Mutations Notes
Mutation—change in the structure of DNA
--may cause changes to physical traits or how body parts function
*Sometimes the wrong code is copied when DNA is replicated
--if change is permanent, then the mutation will become part of each cell; each cell will carry the mutation as the cells replicate
--may cause proteins to be made incorrectly and affect how well they work
*Mutations may be good, bad, or neutral
*good increase chance of survival; bad decrease chance of survival
Neutral (not good or bad) example: heterochromia (each eye is a different color)
Good example: humans can see more colors than some animals (still less than others)
--helps us to see prey and predators, and to identify good/bad foods
Bad example: Sickle cell: blood cells are the wrong shape, reduce ability to carry oxygen
*Some depend on the organism and the environment:
Albinism: mutation of gene for melanin (produces color in skin and eyes)
--results in no melanin production = white skin
--bad for alligators—can’t sneak up on prey in swamps
--bad for rabbits in forests—hard to hide from predators
--good for rabbits in snow—easy to hide from predators
Causes of mutations
*Errors in DNA replication
--insertion—piece of one chromosome misplaced inside a difference chromosome
--deletion—piece of a chromosome is lost/disappears
--substitution—one base is replaced by a different base in the DNA
*Spontaneous mutation—base is chemically changed or lost
*Mutagens (outside factors in the environment that can change genes)
--If DNA is damaged, body tried to guess the correct matching base, but can be wrong
--chemicals (like tobacco smoke) can alter genes (cause lung cancer, etc)
--UV (sun) and other types of radiation can alter genes (cause skin cancer, etc)