A young woman comes to the emergency room with a vertebral compression fracture. Radiographs of the spine indicate generalized demineralization. She is vegetarian, does not smoke or drink alcohol, has normal plasma potassium concentration of 5.4 mEq/L, sodium concentration of 136 mEq/L, plasma calcium concentration is 7.0 mg/dL. Her vitamin D3 value is several times greater than normal, although her 1,25-dihydroxycholecalciferol concentration is at the lower limit of detectability. She has been in renal failure for the last 5 years and undergoes hemodialysis three times each week. What is the cause of her low 1,25-dihydroxycholecalciferol level?

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#Question id: 28852

#Unit 2. Cellular Organization

Which of the following proteins are End-Binding Proteins?

a) XMAP215

b) Op18

c) Kinesin-13

d) stathmin

TLS Online TPP Program

#Question id: 28853

#Unit 2. Cellular Organization

Stathmin enhances that a growing microtubule will switch to the shrinking state in which condition?

a) When it increases the effective concentration of tubulin subunits that are available for polymerization 

b) When it decreases the effective concentration of tubulin subunits that are available for polymerization 

c) When stathmin is in phosphorylated condition

d) When stathmin is in dephosphorylated condition

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#Question id: 28854

#Unit 2. Cellular Organization

which protein promotes breakage by extracting tubulin subunits from the wall of the microtubule (also releases microtubules from MTOCs) ?

TLS Online TPP Program

#Question id: 28855

#Unit 2. Cellular Organization

which protein promotes breakage by extracting tubulin subunits from the wall of the microtubule (also releases microtubules from MTOCs) ?

TLS Online TPP Program

#Question id: 28856

#Unit 2. Cellular Organization

The main families of motor proteins mediate transport along microtubules Kinesin-1 which is similar to myosin II that contain various domains such as

I) Head domain

II) Stalk domain

III) Tail domain

a) forms a long coiled-coil

b) at the C-terminus that attaches to cargo

c) at the N-terminus of the heavy chain

d) at the C-terminus of the heavy chain

Correctly match the following domains with given characters;

TLS Online TPP Program

#Question id: 28857

#Unit 2. Cellular Organization

Which of the following motor proteins mediate the  transport along microtubules similar to myosin II ?