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DNA and Cell Replication

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

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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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