Download Mutations PPT (Day 2)

Genetic Mutations
Topic: Mutations
INB page 35
• Essential Question: What happens when DNA is changed?
• Mutation: any change in the DNA of a gene or
chromosome.
• Base DNA sequence?
• AT and CG
• A mutation can occur when the DNA base pairs are
incorrectly matched, a extra base is added, or a base is
missing.
Two Types of Mutations:
1. Hereditary Mutations: occur in a sex cell (egg or sperm) and
can be passed on to organism’s offspring.
2. Acquired Mutations: also called somatic mutations (soma
means body), occur in body cells
• due to environmental factors like radiation, chemicals, and viruses
• will not be passed on to offspring.
• Only affects the current cells, not future cells
• Ex: UV rays from the sun
• Hereditary Mutations can only occur when the mutation is in
the sex cell!
Beneficial, Harmful, or Neither?
• Beneficial mutations: changes that may be useful to
organisms in different or changing environments.
• These mutations result in phenotypes that are favored by
natural selection to increase a population.
• Ex: Brown bunny lives in snow.
• Harmful mutations: reduce the organism’s chances for
survival and reproduction.
• Whether a mutation is harmful or not depends mainly on
the organisms environment.
• White alligator--leucism (wild vs. zoo)
• Mutations can be considered both beneficial and harmful—
at the same time.
• Sickle Cell Anemia
• Most mutations are automatically repaired by the organisms body or
are in a part of the DNA that is not too important and have no effect on
the organism.
• Sometimes the body misses a type in the DNA and the organism
develops a mutation.
• FYI: genetic alterations that occur in more than 1% of the population
are called polymorphisms and are common enough to be considered
normal variation in DNA (ex. Eye color, hair color, and blood type)
Beneficial Mutation
• Lactose Tolerance: The ability to process milk.
• Only around 1/3 of the entire world can process milk as adults or are
lactose tolerant.
• Lactose Intolerance: Individuals cannot process milk after the age of 45.
• Why do you think after 4-5 years old?
• This mutation is mainly found in cattle-raising populations.
• Being able to process lactose (found in milk) allows adults to prevent
diseases such as osteoporosis, encourages muscle and bone health, and
can provide milk drinkers with longer and healthier lives.
Harmful Mutation
• Cystic Fibrosis
• Characteristic: buildup of thick, sticky mucus that damages the body’s
organs.
• Signs and Symptoms: clog airways, results in problems breathing,
bacterial infections in lungs, heavy coughing, wheezing, and
inflammation. Over time cysts and scar tissue (fibrosis) will form in
the lungs.
• Affects 1 in 2500 white newborns, 1 in 17,000 African Americans.
• Mutations in the CFTR causes cystic fibrosis.
“Neither” Mutation (one that does not affect
the life of the organism)
• Color Vision Deficiency also called Color Blindness: Affects the
perception of color.
• Red-Green color blind most common
• Affects males much more often than females.
• 1 in 12 males and 1 in 200 females.
• Mutations in the OPN1LW, OPN1MW, and OPN1SW genes causes
color blindness.
• Effects the ability of the cones in the eye to determine color.
Directions: Determine if the given mutation is beneficial, harmful, or
neither in the given situation. Be sure to state if the mutation is
beneficial, harmful, or neither and explain why. Answer all questions in
complete sentences.
1. Polar Bears are known to live in the Arctic. These bears have thicker fur
than bears that live in warmer climates. Would the mutation in the bears
genes that results in thicker fur be beneficial, harmful, or neither? Why?
(Think about the climate in the Arctic.)
2. An albino (white) snake lives in a zoo in its own cage. Would the
mutation that results in the white skin of the snake be considered
beneficial, harmful, or neither? (think about how an animal lives in a zoo.)
3. Think about the albino snake again, would the effect of the mutation
change if the snake lived in the wild? Would it be considered beneficial,
harmful, or neither? (what is different between an animal living in a zoo
and living in the wild?)