Which of the following steps is required to generate a knockout mouse?

a. microinjection of DNA into the pronucleus of a fertilized mouse egg

b. introduction of DNA into mouse embryonic stem cells

c. selection for cells containing the gene targeted insertion

d. expression of Cre protein during embryonic development

#Question id: 15729

#Unit 12. Applied Biology

#Question id: 26894

#Unit 10. Ecological Principles

Number of species of vertebrate animal (Global) in decreasing order

#Question id: 5673

#Unit 5. Developmental Biology

Species-specific sperm attraction has been documented in numerous species. In echinoderms, sperm are attracted toward eggs of their species by chemotaxis. Following statements are about chemoattraction-

A. In this process Sperm follows a gradient of a chemical secreted by the egg.

B. These oocytes control only the type of sperm they attract, but not the time at which they attract them.

C. Releasing the chemotactic factor only when the sea urchin egg has completed all of its meiotic divisions .

D. Releasing the chemotactic factor only when the sea urchin egg is in second metaphase of its meiotic division.

E. The mechanisms of chemotaxis differ among species and chemotactic molecules are different even in closely related species.

Which of the following statement are incorrect about this process?

#Question id: 11159

#Unit 9. Diversity of Life Forms

Which kind of DNA should provide the best molecular clock for gauging the evolutionary relatedness of several species whose common ancestor became extinct billions of years ago?

#Question id: 1871

#Unit 4. Cell Communication and Cell Signaling

Deletions in the T-cell CD154 (CD40L) gene produce: