BIOLOGY 1A03 Lecture 7: Applied Lecture 7
4 Mar 2017
School
Department
Course
Professor
9
BIOLOGY 1A03 Full Course Notes
Verified Note
9 documents
Document Summary
Aging may be linked to a lack of telomeres. older differentiated cells die and are replaced by the cell division of adult stem cells. tissue homeostasis: generate new cells at the same rate that cells are lost. Cancer: increase in cell number, less cell death. Aging: decrease in cell number, cells die and are not replaced. Bone marrow, liver, and teeth, heart brain, blood vessels, skin, skeletal muscle, blood and gut have stem cells. Cells can divide a limited number of times (hay ick limit)(between 50 and 60 times. the 60th division cells look very different from the original cell, due to shortening of telomeres and a change in gene expression. after every replication, telomeres shorten around 50 nucleotides (we start with over 10,000) . telomere shortening rate increases as we get older. Telomerase enzyme extends the telomeric ends of the chromosome. present in cancer cells and stem cells, but not somatic cells.
