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1. Aneuploidy: changes in parts of chromosome sets -monosomics (2n-1) -trisomics (2n+1) etc. Aberrant euploidy: abnormal # of whole chromosome sets -triploidy.

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Presentation on theme: "1. Aneuploidy: changes in parts of chromosome sets -monosomics (2n-1) -trisomics (2n+1) etc. Aberrant euploidy: abnormal # of whole chromosome sets -triploidy."— Presentation transcript:

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2 Aneuploidy: changes in parts of chromosome sets -monosomics (2n-1) -trisomics (2n+1) etc. Aberrant euploidy: abnormal # of whole chromosome sets -triploidy (3n) -tetraploidy (4n) etc. 2

3 3 Chromosome Constitutions in a Normally Diploid Organism with Three Chromosomes (Labeled A, B, and C) in the Basic Set Name Designation Constitution Number of chromosomes Monoploidn A B C3 Diploid2nAA BB CC6 Triploid3nAAA BBB CCC9 Tetraploid4nAAAA BBBB CCCC12 Monosomic2n − 1A BB CC5 AA B CC5 AA BB C5 Trisomic2n + 1AAA BB CC7 AA BBB CC7 AA BB CCC7

4 4 Chromosome mutations

5 Diploid 5 Tetraploid Polyploid Octaploid

6 2n 6 Grapes Watermelon 4n

7 מונחים *Polyploids-individual with more than two chromosomes sets. i.e. Triploids-3n,tetraploid- 4n,pentaploid-5n,hexa…. *Monoploid- one chromosome set (not a haploid) *Autopolyploid (chromosomes within species) vs. allopolyploids (chromosomes from closely related species) *Homeologous- Partially homologous (common ancestor) *Aneuploidy- chromosomes number is abnormal, i.e. trisomic; 2n+1, monososmic; 2n-1 and nullsomic; 2n-2. In haploid n+1 is disomic 7

8 Cold treatment Generation of monoploid Embrioyoid-a small dividing mass of monoploid cells 8 2n -> 1n X

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10 Breeder – search for special phenotype of a/a b/b c/c d/d A/a B/b C/d D/d recombination a b c d Cold treatment monoploid ( Diploid ) 10

11 Cold treatment Generation of monoploid Embrioyoid-a small dividing mass of monoploid cells 11 2n -> 1n A/a B/b C/c D/dAmong them: a b c d Among them: a b c d

12 Breeder – search for special phenotype of a/a b/b c/c d/d A/a B/b C/d D/d recombination a b c d Cold treatment monoploid colchicine Diploid 12

13 13 a/a b/b c/c d/da b c d

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16 16 How does colchicine work?

17 17 a/a b/b c/c d/da b c d

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19 19 Why is a monoploid sterile? When they enter meiosis, Segregation leading to normal gametes is rare OR n=2 OKNot OK n=2 2 * 1/2 n are OK = 1/2 n=10 2 * 1/2 n are OK = 1/516 -chance that all chromosomes go to one gamete More typical for plant

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21 Three homologous chromosomes Autopolyploids: the case of triploids in meiosis 3:02:1 As more chromosomes we have the less chance to get viable gamete 21

22 Polyploid with odd number of chromosome set are sterile or infertile Since their gametes and offspring are aneuploid 22

23 Aneuploid, aberrant euploidy, and gene balance Usually aneuploids are not viable or severely affected due to changes in gene balance. In a euploid the ratio between genes is 1:1 **even in aberrant euploidy, -whereas in aneuploid this balance is variable 23

24 מונחים *Polyploids-individual with more than two chromosomes sets. i.e. Triploids-3n,tetraploid- 4n,pentaploid-5n,hexa…. *Monoploid- one chromosome set (not a haploid) *Autopolyploid (chromosomes within species) vs. allopolyploids (chromosomes from closely related species) *Homeologous- Partially homologous (common ancestor) *Aneuploidy- chromosomes number is abnormal, i.e. trisomic; 2n+1, monososmic; 2n-1 and nullsomic; 2n-2. In haploid n+1 is disomic 24

