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DNA and RNA

DNA and RNA. Ch. 12. They were done to determine whether genes are made up of DNA or protein. He injected bacteria into mice in four separate experiments. Griffith’s Experiments. S bacteria caused pneumonia and death when injected. R bacteria had no visible effect.

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DNA and RNA

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  1. DNA and RNA Ch. 12

  2. They were done to determine whether genes are made up of DNA or protein. He injected bacteria into mice in four separate experiments. Griffith’s Experiments

  3. S bacteria caused pneumonia and death when injected. R bacteria had no visible effect. Heat killed S bacteria did no harm. Heat killed S and live R were injected and the mouse died of pneumonia. Streptococcus pneumonia bacteria were used. S strain was smooth and caused pneumonia. R strain was rough and did no harm. His results..

  4. If the mice died with S and heat-killed S and R, but not when S was heat-killed or R by itself, then there had to be some transforming material that was transformed from the heat-killed S to living R changing it into S bacteria. What was this transforming material? DNA What can we conclude?

  5. Repeated Griffith’s experiment. Discovered that it is the nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next. Oswald Avery

  6. 2 experiments. Used bacteriophages (viruses) that injected radioactive material into bacteria. They they looked to see if the bacteria became radioactive. Phages with green radioactive DNA 32-P injected it into bacteria and the bacteria became radioactive. Phages with green radioactive protein 35-S injected it into bacteria and it did not become radioactive. Hershey and Chase’s Experiment What can we conclude?

  7. Remember that the structure of a molecule is related to its function, so knowing what a molecule looks like gives researchers insight into how DNA works. What do you know about DNA? Deoxyribonucleic acid Double Helix 5’C sugar, Deoxyribose Phosphate Group 4 Nitrogen Bases First double helix structure built by Watson and Crick Published in 1953 DNA Structure Nucleotide

  8. Rosalind Franklin used X-ray diffraction to reveal the shape of DNA. Discovery of DNA: X-Ray evidence • The X-shaped pattern shows that the strands of DNA are twisted around each other.

  9. Purines- larger Adenine and Guanine Pyrimindines- smaller Cytosine and Thymine Purines and Pyrimidines make up the 4 N bases Pairing of the bases in the DNA structure: Chargaff’s Rule (amount of A = amount of T and amount of C =amount of G A—T C—G

  10. The shape of DNA is that of a “twisted ladder”. The P group is attached to the sugar and that forms the backbone. The “rungs” of the DNA are the pairing of the bases. Watson and Crick Double Helix

  11. DNA ReplicationSemi-conservative The DNA unzips. Enzymes split apart the base pairs and unwind the DNA. Free nucleotides in the cell find bases to pair up with on each side along the “open” DNA via DNA polymerase. The sugar-phosphate backbone completes the 2 new DNA strands. Each strand has a new and old strand. DNA Replication Simulation

  12. DNA Double Stranded Base Pairs (A-T, G-C) Deoxyribose sugar RNA Single Stranded Base Pairs (A-U, G-C) Uracil is used instead of Tymine Ribose Sugar DNA vs. RNA

  13. Process when the organism’s genotype is translated into it’s phenotype. Remember that proteins are made up of chains of Amino Acids. How many a.a. are there? 2 Processes Transcription- DNA to RNA Translation- RNA Protein Protein Synthesis • 1.26 The genetic material in DNA molecules provides the instructions for assembling proteins. This works the same in nearly all life forms.

  14. RNA polymerase unwinds a section of DNA RNA polymerase binds unattached RNA nucleotides to complementary DNA strand. A new strand of mRNA (messenger RNA) is made. DNA will signal RNA pol to leave and transcription stops. It occurs in the nucleus. Tutorial Transcription

  15. Before mRNA can leave the nucleus, RNA must be spliced. It gets rid of introns and exons are spliced together. mRNA now leaves the nucleus and into the cytoplasm where it finds a ribosome. Introns- non-coding regions of DNA or RNA. Exons-coding regions RNA splicing

  16. Codon- 3 base sequence of mRNA that codes for an amino acid. Anti-codon: complementary 3 base sequence to mRNA on a tRNA. rRNA- ribosome where amino acids are put together. tRNA (transfer RNA)- matches up anticodons to codons to make amino acids that form proteins. Things to Know before we go on.

