Txhua yam kab mob nyob hauv peb lub ntiaj teb no txawv. Tsis yog tib neeg sib txawv ntawm ib leeg. Tsiaj txhu thiab cov nroj tsuag ntawm tib hom kuj muaj qhov sib txawv. Yog vim li cas rau qhov no tsis yog qhov txawv ntawm kev ua neej nyob thiab kev ua neej nyob. Tus kheej ntawm txhua yam kab mob tau muab tso rau hauv nws nrog kev pab ntawm cov khoom siv caj ces.
cov lus nug tseem ceeb thiab nthuav txog nucleic acids
Txawm tias ua ntej yug los, txhua yam kabmob muaj nws tus kheej cov noob caj noob ces, uas txiav txim siab tag nrho cov qauv tsim. Nws tsis yog xim ntawm lub tsho loj lossis cov duab ntawm nplooj, piv txwv li. Cov yam ntxwv tseem ceeb dua yog muab tso rau hauv cov noob. Tom qab tag nrho, hamster tsis tuaj yeem yug los rau miv, thiab baobab tsis tuaj yeem loj hlob los ntawm cov noob nplej.
Thiab nucleic acids - RNA thiab DNA molecules - yog lub luag haujlwm rau tag nrho cov ntaub ntawv loj no. Lawv qhov tseem ceeb yog qhov nyuaj heev rau overestimate. Tom qab tag nrho, lawv tsis tsuas yog khaws cov ntaub ntawv thoob plaws hauv lub neej, lawv pab kom paub nws nrog kev pab ntawm cov protein, thiab ntxiv rau qhov no, lawv dhau mus rau lwm tiam neeg. Lawv ua li cas, cov qauv ntawm DNA thiab RNA molecules complex yog dab tsi? Lawv zoo sib xws thiab lawv qhov txawv li cas? Hauv txhua qhov no pebthiab peb yuav txheeb xyuas nws hauv tshooj tom ntej ntawm tsab xov xwm.
Peb yuav tshuaj xyuas txhua cov ntaub ntawv ib ntus, pib nrog cov hauv paus ntsiab lus. Ua ntej, peb yuav kawm seb nucleic acids yog dab tsi, lawv nrhiav tau li cas, ces peb yuav tham txog lawv cov qauv thiab kev ua haujlwm. Thaum kawg ntawm tsab xov xwm, peb tab tom tos lub rooj sib piv ntawm RNA thiab DNA, uas koj tuaj yeem xa mus rau txhua lub sijhawm.
Nucleic acids yog dab tsi
Nucleic acids yog cov organic tebchaw uas muaj qhov hnyav molecular, yog polymers. Xyoo 1869 lawv tau piav qhia thawj zaug los ntawm Friedrich Miescher, tus kws kho mob Swiss biochemist. Nws cais cov khoom, uas suav nrog phosphorus thiab nitrogen, los ntawm cov kua qaub. Piv txwv tias nws nyob hauv lub nuclei nkaus xwb, tus kws tshawb fawb hu ua nws nuclein. Tab sis dab tsi tshwm sim tom qab kev sib cais ntawm cov proteins hu ua nucleic acid.
Nws cov monomers yog nucleotides. Lawv tus lej hauv cov kua qaub molecule yog tus kheej rau txhua hom. Nucleotides yog cov molecules ua los ntawm peb ntu:
- monosaccharide (pentose), tuaj yeem yog ob hom - ribose thiab deoxyribose;
- nitrogenous puag (ib ntawm plaub);
- phosphoric acid residue.
Tom ntej no, peb yuav saib qhov sib txawv thiab zoo sib xws ntawm DNA thiab RNA, cov lus nyob rau hauv kawg ntawm tsab xov xwm yuav xaus.
qauv nta: pentoses
thawj qhov zoo sib xws ntawm DNA thiab RNA yog tias lawv muaj monosaccharides. Tab sis rau txhua tus acid lawv txawv. Nyob ntawm seb pentose nyob rau hauv lub molecule, nucleic acids muab faib ua DNA thiab RNA. DNA muaj deoxyribose, thaum RNA muajribose. Ob lub pentoses tshwm sim hauv cov kua qaub nkaus xwb hauv β-form.
Deoxyribose tsis muaj oxygen ntawm lub thib ob carbon atom (suav nrog 2 '). Cov kws tshawb fawb qhia tias nws tsis tuaj:
- shortens the link between C23;
- ua rau DNA molecule muaj zog;
- tsim cov xwm txheej rau kev cog lus DNA ntim rau hauv lub nucleus.
