1. Below is a model of the aggrecan molecule. Over our lives the aggrecan molecule as characterized from the ECM of human patients with osteoarthritis changes in structure. Some changes include loss of the HA binding region, reduction in glycosaminoglycan number and size and so on. It is the same gene but a different looking aggrecan molecule. Describe how such changes could occur at the genetic or cellular level (choose one pathway).

2. Design characteristics are important in engineering dental and orthopedic tissues. Listed below are four important design characteristics you must consider in engineering a successful TMJ implant. Your objective is to design a replacement implant and specifically indicate the type, amount, and arrangement of the ECM proteins and other constituents (collagens, proteoglycans, glycosaminoglycans, glycoproteins, etc.) in your design. Design Characteristics

• It is a son tissue designed to provide resistance to major tensional loads, compressional loads and shear forces.

• It is mostly avascular except for its attachment regions.

• It is a composite tissue consisting of microheterogenous domains composed of a unique suite of ECM proteins organized in unique functional arrays.

• It has three regions, an anterior and posterior viscoelastic hand regions and a thinner fibrous intermediate region. The functional properties of each region are different. Refer to the figures provided below for more details.