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DNA and RNA

DNA and RNA. The Code of Life. Genes. 1. Genes are inherited characteristics passed from one generation to the next. 2. Genes are segment of DNA on a chromosome, which codes for a specific trait.

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DNA and RNA

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  1. DNA and RNA The Code of Life

  2. Genes 1. Genes are inherited characteristics passed from one generation to the next. 2. Genes are segment of DNA on a chromosome, which codes for a specific trait. 3. Chromosomes are made of protein and DNA. DNA stands for deoxyribonucleic acid (dee AHKS ee RIE boh noo KLEE ik AS id).

  3. The Gene(tic) Code Q. What is the main function of a gene? • To control the production of protein in an organism’s cell. Q. Why does the cell need to produce protein? A. Proteins help determine the size, shape, and many other traits of an organism.

  4. Genetic material that carries information about an organism and passes inherited traits from parent to offspring. What is DNA? (deoxyribonucleic acid)

  5. Who discovered DNA? • Chargaff Rules -1950s, a biochemist found that the amount of: adenine always equals the amount of thymine (AT) and guanine always equals the amount of cytosine (GC) • Chemist Rosalind Franklin was able to make images of DNA molecules that suggested DNA has a spiral shape. HOWEVER • James Watson and Francis Crick used the information from Chargaff’s x-rays and Franklin’s findings to build a model of DNA molecule.

  6. DNA • What is the Main Job of DNA? • It contains the code for the proteins an organism may produce. • What are the basic units (or monomers) of DNA? • Nucleotides make up DNA. • Where is DNA found? • It is found mostly in the nucleus of a cell making up its chromosomes.

  7. DNA is made of subunits called nucleotides. A nucleotide consists of a sugar, a phosphate, and a nitrogenous base. The nucleotides are identical except for the base. Most importantly it contains the Code for ALL the proteins in the body. But what does DNA look like?

  8. The four nucleotides of DNA • The four bases are adenine,thymine, guanine, and cytosine. Each base has a different shape. Scientists often refer to a base by the first letter of the nitrogen base, A,T, G, and C

  9. Always pair up the same way A – T Adenine (A) and Thymine (T) G – C Guanine (G) and Cytosine (C) Pairing of bases allows the cell to replicate, or make copies of, DNA. DNA Nitrogenous Bases

  10. DNA is copied (replicated) each time a cell divides, so that each cell contains identical genes. During replication a DNA molecule is split down the middle, where the bases meet. The bases on each side of the molecule are used as a pattern for a new strand. As the bases on the original molecule are exposed, complementary nucleotides are added to each side of the ladder. Two DNA molecules are formed. Half of each of the molecules is old DNA, and half is new DNA.

  11. Replication of DNA

  12. Protein SynthesisHow does the cell know how to produce a specific protein for a size, shape or trait? • Order of the nitrogenous bases (genetic code) specifies what type of protein will be produced. • A group of three bases determines the code for an attachment of a specific amino acid. • This code tells the cell which amino acid to add to the growing protein chain.

  13. Genes and Proteins • The DNA code is read like a book • It is read in only one direction • The bases form the alphabet of the code. • Groups of three bases are the codes for specific amino acids. • A long string of amino acids forms a protein. Thus, each gene is usually a set of instructions for making a protein.

  14. The Making of a Protein The Problem??? • Protein synthesis (process in which cells build proteins) takes place in the ribosomes in the cytoplasm outside the nucleus. • The chromosomes are inside the nucleus. How does the information needed to produce proteins get out of the nucleus into the cytoplasm???

  15. Protein Synthesis “Transcription” The first step in making a protein is to copy the genetic code (like a recipe) one side (single strand) of the segment of DNA. This copy of the DNA segment is called messenger RNA (mRNA).

  16. Here comes the role of mRNA! • What is the Main Job of mRNA? • To deliver to the Ribosomes (protein maker). the code for making a protein. • mRNA travels from inside the nucleus to the Ribosome in the cytoplasm.

  17. Four Nitrogen Bases the make up the mRNA molecule RNA nitrogenous bases always pair up the same way A – U Adenine (A) and Uracil (U) G – C Guanine (G) and Cytosine (C) What is difference between DNA and RNA nitrogenous bases?? Adenine pairs up with Uracil Just so you can tell it is the copy!!

  18. “Translation” in the Ribosome produces Protein Synthesis • 3 base pairs make up a code (message) called a codon for protein synthesis. • Ribosome reads the message on the mRNA molecule and the tRNA (transfer RNA which is floating in the cytoplasm) molecule brings in the appropriate amino acids. • A chain of these amino acids is known as a polypeptide chain. • A stop code ends the process and the polypetide chain stops then Protein synthesis takes place.

  19. RNA • RNA is made up of Ribose Sugar, Nitrogenous base pairs, and phosphate • RNA assists DNA in manufacturing needed proteins

  20. Questions • Name one difference between DNA and RNA. • DNA – Double Helix RNA – Single Stranded • DNA pairs A-T RNA pairs A-U 3. DNA ---Deoxyribose Sugar RNA---Ribose • What is a similarity of DNA and RNA? • G binds with C in both DNA and RNA • Both have sugar and phosphate backbone

  21. Practice • On your paper, complete the missing DNA strand by adding the complementary bases. • A T C G T T G C C A T C • T A G C A A C G G T A G • Make the complementary RNA strand for the single strand of DNA below: • A A T C A T C A C G T T • U U A G U A G U G C A A

  22. Get Your DNA Jewelry

  23. Elaborate:Make a your DNA Model • Color the following nitrogenous bases: Cytosine - Yellow Adenine - Red Guanine - Green Thymine – Blue Color the Phospate – Black Color the Deoxyribose - Pink

  24. Analysis: • Name 2 molecules which make up the side or upright portion of a DNA molecule. ____ and _____ • Name the molecules which form the rungs or steps of the ladder___,___,___,___ and how they pair up. • List the 4 pairs of nitrogenous bases that your DNA molecule show. Use abbreviations

  25. DNA Replication • Open your DNA model along the point of attachment between base pairs and separate the 2 ladder halves (unzip in the middle). • Using the left half of your model as a pattern, add new nitrogen base units to form a new right side. • Build a second DNA model by adding new nitrogenous bases to the right half of the original model.

  26. Review/Explain:Types of Nucleic Acids What are the two types of nucleic acids? 1 - DNA (Deoxyribonucleic Acid) Double Helix or a Twisted Ladder 2 - RNA (Ribonucleic Acid) Single Stranded

  27. ANALYSIS • Do the 2 new molecules contain the same number of nitrogenous bases? • Compare the order of nitrogenous base pairs from top to bottom for each of the two molecules. • When does DNA replication take place? In what cell structure does DNA replication occur?

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