Tsim kev sib piv: Nitrogenous Bases
Kev sib piv tus yam ntxwv ntawm DNA thiab RNA tsis yooj yim. Tab sis qhov sib txawv yog pom los ntawm qhov pib. Nitrogenous bases yog lub tsev tseem ceeb tshaj plaws hauv peb cov molecules. Lawv nqa cov ntaub ntawv ntawm caj ces. Ntau precisely, tsis yog lub hauv paus lawv tus kheej, tab sis lawv cov kev txiav txim nyob rau hauv cov saw. Lawv yog purine thiab pyrimidine.
Cov muaj pes tsawg leeg ntawm DNA thiab RNA sib txawv nyob rau theem ntawm monomers: hauv deoxyribonucleic acid peb tuaj yeem pom adenine, guanine, cytosine thiab thymine. Tab sis RNA muaj uracil hloov thymine.
tsib lub hauv paus no yog lub ntsiab (qhov tseem ceeb), lawv ua rau feem ntau ntawm cov nucleic acids. Tab sis dhau ntawm lawv, muaj lwm tus. Qhov no tshwm sim tsis tshua muaj, xws li hauv paus hu ua me. Ob leeg pom nyob rau hauv ob qho tib si acids - qhov no yog lwm qhov zoo sib xws ntawm DNA thiab RNA.
Qhov sib lawv liag ntawm cov nitrogenous hauv paus (thiab, raws li, nucleotides) hauv DNA saws txiav txim siab cov proteins uas muab lub xovtooj sib txuas tuaj yeem ua ke. Cov molecules twg yuav raug tsim nyob rau ib lub sijhawm yog nyob ntawm qhov xav tau ntawm lub cev.
mus rautheem ntawm lub koom haum ntawm nucleic acids. Txhawm rau kom qhov sib piv cov yam ntxwv ntawm DNA thiab RNA ua tiav thiab lub hom phiaj raws li qhov ua tau, peb yuav xav txog cov qauv ntawm txhua tus. DNA muaj plaub ntawm lawv, thiab tus naj npawb ntawm cov koom haum hauv RNA nyob ntawm nws hom.
Tshawb nrhiav cov qauv ntawm DNA, cov qauv ntawm cov qauv
Txhua yam kab mob tau muab faib ua prokaryotes thiab eukaryotes. Qhov kev faib tawm no yog nyob ntawm tus qauv tsim ntawm lub hauv paus. Ob leeg muaj DNA nyob rau hauv lub cell nyob rau hauv daim ntawv ntawm chromosomes. Cov no yog cov qauv tshwj xeeb uas deoxyribonucleic acid molecules txuam nrog cov proteins. DNA muaj plaub theem ntawm lub koom haum.
Cov qauv tseem ceeb yog sawv cev los ntawm cov saw hlau ntawm nucleotides, cov kab ke uas tau ua nruj me ntsis rau txhua tus kab mob thiab uas cuam tshuam los ntawm phosphodiester bonds. Kev vam meej loj hauv kev kawm txog DNA strand qauv tau ua tiav los ntawm Chargaff thiab nws cov neeg koom tes. Lawv txiav txim siab tias qhov sib piv ntawm cov hauv paus nitrogen ua raws qee txoj cai.
Lawv hu ua Chargaff cov cai. Thawj ntawm cov no hais tias cov lej ntawm cov purine hauv paus yuav tsum sib npaug rau cov lej ntawm cov pyrimidines. Qhov no yuav paub meej tom qab tau paub txog cov qauv thib ob ntawm DNA. Txoj cai thib ob ua raws li nws cov yam ntxwv: cov molar ratios A / T thiab G / C yog sib npaug rau ib qho. Tib txoj cai muaj tseeb rau qhov thib ob nucleic acid - qhov no yog lwm qhov zoo sib xws ntawm DNA thiab RNA. Tsuas yog qhov thib ob muaj uracil es tsis txhob thymine nyob txhua qhov chaw.
Tsis tas li, ntau tus kws tshawb fawb tau pib faib DNA ntawm ntau hom tsiaj raws li ntau lub hauv paus. Yog tias tus lej yog "A + T"ntau tshaj "G + C", xws li DNA hu ua AT-type. Yog tias nws yog lwm txoj hauv kev, peb tab tom cuam tshuam nrog GC hom DNA.
Tus qauv qauv thib ob tau npaj rau xyoo 1953 los ntawm cov kws tshawb fawb Watson thiab Crick, thiab nws tseem tau lees paub niaj hnub no. Tus qauv yog ob lub helix, uas muaj ob txoj hlua sib txuas. Cov yam ntxwv tseem ceeb ntawm cov qauv theem nrab yog:
- qhov muaj pes tsawg leeg ntawm txhua DNA strand yog nruj me ntsis rau cov hom;
- daim ntawv cog lus ntawm cov chains yog hydrogen, tsim raws li lub hauv paus ntsiab lus ntawm complementarity ntawm nitrogenous bases;
- polynucleotide chains qhwv ib ncig, tsim ib sab tes xis hu ua "helix";
- phosphoric acid residues nyob sab nraum lub helix, nitrogenous bases nyob rau hauv.
