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Microbiology Chapter 9

Microbiology Chapter 9. Genetics - Science of the study of heredity, variations in organisms that are transferable from generations to generation

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Microbiology Chapter 9

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  1. Microbiology Chapter 9 Genetics - Science of the study of heredity, variations in organisms that are transferable from generations to generation DNA is the key to understanding genetics, DNA is the genetic material of life and the macromolecule is responsible for storing all the information necessary to the function of an organism Genes – units of heredity, segments of DNA; they code for functional products (proteins) – these products, cause something – synthesis of pigments, enzymes etc. Result in some observable trait Genome is the total genetic information in a cell (all of the potential information, coded in the total DNA)

  2. Microbiology Chapter 9 DNA double helix, two strands held together by Hydrogen bonds

  3. Microbiology Chapter 9 Chromosome – structures that carry the DNA (genes), often in Eukaryotic organisms there is protein associated with the genes. Chromosomes - can have many linear ones as in the eukaryotic cells. Single and circular chromosomes in bacteria Plasmids – bacteria can have an extra piece of genetic information separate from the chromosome (extrachromosomal DNA)

  4. Microbiology Chapter 9

  5. Microbiology Chapter 9 Genotype – the genetic make up of an organism, sum total of all the information (expressed and unexpressed) Phenotype – the actual expressed information (what you can see or detect) color of a colony, abilities to ferment sugars, etc.

  6. Microbiology Chapter 9 Serratia marcesens; temp. dependent colony pigment, genotype for pigment, cooler temp. than 37 to see it; Phenotype

  7. Microbiology Chapter 9 Structure of DNA - its chemical make up (transparency of pg 251) 3 parts: 5 carbon sugar (deoxyribose), a nitrogenous base, and a phosphate 1. Together they form what we call a nucleotide 2. There are four bases so there are four possible nucleotides 3. These are adenine, guanine, cytosine, thymine (A,G,C,T) 4. These nucleotides are combined to form long chains 5. In DNA the chains are paired into a ladder like double helix 6. The bases on one chain pair with bases on the corresponding chain by weak hydrogen bonds (A-T and G-C)

  8. Microbiology Chapter 9 DNA double helix, two strands held together by Hydrogen bonds

  9. Microbiology Chapter 9 • ******* BE SURE TO LOOK OVER FIG. 9.5 PG 252. 9.6, pg 254 Go to web and view the animation on Mcgraw-Hill web site******* Slide 13 • DNA replication – the process of making an exact copy of DNA molecule • DNA replication has to occur before cell division in order for each cell to have a copy of • the genetic information • One strand of DNA acts as template for the formation of the corresponding strand • 2. Replication is carried out in an orderly sequence • a. It is biosynthesis, making macromolecules from smaller nucleotide subunits • b. ATP is used to drive this biosynthesis process • 3. Replication starts by unwinding of the double helix and the two strands separate exposing the now unpaired nitrogenous bases • a. The two strands act as templates for the formation of the other strand

  10. Microbiology Chapter 9 DNA replication

  11. Microbiology Chapter 9 b. Specific enzymes are required and of course the precursor molecules must be available c. The most important enzyme is DNA polymerase d. The enzyme cause bonds to form and new chains are formed – everywhere on the parent strand an adenine appears, a thymine will be linked to form the compliment on the forming daughter strand (see page 252, 254) e. Note that the forming strands are linked by joining phosphate of one nucleotide monomer with the OH of the other (note the nucleoside has a tri-phosphate and two phosphates are removed when one nucleoside is joined to the other) f. Each chain has a 3’ end and 5’ end (pg 254) – lots of detail and we can’t begin to cover it all

  12. Microbiology Chapter 9 Remember: Helicase DNA polymerase - one on leading strand, continuous DNA polymerase - one on lagging strand, discontinuous Requires Ligase to stitch the pieces together We will see it in animation on the DNA video

  13. Fig. 9.5

  14. Microbiology Chapter 9 • Transcription: PG. 259 The assembly of a complimentary mRNA strand from a DNA template • (remember there are 3 kinds of RNA: mRNA, rRNA, tRNA) • Messenger RNA carries a message to site of protein synthesis – make a chain of amino acids with this specific sequence • 2. Transfer rRNA is involved in protein synthesis, it carries the amino acids to the ribosome where they are assembled (SEE PG. 258, 260, 262) • 3. Ribosomal RNA forms the ribosome unit where proteins are assembled • DNA codes for a specific messenger RNA with a specific sequence of nucleotide bases • (RNA has ribose, and the bases are adenine, guanine, cytosine, and uracil) A pairs with U and of course G pairs with C, (A-U, G-C)

  15. Microbiology Chapter 9

  16. Fig. 9.8

  17. Microbiology Chapter 9 RNA polymerase is the enzyme that causes mRNA to form Translation: the process of actually translating the genetic information, coded on DNA, transferred to mRNA and then expressed by the specific synthesis of a particular protein see pages 260 - 263 1. Codon – triplet code on the mRNA 2. Anticodon – corresponding code on tRNA 3. tRNA carries specific amino acid, codon-anticodon match insures proper sequence of amino acids (see pg. 261 – codons code for only specific amino acids) transparency

  18. Microbiology Chapter 9 Transcription – to Translation As Polypeptide forms it coils and folds into a specific shape

  19. Figure 9.9

  20. Figure 9.10

  21. Figure 9.12

  22. Figure 9.13

  23. Figure 9.14

  24. Figure 9.16Very “too” Cool

  25. Figure 9.18 Differences in eukaryote and prokaryote DNA: Exon and introns Exons: Coding regions; genetic information, transcribed and then translated Introns: Interspersed between exons, and don’t code for protein

  26. Microbiology Chapter 9 • Mutations: an inheritable change in an organisms genetic information, in its DNA • Can be simple as one base pair, or complex involving many bases • 2. Can be natural (spontaneous - random mistakes), biological (jumping genes – transposable elements – transposons – can jump around and when inserted they can alter the genetic make up of a cell) • 3. Induced – created in the laboratory as result of use of chemicals (mutagens) or radiation

  27. Transformation: Naked DNAfig. 9:24

  28. Conjugation: Sex pilus and plasmidFigure 9.23

  29. Transduction; Phage assisted DNA transfer

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