Nucleic Acids lab Flashcards
what are the 2 basic structural forms of nucleic acids?
- DNA
- RNA
Which among the two structural forms of nucleic acids provides a template for the transcription of another?
DNA
also the genetic material (of a cell, or an organism duh malamang)
Which among the two structural forms of nucleic acids are carriers of genetic information for protein translation?
RNA
Components of a nucleotide?
- Pentose
- Heterocyclic Nitrogen bases
- Phosphate group
Nucleic acids are comprised of 2 sugar types, what are they?
- 2-deoxy-D-ribose
- D-ribose
furan din daw 1 type idk why
the heterocyclic bases are attached to the sugar component by bonds called?
glycosidic bonds
The Carbon-1 of the sugar component attaches to the N-what of the nitrogenous bases?
“N-what” is nitrogen # what in its heterocyclic structure
- Purines = N-9
- Pyrimidines = N-1
The glycosidic bonds of purine bases are more susceptible to acid hydrolysis because of ____.
greater dipositivity
Purines are nitrogenous bases that are fused with what ring?
what do u call the 2nd ring?
imidazole ring
https://sciencenotes.org/purines-and-pyrimidines/
The phosphate group is attached to C-what of the sugar component?
C-5
carbon #5
what component of the nucleic acid accounts for its acidic and anionic (negative) character?
phosphate
when phosphoric acid forms a ____ bond with a nucleoside, the result is a compound known as a nucleotide.
phosphate ester bond
A phosphoester bond occurs when the hydroxyl groups in phosphoric acid react with hydroxyl groups on other molecules to form an ester bonds. eh
The first phosphate group in ATP is connected via ester bond w/ the C-5 of the pentose and then the other two phosphate grps are joined together with ____ bonds.
phosphate anhydride bonds
the sugar-phosphate linkages forms the ____ of the nucleic acid with the 5’ end of one sugar molecule linked to the 3’ end of the adjacent sugar.
backbone
symmetrical backbone
What do you call the bonds that links nucleotides in the polynucleotide chain?
phosphodiester bonds
a phosphodiester bond occurs when* two of the hydroxyl groups in phosphoric acid react with hydroxyl groups on other molecules* to form two ester bonds. eh
what do you call the bonds involved in the complementary base pairing in nucleic acids?
Hydrogen bonds
These are the bonds involved in pi-pi complexation and results in base stacking of nucleic acids. What do u call these bonds?
Van der Waal’s forces
or LDF (London Dispersion Forces)
What do u call the process of DNA purification from a sample using a combination of physical and chemical methods wherein the aim is to separate the DNA present in the nucleus of its cell from other cell components?
DNA Isolation
DNA Isolation is dependent on what factors of the sample?
2 lang cla (or tatlo maybe)
- source
- age & size
Nucleic acids are major components of cells. It comprises ____ to ____% of the cell’s dry weight
bakit walang wet weight? :<
5-15%
DNA Applications include ____ & ____, among others.
2 applis given sa ppt?
- Paternity testing
- Forensics
The presence of other components (proteins, lipids, etc.) may ____ DNA analysis methods and will ____ the quality of DNA leading to its shorter storage life.
interfere; reduce
In comparison to DNA, RNA is a single-stranded molecule and has the presence of a hydroxyl grp at C2, this makes RNA ____ stable.
more or less
less stable
What are the 4 factors to consider in nucleic acid isolation?
- DNA & RNA content
- DNAse & RNAse activity
- Large size & fragile nature of DNA (Intact vs Sheared)
- Stability between RNA & DNA
What are the experimental factors affecting DNA isolation?
i think no need to memo, just be familiar
- pH extremes
- Temperature
- Ionic strength
- Cellular conditions
- Mechanical stress
- DNA/RNA storage
Hydrogen bonding between complementary strands is stable between pH 4 and pH 10. Therefore, DNA is hydrolyzed at pH what?
< 3 or > 12
hydrolyzed at pH less than 3 or greater than 12
Most DNA strands begin to unwind inwhat temperature range?
80-90oC
Phosphodiester bonds and glycosidic bonds are stable up to ____oC.
