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DNA Deoxyribonucleic Acid

DNA Deoxyribonucleic Acid. DNA Structure. What is DNA?. The information that determines an organisms traits. DNA produces proteins which gives it “The power” Many things contain and are made of proteins. Skin, hair, bones, etc are made of proteins. What is DNA? Cont’d.

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DNA Deoxyribonucleic Acid

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  1. DNADeoxyribonucleic Acid

  2. DNA Structure

  3. What is DNA? • The information that determines an organisms traits. • DNA produces proteins which gives it “The power” • Many things contain and are made of proteins. • Skin, hair, bones, etc are made of proteins.

  4. What is DNA? Cont’d • Enzymes are special proteins. • Enzymes control chemical reactions needed for life. • DNA contains all the information for making all and any proteins for human life.

  5. DNA Structure: • DNA is made of repeating subunits called nucleotides. • Nucleotides have three parts: • Simple sugar • Phosphate group • Nitrogen base

  6. 1 Nucleotide Phosphate Group Nitrogen Base Sugar (Deoxyribose)

  7. DNA Structure • The simple sugar is called deoxyribose. • The phosphate group is made of phosphate and oxygen.

  8. DNA Structure • Four possible Nitrogen Bases: • Thymine (T) • Adenine (A) • Cytosine (C) • Guanine (G)

  9. DNA “Backbone” • Nucleotides join together to form long chains. • The phosphate group of one nucleotide joins together with the deoxyribose sugar of an adjacent nucleotide. “Teeth”

  10. DNA • Nitrogen bases pair up • Adenine & Thymine (A-T) • Cytosine & Guanine (C-G) Complementarybases

  11. Watson & Crick, 1953 • Proposed DNA is put together like a “twisted zipper” • DNA = 2 chains of nucleotides joined by nitrogen bases

  12. Watson & Crick, 1953Double Helix • Double = DNA has two strands • Helix = twisted like a spring, “spiral”

  13. Importance of Sequencing • The sequence of the four different nucleotides determines what organism is created. • For instance: T-A-A-G-C-A is different than A-G-C-A-A-G • Another example: E-A-R-T-H is different than H-E-A-R-T vs.

  14. Importance of Sequencing • The more similar the order of nucleotides are, the closer the relationship between 2 organisms

  15. DNA Replication

  16. DNA Replication • Replication = to copy • Process of copying DNA in the chromosomes • Without DNA replication, a new cell would only have half of it’s information.

  17. DNA Replication • DNA Replication Video

  18. DNA Replication 2 • Replication VIDEO

  19. DNA Replication • Because of the pairing- if you have one strand, it is easy to predict the replicated strand. T-A-G-C-C-G-T • Remember: A goes with T, C goes with G A-T-C-G-G-C-A

  20. DNA Replication • Remember: The nitrogen bases are held together by hydrogen bonds • An enzyme goes to those hydrogen bonds and breaks them = Double Helix Unzips

  21. DNA Replication Step 1: Separate the two DNA strands

  22. DNA Replication Step 2: Original DNA strands act as templates & complementary nucleotides fill in.

  23. DNA Replication Step 3: Nucleotides connected and a new sugar-phosphate “backbone” is formed.

  24. DNA Replication Each new DNA molecule consists of one original strand and one new strand

  25. So now what??

  26. DNA to Protein • DNA encodes the instructions for making proteins. • Remember proteins make up your bones, skin, etc. • Enzymes are special proteins • Enzymes control all chemical reactions in an organism

  27. DNA to Protein • Proteins are made up of many aminoacids • The order of nucleotides in each gene has information on how to make the string of amino acids which is a protein. • ESTIMATE: Each cell contains about 800,000 genes

  28. We need to figure out how to get from DNA to Proteins!

  29. RNA What is it? What does it do?

  30. RNA Single Stranded- only half of a zipper Contains the sugar Ribose Contains the nitrogen bases: Adenine Uracil Guanine Cytosine DNA Double Stranded- double helix Contains the sugar Deoxyribose Contains the nitrogen bases: Adenine Thymine Guanine Cytosine RNA vs. DNA

  31. RNA • It’s job: Copying DNA • It’s goal: To create proteins • There are 3 types, each with a different job: • mRNA= Messenger RNA: copies DNA to take it out in the cytoplasm • rRNA= Ribosomal RNA: works on matching mRNA - to create the amino acids in the correct order • tRNA= Transfer RNA: gives amino acids to rRNA to produce the protein.

  32. mRNA • Brings information (in the form of an RNA strand) from the DNA in the nucleus to the cytoplasm

  33. rRNA • Ribosomes are made of rRNA • Where are ribosomes found? Cytoplasm • rRNA attaches to the mRNA and uses its information to set up the amino acids in the correct order Ribosome mRNA

  34. tRNA Amino Acid • The supplier • Brings amino acids to the ribosome so that it can assemble the protein

  35. Review Questions • How does information from the DNA get to the cytoplasm? • How does the zipper get unzipped in DNA replication? • Who does the work in getting the amino acids to the worker? • What is the formal name of the worker

  36. Transcription

  37. Transcription • Transcription’s purpose is to create a single stranded RNA molecule rather than a double stranded DNA molecule. • This is needed to allow the single stranded RNA to be taken out of the nucleus by the mRNA to the cytoplasm.

  38. Transcription • Transcription Tutorial / SHOW • Transcription mRNA VIDEO

  39. Genetic Code with mRNA • In order to take the DNA and create a mRNA, there are special codes used. • In mRNA, three nitrogen bases togetherform a code – this is called a codon. • Looking ahead: • this code is matched with an amino acid. • A string of amino acids form a protein.

  40. Genetic Code with mRNA • Some codons code for information other than amino acids • UAG is an example of a stop codon. • AUG is an example of a start codon. • NOTE: For every one codon, there is only ONE amino acid that can join.

  41. Transcription Pictures

  42. Transcription Pic’s

  43. How does this work in the cell? mRNA COPIES DNA INTO CYTOPLASM NUCLEUS DNA rRNA USES PLAN FROM mRNA TO PUT AMINO ACIDS IN ORDER TO MAKE PROTEINS AMINO ACIDS TRANSPORTED BY tRNA RIBOSOME

  44. Translation

  45. Translation: From mRNA to Protein • The process of changing the information from an order of nitrogen bases in mRNA into the order of amino acids • Occurs at the ribosomes in the cytoplasm

  46. Translation • When mRNA enters the cytoplasm, ribosomes attach • 20 different amino acids must be brought to the ribosomes for proteins to be made • tRNA brings the amino acids to the mRNA strand

  47. Translation Amino Acid • On the opposite side of the tRNA amino acid side is a set of three nucleotides that are the complement of the nucleotides codon • This is called an Anticodon

  48. Translation • When a match is made between codons and anticodons- a temporary bond is formed. • This places the amino acid in the correct position to enable it to bond with the next amino acid

  49. Translation • The next tRNA bonds to it’s codon and then the two amino acid’s bond together. • The first amino acid then releases itself from the mRNA

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