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DNA Replication & Protein Synthesis

DNA Replication & Protein Synthesis . DNA. Deoxyribonucleic Acid (DNA) is found in what part of the cell?. Nucleus. What is DNA made of?. Monomers called Nucleotides (Biochemical group Nucleic Acid: 3 parts: Sugar (deoxyribose) Phosphate group Nitrogen base. NUCLEOTIDES.

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DNA Replication & Protein Synthesis

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  1. DNA Replication & Protein Synthesis

  2. DNA • Deoxyribonucleic Acid (DNA) is found in what part of the cell? Nucleus

  3. What is DNA made of? • Monomers called Nucleotides (Biochemical group Nucleic Acid: • 3 parts: • Sugar (deoxyribose) • Phosphate group • Nitrogen base

  4. NUCLEOTIDES • Named for the base it contains • Looks like: Sugar-----------Adenine | phosphate THIS IS AN ADENINE NUCLEOTIDE

  5. A nucleotide

  6. DNA Structure • 2 Nucleotide monomersare linked by a bond between the SUGAR of one nucleotide & the PHOSPHATE of the next nucleotide. (Dehydration Synthesis using an enzyme) • More monomers are added on the end to form a long polymer

  7. Monomers are linked on the end to form a Single Long Strand • This “backbone” formed by linking sugar to phosphate forms the “sides” of the DNA ladder: the STRONG, backbone of the DNA strand (polymer)

  8. But DNA is double stranded- How are the 2 DNA strands held together? • Pairing of nitrogenous bases(by hydrogen bonds)! • The “steps” of the ladder are the same distance across- ALWAYS a purine (2 ring) with a pyrimidine (1 ring) • Adenine (pur) pairs with thymine(pyr); Guanine (pur) pairs with cytosine (pyr)

  9. Bases Bond to Join 2 DNA Strands (polymers) • Joined pairs of nucleotides are called “base pairs” (PO4) | Sugar----A---T----Sugar | (PO4)

  10. MORE ABOUT THE BASES… • Adenine always bonds to thymine • Cytosinealways bonds toguanine

  11. Adenine –Thymine (A-T) • Cytosine-Guanine (C-G)

  12. DNA is a Double Stranded Molecule • The four bases (ATGC) form complementary pairs in the double helix. • This means that: • A always pairs with T. • G always pairs with C.

  13. Double stranded DNA….. • If one strand is ACGCAATTGCATT • The other is TGCGTTAACGTAA • This also makes it possible for DNA copy it’s self…

  14. BUT THERE’S MORE… • The DNA molecule isn’t flat, it’s 3-D!!! • The whole thing coils to look like a “spiral staircase”

  15. What are Chromosomes? • Structures the DNA forms (with proteins) to allow ALL of it to fit in the nucleus • All the DNA from 1 of our cells is 6-1/2 FEET long!!! • Our cells have 23 different pairs of chromosomes- 46 total. • These store ALL the genetic information to make YOU!!!!

  16. What has to happen before a cell divides? • All the DNA has to be copied, so there will be 2 sets of chromosomes in the cell • This way, BOTH daughter cells (after division) will contain the SAME genetic information as the parent cell.

  17. How does Replication happen? • DNA strands separate at the ‘origin’ & the DNA ‘unzips’ • Enzymes (protein machines) match free nucleotides to each ‘parent strand’ • & bonds them to the backbone of the newly synthesized strand.

  18. Initiation of Replication

  19. Semi-conservative Replication • Replication is like making a second identical copy of each DNA strand. • The 2 strands separate, and each is copied separately. • This makes 2 double stranded molecules that have one parent strand and one new strand.

  20. This is called Semi-Conservative Replication. • Each new ‘Daughter’ DNA has 1 copy of parent DNA (dk blue) and one new strand of DNA (light blue).

  21. Summary: • DNA replication results in 2 identical copies from 1 original. • Each ‘daughter’ DNA contains 1 ‘parent’ strand and 1 ‘new’ strand • Because base pairing is always complimentary (A-T; G-C), replication enzymes can use the parent strand as a ‘template’.

  22. Fill in the Newly synthesized Strand. • A T C G T G G C T A ATTGGCC…. T CCGG….

  23. What is the role of DNA? • Store ALL the information • The material genes are made of… • Gene - segment of DNA that carries the information necessary to make a protein. • How is the information stored? - The order of the DNA bases!!

  24. Genes, cont… • A gene is usually thousands of bases long! • Because a gene is a series of DNA bases that codes for a protein, the information for the protein is encoded in the sequence (order) of the four DNA bases, ATGC.

  25. The DNA in a single human cell = 3,000,000,000 bases (3 billion) • However, scientists were surprised that there are only about 30,000 genes!!

  26. How is the information used by the cell? • It needs to change languages to a form the cell uses to do work- PROTEINS • But first, the gene needs to be COPIED!

  27. Transcription • Genetic information in DNA is copied to mRNA. • Where does it happen? • What is mRNA? • Why is it necessary?

  28. Answers: • Nucleus • messenger RNA • Needed to transport coding info from the nucleus to the ribosomes.

  29. How is RNA different from DNA? • RNA= ribonucleic acid; • Ribose sugar; phosphate; nitrogen base • Adenine, Guanine, Cytosine, and URACIL (base pairs= C-G; A-U) • Single Stranded

  30. Transcription has three main phases: • Initiation • Elongation • Termination

  31. Initiation – RNA polymerase binds to DNA at the START sequence (Promoter) & DNA uncoils • Elongation – Complimentary nucleotides are added along the sense strand

  32. 3. Termination – When it reaches the stop sequence in the DNA, the RNA polymerase is released from DNA

  33. Transcription Animation • http://www.johnkyrk.com/DNAtranscription.html • http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/transcription.swf

  34. mRNA Splicing – Non-coding sequences (introns) are removed and coding (exons) are spliced together to make mature mRNA

  35. Overview of Protein Synthesis

  36. Transcribe! • Write the DNA sequence of a gene (at least 36 nucleotides long.) • Transcribe the sequence of the gene into mRNA

  37. What happens next- TRANSLATION • What do you do when you go from one language to another? You TRANSLATE! • Languages? nucleic acid is translated to amino acid (protein)

  38. Translation, cont. • Key “Players”: • mRNA • tRNA (transfer RNA) • Ribsosomes • Amino acids • Where does it happen? • The CYTOPLASM

  39. mRNA is the instructions for building the protein • How is the info stored? • In the order of the bases!!! (A,C,U,G) • Translation takes place on the ribosomes (machine that makes the protein) • tRNA (transfer RNA) “reads” the nucleic acid and supplies the CORRECT, corresponding amino acid

  40. CODON • These serve as the “words” in the genetic code • A codon is made up of three nucleotide bases (A, U, G, C). • Each codon specifies an amino acid (MONOMER) in the protein being made (POLYMER) • The codon is “read” by the tRNA anticodon and the correct amino acid is linked to the growing polypeptide chain

  41. Quick Quiz • The process where genetic information is copied from DNA to mRNA is called ___________. • List 3 differences between DNA and RNA • List the 3 phases of transcription. • Write the complimentary RNA sequence for the following DNA sequence: AAGGCCTTAGACTGT

  42. Quick Quiz, cont… • The process of synthesizing a protein FROM the mRNA is called ________________. • How many nucleotides in a codon? • The anticodon is part of the _________. • The codon is part of the ___________. • What “machine” is necessary for translation to take place? • What is the monomer of a protein?

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