100oC
DNA is most stable and soluble in ____ salt concentrations and insoluble in ____ salt concentrations.
higher or lower
higher; lower
higher salt = more stable & soluble
lower salt = less soluble
Under cellular conditions, the lysis or disruption of the biological membrane releases DNA when the tissue is ____.
homogenized
presence of nucleases also affects cellular conditions
Mechanical stress may cause cleavage (shearing or scission) of the DNA chains that does not damage DNA 2ndary structure but ____ DNA length.
increases or reduces
reduces
2o structure = ordered arrangement of nucleic acid strands
Purified DNA is best kept in solution, why?
because precipitated DNA is kept dry
The general steps in DNA Isolation include:
- Homogenization
- Dissociation & denaturation of nucleoprotein
- Precipitation
- Purification of nucleic acid
Homogenization, which involves the process of lysis or disruption of biological membranes has two types namely:
- Mechanical
- Chemical
- mech = mincing, grinding, etc.
- chem = detergents, chaotropic agents
The addition of shampoo contains EDTA, which removes ____ ions, making it an essential component for the preservation of the overall structure of the cell membrane
Mg2+
The addition of salt precipitates nucleoproteins and the process is called what?
salting out
actually, sabi kanina higher salt higher solubility but ill ask sir ian abt this xtra ref
The addition of chilled alcohol ____ nuclease activity.
hastens or slows down
slows down
nuclease not on its optimum temp ata hehehehe
The addition of chilled alcohol precipitates ____ only because of polarity.
DNA
DNA is less polar than RNA (RNA has presence of hydroxyl on C2, ryt?)
The absorbance of nucleic acids are measured at what nanometers?
- 260 nm
- 280 nm
- 230 nm
The lambda max of nucleic acids are at what nm?
260 nm
this is due to bcoz of:
- aromatic nitrogenous bases
- structural changes from denaturation
The lambda max of proteins are at what nm?
280 nm
Trp, Phe, Tyr (Aromatics are primary contaminants)
Nucleic acid to protein content is measured by dividing the absorbance of what over the what?
nucleic acid/protein
bale, A260/A280 wherein A = Absorbance
You’ll know that the quality of your nucleic acid is good when A260/A280 is equal to?
1.8 - 2.0
Pure DNA has a A260/A280 value equal to?
1.8
In the equation x < 1.8 < y, x and y indicates increased contaminations by what?
- x = proteins
- y = RNA or denatured DNA
Acid hydrolysis of nucleic acids will yield to what products?
- sugar
- phosphate group
- nitrogenous bases
basically, all 3 components
Basic hydrolysis of nucleic acids will yield to what products?
Mixture of 2’ and 3’ nucleotides
not complete for RNA
DNA is not readily hydrolyzed by dilute alkali
Identify the test based on characteristics, reagents, or products
The mixture is heated to remove excess H2SO4 as colorless or white SO3. The phosphate ion then reacts with ammonium molybdenate ion in a HNO3- solution to form a yellow crystalline ppt
yellow crystalline ppt = ammonium phosphomolybdate
Test for phosphates
Identify the test based on characteristics, reagents, or products
Reagents used are diphenylamine in conc H2SO4
Test for Deoxyribose
Diphenylamine or Dische test
The test for deoxyribose is also called as what?
Diphenylamine or Dische test
Identify the test based on characteristics, reagents, or products
DNA + Diphenylamine = blue compound with sharp absorption maxima at 595 nm
Test for deoxyribose
Diphenylamine or DIsche test
Identify the test based on characteristics, reagents, or products
Orcinol in HCl and is frequently employed for estimation of RNA
Test for Ribose
Bial’s Orcinol test
Test for Ribose is also called as what?
Bial’s Orcinol Test
not specific for pentoses since prolonged heating of some hexose yields to product that reacts w/ orcinol to give colored complex :c
Identify the test based on characteristics, reagents, or products
(+) result of this test is a bluish colored complex
Test for Ribose
Bial’s Orcinol test
Identify the test based on characteristics, reagents, or products
Test for 1,3-diazine and its derivatives
Test for Pyrimidines
Wheeler and John test
Wheeler and Johnson Test detects all pyrimidines except what?
Thymine
yields negative result
Test for Pyrimidines is otherwise known as?
Wheeler and John Test
Identify the test based on characteristics, reagents, or products
(+) result is purple coloration
Test for Pyrimidines
Wheeler and John test
Identify the test based on characteristics, reagents, or products
this tests guanine and adenine
Test for Purines
Murexide Test
Test for Purines is also known as?
Murexide test
Identify the test based on characteristics, reagents, or products
Degradative oxidation by means of HNO3 and then a combination to yield a two ring product, purpuric acid
Test for Purines
Murexide Test
Identify the test based on characteristics, reagents, or products
(+) is a two ring product, purpuric acid
Test for Purines
Murexide Test
