Understanding Mutation

T3.3

• Mutation involves changes in DNA at the molecular or chromosomal level.
• Mutations can occur in gametes, affecting offspring, or in somatic cells, which cannot be passed on.

Causes of Mutation

• Mutagens in the environment, such as radiation, chemicals, and infectious agents, can cause mutations.

Types of Mutation

• Gene mutations are small and affect one gene, involving point or shift mutations.
• Chromosomal mutations are large, affecting many genes and including deletions, duplications, inversions, translocations, and nondisjunction.

Types of Gene Mutation

• Point mutation: A change occurs at single point in the DNA sequence as "ABC" becomes "ABD."
• Frameshift mutation: Insertion or deletion of nucleotide(s) can alter the reading frame of the gene sequence in "ABCDEFG" becomes "ABGEFG" due to deletion.
• Deletion: A segment of the gene is removed as "ABCDEFGHIJ" becomes "ABCDHIJ."
• Duplication: A segment of the gene is repeated as "ABCDEFGHI" becomes "ABCDEFGHIFGHI."
• Inversion: The order of a segment of the gene is reversed as "ABCDEF" becomes "ABCFED"
• Translocation: A segment of the gene moves to another location as "ABCDEF GHIJK" becomes "ABGDEFJK GHI".
• Non-disjunction: Chromosomes fail to separate during cell division.

Sickness

• Down Syndrome (DS): Involves multiple copies of chromosomes.
• Klinefelter Syndrome (Kin.): Presence of an extra X chromosome in males.
• Turner Syndrome: Absence of an X chromosome in females.
• Cri Du Chat: Missing chromosome.
• Sickle Cell Anemia: Causes blockage due to misshapen red blood cells, where a normal cell "O" becomes a sickle cell ")"
• Cystic Fibrosis: Results in mucus buildup, affecting breathing.

Other

• Embryonic: Similar embryos
• Genetic: Small mutations in DNA

Adaptation to Climate

• Bergman's rule: Colder climates correlate to thicker skin.
• Allen's rule: Hotter climates correlate to shorter appendages.
• Gloger's rule: Darker skin is common in warm, humid environments while lighter skin is in cold environments.

Types of Evolution

• Evolution involves changes in traits that allow organisms to adapt and survive.
• The two theories of evolution are acquired traits and natural selection.

Evidences of Evolution

• Fossils are remains of extinct organisms such as:
  • Imprints
  • Molds
  • Casts
  • Petri
  • Amber
  • Trace
  • Relative dating determines events while absolute dating is more exact.
• Anatomy studies reveal homology or analogy.
  • Homologous structures have different functions but the same origin.
  • Analogous structures have the same function but different origins.
  • Vestigial structures are useless remnants of evolutionary past.

Convergent and Divergent Evolution

• Convergent Evolution: Organisms do not share a recent ancestor, but share similar traits.
• Divergent Evolution: Organisms share a recent ancestor.