ | Ⓐ Ⓐ |
ⓐ | U+24D0 |
1-12-33 | ⓐ ⓐ |
丸囲み |
🄐 | U+1F110 |
‐ | 🄐 🄐 |
⒜ | U+249C |
‐ | ⒜ ⒜ |
括弧付き |
ᴬ | U+1D2C |
‐ | ᴬ ᴬ |
ᵃ | U+1D43 |
‐ | ᵃ ᵃ |
上付き文字 |
𝐀 | U+1D400 |
‐ | 𝐀 𝐀 |
𝐚 | U+1D41A |
‐ | 𝐚 𝐚 |
太字 |
𝐴 | U+1D434 |
‐ | 𝐴 𝐴 |
𝑎 | U+1D44E |
‐ | 𝑎 𝑎 |
イタリック体 |
𝑨 | U+1D468 |
‐ | 𝑨 𝑨 |
𝒂 | U+1D482 |
‐ | 𝒂 𝒂 |
イタリック体太字 |
𝒜 | U+1D49C |
‐ | 𝒜 𝒜 |
𝒶 | U+1D4B6 |
‐ | 𝒶 𝒶 |
筆記体 |
𝓐 | U+1D4D0 |
‐ | 𝓐 𝓐 |
𝓪 | U+1D4EA |
‐ | 𝓪 𝓪 |
筆記体太字 |
𝔄 | U+1D504 |
‐ | 𝔄 𝔄 |
𝔞 | U+1D51E |
‐ | 𝔞 𝔞 |
フラクトゥール |
𝔸 | U+1D538 |
‐ | 𝔸 𝔸 |
𝕒 | U+1D552 |
‐ | 𝕒 𝕒 |
黒板太字 |
𝕬 | U+1D56C |
‐ | 𝕬 𝕬 |
𝖆 | U+1D586 |
‐ | 𝖆 𝖆 |
フラクトゥール太字 |
𝖠 | U+1D5A0 |
‐ | 𝖠 𝖠 |
𝖺 | U+1D5BA |
‐ | 𝖺 𝖺 |
サンセリフ |
𝗔 | U+1D5D4 |
‐ | 𝗔 𝗔 |
𝗮 | U+1D5EE |
‐ | 𝗮 𝗮 |
サンセリフ太字 |
𝘈 | U+1D608 |
‐ | 𝘈 𝘈 |
𝘢 | U+1D622 |
‐ | 𝘢 𝘢 |
サンセリフイタリック |
𝘼 | U+1D63C |
‐ | 𝘼 𝘼 |
𝙖 | U+1D656 |
‐ | 𝙖 𝙖 |
サンセリフイタリック太字 |
𝙰 | U+1D670 |
‐ | 𝙰 𝙰 |
𝚊 | U+1D68A |
‐ | 𝚊 𝚊 |
等幅フォント |
記号 | Unicode | JIS X 0213 | 文字参照 | 名称 |
---|---|---|---|---|
ᴀ | U+1D00 |
‐ | ᴀ ᴀ |
LATIN LETTER SMALL CAPITAL A |
🄰 | U+1F130 |
‐ | 🄰 🄰 |
SQUARED LATIN CAPITAL LETTER A |
🅐 | U+1F150 |
‐ | 🅐 🅐 |
NEGATIVE CIRCLED LATIN CAPITAL LETTER A |
🅰 | U+1F170 |
‐ | 🅰 🅰 |
NEGATIVE SQUARED LATIN CAPITAL LETTER A |
ₐ | U+2090 |
‐ | ₐ ₐ |
LATIN SUBSCRIPT SMALL LETTER A |
他、EBCDIC では、「A」は 193 で表され、「a」は 129 で表される。
ウィクショナリーにAの項目があります。 |
ウィクショナリーにaの項目があります。 |
ウィキメディア・コモンズには、Aに関連するメディアがあります。 |
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This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (December 2014) |
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A (named a /ˈeɪ/, plural aes[nb 1]) is the first letter and vowel in the ISO basic Latin alphabet.[1] It is similar to the Ancient Greek letter alpha, from which it derives.[2] The upper-case version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lower-case version can be written in two forms: the double-storey a and single-storey ɑ. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children. It is also found in italic type.
