Biochemistry Lab Midterm 1

Nucleic Acid

is an unbranched polymer in which the monomer units are nucleotides

Nucleotides

Monomer units of Nucleic Acid

DNA & RNA

Types of Nucleic Acid

DNA

stores the genetic information of an organism and transmits that information from one generation to another

RNA

translates the genetic information contained in DNA into proteins needed for all cellular function

DNA

is located in the nucleus of the cell

RNA

is located in different parts of the cell

hnRNA

RNA found in nucleus

mRNA & tRNA

RNA found in cytoplasm

rRNA

RNA found in in ribosome

DNA Extraction Step 1

Breaking of cell wall

mechanical disruption

DNA Extraction Step 1: Breaking of cell wall (if sample is plant) - done by __ through crushing or blending

DNA Extraction Step 2

Breaking of cell membrane to expose organelles

dishwashing liquid

DNA Extraction Step 2: Breaking of cell membrane to expose organelles - done by adding the __ which is an amphipathic substance.

False

T/F - dishwashing liquid is not an amphipathic substance

tail, head

The long hydrocarbon __ of soap breaks the lipid bilayer of cell membrane while the soap's polar __ is attracted to the water

DNA Extraction Step 3

Salt binds to the negatively charges phosphate end of the DNA chain

Salt

DNA Extraction Step 3: __ binds to the negatively charges phosphate end of the DNA chain to protect the chain as well as increases the separation of DNA from the hydrophobic layer

DNA Extraction Step 4

Filtration

Filtration

DNA Extraction Step 4: __ removes cellular debris from the sample

DNA Extraction Step 5

Precipitation with cold alcohol

salt and alcohol white gelatinous material

DNA Extraction Step 5: Precipitation with cold alcohol

DNA becomes insoluble in water in the presence of ___ (more polar)

DNA precipitate as a __

base, sugar and phosphate group

Nucleotide is composed of _

Glycosidic bond phosphodiester bond

__ joins the base and the sugar, while __ joins the phosphate and sugar group

3'5' phosphodiester bond/linkage

The nucleotide chain is joined together by __

False

T/F - Nucleotide chain is affected by addition of base

Break down

Lysis means:

Depurination

break down of glycosidic bonds only if pH > 3

purine base and deoxyribose with phosphate group

Products of Depurination

Total breakdown

break down of glycosidic bond with phosphodiester bond if pH < 2 plus heat

Extremely low pH

__ hydrolyses DNA completely

phosphate group purine or pyrimidine base deoxyribose

Products of Total Breakdown

hydrogen bonding

ACID HYDROLYSIS Reactions starts with an acid attacking the __ between complementary bases

purines glycosidic bond

Further hydrolysis breaks the nucleobases specifically the __. This happens because it is easy to attack the __ than the phosphodiester bond.

DISCHE TEST/DISCHE DIPHENYLAMINE TEST

Test for the deoxyribose in DNA

diphenylamine, Sulfuric acid

Reagents of Dische Test

Dische Test

Positive Result: light blue to blue solution depending on the amount of DNA

bright blue (positive)

Result of Hydrolyzed in Dische Test

brownish blue (positive)

Result of Unhydrolyzed in Dische Test

FEHLING'S TEST

Test for reducing sugar

Fehling's A & Fehling's B

Reagents of Fehling's Test

Fehling's A

Copper sulfate solution

Fehling's B

aqueous potassium sodium tartrate and sodium hydroxide

Fehling's Test

Positive result: formation of brick red precipitate

Formation of brick-red ppt (positive)

Result of Hydrolyzed in Fehling's Test

remains blue and no formation of brick-red ppt (negative)

Result of Unhydrolyzed in Fehling's Test

BIAL'S TEST/ BIAL'S ORCINOL TEST

Test for pentoses

pentose & hexose sugar

Bial's Test can only distinguish between __ & __

Orcinol, hydrochloric acid, FeCl3

Reagents of Bial's Test

Bial's Test

Positive result: Blue or green solution

Brown solution (negative for ribose)

Result of Hydrolyzed in Bial's Test

brown solution (negative for ribose)

Result of Unhydrolyzed in Bial's Test

TEST FOR PURINES BASES

Test for the presence of Adenine and Guanine

Silver Nitrate and Ammonium Hydroxide

Reagents of Test for Purines Bases

Silver ion nitrogen

__ in ammoniacal solution precipitates purine bases reacting to the __ of purine base

Test for Purines Bases

Positive result: gelatinous white precipitate

Gelatinous white precipitate (positive)

Result of Hydrolyzed in Test for Purines Bases

brown solution (negative)

Result of Unhydrolyzed in Test for Purines Bases

PHOSPHATE TEST

Test for free phosphate group

Ammonium hydroxide, nitric acid, ammonium molybdate

Reagents for Phosphate Test

Phosphate Test

Positive result: Yellow precipitate

Formation of yellow precipitate (positive)

Result of Hydrolyzed in Phosphate Test

No precipitate (negative)

Result of Unhydrolyzed in Phosphate Test