Major types of alkaloids, their amino acid precursors, and well-known examples of each type;

Alkaloid class	Biosynthetic precursor	Examples
A. Pyrrolidine	i. Lysine	a. Coniine
B. Tropane	ii. Ornithine	b. Retrorsine
C. Piperidine		c. Lupinine
D. Pyrrolizidine		d. Nicotine
E. Quinolizidine		e. Atropine and Cocaine

Which of the following combination from the given table is correct?

#Question id: 2123

#Unit 2. Cellular Organization

Which of these statements about the composition of membranes is true?

#Question id: 26839

#Unit 10. Ecological Principles

#Question id: 5145

#Unit 5. Developmental Biology

Doris Taylor’s research group used detergents to remove all the cells from a cadaveric rat heart, which left behind the natural extracellular matrix. Proteins such as fibronectin, collagen, and laminin held together the rest of the extracellular matrix and maintained the intricate shape of the heart. The researchers then infused this extracellular matrix scaffold with cardiomyocyte progenitor cells. Surprisingly, these cells differentiated and organized into a functionally contracting “recellularized” heart. The behavior of extracellular matrix scaffold can promote the differentiation and rebuilding of a beating heart is analogous to which of the interactions?

#Question id: 18807

#Unit 13. Methods in Biology

#Question id: 1235

#Unit 4. Cell Communication and Cell Signaling

Arrange the following events in the proper order in which they occur during transduction of the EGF signal:

a. transphosphorylation of the EGF receptor

b. dissociation of GDP from Ras                   

c. dissociation of Ras from Sos         

d. binding of GRB2 to the EGF receptor      

e. binding of GTP to Ras