DNA is extracted from human cells for a variety of reasons. With a pure sample of DNA you can test a newborn for a genetic disease, analyze forensic evidence, or study a gene involved in cancer.Try this virtual laboratory to perform a cheek swab and extract DNA from human cells.Javascript is required to view this content.ith a pure sample of DNA you can test a newborn for a genetic disease, analyze forensic evidence, or study a gene involved in cancer. Try this virtual laboratory to perform a cheek swab and extract DNA from human cells. Javascript is required to view this content.
Knee flexion means bending your leg at the knee joint, reducing the angle between your lower leg and upper leg.
The gastrocnemius branches at the top behind the knee; the two branches are known as the medial and lateral heads. The flexing of this muscle during walking and bending of the knee creates traction on the femur, pulling it toward the tibia in the lower leg and causing the knee to bend. Both the gastrocnemius muscle and the soleus join onto the Achilles tendon, which is the strongest and thickest tendon in the human body.