心智圖資源庫 核酸化學
這是一篇關於核酸化學的心智圖,主要內容包括:核酸理化性質,核酸分子組成與結構。希望可以對大家有幫助。
編輯於2024-03-16 21:21:18This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
核酸化學
核酸分子組成與結構
元素組成
C、H、O、N、P
基本結構
磷酸
五碳糖(均為β-D構型)
脫氧核糖(DNA,β-D-2-脫氧核糖)
核糖(RNA,β-D-核糖)
鹼基
嘧啶鹼
胞嘧啶(C)、尿嘧啶(U)、胸腺嘧啶(T)
嘌呤鹼
腺嘌呤(A)、鳥嘌呤(G)
稀有鹼基
核苷
DNA(脫氧腺苷、脫氧鳥苷·····)
RNA(腺嘌呤核苷、尿嘧啶核苷······)
核苷酸
分子結構
核酸一級結構(稱鹼基序列)
核苷酸間相連接的鍵:3',5'-磷酸二酯鍵
核酸鏈具有方向性,5'~3'端;5'端有遊離磷酸基,3'端有遊離羥基
DNA空間結構
二級結構(兩條反向平行的多鏈核苷酸,繞同一中心軸所構成的雙螺旋結構)
右手螺旋
兩條鏈鹼基互補配對
鹼基堆積力維繫縱向穩定,氫鍵維繫橫向穩定
特點
三級結構(雙螺旋二級結構基礎上,盤旋形成超螺旋結構)
正超螺旋(與雙螺旋方向相同)
負超螺旋(與雙螺旋方向相反)
RNA種類及結構
信使RNA(mRNA)
含量少,是合成蛋白質的模板
真核細胞mRNA5'端有7-甲基鳥嘌呤核苷三磷酸結構(7-甲基鳥苷)稱為帽結構;原核生物mRNA無帽結構
真核細胞mRNA3'端有一段長約200個鹼基的多腺苷酸[poly(A)]尾;原核生物一般沒有
特徵
轉運RNA(tRNA)
一級結構
二級結構(呈三葉草式)
三級結構(呈倒L型)
核醣體RNA(rRNA)
主要RNA,存在於核醣體,細胞內蛋白質生物合成的場所,核醣體由大亞基和小亞基組成
核酸理化性質
一般性質(分子大小、溶解度、黏度、酸鹼度),其中DNA在PH4~11最穩定,此範圍外DNA變性
紫外線吸收
260nm
增色效應:變性後,DNA在260nm處吸光度顯著增加
減色效應:複性後吸光度恢復原值
可作為變性、複性指標
變性、複性
熱變性(該過程是躍變過程)
喪失半數雙螺旋結構的溫度稱解鏈溫度,即Tm;DNA的Tm值一般在70~85℃;同時數值與G C比例相關,比例越高,數值越高
冷複性(需緩慢冷卻至4℃,才可複性)
破壞鹼基堆積力和氫鍵,空間結構改變,一級結構不變
主要為單股結構,局部可捲曲形成鏈內雙股螺旋結構,即發卡結構
使二級結構處於松纏狀態,利於DNA複製、轉錄、基因重組
使結構分子更加穩定
相鄰鹼基對平面產生的疏水性的鹼基堆積力
AT間兩氫鍵,GC之間三氫鍵
基本結構(A-P~P~P稱NTP/dNTP),其中A-P稱NMP/dNMP;A-P~P稱NDP/dNDP;~稱高能量磷酸鍵
戊糖與鹼基相連鍵稱N-糖苷鍵;此鍵有兩種構型(α、β),核酸分子中皆為β-糖苷鍵
P的含量較穩定,9%~10%