#Question id: 562
#Unit 1. Molecules and their Interaction Relevant to Biology
Phenyl-methane-sulfonyl-fluoride (PMSF) inactivates serine proteases by binding covalently to the catalytic serine residue at the active site; this enzyme-inhibitor bond is not cleaved by the enzyme. This is an example of what kind of inhibition?
#Question id: 5671
#Unit 5. Developmental Biology
Match the following mechanism of polyspermy (Column I) with events (Column II).
|
Column I |
Column II |
|
A. Fast block to polyspermy |
i. chemicals from the fusing sperm cytoplasm alter the sodium ion (Na+) channels on the membrane |
|
B. Slow block to polyspermy |
ii. enzyme cortical granule serine protease, cleaves the protein posts that connect the vitelline envelope |
|
iii the concentration of free Ca2+ in the egg cytoplasm increases |
|
|
iv. an electric change in the egg cell membrane |
|
|
v. the concentration of free Na+ in the egg cytoplasm increases |
Which of the following is correct?
#Question id: 53
#Unit 1. Molecules and their Interaction Relevant to Biology
Calculate the number of times the DNA of a modern E. coli cell has been copied accurately since its earliest bacterial precursor cell arose about 3.5 billion years ago. Assume for simplicity that over this time period, E. coli has undergone, on average, one cell division every 12 hours (this is an overestimate for modern bacteria, but probably an underestimate for ancient bacteria).
#Question id: 2979
#Unit 2. Cellular Organization
Use the data in the accompanying table to answer the question. Minutes Spent in Cell Cycle Phases-
|
Cell type |
G1 |
S |
G2 |
M |
|
Beta |
18 |
24 |
12 |
16 |
|
Delta |
100 |
1 |
0 |
0 |
|
Gamma |
18 |
48 |
14 |
20 |
#Question id: 10970
#Unit 1. Molecules and their Interaction Relevant to Biology
A mother of blood type A+ who has always been perfectly healthy just delivered her second child. The father is of blood group O−. Knowing that the child is of blood group O− (O, Rh−), what would you expect to find in this child?