Chapter 23 - 204-325 1 Summary of the Last Lecture Most...

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Unformatted text preview: 204-325 1 Summary of the Last Lecture Most cancers result from mutations of multiple genes, including protooncogenes, tumor-suppressor genes and mutator genes. The tumor-suppressor gene products normally inhibit cell proliferation. The products of proto-oncogenes normally stimulate cell proliferation. The mutator genes are required for DNA replication and repair in normal cells. Some cancers are caused by viruses, including DNA virus and RNA retrovirus. 2 Today's Topics 1. Extranuclear Genomes 2. Non-Mendelian Inheritance of the Extranuclear Genes 3. Maternal Effect 4. Genomic Imprinting 5. Protein-based Inheritance 3 Topic 1 Extranuclear Genomes 4 Mitochondrion 5 Mitochondrial DNA Replication (D Loop Model) Semi-conservative, continuous 6 Human Mitochondrial Genome 7 Human Mitochondrial Genome Encodes 13 Peptides None Coding NADH Dehydrogenase Cytochrome C ATP Synthetase 8 Yeast and Human Mitochondrial Genome 9 Differences between "Universal" and Mitochondrial Genetic Codes 10 Cytoplasmic and Mitochondrial Ribosomes 11 Chloroplast 12 Chloroplast Genome of Rice 13 Endosymbiotic Origin of Mitochondrion and Chloroplast 14 Topic 2 Non-Mendelian Inheritance of the Extranuclear Genes 15 Most if not All Cytoplasm Comes from Egg 16 Variegation in the Four O'clock 17 Another Variegated Plant (Tomato) 18 Maternal Inheritance of Chloroplast 19 Inheritance of Shoot Color in the Four O'clock 20 Animation 1: Maternal Inheritance 21 Maternal Inheritance of Mitochondrial DNA 22 The Concept of Mitochondrial Eve Mitochondrial Eve female male 23 Mitochondrial Eve Mitochondrial Eve ~200,000 yr 24 Out of Africa Model 25 Human Migration According to Out of Africa Model 26 Reciprocal Crosses of [poky] and Normal Neurospora 27 Mendelian Inheritance of nuclear petite 28 Non-Mendelian Inheritance of neutral petite 29 Non-Mendelian Inheritance of suppressive petite 30 Uniparental Inheritance of Chloroplast in Chlamydomonas 31 Cytoplasmic (Non-Mendelian) Inheritance of Virus Chapter 7 32 Uniparental (Non-Mendelian) Inheritance Several Mechanisms for Uniparental Inheritance 1. Mating involving two parental cells of very different sizes 2. Extranuclear DNA from one parent is destroyed in the zygote 3. Organelles from one parent replicates faster then the others 4. One extranuclear genotype is dominant over the other 33 Topic 3 Maternal Effect 34 Most if not All Cytoplasm Comes from Egg 35 Maternal Effect: Inheritance of Shell Coiling in Snail 36 Animation 2: Maternal Effect 37 Topic 4 Genomic Imprinting 38 Genomic Imprinting: Gamete-of-Origin Dependent Modifications In genomic imprinting, chemical tags are placed on the allele inherited from one of the parents. Such genomic imprinting results in a gene being differentially expressed depending on which parent it comes from. Imprinting is a form of epigenetic regulation. 39 Genomic Imprinting by DNA Methylation Insulinlike growth factor 40 Genomic Imprinting Could be Different in Male and Female 41 Only Small Number of Genes are Known to be Imprinted Known Mammalian Imprinted Loci 42 Genomic Imprinting Cycles Gamete Specific 43 Topic 5 Proteinbased Inheritance 44 Prion ( Mad Cow) Diseases: No DNA Mutation Protein Based Infection and Inheritance Prion diseases are caused by a protein with an altered shape transmitted from one organism to another and altering the same protein in the second organism. 45 How Prion Works 46 Summary Extranuclear DNAs, including the mitochondria genome, chloroplast genome and some symbiotic bacteria and viruses follow rules different from the Mendelian inheritance of the meiosis based nuclear genes. Many but not all cases of extranuclear inheritance are maternal inheritance. Maternal effect refers to certain phenotypes of an individual that are determined by the maternal nuclear genome. Genomic imprinting results in a gene being differentially expressed depending on which parent it comes from. 47 ...
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