The earliest certain ancestor of "A" is aleph (also written 'aleph), the first letter of the Phoenician alphabet[3] (which consisted entirely of consonants, thereby being an abjad rather than a true alphabet). In turn, the origin of aleph may have been a pictogram of an ox head in proto-Sinaitic script[4] influenced by Egyptian hieroglyphs, styled as a triangular head with two horns extended.
Egyptian | Cretan | Phoenician aleph |
Semitic |
Greek Alpha |
Etruscan A |
Roman/Cyrillic A |
Boeotian 800–700 BC |
Greek Uncial |
Latin 300 AD Uncial |
---|---|---|---|---|---|---|---|---|---|
In 1600 B.C.E., the Phoenician alphabet's letter had a linear form that served as the base for some later forms. Its name must have corresponded closely to the Hebrew or Arabic aleph.
Blackletter A |
Uncial A |
Another Blackletter A |
Modern Roman A |
Modern Italic A |
Modern script A |
When the ancient Greeks adopted the alphabet, they had no use for the glottal stop—the first phoneme of the Phoenician pronunciation of the letter, and the sound that the letter denoted in Phoenician and other Semitic languages—so they used an adaptation of the sign to represent the vowel /a/, and gave it the similar name of alpha. In the earliest Greek inscriptions after the Greek Dark Ages, dating to the 8th century BC, the letter rests upon its side, but in the Greek alphabet of later times it generally resembles the modern capital letter, although many local varieties can be distinguished by the shortening of one leg, or by the angle at which the cross line is set.
The Etruscans brought the Greek alphabet to their civilization in the Italian Peninsula and left the letter unchanged. The Romans later adopted the Etruscan alphabet to write the Latin language, and the resulting letter was preserved in the Latin alphabet used to write many languages, including English.
During Roman times, there were many variations on the letter "A". First was the monumental or lapidary style, which was used when inscribing on stone or other "permanent" mediums. For perishable surfaces, which were used for everyday or utilitarian purposes, a cursive style was used. Due to the "perishable" nature of the surfaces, examples of this style are not as common as those of the monumental. This perishable style was called cursive and numerous variations have survived, such as majuscule cursive, minuscule cursive, and semicursive minuscule. There were also variants intermediate between the monumental and the cursive. The known variants include the early semi-uncial, the uncial, and the later semi-uncial.[5]
At the end of the Roman Empire (5th century AD), several variants of the cursive minuscule developed through Western Europe. Among these were the semicursive minuscule of Italy, the Merovingian script in France, the Visigothic script in Spain, and the Insular or Anglo-Irish semi-uncial or Anglo-Saxon majuscule, of Great Britain. By the 9th century, the Caroline script, which was very similar to the present-day form, was the principal form used in book-making, before the advent of the printing press. This form was derived through a combining of prior forms.[5]
15th-century Italy saw the formation of the two main variants that are known today. These variants, the Italic and Roman forms, were derived from the Caroline Script version. The Italic form used in most current handwriting consists of a circle and vertical stroke ("ɑ"), called Latin alpha or "script a". This slowly developed from the fifth-century form resembling the Greek letter tau in the hands of medieval Irish and English writers.[3] Most printed material uses the Roman form consisting of a small loop with an arc over it ("a").[5] Both derive from the majuscule (capital) form. In Greek handwriting, it was common to join the left leg and horizontal stroke into a single loop, as demonstrated by the uncial version shown. Many fonts then made the right leg vertical. In some of these, the serif that began the right leg stroke developed into an arc, resulting in the printed form, while in others it was dropped, resulting in the modern handwritten form.
