Human Genetics Dominant Recessive Traits Copyright 2004 Stevens

Human Genetics: Dominant & Recessive Traits Copyright © 2004 Stevens Institute of Technology, CIESE, All Rights Reserved.

Human Genetics: Dominant & Recessive Traits • The physical characteristics below are common genetic traits inherited from one generation to the next: § § Free vs. Attached Earlobes Straight vs. Curved Thumbs Bent vs. Straight Pinky With vs. Without White Forelock • Review the following slides that contain: § Definition and images of each genetic trait § Identification of the Dominant / Recessive trait Copyright © 2004 Stevens Institute of Technology, CIESE, All Rights Reserved.

Free vs. Attached Earlobes • Free earlobes (dominant trait) hang below the point of attachment to the head. • Attached ear lobes (recessive trait) are attached directly to the side of the head. Copyright © 2004 Stevens Institute of Technology, CIESE, All Rights Reserved.

Straight vs. Curved Thumbs • Straight thumbs (dominant trait) can be seen as nearly a straight line and may contain a slight arch when viewed from the side as in the illustrations. • Curved thumbs (recessive trait) can be seen as part of a circle. Copyright © 2004 Stevens Institute of Technology, CIESE, All Rights Reserved.

Bent vs. Straight Pinky Bent pinky (dominant trait) vs. Straight pinky (recessive trait): 1. Hold your hands together as if you are covering your face. 2. If the tips of the pinkies (or baby fingers) point away from one another, the pinkies are bent (recessive trait). Copyright © 2004 Stevens Institute of Technology, CIESE, All Rights Reserved.

With vs. Without White Forelock • A White Forelock (dominant trait) is a patch of white hair, usually located at the hairline just above the forehead. The photo to the left clearly shows an exaggerated white forelock. • No White Forelock is the recessive trait. Copyright © 2004 Stevens Institute of Technology, CIESE, All Rights Reserved.