In 2000, Bob Harmon discovered the best-preserved Tyrannosaurus rex skeleton ever found. The fossilized dinosaur was sticking ou
t of the wall of a canyon in Montana. Many scientists were eager to study the fossils. Dr. Mary Schweitzer got one of the leg bones to analyze. Dr. Schweitzer’s assistant dissolved the bones in acid and discovered that some soft tissue had survived even after 68 million years. The discovery was a shock to the scientific community. No one had ever found such old tissues.
Next, Dr. Schweitzer looked for evidence of proteins in the T. rex tissues. She matched several samples from the fossil to parts of the modern protein collagen. Dr. Schweitzer’s discovery was so revolutionary that very few scientists believed her results. She repeated the experiment several times with great care. Each time she got the same results. In 2017, the scientific community finally accepted that proteins really could survive intact for 68 million years.
Considering the body’s organization from atoms to organ systems, in which level of organization are proteins like collagen? Describe how this level of organization fits into the organization of the whole body.
pls keep it at 7th grade level and it is a written questions. thx and is due at 11:59 tonight
An example of a myelin producing cell in the CNS is oligodendrocyte
The major function of oligodendrocytes is the formation of myelin
Myelin acts as an insulator of axonal segments and is a prerequisite for the high velocity of nerve conduction
Larger axons form thicker myelin
During development, oligodendrocytes arise from precursors located in the sub-ventricular zone such as the sub-ventricular zone of the lateral ventricles for the cerebrum or the fourth ventricle for the cerebellum
In the spinal cord, oligodendrocytes originate from the ventral regions of the neural tube and in the optic nerve they migrate into the nerve from the third ventricle
It is the oligodendrocyte precursor cells which migrate to their destination where they then differentiate into the more mature oligodendrocytes
The proliferation of the oligodendrocyte progenitor cells is controlled by a number of growth factors released predominantly from neurons but also from astrocytes such as platelet derived growth factor (PDGF) or fibroblast growth factor (FGF)
Crossing over, or recombination, is the exchange of chromosome segments between nonsister chromatids in meiosis. Crossing over creates new combinations of genes in the gametes that are not found in either parent, contributing to genetic diversity.
