1. Gene Expression Chapter 11

2. Gene Expression…Why? Your cells use the message contained in your genome (DNA) to produce several thousand different proteins. Your Genome is all the genetic material (DNA)you have. However, your cell doesn’t need all the proteins at the same time. By regulating when genes are expressed, your cells control when each protein is produced. By understanding Gene Expression, scientists may some day be able to cure many common ailments and diseases.

3. Gene Expression: a two step process 1. Transcription…DNA is transcribed into mRNA. Both segments of DNA are transcribed, introns & exons. 2. Translation…mRNA is translated into a polypeptide that eventually ‘folds’ into a protein. Only exons are translated into a polypeptide. Problems with Gene Expression can occur at any point in the processes and can lead to an error/or lack of protein production.

4. Gene Expression: Growth & Development Gene Expression plays an important roll during growth and development of eukaryotes. Also, gene expression continues on throughout life when needed. (Your body tries to be efficient.) Example: genes for insulin production are turned on when an increase in blood sugar is detected and turned off when blood sugar is normal.

5. Gene Expression in Eukaryotic Development: Cell Differentiation- development of cells to perform specific functions. (Stem cells) Morphogenesis- organs and tissues develop to produce a specific form. Homeotic Genes- regulatory genes that determine where certain anatomical structures will develop. Example: appendages

6. Gene Expression & Cancer: Proto-oncogenes: regulate cell growth (mitosis). Oncogenes: mutated proto-oncogenes that can cause cancer. Tumor suppressor genes: prevent tumor formation. Mutations cause these genes to be ineffective and tumors can form.

7. Tumors can result from oncogenes. Tumors can be: 1. Benign (non-cancerous) 2. Malignant (cancerous) and can experience metastasis. Metastasis is when cancer spreads to other tissues/organs in an organism. Causes of Cancer can be spontaneous or as a result from exposure to a carcinogen. Examples of carcinogens: tobacco smoke, asbestos, X-rays, UV light. Viruses also have been shown to cause an increase in cancer. Example: HPV’s link to cervical cancer.

8. Risks of developing Cancer: 1. Genetic Predisposition (It’s in your genes!) 2. Exposure to a carcinogen (amount & frequency) Types of Cancer: 1. Carcinomas (skin & tissue linings) 2. Sarcomas (bone & muscle) 3. Lymphomas (lymphatic system) 4. Leukemia (blood forming tissues)