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.
Legs together and knee straight; Toes pointing straight forwards; Arms by the side; Palms facing forwards; Movements. Flexion and Extension . Flexion is a movement in the sagittal plane, which decreases the angle at the moving joint. Extension is the opposite movement, which increases the angle at the joint. Many types of synovial joint are capable of flexion and extension (hinge; ball and socket; saddle; condyloid) including the shoulder, elbow, wrist, hip and knee.