CHAPTER 8 MICROBIAL GENETICS: BIO 244 MICROBIOLOGY the structure of _______ how ______ carry information how information is _________ and how _______ are replicated

GENETIC TERMINOLOGY _______ segment of ___ that codes for a trait or product, usually a protein _____TYPE genetic makeup (genes) of an organism ______TYPE expression of genes

BACTERIAL __________

_________ CHROMOSOMES __________ _ CHROMOSOMES _________ CHROMOSOMES

_________ ACIDS _________ ________ Information Molecule Double-stranded helix of nucleotides Protein Synthesis Single-strand of nucleotides Energy Storage Single nucleotide

_______________ Polymer of __________: 1.phosphate 2.sugar 3._____ (adenine, thymine, cytosine, guanine) Double Helix: associated with proteins "Backbone”: deoxyribose-phosphate __________ Bonds: found between AT and CG; hold strands together ____________ strands Figure 8.4

DNA REPLICATION semi-_____________ mechanism Double-stranded helix __________ Each strand serves as a ________ for synthesis of new strand Each new double-stranded DNA helix contains: One original strand from parent One new strand Figure 8.3

Semi-conservative Replication of DNA

DNA REPLICATION SUMMARY Semi-Conservative Mechanism DNA is copied by DNA _______________ In the _________ direction Initiated by an RNA primer _________ strand synthesized continuously ________ strand synthesized discontinuously Okazaki fragments RNA primers are removed and Okazaki fragments are joined by _______________ and DNA ligase

DNA SYNTHESIS Figure 8.6

RIBONUCLEIC ACID (RNA) TYPES of RNA: Messenger RNA (mRNA) Complementary to base sequence in ______ Carries genetic information from DNA to ribosomes Ribosomal RNA (rRNA) Makes up ___________ Functions in protein synthesis Transfer RNA (tRNA) Transports __________ to growing peptide chains in ribosomes FUNCTION: protein synthesis STRUCTURE: Single-stranded chain of nucleotides _________ replaces thymine Ribose sugar

Big Picture pg. 202 (2 of 9).

PROTEIN SYNTHESIS 2 Step Mechanism: 2. ____________ - Takes place in the ribosome - Information in mRNA is translated into a sequence of ________________ - Involves mRNA, ribosomal RNA (rRNA) and transfer RNA (tRNA) 1. ________________ - Takes place in the ____________ - _________copy of DNA-base sequences is made - Involves DNA and messenger RNA (mRNA)

TRANSCRIPTION -Involves ____ and ____ -Takes place in the nucleus 1. RNA polymerase binds to promoter sequence in DNA 2. mRNA is made by complementary base pairing of free nucleotides with the nucleotide bases on the template strand of DNA 3. DNA that has been transcribed __________ 4. Messenger RNA and RNA polymerase are released and DNA helix reforms

______ and CORRESPONDING AMINO ACIDS CODON- a sequence of 3 bases in _______ molecule: -Specifies a single amino acid Start codon = AUG-specifies the start of protein synthesis Stop codon = UAA, UAG, UGA-specifies the end of protein synthesis -Universal All species use same mRNA codons to specify same amino acids Figure 8.9

__________________ Information in mRNA is translated into a sequence of ___________ that result in proteins -Takes place at the ribosome -Involves __________________ -Information for each amino acid is contained in mRNA codons (3 nucleotides) -Translation of mRNA begins at the START codon: AUG -Translation ends at a STOP codon: UAA, UAG, UGA Figure 8.2

The Process of Translation Figure 8.9

The Process of Translation Figure 8.9

The Process of Translation Figure 8.9

The Process of Translation Figure 8.9

GENE _____________ The majority of genes within a cell do function most of the time Some genes __________________ Some genes ______________________ Two major types of genes: STRUCTURAL: Contain information that code for amino acids REGULATORY: Control expression of structural genes Model representing structural and regulatory genes in prokaryote: LAC OPERON: a model representing regulation of gene expression

_______________ Groups of genes that interact as a unit to control the use or synthesis of metabolic products Model representing structural and regulatory genes in prokaryotes. Model representing regulation of gene expression in prokaryotes. Figure 8.14.1

_____________ OPERON Model for ___________ gene regulation in prokaryotes Represents induction of enzymes involved in lactose catabolism FEATURES: Regulator (I) gene – codes for repressor protein Lac Operon _________ region Promotor - where RNA polymerase initiates transcription Operator – on/off switch for transcription __________ Region Genes for three enzymes involved in lactose catabolism Induction-process that _______ gene transcription

REGULATION of GENE EXPRESSION: Repression of Lac Operon ________ gene expression and synthesis of one or more enzymes Figure 8.14.2

REGULATION of GENE EXPRESSION: ___________ of Lac Operon Figure 8.14.4

INDUCIBLE OPERON – Lac OPERON ____________________ If enzyme substrate (lactose) is absent – no enzyme synthesis Repression protein binds to operator – no transcription of enzymes __________________ Enzyme substrate (lactose) present – enzyme synthesis Repressor binds to ___________, not operator – enzymes are transcribed Inducible transcription of enzymes

Enzymatic Regulation of Gene Expression Enzymes involved in gene expression: ____________ enzymes Expressed at a fixed, constant rate Ex.: enzymes of glycolysis Repressible enzymes Inducible enzymes Not always needed Regulated by mRNA transcription

CATABOLIC REPRESSION Ability of ____________ to repress enzymes needed for lactose utilization (catabolism)

MECHANISMS of GENETIC REGULATION ___________ GENETIC _____________ Transformation Conjugation Transduction TRANSPOSONS

______________ Change in genetic material Mutations may be neutral, beneficial or harmful MUTAGEN: agents that cause mutations; agents that alter DNA: _________________ Ultraviolet (uv) -causes harmful covalent bonds between adjacent pyrimidine bases Ex.: thymine dimers ___________ Nitrous Acid – changes nucleotide base pairs. Ex. A is changed; binds to C instead of T Nucleoside analogs SPONTANEOUS MUTATIONS: occur in the absence of a mutagen

GENETIC TRANSFER and RECOMBINATION ________ Gene Transfer: Occurs during reproduction, between generations of cells Transfer of genes between cells of the same generation RECOMBINATION ________________ ______________

_______________ Figure 8.25

GENETIC EXCHANGE in BACTERIA Natural processes by which bacteria can gain new genetic material TRANSFORMATION DNA is taken up from _______________ CONJUGATION Plasmid (extrachromosomal DNA) is taken up from environment involving ______________ TRANSDUCTION _________phages act as vectors of DNA transfer between bacteria

______________________ Figure 8.24

_______________ * ___ plasmids are one type of plasmid Figure 8.27a

Recipient bacterial DNA ______________ Phage protein coat Bacterial chromosome Recombinant 1 A phage infects the donor bacterial cell. 2 Phage DNA and proteins are made, and the bacterial chromosome is broken down into pieces. Bacterial DNA Donor bacterial DNA Recipient bacterial DNA Phage DNA Recipient cell Recombinant cell 3 Occasionally during phage assembly, pieces of bacterial DNA are packaged in a phage capsid. Then the donor cell lyses and releases phage particles containing bacterial DNA. 4 A phage carrying bacterial DNA infects a new host cell, the recipient cell. 5 Recombinant can occur, producing a recombinant cell with a genotype different from both the donor and recipient cells. Figure 8.28

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