Gel electrophoresis (article) | Khan Academy Gel electrophoresis is a technique used to separate DNA fragments (or other macromolecules, such as RNA and proteins) based on their size and charge Electrophoresis involves running a current through a gel containing the molecules of interest Based on their size and charge, the molecules will travel through the gel in different directions or at different speeds, allowing them to be separated
Gel electrophoresis (video) | Biotechnology | Khan Academy Gel electrophoresis is a technique used to separate DNA, RNA, or protein fragments by size It involves a gel, electric charge, and migration of molecules DNA samples are placed in wells within an agarose gel, and an electric field is applied Smaller molecules move faster through the gel, allowing for separation and estimation of fragment lengths using a DNA ladder as a reference Ethidium
Restriction enzymes DNA ligase (article) | Khan Academy A restriction enzyme is a DNA-cutting enzyme that recognizes specific sites in DNA Many restriction enzymes make staggered cuts at or near their recognition sites, producing ends with a single-stranded overhang If two DNA molecules have matching ends, they can be joined by the enzyme DNA ligase
DNA sequencing (article) | Biotechnology | Khan Academy Key points: DNA sequencing is the process of determining the sequence of nucleotides (As, Ts, Cs, and Gs) in a piece of DNA In Sanger sequencing, the target DNA is copied many times, making fragments of different lengths Fluorescent “chain terminator” nucleotides mark the ends of the fragments and allow the sequence to be determined
Overview: DNA cloning (article) | Khan Academy Overview of DNA cloning DNA cloning is the process of making multiple, identical copies of a particular piece of DNA In a typical DNA cloning procedure, the gene or other DNA fragment of interest (perhaps a gene for a medically important human protein) is first inserted into a circular piece of DNA called a plasmid
MCAT training passage: DNA motion in gel electrophoresis CGE can only separate DNA fragments between 5 and 20,000 base pairs in length Pulsed Field Gel Electrophoresis (PFGE) is a powerful technique that can separate DNA fragments differing by as many as 106 base pairs There are several variants of PFGE, all of which share the essential characteristic that the orientation of the electric field is abruptly changed thousands of times during the
DNA sequencing (video) | Biotechnology | Khan Academy DNA sequencing involves three main steps: 1) using PCR to amplify DNA fragments, 2) introducing dideoxynucleotides that halt DNA strand elongation, and 3) employing a computer to analyze the fluorescent labels on the DNA fragments to determine the sequence
Leading and lagging strands in DNA replication - Khan Academy DNA replication is a precise process where DNA unwinds and splits into two strands Each strand then serves as a template for a new DNA molecule The leading strand is built continuously, while the lagging strand is built in fragments, called Okazaki fragments