Mutation and Evolution

• Mutations are necessary for evolution; they can damage the existing adaptations as well
• MUTATIONS are changes in the genetic sequence, and they are a main cause of diversity among organisms
• Heredity also called biological inheritance, is the passing on of traits from parents to offspring
• A mutations is a change that occurs in our DNA sequence either due to mistakes when the DNA is copied or as the result of environmental factors such as UV light and cigarette smoke
• We call the factors that causes mutation mutagens
• MUTAGENS are commonly in the form of toxic chemicals and harmful radiation
• Mitosis is a process where a single cell divides into two identical daughter cells or even during meiosis
• Mistake during Mitosis lead to the production of daughter cells with too many or too few chromosomes, a feature known as aneuploidy
• The most common error of meiosis is nondisjunction, when chromatids fail to separate during either anaphase I or II, creating imbalances in the number of chromosomes in each daughter cell
• Mutations can occur in two different cells: Reproductive Cells and Body Cells
• Only mutations in sex cells or reproductive cells pass on to offspring. Mutations can affect the reproductive cells of an organism by changing the sequence of nucleotides within a gene in a sperm or an egg cell
• Types of Mutation:

  Missense Mutation

  Nonsense Mutation

  Silent Mutation

  Insertion or Deletion Mutation

  Duplication Mutation

  Frameshift Mutation

  Repeat Expansion Mutation
• Missense Mutation is a change in one DNA base pair that results in the substitution of one amino acid for another in the protein made by gene
• Missense Mutation occur when a single nucleotide base in a DNA sequence is swapped for another one, resulting in a different codon and, therefore, a different amino acid
• Nonsense Mutation is a type of mutation results in a shortened protein that may function improperly or not at all
• Silent Mutation do not affect the structure or function of the protein because there is no effect on the amino acid sequence
• Insertion or Deletion Mutation: Insertions changes the number of DNA bases in a gene by adding a piece of DNA. Deletions removes a piece of DNA
• Duplication Mutation consists of a piece of DNA that abnormally copied one or more times
• Frameshift Mutation occurs when the addition or loss of DNA bases changes a gene’s reading frame
• REMEMBER: Insertions, deletions, and duplications can all be frameshift mutations
• Repeat Expansion Mutation increases the number of times that the short DNA sequence is repeated. This type of mutation can cause the resulting protein to function
• Evolution is the change in characteristics of a species over several generations and relies on the process of natural selection
• Natural Selection is the process through which populations of living organisms adapt and change
• Evolution is a change in the genetic makeup of a population over time
• Macroevolution refers to large-scale that occur over extended time periods, such as the formation of new species and groups
• Microevolution refers to small-scale changers that affect just one or few genes and happen in populations over shorter timescales
• Natural Selection is sometimes summed up as "Survival of the Fittest"
• Homologous Structures: If two or more species share a unique physical feature, such as a complex bone structure or a body plan, they may all have inherited this feature from a common

  ancestor
• Homologous structures parts with similar basic structure
• Vestigial Structures are reduces body parts that have little to no function; remnant of an ancestor
• Analogous structures are structures that have the same function but have different structures and DO NOT have a common descent
• Fossil are preserved remains or traces of an organism that is no longer living which are usually found in sedimentary rocks
• Methods Used in Determining the Age of Fossils:

  Relative Dating

  Radiometric/ Radioactive Dating

  Carbon/ Radiocarbon Dating
• Types of Fossils:

  Imprint

  Mold

  Cast

  Petrification

  Amber

  Frozen

  Trace
• How can fossil age be determined?

  Depth of fossils help to determine their age
• Why is the fossil record incomplete?

  1. Soft tissue rarely preserved
  2. Movement of the earth's crust has obliterated or covered many fossils
  3. Fossilization takes place only in certain types of habitats and under favorable conditions
  4. Paleontologists have not dug up every place on earth
• Embryonic development

  Species that are closely related exhibit similar embryonic development. Even when in adult stage, the organisms are quite different
• Embryology

  Patterns of embryological development can indicate a common ancestry
• Molecular Biology

  Similarities between biological molecules can reflect shared evolutionary ancestry
• All the most basic level, all living organisms share the same:

  • Genetic material (DNA)
  • Genetic code (highly similar)
  • Basic process of gene expression (transcription and translation)
  • Molecular building blocks such as amino acid