In modern English orthography, the letter A represents six different vowel sounds: A by itself frequently denotes the near-open front unrounded vowel (/æ/) as in pad; the open back unrounded vowel (/ɑː/) as in father, its original, Latin and Greek, sound;[4] a closer, further fronted sound as in "hare", which developed as the sound progressed from "father" to "ace";[3] in concert with a later orthographic vowel, the diphthong /eɪ/ as in ace and major, due to effects of the Great Vowel Shift; the more rounded form in "water" or its closely related cousin, found in "was".[3]
The double "a" sequence does not occur in native English words; however, it is found in some words derived from foreign languages such as Aaron and aardvark.[6]
"A" is the third-most-commonly used letter in English (after "E" and "T"),[7] and the second most common in Spanish and French. In one study, on average, about 3.68% of letters used in English texts tend to be 'a', while the number is 6.22% in Spanish and 3.95% in French.[8]
In most languages that use the Latin alphabet, A denotes an open unrounded vowel, such as /a/, /ä/, or /ɑ/. An exception is Saanich, in which A (and Á) stands for a close-mid front unrounded vowel /e/.
In algebra, the letter "A" along with other letters at the beginning of the alphabet is used to represent known quantities, whereas the letters at the end of the alphabet (x,y,z) are used to denote unknown quantities.
In geometry, capital A, B, C etc. are used to denote segments, lines, rays, etc.[5] A capital A is also typically used as one of the letters to represent an angle in a triangle, the lowercase a representing the side opposite angle A.[4]
In logic, A is used to signify the universal affirmative.
In physics, A is the SI unit symbol for Ampere.
In phonetic and phonemic notation:
"A" is often used to denote something or someone of a better or more prestigious quality or status: A-, A or A+, the best grade that can be assigned by teachers for students' schoolwork; "A grade" for clean restaurants; A-list celebrities, etc. Such associations can have a motivating effect, as exposure to the letter A has been found to improve performance, when compared with other letters.[9]
A is a common symbol of school and basic phonetics in the US, along with B and C.
Finally, the letter A is used to denote size, as in a narrow size shoe,[4] or a small cup size in a brassiere.
Character | A | a | ||
---|---|---|---|---|
Unicode name | LATIN CAPITAL LETTER A | LATIN SMALL LETTER A | ||
Encodings | decimal | hex | decimal | hex |
Unicode | 65 | U+0041 | 97 | U+0061 |
UTF-8 | 65 | 41 | 97 | 61 |
Numeric character reference | A | A | a | a |
EBCDIC family | 193 | C1 | 129 | 81 |
ASCII 1 | 65 | 41 | 97 | 61 |
NATO phonetic | Morse code |
Alpha | ·– |
