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Biology – Lecture 53

Biology – Lecture 53. Intro to Pedigrees. Pedigree Chart. a diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next. . Pedigree Chart. Pedigree Chart. Reading a Pedigree.

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Biology – Lecture 53

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  1. Biology – Lecture 53 Intro to Pedigrees

  2. Pedigree Chart • a diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next.

  3. Pedigree Chart

  4. Pedigree Chart

  5. Reading a Pedigree • A pedigree chart is like a family tree. • It allows you to track the generations of an animal starting with a single couple.

  6. Helpfulness of Pedigree • Watching for certain traits • The pedigree chart shows the parents and its offspring, along with the gender of each individual and which ones have the specific trait.

  7. Reading a Pedigree Chart • Step 1 – Find the starting couple or couples (at the top of the pedigree chart).

  8. Pedigree Chart Symbols • A square is the symbol for a male and a circle is the symbol for a female. • The horizontal lines connecting a square and circle show that the pair mated. • Vertical lines connecting a pair to other squares or circles show its offspring.

  9. Pedigree Symbols

  10. Step 2 • Follow the vertical lines to trace the reproduction cycle through the various generations. • The pedigree chart can become quite large depending on how many generations are recorded and how many offspring were produced.

  11. Step 3 • Examine the key for the chart to determine what colors represent what traits.

  12. Step 4 • Use the chart to determine how the trait was passed on. • Over time, a pattern becomes evident and its easier to predict how likely it is that the next generation will have the trait in question.

  13. How to Construct a Pedigree

  14. Step 1 • Identify all of the males and females • Males = • Females =

  15. Step 2 • Determine relationships between individuals • Married or mated = • Siblings =

  16. Special Siblings • Identical Twins = • Non-identical Twins =

  17. Step 3 • Determine what trait is going to be traced throughout the pedigree. • Make a key that represents that trait.

  18. Step 4 • Determine which are “affected” (will have the trait) and “non-affected” (will not have the trait). • Affected = or • Non-affected = or

  19. Step 5 • Draw the pedigree with the appropriate relationships between individuals. • You may start with one individual and work your way up, or start at the top with 1 couple and work your way down.

  20. Example - Making a Pedigree

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