1. MS-LS 3-1

2. I will explain how mutations can effect organisms in positive, negative, and neutral ways.

3. How DNA Works Living organisms are made of cells. Humans have approx. 30 trillion cells. 1.Organisms grow and develop by making new cells. This cell division process is called Mitosis 2.To ensure that the new cells will perform the correct task, there is a recipe inside of the nucleus called DNA.

4. 3. In Mitosis, the new cells each need a copy of the coding located in the DNA, so it duplicates (replicates).

5. 4. Sometimes the replication process will include an error to the coding that is being duplicated causing a mutation.

6. Mutation - a change in DNA, the hereditary material of life. Mutations can be caused by external or by errors in the cellular machinery.

7. Mutagens - physical or chemical agents that cause mutations in DNA (are said to be mutagenic). - External factors : environmental factors such as sunlight, radiation, and smoking can cause mutations. - Genetic factors : errors during DNA replication can lead to genetic changes.

8. There are three types of mutations of nitrogenous bases: Substitution Insertion Deletion

9. The replacing of a nitrogenous base or base sequence with an incorrect base or sequence.

10. The introduction of additional base or bases into a genetic code.

11. The removal of a base or bases from a genetic code (with no replacement).

12.  Neutral Effect - some mutations don't have any noticeable effect on the phenotype of an organism.  This can happen in many situations, like when: - the mutation occurs in a stretch of DNA with no function - the mutation occurs in a protein-coding region, but ends up not affecting the amino acid sequence of the protein.

13.  Mutations can also be harmful, causing disease, developmental delays, structural abnormalities, or other effects.  Negative Effects – when a mutation reduces an organisms chances for survival. o Ex. Sickle cell anemia - a genetic disease with severe symptoms, including pain and anemia. o The disease is caused by a mutated version of the gene that helps make hemoglobin — a protein that carries oxygen in red blood cells.

14. Positive Effects – when a mutation increases an organism’s chances of survival. Mutations can be advantageous and lead to an evolutionary advantage of a certain genotype.