Signal flag | Flag semaphore | Braille dots-1 |
Wikimedia Commons has media related to A. |
Look up A or a in Wiktionary, the free dictionary. |
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リンク元 | 「アミノ酸」「チミン」「アラニン」「alanyl」「alanine」 |
拡張検索 | 「PEMA症候群」 |
関連記事 | 「Ad」 |
分類 | 極性 | 電荷 | 名前 | 1 | 3 | 糖原性 | ケトン原性 | 必須アミノ酸 | 分枝アミノ酸 | pK1 α-COOH |
pK2 α-NH2 |
pKR 側鎖 |
側鎖 | |
疎水性アミノ酸 | 無 | 無 | グリシン | G | Gly | 2.35 | 9.78 | ―H | ||||||
無 | 無 | アラニン | A | Ala | 2.35 | 9.87 | ―CH3 | |||||||
無 | 無 | バリン | V | Val | ○ | ○ | 2.29 | 9.74 | ―CH(CH3)2 | |||||
無 | 無 | フェニルアラニン | F | Phe | ○ | ○ | ○3 | 2.2 | 9.31 | ―○C6H5 | ||||
無 | 無 | プロリン | P | Pro | 1.95 | 10.64 | αCとNH2の間に ―CH2CH2CH2- | |||||||
無 | 無 | メチオニン | M | Met | ○2 | 2.13 | 9.28 | ―CH2CH2-S-CH3 | ||||||
無 | 無 | イソロイシン | I | Ile | ○ | ○ | ○ | ○ | 2.32 | 9.76 | ―CH(CH3)CH2CH3 | |||
無 | 無 | ロイシン | L | Leu | ○ | ○ | ○ | 2.33 | 9.74 | ―CH2CH(CH3)2 | ||||
荷電アミノ酸 | 有 | 酸性 | アスパラギン酸 | D | Asp | 1.99 | 9.9 | 3.9 β-COOH |
―CH2COOH | |||||
有 | 酸性 | グルタミン酸 | E | Glu | 2.1 | 9.47 | 4.07 γ-COOH |
―CH2CH2COOH | ||||||
有 | 塩基性 | リシン | K | Lys | ○ | ○ | 2.16 | 9.06 | 10.54 ε-NH2 |
側鎖のCH2は4つ ―-CH2CH2CH2CH2NH2 | ||||
有 | 塩基性 | アルギニン | R | Arg | ○1 | 1.82 | 8.99 | 12.48 グアニジウム基 |
側鎖のCH2は3つ ―CH2CH2CH2-NH-C-(NH2)NH | |||||
極性アミノ酸 | 有 | 無 | セリン | S | Ser | 2.19 | 9.21 | ―CH2OH | ||||||
有 | 無 | スレオニン | T | Thr | ○ | ○ | ○ | 2.09 | 9.1 | ―CH(CH3)OH | ||||
有 | 無 | チロシン | Y | Tyh | ○ | ○ | 2.2 | 9.21 | 10.46 フェノール |
―CH2-φ | ||||
有 | 塩基性 | ヒスチジン | H | His | ○ | 1.8 | 9.33 | 6.04 イミダゾール基 |
―CH2-C3H3N2 | |||||
有 | 無 | システイン | C | Cys | 1.92 | 10.7 | 8.37 -SH基 |
―CH2-SH | ||||||
有 | 無 | アスパラギン | N | Asn | 2.14 | 8.72 | ―CH2-CO-NH2 | |||||||
有 | 無 | グルタミン | Q | Gln | 2.17 | 9.13 | ―CH2-CH2-CO-NH2 | |||||||
無 | 無 | トリプトファン | W | Trp | ○ | ○ | ○ | 2.46 | 9.41 | ―Indol ring | ||||
1 人体で合成できるが、不十分。 | ||||||||||||||
2 Cysが足らなければ、Metから合成することになる。 |
名称 | 基となるアミノ酸 | ||
修飾されたアミノ酸 | シスチン | システイン | システイン2分子が酸化されて生成する。 |
ヒドロキシプロリン | プロリン | ゼラチン、コラーゲンに含まれる。 | |
ヒドロキシリジン | リジン | ||
チロキシン | チロシン | 甲状腺タンパク質に含まれる。 | |
O-ホスホセリン | カゼインなど、多くのリンタンパク質に含まれる。 | ||
デスモシン | |||
蛋白質の構成要素ではない | オルニチン | アルギニン | ミトコンドリア中でカルバモイルリン酸と反応 |
シトルリン | オルニチン、カルバモイルリン酸 | ||
クレアチン | アルギニン、グリシン | ||
γアミノ酪酸 | アルギニン |
準必須 | ア | アルギニン |
必須 | メ | メチオニン |
フ | フェニルアラニン | |
リ | リジン | |
バ | valine | |
ス | スレオニン | |
ト | トリプトファン | |
ロ | ロイシン | |
イ | イソロイシン | |
準必須 | ヒ | ヒスチジン |
プリン塩基 | ピリミジン塩基 | |||||
塩基 | アデニン | グアニン | シトシン | チミン | ウラシル | |
Ade | Gua | Cyt | Thy | Ura | ||
A | G | C | T | U | ||
ヌクレオシド | アデノシン | グアノシン | シチジン | デオキシチミジン | ウリジン | |
Ado | Guo | Cyd | dThd | Urd | ||
A | G | C | dT | U | ||
ヌクレオチド | アデニル酸 | グアニル酸 | シチジル酸 | デオキシチミジル酸 | ウリジル酸 | |
アデノシン一リン酸 | グアノシン一リン酸 | シチジン一リン酸 | デオキシチミジン一リン酸 | ウリジン一リン酸 | ||
for DNA | dAMP | dGMP | dCMP | dTMP | ||
for RNA | AMP | GMP | CMP | UMP |
アラニル、アラニンの
.