EXTRA CHROMOSOMAL INHERITANCE

Full description of the process

1. EXTRA CHROMOSOMAL INHERITANCE Rupen Chakma 17/BBT/11 Amarjit Singh 17/BBT/29

2. CONTENTS Introduction Chloroplast inheritance Variegation in Four o’clock plant Chloroplast segregation in Chlamydomonas Mitochondrial inheritance - Pokyness in N eurospora - Cytoplasmic male sterility Maternal effects Conclusion Reference

3. Introduction Extra nuclear inheritance is defined as non mendelian inheritance, which occurs when phenotype result from genetic influence other than the biparental transmission of genes located on chromosomes in the nucleus The genes that have been called cytoplasmic genes, extrachromosomal genes, or extranuclear genes are located on a unique kind of chromosome inside cytoplasmic organelle Commonly defined as transmission through the cytoplasm (or things in the cytoplasm, including organelles) rather than the nucleus

4. Generally only one parents contributes organelle heredity Organelles that contain chromosomes-Chloroplasts and mitochondria Infectious heredity - Involves a symbiotic or parasitic association with a microorganism Maternal effect – When the expression of a character is influenced by the genotype of female parent

5. Variegation in Four O’clock plant In 1909, Carl C orrens used Mirabilis jalapa as a model study for his study on cytoplasmic inheritance. Variants of M irabilis jalapa in which some branches had white leave some had green leaves and some had variegated leaves

6. VARIEGATED LEAVES IN FOUR O’CLOCK PLANT

7. They maybe intercrossed in a variety of different combinations by transferring pollen from one flower to another

8. Segregation In chlamydomonas Chlamydomonas is a single celled haploid green algae with a single chloroplast containing 50 to 100 genome It as two mating type mt (+) and mt (-)which can fuse to form a diploid zygote

9. 1/2mt+ 1/2mt- 1/2mt+ 1/2mt- All streptomycin resistance All streptomycin sensitiven

10. Pokyness in Neurospora In 1952, Mary Mitchell isolated a mutant strain of Neurospora that she called poky. Poky Neurospora is: -Slow growing -It shows maternal inheritance -It has abnormal amount of cytochromes

11. It is possible to cross some fungi in such a way that one parent contributes the bulk of cytoplasm to the progeny and this cytoplasmic contributing parent is called female even though no true sex is involved Maternal inheritance for the poky phenotype was established in the following crosses Poky(female) x wild type (male) → all poky Wild type (female) X poky (male) → all wild type

12. Cytoplasmic male sterility -CMS is a condition in which a plant does not produce functional pollen, but the female reproduction organs and fertility are normal. -Important in agriculture extensively used to produce hybrid corn seeds. -In 1930s, Rhoades demonstrated that male sterility in maize can be caused by maternally inherited factor

13. -Male sterility is transmitted through the egg cytoplasm from generation to generation. -Rhoades pollinated the ears of male sterile strain with the pollen from a male fertile strain. -Repeated backcrossing of a male sterile variety, does not restore male fertility.

14. Maternal effects When the expression of a character is influenced by the genotype of female parent, it is referred to as maternal effects. Such characters exhibit clearcut differences in F1 for reciprocal crosses. Maternal effects are known in both plants and animals.

15. Coiling pattern of shell in snail The effect of maternal genotype on the coiling behavior in snail was studied by Sturtevant. The coiling behavior is controlled by a single gene. In a cross between dextral female and sinistral male, it produces dextral snails in F1 as well as in F2. But in a cross between sinistral female and dextral male, all the snails in F1 are sinistral and in F2 all the snails are dextral.

16. C onclusion Thus we know that not only nuclear inheritance is responsible for gene expression in an individual but cytoplasmic inheritance is also responsible for various characters.

17. REFERENCE Principle of GENETICS by Eldon John Gardner, Michael J. Simmons, D. Peter Snustad Genetics by Phudan singh

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