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Genetics is a study of heredity

Genetics is a study of heredity. How traits are passed from one generation to the next. DNA is the material that holds the information about your traits. Chromosomes are long pieces of DNA. Segments of DNA along the chromosomes hold instructions for different traits.

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Genetics is a study of heredity

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  1. Genetics is a study of heredity How traits are passed from one generation to the next.

  2. DNA is the material that holds the information about your traits • Chromosomes are long pieces of DNA. • Segments of DNA along the chromosomes hold instructions for different traits

  3. How are traits passed to offspring? Two types of reproduction: Asexual and Sexual

  4. Asexual reproduction • Prokaryotes • Requires only ONE parent • Offspring inherit DNA from just one parent and are therefore identical to parent. • Process is called BINARY FISSION and happens just like mitosis to form TWO identical offspring.

  5. Sexual Reproduction • Eukaryotes: plants, animals, fungi and protists • TWO parents • Offspring get a complete set of chromosomes from BOTH parents for a total of TWO copies of every gene in all body cells. • Requires specialized SEX CELLS called gametes (egg and sperm cells)

  6. Sexual Reproduction • Offspring have some traits like the mother and some like the father. • How are SEX CELLS made???

  7. Meiosis makes sex cells • Makes egg and sperm cells • Like mitosis • DNA gets copied before it starts • Different because the nucleus divides TWO TIMES to make four cells • Each sex cell has just ONE copy each chromosome, where body cells have TWO copies

  8. REMEMBER: • Gametes (egg and sperm cells) have HALF as much DNA (one set) as body cells (two sets).

  9. Fertilization: no peeking… You are kidding, right???

  10. This works PERFECTLY • Egg and sperm each give ONE copy of DNA to the baby so that it has TWO copies, one from each parent. • This is how you get traits from both your mom and your dad

  11. Humans • We inherit one set of 23 chromosomes from each parent for a total of 46 chromosomes. • Scientists number them from 1-23 • Each matching pair of chromosomes (ex: chromosomes #1 inherited from mom and #1 inherited from dad are called HOMOLOGOUS CHROMOSOMES.

  12. Mitosis Meiosis Purpose To make BODY cells To grow To repair injuries To make SEX cells for reproduction Sex cells = gametes = eggs and sperm cells

  13. Mitosis Meiosis Which cells do it Happens in all BODY cells Happens in SEX organs of eukaryotes

  14. Mitosis Meiosis # Daughter Cells TWO daughter cells FOUR daughter cells

  15. Mitosis Meiosis How much DNA In Eukaryotes, SAME amount of DNA as parent cell. Daughter cells identical to parent cell In Eukaryotes, HALF as much DNA as parent cell. Daughter cells are ready to combine with another sex cell to reproduce.

  16. Mitosis Meiosis In Humans: TWO sets of 23 chromosome: One set inherited from mom and one set inherited from dad ONE set of 23 chromosomes: MIXED from parent’s DNA

  17. Mitosis Meiosis Remember My-TOE- sis Mitosis makes body cells for growth and repair Mini-Meiosis Meiosis makes SEX cells to make a mini me.

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