25 כרוב צנון Karpechenko’s experiment 25

26 Non functional gamete 26

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28 Distribution of haploid chrmosome number in dicotyledonous The distribution above 12 show mainly even number suggesting doubling of chromosome sets. 28 דו-פסיגיים

29 6n=42 29

30 30 Guns, Germs, and Steel. Jared Diamond

31 Nullisomics of modern (hexaploid) wheat 31

32 Trisomics of Datura 32

33 Aneuploid, aberrant euploidy, and gene balance Usually aneuploids are not viable or severely affected due to changes in gene balance. In a euploid the ratio between genes is 1:1 **even in aberrant euploidy, -whereas in aneuploid this balance is variable 33

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35 35 So why not polyploid mammals? Remember the issue of balance between chromosomes For plants, tetraploidy works–TWICE as much of EVERY GENE, so ok. In mammals, a balance has evolved for all chromosomes, including sex chromosomes e.g.: humans have 45 active chromosomes (and sometimes Y). Dosage compensation, through Barr Bodies, makes sure That only 1 X is active (even when 2, 3, 4, and more are present) So, with higher multiples of autosomes, but active X # not budging, balance can never be correct. Imprinting, a later topic, is also a problem. XXX, XXY, XXYY

36 36 תורשה חוץ גרעינית

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39 39 Molecular Biology of the Cell

40 40 Endosymbiosis Biology - Campbell and Reece, 8th Ed. (2008). Primary

41 Figure 1 Primary and secondary endosymbiosis might explain the extraordinary diversity of protists. Primary endosymbiosis Mito-ONCE >1.5 BYa, Plastids-ONCE ±1.5 BYa --Organelles gained through endosymbiosis. Secondary endosymbiosis --A eukaryote, the product of an endosymbiosis, participates in another. --Evolved multiple times.

42 Figure 3 Diversification of protists into 7 main groups Archaeplastids led to modern plants. Unikonts led to modern fungi and animals.

43 43 4 Red algae (Chlorophyll a and phycobiliproteins) Green algae (Chlorophyll a and b) Archaeplastida

44 44 Modern phylogenetic tree of protists, plants, fungi and animals Biology - Campbell and Reece, 8th Ed. (2008).

45 Modern phylogenetic tree of protists, plants, fungi and animals Arche a

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52 Organelle genomes work with an alternative genetic code!

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55 Mitochondrial fission and fusion play critical roles in maintaining functional mitochondria when cells experience metabolic or environmental stresses. Fusion helps mitigate stress by mixing the contents of partially damaged mitochondria as a form of complementation. Fission is needed to create new mitochondria, but it also contributes to quality control by enabling the removal of damaged mitochondria and can facilitate apoptosis during high levels of cellular stress. Disruptions in these processes affect normal development, and they have been implicated in neurodegenerative diseases, such as Parkinson’s.

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57 POL G mutation

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60 Male parents generally DO NOT Contribute cytoplasm to zygotes SO… mitochondria and chloroplasts are MATERNAL CONTRIBUTIONS

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62 Ron ended Here on Jan 12.

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67 Male parents generally DO NOT Contribute cytoplasm to zygotes SO… mitochondria and chloroplasts are MATERNAL CONTRIBUTIONS

68 Note: In human mitochondria, the mutation rate is ±10 -5 (per generation per bp) Here too: For Mitochondrial DNA, recombination is NOT AN ISSUE

69 Cytokinesis (Cell Division) -actin microfilaments and Karyokinesis (Nuclear division, including mitosis) -tubulin microtubules

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76 דוגמא : שיח נוי (Variegated) Pittosporum

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81 Maternal effect (NOT Maternal inheritance)

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86 Case for alloploids 86

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