Lab 5 DNA Extraction

(1) DNA Extraction from Plant Cells Objective: Isolating DNA from plant cells and visualizing it directly . To extract DNA from plant cells like strawberry, banana and peas, 1-we need to (destroy cell wall and cell membrane) 2-we need to separate DNA from other cell components like proteins, carbohydrates and lipids through precipitation. 3-we can collect DNA molecules by cold alcohol and DNA can be seen directly. Strawberry character : 1- Is octoploid, meaning that it has 8 copies of each chromosome, so it has a large amount of nucleic acid. 2- Fresh fruit contains pectinase and cellulase enzymes that helps lysing cell wall.

Cell organelles and other components can be separated from each other by : centrifugation : 1-depending on their physical properties as: size and density. 2-This can be done by using different speeds at different periods of time. 3-Centrifugation speed is measured by revolutions per minute (rpm). 4-Bigger and heavier components precipitate at the bottom and called pellet, 5-smaller lighter substances float upper and called supernatant. Materials : (Strawberry or banana or green peas)- Ice ethanol alcohol 99%- Buffer (90ml water +10 ml detergent +small amount of NaCl)- large tube- glass rod.

Steps: 1- Put fruit in mortar or inside plastic bag, then mash manually till it becomes creamy. 2- Add 10 ml of buffer. 3- Leave for 2 min. 4- Filtrate the mixture with piece of Gauze in glass cone. 5- Discard the precipitant in the Gauze. And put the liquid filtrate in large tube. 6- Put the glass rod in ice to become iced , then put it in the large tube. 7- Pour ice ethanol alcohol on the glass rod (inside tube) 8- Observe fibers of DNA stuck on the glass rod. Observation: DNA molecules appears as colorless gelatinous substance sticking to the glass rod.