I- choose the correct answer :
1- In D.P.A reaction :
a- only the ribose of purine nucleotide is react with D.P.A
b- only the deoxyribose of purine nucleotide is react with D.P.A
c- is a specific reaction for DNA estimation .
d- is general and not specific for DNA and can be used for RNA estimation .
2- In RNA extraction :
a- phenol and ethanol are used to precipitate RNA .
b- potassium acetate and ethanol are used to precipitate the RNA
c- the RNA is in the lower layer after the second centrifugation, then
precipitated by ethanol .
d- the RNA is in the lower layer after the first centrifugation .
3- In Orcinol reaction :
a- give green color when react with RNA .
b- orcinol react with furfural in the presence of ferric chloride .
c- furfural is formed by heating pentose with hydrochloric acid .
d- all of the above .
4- In DNA extraction from spleen :
a- sodium chloride inhibits deoxyribonuclease activity by binding with Ca2+ and Mg2+ which are cofactors for this enzyme .
b- sodium citrate inhibits deoxyribonuclease activity by chelating Ca2+ and Mg2+ which are cofactors for this enzyme .
c- sodium chloride inhibits DNAse activity by binding with Ca2+ and Mg2+ which are cofactors for this enzyme .
d- sodium hydroxide inhibits deoxyribonuclease activity by binding with Ca2+ and Mg2+ which are cofactors for this enzyme .
II- Put ü or û :
1- Folin test is used for protein estimation and give a green color ( )
2- DNA is precipitated as a viscous mass of white fibers ( )
3- Spleen is a good source for DNA isolation and has a large amount of DNA and high deoxyribnuclease activity ( )
4- The last step in DNA extraction is the washing by different solution to remove excess salts ( )
answers :