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MODEL ORGANISMS 1 : EXAMPLES, CONTRIBUTION, ADVANTAGES
MODEL ORGANISMS 1 : EXAMPLES, CONTRIBUTION, ADVANTAGES
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MODEL ORGANISMS 1 : EXAMPLES, CONTRIBUTION, ADVANTAGES
- 1. “ STARTING INTHE NAME OF ALLAH, THE MOST BENEFICENT, THE MOST MERCIFUL" MADE BY: SIDRA IFTIKHAR M.Sc (MICROBIOLOGY) MOLECULAR BIOLOGY AND VIROLOGY GENETIC MODEL ORGANISMS PART # 01
- 2. Model organisms—organisms studiedby many different researchers so they can compare their results and determine scientific principles that apply more broadly to other species. GENETIC MODEL ORGANISMS
- 3. 1. a shortgeneration time, and so several generations of genetic crosses can be examined in reasonable time; 2. the production of numerous progeny, and so genetic ratios can be easily observed; 3. the ability to carry out and control genetic crosses in the organism; 4. the ability to be reared in a laboratory environment, requiring little space and few resources to maintain; 5. the availability of numerous genetic variants; 6. and an accumulated body of knowledge about their genetic systems. KEY FEATURES OF GENETIC MODEL ORGANISMS
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- 6. STATS Taxonomy Insect Size: 2–3mm in length Anatomy 3 body segments, 6 legs, 1 pair of wings Habitat Feeds and reproduces on fruit ADVANTAGES 1 Small size 2 Short generation time of 10 days at room temperature 3 Each female lays 400–500 eggs 4 Easy to culture in laboratory 5 Small genome 6 Large chromosomes except 4 chromosome pair 7 Many mutations available Drosophila melanogaster (fruit fly)
- 7. GENOME Chromosomes 3 pairsof autosomes and X and Y (2n = 8) Amount of DNA 175 million base pairs Number of genes 14,000 Percentage of genes in common with humans ~50% Average gene size 3000 base pairs Genome sequenced in year 2000 CONTRIBUTIONS TO GENETICS 1 Basic principles of heredity including sex-linked inheritance, multiple alleles, epistatsis, gene mapping, etc. 2 Mutation research 3 Chromosome variation and behavior 4 Population genetics 5 Genetic control of pattern formation 6 Behavioral genetics Drosophila melanogaster (fruit fly)
- 8. Escherichia coli (abacterium)
- 10. STATS Taxonomy Eubacteria Size: 1–2μm in length Anatomy Single cell surrounded by cell wall with nucleoid region Habitat Intestinal tract of warm-blooded animals ADVANTAGES 1 Small size 2 Rapid reproduction, dividing every 20 minutes under optimal conditions 3 Easy to culture in liquid medium or on petri plates 4 Small genome 5 Many mutants available 6 Numerous methods available for genetic engineering Escherichia coli (a bacterium)
- 11. GENOME Chromosomes 1 circularchromosome Amount of DNA 4.64 million base pairs Number of genes 4300 Percentage of genes in common with humans 8% Average gene size 1000 base pairs Genome sequenced in year 1997 CONTRIBUTIONS TO GENETICS 1 Gene regulation 2 Molecular biology and biochemistry of genetic processes, such as replication, transcription, translation, recombination 3 Gene structure and organization in bacteria 4 Workhorse of recombinant DNA 5 Gene mutations Escherichia coli (a bacterium)
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- 14. STATS Taxonomy Nematode Size: 1mm Anatomy Unsegmented, elongated body Habitat Lives and reproduces in soil ADVANTAGES 1 Small size 2 Short generation time of 3 days 3 Each female can produce 200–1000 eggs 4 Easy to culture in laboratory 5 Simple body plan 6 Transparent 7 Capable of self-fertilization or crossing C. elegans
- 15. GENOME Chromosomes 5 pairsof autosomes plus 2 X chromosomes in females (hermaphrodites) or 1 X chromosome in males Amount of DNA 103 million base pairs Number of genes 20,500 Percentage of genes in common with humans 25% Average gene size 5000 base pairs Genome sequenced in year 1998 CONTRIBUTIONS TO GENETICS 1 Genetics of development 2 Apoptosis (programmed cell death) 3 Genetic control of behavior 4 Aging C. elegans
- 16. OTHER 1 Nematodes are amongthe most abundant organisms on Earth, inhabiting soils throughout the world 2 Most are free living and cause no harm, but a few are important parasites. 3 First introduced to the study of genetics by Sydney Brenner, who formulated plans in 1962 to use C. elegans for the genetic dissection of behavior. C. elegans
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- 19. STATS Taxonomy Flowering plant Size:10–20 cm Anatomy Roots, one primary shoot, simple leaves, flowers Habitat Meadows ADVANTAGES 1 Small size 2 Short generation time of 6 weeks 3 Each plant can produce from 10,000 to 40,000 seeds 4 Ability to grow in laboratory 5 Small genome for a plant 6 Many variants available 7 Self-fertilizes and outcrosses Arabidopsis thaliana (a flowering plant)
- 20. GENOME Chromosomes 5 pairs(2n = 10) Amount of DNA 125 million base pairs Number of genes 25,700 Percentage of genes in common with humans 18% Average gene size 2000 base pairs Genome sequenced in year 2000 CONTRIBUTIONS TO GENETICS 1 Plant-genome organization 2 Gene regulation 3 Genetics of plant development 4 Genetics of flowering Arabidopsis thaliana (a flowering plant)