MOLEKULARNA BIOLOGIJA-HITNO

Treba mi pomoc oko sledecih zadataka... POTREBNA POSTAVKA
HVALA U NAPRED

1)U populaciji koja je u ravnotezi gde je ucestalost dominantnih alela 2x veca od ucestalosti recesivnog alela, ucestalost dominantnih homozigota je...?!
2)Kada se ucestalost dominantnog alela sa 10% poveca na 20% ucestalost heterozigota u populacije se kako menja?!
3)Fenotipski normalni roditelji cije je prvo dete bilo albino dobili su fenotipski normalno dete. Kolika je verovatnoca da ono nije prenosilac gena za albinizam?
4)Koliko ce tipova gameta formirati jedinka genotipa AaBbCCDd kod tetrahibridnog nasledjivanja?
5) Koloka je verovatnoca nalazenja dominantnog homozigota na oba genska lokusa pri dihibridnom ukrstanju 2 heterozigotne osobe genotipa AaBb?

Pozdrav! Evo ja ti neke resih...
1. p=2q
p^2(tj. p na kvadrat)= ucestalost dominantnih homozigota
p^2=4q^2
p+q=1
2q+q=1
q=1/3
p^2=4q^2

2. I slucaj p=10%=0.1 2pq=ucestalost heterozigota 2pq=2p(1-p)
II slucaj p=0.2 2pq=2p(1-p)

3. Roditelji su nosioci jer imaju albino dete Aa* Aa=> AA Aa Aa aa
Moguci genotipovi zdravog deteta su AA Aa Aa verovatnoca da nije nosilac je kao sto vidis 1/3
4. uf kombinacije...Punnetov kvadrat crtkas dosta ili ako matematicari nadju bolji nacin preko kombinacija..
5.Punnet kvadrat moguci gameti AB,Ab,aB,ab..... AaBb*AaBb=> AABB 1/16

Izvini ako ima neka greska...III sam gimnazije(long story)



zami'87.

Hvaaaalllllllllaaaaaaaaaaaa....... puunnnnooooooooooooooooo

sitnica

znam da mi je receno da ne pitam ali zastos i 3. godina a ne 4.??

pao sam zbog zdravstvenih razloga

Zami:

pao sam zbog zdravstvenih razloga

Kliknite za proširenje...

O pa to je ok
Vazno je da si ti pametna pcelica

PcelicaMaja20:

O pa to je ok
Vazno je da si ti pametna pcelica

Kliknite za proširenje...

hvala.sad mi ego +100

a little gift-21. aminokiselina

Selenocysteine is an amino acid that is present in several enzymes (for example glutathione peroxidases, tetraiodothyronine 5' deiodinases, thioredoxin reductases, formate dehydrogenases, glycine reductases and some hydrogenases). Selenocysteine has a structure similar to cysteine, but with an atom of selenium taking the place of the usual sulfur. Proteins that include a selenocysteine residue are called selenoproteins.

Unlike other amino acids present in biological proteins, however, it is not coded for directly in the genetic code. Selenocysteine is encoded in a special way by a UGA codon, which is normally a stop codon. The UGA codon is made to encode selenocysteine by the presence of a SECIS element (SElenoCysteine Insertion Sequence) in the mRNA. The SECIS element is defined by characteristic nucleotide sequences and secondary structure base-pairing patterns. In eubacteria, the SECIS element is located immediately following the UGA codon within the reading frame for the selenoprotein. In archaea and in eukaryotes, the SECIS element is in the 3' untranslated region (3' UTR) of the mRNA, and can direct multiple UGA codons to encode selenocysteine residues. When cells are grown in the absence of selenium, translation of selenoproteins terminates at the UGA codon, resulting in a truncated, nonfunctional enzyme.

Like the other amino acids used by cells, selenocysteine has a specialized tRNA. The primary and secondary structure of selenocysteine tRNA, tRNA(Sec), differ from those of standard tRNAs in several respects, most notably in having an 8-base (bacteria) or 9-base (eukaryotes) pair acceptor stem, a long variable region arm, and substitutions at several well-conserved base positions. The selenocysteine tRNAs are initially charged with serine by seryl-tRNA ligase, but the resulting Ser-tRNA(Sec) is not used for translation because it is not recognised by the normal translation factor (EF-Tu in bacteria, EF1alpha in eukaryotes). Rather, the tRNA-bound seryl residue is converted to a selenocysteyl-residue by the pyridoxal phosphate-containing enzyme selenocysteine synthase. Finally, the resulting Sec-tRNA(Sec) is specifically bound to an alternative translational elongation factor (SelB or mSelB) which delivers it in a targeted manner to the ribosomes translating mRNAs for selenoproteins. The specificity of this delivery mechanism is brought about by the presence of an extra protein domain (in bacterial SelB) or an extra subunit (SBP-2 for eukaryotic mSelB) which bind to the corresponding RNA secondary structures formed by the SecIS elements in selenoprotein mRNAs. The SecIS elements of bacterial selenoproteins (as far as analysed) are located within the coding sequences immediately following the UGA codons for selenocysteine, those of Eukarya and Archaea are located in the 3' UTR of the respective mRNAs. In addition, at least one case has been described for an archaeal selenoprotein mRNA containing its SecIS in the 5' UTR.