Ntawm, denser, nyuaj
Cov qauv tertiary ntawm DNA yog cov qauv supercoiled. Ntawd yog, tsis tsuas yog ua ob txoj hlua sib tw nrog ib leeg hauv ib lub molecule, rau kev sib cog lus ntau dua, DNA raug mob nyob ib ncig ntawm cov proteins tshwj xeeb - histones. Lawv muab faib ua tsib chav nyob ntawm cov ntsiab lus ntawm lysine thiab arginine hauv lawv.
Qib kawg ntawm DNA yog chromosome. Txhawm rau kom nkag siab tias cov ntaub ntawv caj dab nruj npaum li cas tau ntim rau hauv nws, xav txog cov hauv qab no: yog tias Eiffel Ntauwd tau dhau los ntawm txhua theem ntawm kev sib cog lus, zoo li DNA, nws tuaj yeem muab tso rau hauv lub thawv sib tw.
Chromosomes yog ib leeg (muaj ib chromatid) thiab ob (muaj ob chromatids). Lawv muab kev ruaj ntseg ciaCov ntaub ntawv caj ces, thiab yog tias tsim nyog, lawv tuaj yeem tig thiab qhib nkag mus rau thaj chaw uas xav tau.
Hom RNA, yam ntxwv nta
Ntxiv rau qhov tseeb tias txhua RNA txawv ntawm DNA hauv nws cov qauv tseem ceeb (tsis muaj thymine, muaj uracil), cov qib hauv qab no kuj txawv:
- Transfer RNA (tRNA) yog ib qho molecule ib leeg. Txhawm rau ua kom tiav nws txoj haujlwm ntawm kev thauj cov amino acids mus rau qhov chaw ntawm cov protein synthesis, nws muaj cov qauv sib txawv heev. Nws hu ua "cloverleaf". Txhua qhov ntawm nws cov voj voog ua nws txoj haujlwm, tab sis qhov tseem ceeb tshaj plaws yog cov qia txais (ib qho amino acid clings rau nws) thiab anticodon (uas yuav tsum phim lub codon ntawm tub txib RNA). Lub tertiary qauv ntawm tRNA tau kawm me ntsis, vim hais tias nws yog ib qho nyuaj heev rau cais xws li ib tug molecule yam tsis muaj kev cuam tshuam rau theem siab ntawm lub koom haum. Tab sis cov kws tshawb fawb muaj qee cov ntaub ntawv. Piv txwv li, nyob rau hauv poov xab, hloov RNA yog zoo li tus ntawv L.
- Messenger RNA (tseem hu ua cov ntaub ntawv xov xwm) ua haujlwm ntawm kev xa cov ntaub ntawv los ntawm DNA mus rau qhov chaw ntawm cov protein synthesis. Nws qhia tias hom protein twg yuav tig tawm thaum kawg, ribosomes txav raws nws hauv cov txheej txheem ntawm kev sib txuas. Nws lub hauv paus qauv yog ib leeg-stranded molecule. Cov txheej txheem thib ob yog qhov nyuaj heev, tsim nyog rau kev txiav txim siab ntawm qhov pib ntawm cov protein synthesis. mRNA yog folded nyob rau hauv daim ntawv ntawm hairpins, nyob rau hauv lub kawg ntawm uas muaj qhov chaw rau pib thiab xaus ntawm protein ua.
- Ribosomal RNA muaj nyob hauv ribosomes. Cov organelles muaj ob lub subparticles, txhua tus ntawm cov uashosts nws tus kheej rRNA. Qhov no nucleic acid txiav txim qhov chaw ntawm tag nrho cov ribosomal proteins thiab chaw ua hauj lwm ntawm lub organelle. Lub hauv paus qauv ntawm rRNA yog sawv cev los ntawm ib theem ntawm nucleotides, raws li nyob rau hauv yav dhau los ntau yam ntawm acid. Nws paub tias theem kawg ntawm rRNA folding yog kev sib koom ua ke ntawm lub davhlau ya nyob twg ntawm ib txoj hlua. Kev tsim ntawm cov petioles no ua rau muaj txiaj ntsig ntxiv rau kev cog qoob loo ntawm tag nrho cov qauv.
