Qhov Tseem Ceeb Qhov txawv - Histones vs Nucleosomes
Nws kwv yees tias tib neeg lub cev muaj kwv yees li 50 trillion hlwb. Hauv txhua lub cell, muaj genome uas muaj 46 chromosomes. Cov 46 chromosomes no muaj kwv yees li 6 billion base khub ntawm DNA ntim. Qhov ntev ntawm ob lub hauv paus yog kwv yees li 0.3 nm, thiab tag nrho qhov ntev ntawm DNA hauv 46 chromosomes account 2 meters kwv yees. Thaum xam tag nrho qhov ntev ntawm DNA hauv tib neeg lub cev, nws yog 100 trillion meters ntawm DNA. Qhov ntev tag nrho ntawm chromosomal DNA no zoo ntim rau hauv lub nucleus los ntawm cov protein tshwj xeeb hu ua histones. Cov DNA thiab histone complexes yog hu ua chromatin fiber. Histone proteins muab lub zog rau folding los yog coiling DNA thiab ntim lawv nruj nreem nyob rau hauv lub nucleus. DNA ntim yog txheej txheem tseem ceeb hauv eukaryotes, thiab nws yooj yim rau kev pab ntawm tag nrho cov DNA ntev nyob rau hauv lub cell nucleus. Lub hauv paus ntawm DNA ntim nrog histone proteins yog hu ua nucleosome. Qhov sib txawv tseem ceeb ntawm histones thiab nucleosomes yog tias histones yog cov proteins uas ntim thiab txiav txim rau DNA rau hauv nucleosomes thaum nucleosomes yog lub hauv paus ntawm DNA ntim.
Histones yog dab tsi?
Histone proteins raug txheeb xyuas tias yog cov protein tseem ceeb ntawm chromatin fiber. Lawv yog cov alkaline proteins. Cov proteins no muab lub zog thiab cov qauv tseem ceeb rau cua DNA thiab txo nws qhov ntev thaum lub sij hawm DNA ntim rau hauv lub nucleus. Lawv feem ntau ua raws li cov spools uas DNA cua thiab stabilizes. Yog li ntawd, histone proteins yog qhov tseem ceeb heev hauv kev teeb tsa chromosomes thiab ntim cov khoom siv caj ces hauv lub nucleus. Yog tias tsis muaj cov proteins histone, chromosomes yuav tsis muaj nyob thiab tsis muaj DNA yuav ncab mus rau qhov ntev ua rau lawv nyuaj rau nrhiav tau hauv cov nucleus.
Histone cov proteins ua haujlwm ua ke nrog cov proteins uas tsis yog-histone kom ruaj khov DNA. Yog li ntawd, lub xub ntiag ntawm nonhistone proteins yog qhov tseem ceeb heev rau kev ua haujlwm ntawm histones. Histone proteins dhau los ua cov tseem ceeb ntawm cov protein molecules los tsim cov nucleosomes uas yog ib feem ntawm chromatin. Muaj 8 histone proteins hauv ib nucleosome. DNA coils ob peb zaug nyob ib ncig ntawm histone core octomer thiab stabilize nws.
Daim duab 01: Histones
Thiab kuj muaj cov proteins histone koom nrog hauv kev tswj cov noob. Lawv pab tswj gene qhia. Histone proteins tau txais txiaj ntsig zoo hauv cov tsiaj, tsis zoo li cov proteins uas tsis yog tshuaj.
Nucleosomes yog dab tsi?
A nucleosome yog lub hauv paus txheej txheem ntawm DNA ntim. Nws zoo li cov hlaws dai hauv ib txoj hlua. Nws muaj ib qho DNA tawg nyob ib ncig ntawm histone proteins teem nyob rau hauv ib tug core histone protein. Core histone protein yog octamer uas muaj yim histone proteins. 8 histone proteins uas nyob rau hauv lub octomer yog plaub hom xws li H2A, H2B, H3, thiab H4. Los ntawm txhua hom, ob qho protein molecules tau muab tso rau hauv nucleosome. Core DNA nruj nreem qhwv ib ncig ntawm lub globular core histone octamer thiab ua rau ib tug nucleosome. Nucleosomes tau muab tso rau hauv cov saw zoo li cov qauv thiab qhwv ib ncig ntawm cov proteins histone ntxiv kom nruj kom cov chromatin ruaj khov hauv chromosomes.
Daim duab 02: Nucleosome
Qhov ntev ntawm cov tub ntxhais DNA strand uas qhwv ib ncig ntawm histone octamer hauv nucleosome yog kwv yees li 146 lub hauv paus khub. Kwv yees txoj kab uas hla ntawm nucleosome yog 11 nm, thiab kauv ntawm nucleosomes hauv chromatin (solenoid) muaj txoj kab uas hla ntawm 30 nm. Nucleosomes tau txais kev txhawb nqa los ntawm cov proteins histone ntxiv los ntim rau hauv cov qauv nruj nruj hauv cov nucleus.
Dab tsi yog qhov zoo sib xws ntawm Histones thiab Nucleosomes?
- Ob leeg histones thiab nucleosomes cuam tshuam nrog DNA ntim.
- Ob leeg histones thiab nucleosomes yog qhov tseem ceeb rau genome stability.
- Ob leeg histones thiab nucleosomes yog cov khoom ntawm chromatin.
- Ob leeg histones thiab nucleosomes muaj nyob rau hauv lub nucleus ntawm eukaryotes.
Qhov txawv ntawm Histones thiab Nucleosomes yog dab tsi?
Histons vs Nucleosomes |
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| Histones yog cov proteins tseem ceeb uas muab lub zog thiab cov txheej txheem nto rau cua DNA nyob ib puag ncig lawv. | Nucleosomes yog lub hauv paus units ntawm DNA ntim. |
| Histones yog alkaline proteins. | Nucleosomes yog tsim los ntawm histone proteins, ntu DNA thiab lwm yam kev txhawb nqa proteins. |
Summary – Histones vs Nucleosomes
DNA ntim yog txheej txheem tseem ceeb hauv cov kab mob eukaryotic. Nws tso cai rau DNA kom haum rau hauv lub nucleus yam tsis tau ncab thiab raug rau hauv kev tawg thiab poob. DNA ntim yog txhawb los ntawm cov proteins hu ua histones. Cov proteins histone no ua raws li cov protein tseem ceeb ntawm cov chav hauv paus ntawm DNA ntim thiab muaj plaub yam tseem ceeb. Chav tsev tseem ceeb ntawm DNA ntim yog hu ua nucleosome. Nucleosome yog tsim los ntawm ib ntu ntawm DNA qhwv ib ncig ntawm ib qho tseem ceeb histone protein. Nws zoo li cov hlaws dai hauv ib txoj hlua. Nucleosomes sib sau ua cov qauv ntawm chromatin fiber. Qhov no yog qhov txawv ntawm histones thiab nucleosomes.
Download the PDF of Histones vs Nucleosomes
Koj tuaj yeem rub tawm PDF version ntawm kab lus no thiab siv nws rau offline hom phiaj raws li daim ntawv ceeb toom. Thov rub tawm PDF version ntawm no: Qhov txawv Ntawm Histones thiab Nucleosomes
