In this problem we will explore some of the many ways that mutations in two different genes can interact to produce different Mendelian ratios. Consider a hypothetical insect species that has red eyes. Imagine mutations in two different unlinked genes that can, in certain combinations, block the formation of red eye pigment yielding mutants with white eyes. In principle, there are two different possible arrangements for two biochemical steps responsible for the formation of red eye pigment. The two genes might act in series such that a mutation in either gene would block the formation of red pigment. Alternatively, the two genes could act in parallel such that mutations in both genes would be required to block the formation of red pigment.

Further complexity arises from the possibility that mutations in either gene that lead to a block in enzymatic activity could be either dominant or recessive. If the crosses between a wild type insect with red eyes and a true breeding white eyed strain with mutations in both genes. Such considerations yield the Pathways in parallel with a recessive mutation in one gene and a dominant mutation in the other, determine the phenotype of the F1 progeny and the expected phenotypic ratio of red to white eyed insects in the F2.

#Question id: 7300

#Unit 5. Developmental Biology

Following genes regulate flowering, column I represents genes, column II represents transcription factor family and column III represents functions.

 Which of the following is correct?

#Question id: 22944

#Unit 5. Developmental Biology

#Question id: 22938

#Unit 5. Developmental Biology

#Question id: 7314

#Unit 5. Developmental Biology

With reference to plant flowering pattern; match the terms of Column I with the most appropriate term of Column II. (Se-Sepal; Ca-Carpel; St-stamen; Pe-Petal)

#Question id: 7312

#Unit 5. Developmental Biology

Following statements regarding to the classes of genes that regulate floral development:

A.  Floral organ identity genes directly control floral identity. The proteins encoded by these genes are transcription factors that likely control the expression of other genes whose products are involved in the formation and/or function of floral organs.

B.  Cadastral genes act as spatial regulators of the floral organ identity genes by setting boundaries for their expression.

C.   Meristem identity genes are necessary for the initial induction of the organ identity genes. These genes are the positive regulators of floral organ identity.

D.  Cadastral genes act as negative regulators of the floral organ identity genes by inhibits their expression.

E.   Meristem identity genes are the negative regulators of floral organ identity genes.

Which of the above statements are true?

#Question id: 7311

#Unit 5. Developmental Biology

According to the ABC model of flower development in Arabidopsis, three classes of organ identity genes— designated A, B, and C— are required to specify the identity of floral organs in each whorl of a flower. If wild type Arabidopsis were transformed with a chimeric gene composed of a C class promoter fused to a B class coding sequence, which of the following arrangements   (outer to inner) would be predicted?