  17. rRNA attaches to first codon on mRNA. A tRNA brings an a.a. to the rRNA with the anti-codon and matches it up with the codon. 3. A 2nd tRNA brings in the next one and then a peptide bond bonds the 2 a.a. together. It moves over and the 1st one leaves so the next one can come in. Translation http://www.rothamsted.bbsrc.ac.uk/notebook/courses/guide/trad.htm

  18. AUG- Methionine is the Start Codon. There are 3 Stop Codons: UAA, UAG, and UGA. Starting and Stopping Translation

  19. Protein synthesis

  20. A random change in the sequence of nucleotides in DNA is a mutation. Chromosomal mutations- involve whole chromosomes. Gene mutations- result from changes in a single gene. 4 types of mutations: Deletion Duplication Translocation inversion 1.23a Inserting, deleting, or substituting DNA sequences can alter a gene.

  21. When a chromosome breaks and a piece of it is lost. Chromosomal Deletion

  22. When a part of the chromosome breaks off and is incorporated into its homologous chromosome. Duplication A B C o D E F A B B C o D E F

  23. Occurs when part of a chromosome breaks off and attaches to a different, nonhomologous chromosome. Translocation

  24. Occurs when part of a chromosome breaks off, turns around, and reattaches in the reverse order. Inversion

  25. When nucleotides are deleted or added, it changes the order or code of the codons, results in different a.a. Frameshift mutations (Gene mutation)

  26. Occur when there is only one change in the nucleotide. It only changes one a.a. coded for. Substitution Point Mutations (Gene mutation)

  27. Occurs when a large stretch of DNA is inserted into the gene. 1.28b Genetic variation occurs from crossing over, jumping genes and deletion and duplication of genes. Jumping Genes

  28. When nondisjuction occurs in all chromosome pairs. Occurs often in plants and can make them “robust”. (Plants have too many chromosomes) Polyploidy

  29. When genes are changed, the proteins they code for may change and this can affect cell structure and function,which changes a phenotype. The control of gene expression (protein synthesis), is different in prokaryotes and eukaryotes. Structure Determines Function

  30. Prokaryotes Genes turn on and off primarily in response to changes in environmental factors. 1.1b Different parts of the genetic instructions are used in the different kinds of cells and are influenced by the cell’s environment and past history. Eukaryotes Gene regulation involves several complex systems. Most eukaryotic genes are controlled individually and have regulatory sequences that are much more complex. TATA box Gene Expression

  31. Operons • A group of genes that operate together are known as operons. • In E.coli there are 4288 protein encoding genes that are turned off and on together. • Because the genes must be expressed in order for the bacterium to be able to use the sugar lactose as food, they are called lac operon.

  32. The regulatory gene codes for production of the repressor that binds to DNA, preventing RNA pol from binding to the promoter. Protein synthesis can’t occur. Gene Regulation in Prokaryotes Lac genes (operon)- group of genes that operate together.

  33. 2. Enzymes bind to the repressor and changes it’s shape so it can’t combine to DNA. Now, RNA pol can bind to promoter. The repressor is inactivated.

  34. 3. RNA pol moves along DNA where mRNA is translated to produce product. When there is enough “product” in the cell, the repressor takes back original shape and turns genes back off. The Genes are On

  35. An analogy to gene control would be when a house gets below a certain temp. the furnace kicks on and when it is hot enough it turns back off. What would the promoter be? Analogy of Gene Regulation in Prokaryotes

  36. Gene Expression in Eukaryotes • TATA box is about 30 bp long and helps RNA polymerase to find position by marking a point just before the point for transcription to begin.

  37. Development and Differentiation • Differentiation- cells become specialized in structure and function. • Hox genes- control the differentiation of cells and tissue in the embryo. A mutation can completely change the organs that develop in specific body parts. Legs instead of antennae on fruit fly can grow on head.

  38. Hox gene clusters What do you recognize about where each gene controls in each organism?

  39. DNA and RNA review • Go to the following link and click on your book. Go to Ch. 12. Take the self-test and do the Active Arts. • Ch. 12 Review

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