DNA

DNA Extraction

A method for isolating and purifying DNA from a sample using physical and chemical methods.

Cell Lysis

The step in DNA extraction where the cell and nuclear membranes break open to expose DNA.

Precipitation

The step in DNA extraction that separates DNA from cellular debris using protease, RNase, and alcohol to form a pellet from a centrifuge.

Purification

The final step in DNA extraction that rinses DNA with alcohol to remove cellular debris.

Polymerase Chain Reaction (PCR)

A technique for selectively amplifying a specific segment of DNA.

Denaturation

The step in PCR that separates double-stranded DNA into single strands at approximately 92–95°C.

Annealing

The step in PCR where primers hydrogen bond to single-stranded DNA at approximately 50–65°C.

Extension

The step in PCR where Taq DNA polymerase adds base pairs to extend the DNA strand at approximately 72°C.

Taq DNA polymerase

An enzyme isolated from Thermus aquaticus that extends primers in PCR; effective at 75°C.

Tools for DNA Extraction

Container with cracked ice, microcentrifuge, microcentrifuge tubes, micropipettes, heating blocks, vortexer.

Tools for PCR

Micropipettes, thermal cycler, container with cracked ice, microcentrifuge tube rack.

Mechanical disruption

A method used in cell lysis that involves physical breaking apart of cells.

Detergent in DNA extraction

A chemical agent used to dissolve cellular proteins and aid in cell lysis.

Protease

An enzyme used during precipitation to remove DNA- and RNA-associated proteins.

RNase

An enzyme that degrades RNA and is used during the precipitation step.

Sodium ions in DNA extraction

Used to neutralize the negative charge of DNA molecules to increase solubility.

Alcohol in DNA extraction

Causes the precipitation of DNA from the solution by being less soluble in alcohol.

Vortexer

A tool used to mix solutions thoroughly, especially in DNA extraction.

Microcentrifuge

A laboratory device used to separate components of a sample based on density.

Thermal cycler

A device used in PCR to precisely control temperature changes during the process.

Cracked ice container

A tool used to maintain low temperatures for samples during DNA extraction and PCR.

Nucleotide addition in PCR

Occurs during the extension step, where complementary nucleotides are added to build the new DNA strand.

Sample cooling in PCR

Occurs during annealing, allowing primers to attach to single-stranded DNA.

Amplification in PCR

The process of creating multiple copies of a specific DNA segment.

Hydrogen bond in PCR

The interaction between primers and single-stranded DNA facilitating annealing.

Thermus aquaticus

A bacterium from which Taq DNA polymerase is isolated, known for thriving in hot springs.

Starting temperature for denaturation

Approximately 92–95°C, necessary to separate double-stranded DNA.

Final temperature for extension

Approximately 72°C, optimal for Taq DNA polymerase activity.

Pestle

A tool used for grinding or mixing in laboratory procedures.

Permanent marker in labs

Used for labeling microcentrifuge tubes and other containers.

Steps for PCR

Denaturation, Annealing, and Extension

Steps for DNA extraction

Cell lysis, precipitation, and purification

Primer

Identifies the DNA that’s going to be replicated.