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Warm UP

Warm UP. Illustrate how the chromosome number in a sexually reproducing organism with 8 chromosomes remains constant from one generation to the next by drawing a model of meiosis and showing the TOTAL number of chromosomes in each stage, the steps, and the products for male and female. Warm Up.

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Warm UP

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  1. Warm UP • Illustrate how the chromosome number in a sexually reproducing organism with 8 chromosomes remains constant from one generation to the next by drawing a model of meiosis and showing the TOTAL number of chromosomes in each stage, the steps, and the products for male and female.

  2. Warm Up • Deoxyribonucleic acid, the material that contains the information that determines inherited characteristics • One of the four possible bases in a string of DNA—it pairs with adenine • A subunit of DNA that consists of a sugar, a phosphate, and a nitrogenous base • The complement to guanine

  3. Warm Up • What letters represent the four bases? • Using X-ray diffraction, what did Rosalind Franklin show the shape of DNA to be? • Watson and Crick built a DNA model like a …… • The sides of the DNA “ladder” are made of……. • The “rungs” of the DNA ladder are…..

  4. Pick Up Warm Up • On the back of your warm up, answer the following: • What are the phenotypes based on the genotypes: Ggbb ____________________ ggBB ____________________ ggbb ____________________ GgBb ____________________

  5. Warm Up • A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb. • Determine the phenotypes and proportions in the offspring.

  6. Warm Up • How many out of 16 have grey fur and black eyes? • How many out of 16 have grey fur and red eyes? • How many out of 16 have white fur and black eyes? • How many out of 16 have white fur and red eyes?

  7. DNA

  8. What is DNA • Deoxyriboneucleic Acid: a genetic code (like a blueprint) for making new cell parts, new cells, or an entirely new organism. • DNA wraps around protein cores and forms chromosomes found in the nucleus of eukaryotic cells.

  9. History of DNA • 1952 – Rosalyn Franklin discovered that DNA is made up of 2 chains of molecules arranged in a spiral form.

  10. History of DNA Chargaff’s Rule: -Adenine always equals amount of Thymine. A = T -Guanine always equals amount of Cytosine. G = C

  11. Chargraff’s Rule

  12. History of DNA • 1953 – James Watson and Francis Crick constructed the first model of DNA and win the Nobel Peace Prize.

  13. DNA Structure • DNA is often called a “double helix” or “twisted ladder.” • The sides are made of phosphate and deoxyribose-sugar molecules. • The middle (rungs) are made of nitrogenous base pairs (adenine/thymine, guanine/cytosine).

  14. Four Nucleotides The Four: Adenine Thymine Cytosine Guanine • Nucleotide: combination of a phosphate molecule, deoxyribose-sugar molecule & a nitrogenous base.

  15. Complementary Bases The complementary strand/sequence to G-A-T-T-A-C-A would be… Remember Chargaff’s Rule:

  16. DNA Replication • Before any cell can make a copy of itself, all the DNA must be copied! • This is called DNA replication.

  17. DNA Replication • An enzyme opens the strands of DNA so that they become single stranded. • Complimentary nucleotides come fill in the missing strand. • Two DNA strands are formed.

  18. Let’s Model DNA • Have students stand in two lines that spiral like a DNA molecule. Each line should hold string. • Students should hold cards labeled A, T, C, or G to represent the nucleotide pairs. • Have the two lines move away from each other to model how the DNA molecule separates into two strands. • Have free standing students pair up with matching A, T, C, or G cards to show how the open strands replicate. • This one example of how models can be similar to yet different from the natural occurrences they represent. http://www.classzone.com/books/ml_science_share/vis_sim/chm05_pg141_protein/chm05_pg141_protein.html

  19. Making Proteins • Groups of three nitrogenous bases are a code (codon) for making specific amino acids • Strings of amino acids form proteins • RNA (riboneucleic acid) makes a temporary DNA copy Genes: sections of DNA on chromosomes that control production of proteins for specific traits such as: hair color, eye color, dimples, freckles….

  20. RNA vs. DNA Differences: Similarities: • Are nucleic acids • Contain nitrogenous bases • Contain phosphate & sugar molecules Deoxyribose Sugar

  21. Types of RNA • messengerRNA or mRNA: comes from nucleus w/ genetic information for protein synthesis (mirror image of DNA strand). • transferRNA or tRNA: carries matching amino acids to ribosomes. • ribosomalRNA or rRNA: constitutes 50% of a ribosome, decodes mRNA for tRNA to pick-up matching amino acids.

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