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Paper Topic:

Genetics Lab report

INVESTIGATION OF MENDELLIAN GENETICS USING RAPID CYCLING BRASSICA RAPA

INTRODUCTION

G .J . Mendel was born in 1822 . Although , he was the first person to identify the genetic laws , he was not a well-known scientist he was an Augustinian monk ( HYPERLINK "http /www .accessexcellence .org accessexcellence .org . For a long time it was thought that offspring inherit their traits from their parents , but it has never been proven until Mendel demonstrated in plants . In his 1866 Experiments on Plant hybridisation ' Mendel laid down the basis for the entire subject of genetics by

suggesting for the first time the existence of the discrete hereditary determinants we now call genes (Griffiths et al ,1999 . Though , his work was not fully recognized until the 20th century . Rediscovery of his work led to the foundation of genetics and that is why he is called the father of modern genetics (wikipedia .com

Mendel experiments started with pure-breeding lines of garden peas that showed distinct phenotypes for certain characteristics (yellow and green seeds . When he crossed these lines he obtained the offspring called hybrid . The hybrids were all yellow . When these hybrids were grown up and self-polinated , 75 of the offspring was yellow and 25 was green (Griffiths et al ,1999

Of special importance to this investigation is rapid cycling B . rapa (RCBr . Williams and Hill developed RCBr in University of Wisconsin-Madison in 1986 (Williams and Hill , 1986 . They discovered that these plants require very little attention and therefore were easy to grow , so they bred these rapid cycling RCBr as a research tool to be used for improving disease resistance of cruciferous plants . Cross breeding between RCBr and six related species from the family Cruciferae was tried to obtain shorter life cycles . A new petite , quick-growing plant was developed known as Fast Plants (R (fastplants .org Development of these plants continued so the following characteristics could be obtained : i )short time from planting to flowering (about 2 weeks , ii ) rapid seed maturation with no seed dormancy required , iii ability to produce seeds at higher planting density , iv ) petite plant size , v ) ability to grow under continuous florescent lighting in a standard potting mix . Finally , from six month life cycle of B . rapa RCBr has 35-40 days life cycle from parental seed sown to offspring harvest (Williams and Hill , 1986 . Compared to normal B . rapa , which can produce two generations in a year , under optimal conditions RCBr can produce 10 generations in a year . Additionally , over 150 genetics traits have been described (fastplants .org . Thus , the potential applications of RCBr to experimental botany are diverse (Musgrave , 2000

Here we investigate the patterns of Mendelian separation in two district generations of RcBr . From this dihybrid investigation we expected four phenotypes : 1 ) non-purple stem (single recessive mutant anl /anl , 2 purple stem (dominant for anthocyaninless gene ANL /ANL , 3 ) yellow green leaves (recessive mutant ygr /ygr , 4 ) normal green leaves (dominant allele YGR . The phenotypic classes expected are described in Table 1

Table 1 Phenotypic classes expected

Phenotype...

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