DNA ua haujlwm
Deoxyribonucleic acid ua raws li cov ntaub ntawv ntawm caj ces. Nws yog nyob rau hauv ib theem ntawm nws cov nucleotides uas tag nrho cov proteins ntawm peb lub cev yog "pob ntseg". Hauv DNA, lawv tsis tsuas yog khaws cia, tab sis kuj muaj kev tiv thaiv zoo. Thiab txawm tias muaj qhov yuam kev tshwm sim thaum luam tawm, nws yuav raug kho. Yog li, txhua yam khoom siv caj ces yuav raug khaws cia thiab yuav ncav cuag cov xeeb ntxwv.
Yuav xa cov ntaub ntawv mus rau cov xeeb leej xeeb ntxwv, DNA muaj peev xwm ua ob npaug. Cov txheej txheem no hu ua replication. Ib lub rooj sib piv ntawm RNA thiab DNA yuav qhia peb tias lwm cov nucleic acid tsis tuaj yeem ua qhov no. Tab sis nws muaj ntau yam haujlwm.
RNA Functions
Txhua hom RNA muaj nws tus kheej ua haujlwm:
- Kev thauj ribonucleic acid xa cov amino acids rau ribosomes, uas lawv tau ua rau cov protein. tRNA tsis tsuas yog nqa cov khoom siv hauv tsev, nws tseem koom nrog kev paub txog codon. Thiab yuav ua li cas cov protein kom raug yog nyob ntawm nws txoj haujlwm.
- Xov RNA nyeem cov ntaub ntawv los ntawmDNA thiab nqa nws mus rau qhov chaw ntawm cov protein synthesis. Nyob ntawd nws txuas rau ribosome thiab dictates qhov kev txiav txim ntawm cov amino acids nyob rau hauv cov protein.
- Ribosomal RNA ua kom muaj kev ncaj ncees ntawm cov qauv ntawm lub cev, tswj kev ua haujlwm ntawm txhua qhov chaw ua haujlwm.
Ntawm no yog lwm qhov zoo sib xws ntawm DNA thiab RNA: lawv ob leeg saib xyuas cov ntaub ntawv caj ces uas lub cell nqa.
Sib piv DNA thiab RNA
Yuav npaj txhua cov ntaub ntawv saum toj no, cia peb sau tag nrho rau hauv ib lub rooj.
| DNA | RNA | |
| Cage qhov chaw | Nucleus, chloroplasts, mitochondria | Nucleus, chloroplasts, mitochondria, ribosomes, cytoplasm |
| Monomer | Deoxyribonucleotides | Ribonucleotides |
| qauv | ob-kab helix | Ib txoj saw |
| Nucleotides | A, T, G, C | A, U, G, C |
| Ntse | ruaj khov, muaj peev xwm rov ua dua | Labile, ua tsis tau ob npaug |
| Functions | Kev khaws cia thiab xa cov ntaub ntawv genetic | Hloov cov ntaub ntawv keeb kwm yav dhau los (mRNA), kev ua haujlwm (rRNA, mitochondrial RNA), kev koom tes hauv kev tsim cov protein (mRNA, tRNA, rRNA) |
Yog li, peb tau tham luv luv txog qhov zoo sib xws ntawm DNA thiab RNA. Lub rooj yuav yog tus pab cuam uas tsis tseem ceeb hauv kev xeem lossis kev ceeb toom yooj yim.
Ntxiv rau qhov peb tau kawm dhau los, ntau qhov tseeb tshwm sim hauv lub rooj. Piv txwv li, muaj peev xwm ntawm DNAduplication yog tsim nyog rau kev faib cell kom ob lub hlwb tau txais cov khoom siv caj ces raug tag nrho. Thaum rau RNA, ob npaug ua rau tsis muaj kev nkag siab. Yog hais tias ib lub cell xav tau lwm molecule, nws synthesizes nws los ntawm DNA template.
Cov yam ntxwv ntawm DNA thiab RNA tau dhau los ua luv luv, tab sis peb tau hais txog txhua yam ntawm cov qauv thiab kev ua haujlwm. Cov txheej txheem ntawm kev txhais lus - protein synthesis - yog qhov nthuav heev. Tom qab paub txog nws, nws paub meej tias lub luag haujlwm RNA loj npaum li cas hauv lub neej ntawm lub xovtooj. Thiab cov txheej txheem ntawm DNA duplication yog qhov zoo siab heev. Dab tsi tsim nyog rhuav tshem ob lub helix thiab nyeem txhua nucleotide!
Kawm yam tshiab txhua hnub. Tshwj xeeb yog tias qhov tshiab no tshwm sim hauv txhua lub cell ntawm koj lub cev.
