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DNA and Cell Replication

Explore the fundamentals of DNA, cell replication, mitosis, meiosis, genetic disorders, and hybrids. Understand the steps of mitosis and meiosis, the impact of mutations, and the formation of hybrids. Engage in interactive activities to deepen your knowledge.

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DNA and Cell Replication

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  1. DNA and Cell Replication

  2. DNA • Deoxyribonucleic acid • Sugar-phosphate “backbone” with nucleotide “ladder steps” • Has 2 complementary strands

  3. Nucleotides • 4 different nucleotides • A=adenine • T=thymine • C=cytosine • G=guanine • A always pairs with T • G always pairs with C • Called base pairs

  4. Chromosomes • DNA is wound up and compacted to form chromosomes • Chromosomes are passed from parent to offspring • You have 46 chromosomes, 23 from each parent

  5. Mutations • A mutation is a change in the DNA • Can be good or bad • Can be caused by pollutants, UV rays (sun), or occur naturally

  6. Assignment • Make 2 models of DNA • Include 10 base pairs • Make a key for your base pairs • Be sure to pair up nucleotides correctly!

  7. Mitosis • Cell replication in asexual reproduction and cell duplication • DNA of parent and offspring is identical

  8. Mitosis • Goal-One copy of the DNA is distributed into each of the 2 daughter cells • In order to reach goal, DNA must replicate itself first!

  9. Steps of Mitosis • Prophase- DNA condenses to form chromosomes • Metaphase- Chromosomes line up across center of cell • Anaphase- Chromosomes separate and move to opposite ends of cell • Telophase- Nuclear envelopes form around DNA, 2 new cells are created

  10. Activity • Draw a line down the back of your paper from yesterday. • You are going to draw a cell going through all the steps of mitosis. • Use the diagram on pg C58 to help you.

  11. Meiosis • GOAL- Make 4 copies of cells to be used in sexual reproduction. • Each daughter cell will have ½ the DNA of the parent.

  12. Meiosis • First the DNA duplicates itself • Next it goes through mitosis to create 2 daughter cells • Finally, each cell goes through mitosis a second time • Total cells=4 • Total DNA=1/2

  13. Genetic Disorders • Can be caused by mistakes during meiosis • Mutations can occur by crossing over of chromosomes

  14. Genetic Disorders • Klinefelter Syndrome-males have XXY chromosomes • Turner Syndrome-females only have one X • Down Syndrome- extra copy of chromosome 21 • Sickle Cell Disease- recessive gene chromosome 11 • Hemophilia- recessive x-linked gene

  15. Ligers • Lion and tiger mixed together • Half of its DNA is from lion, half from tiger • Has traits of both animals • Does not occur in nature

  16. Activity • After you have made your model of meiosis, you need to create your own hybrid! • Draw a picture of what your hybrid would look like • List the traits it would get from each of its parents • List the advantages and disadvantages it would have in the wild

  17. Other Hybrids • Splake- hybrid of male brook trout and female lake trout • Africanized honey bee- African and European bees, “killer bees” • Beefalo-cattle and bison • Zebroid-zebra and horse

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