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Zoology linked gene

1. LINKED GENES Eman Akram 22011507-027 BS Chemistry Spring-2024 Course Code: ZOO-103 Course Title: Principles of Animal Life-ll

2. 1 INTRODUCTION 2 LINKED & UNLINKED GENES 3 TEST CROSS 4 CROSSING OVER & RECOMBINATION 5 HUMAN LINKED GENE 6 SIGNIFICANCE CONTENTS

3. 1.DEFINITION OF LINKED GENES: A linked gene refers to genes that are located close to each other on the same chromosome. In genetics, chromosomes carry genes, and their arrangement can influence how traits are inherited. When genes are close together on a chromosome, they tend to be inherited together more often than not, a phenomenon known as genetic linkage.

4. LINKED GENES A linked gene refers to genes that are located close to each other on the same chromosome. They do not obey Mendel’s law of independent assortment Do not segregate independently Inherited together UNLINKED GENES A unlinked genes refer to genes that are located far apart. These obey Mendel’s law of independent assortment These segregate independently Do not inherited together 2.LINKED & UNLINKED GENES

5. 3.DROSOPHILA TEST CROSS The wild type drosphilla had gray bodies and normal wings (b+,vg+) Mutants had black bodies and vestigial wings (b,vg)

6. DIHYBRID TEST CROSS Morgan classified test cross and found that body color and wing size must be inherited together and therefore be located on same chromosome. However , non parentalphenotypes are also produced suggesting that genes are partially linked.

7. 4.CROSSING OVER Morgan concluded that the genes must be on same chromosomes Some process must sometimes break the linkage and allow for the alleles to be rearranged This is called crossing over

8. RECOMBINATION FREQUENCY DEFINITION : Recombination frequency is the percent of meioses in which homologous recombination exchanges two loci. Recombination frequency is high when genes are far apart. Recombination frequency is low when genes are close to each other

9. 5.HUMAN X-LINKED GENE Red-Green Color Blindness Gene (allele for color blindness Hemophilia Gene (allele for hemophilia) Due to their proximity on the X chromosome, the alleles for red-green color blindness and hemophilia are often inherited together in certain populations. This means that individuals with the allele for red-green color blindness are more likely to also carry the allele for hemophilia on the same X chromosome.

10. 6.SIGNIFICANCE OF LINKED GENES Medical genetics Recombination & Genetic diversity Phenotypic effects Research and Analysis Overall, understanding linked genes is essential for unraveling the complexities of inheritance, genetic variation, and the inheritance of traits and disorders in populations. They are fundamental to genetic research and have significant implications for fields such as evolutionary biology, medical genetics, and agriculture.

11. REFRENCES Cooper, DN; Krawczak, M; Polychronakos, C; Tyler-Smith, C; Kehrer-Sawatzki, H (October 2013). "Where genotype is not predictive of phenotype: towards an understanding of the molecular basis of reduced penetrance in human inherited disease". Human genetics. 132 (10): 1077–130. doi:10.1007/s00439-013-1331-2. PMC 3778950. PMID 23820649. Lobo, Ingrid; Shaw, Kenna. "Discovery and Types of Genetic Linkage". Scitable. Nature Education. Retrieved 21 January 2017. Bateson, W; Saunders, ER; Punnett, RC (18 May 1904). Reports to the Evolution committee of the Royal Society. London: Harrison and Sons, Printers. Retrieved 21 January 2017.

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