Lysozyme is an enzyme that destroys bacterial cell walls. It does so by hydrolyzing the β(1→4) glycosidic linkages from N- acetylmuramic acid (NAM or MurNAc) to N- acetylglucosamine (NAG or GlcNAc) in cell wall peptidoglycans. The only functional groups in the immediate vicinity of lysozyme’s reactive center that have the required catalytic properties are the side chains of Glu 35 and Asp 52.

a- Glu perform reaction in its protonated state and Asp perform reaction in its deprotonated state. 

b- Glu perform reaction in its deprotonated state and Asp perform reaction in its protonated state. 

c- both in its protonated form

d- both in its deprotonated form 

Choose the correct option?

TLS Online TPP Program

#Question id: 16956

#Unit 4. Cell Communication and Cell Signaling

Polyclonal antibodies are raised against bovine serum albumin in rabbit. Subsequently IgG in the antiserum is purified and digested with either pepsin or papain. Out of the following possibilities, which one is correct?

TLS Online TPP Program

#Question id: 16955

#Unit 4. Cell Communication and Cell Signaling

Stage thymocytes express neither CD4 nor CD8, markers associated with mature T cells. They are therefore called double negative (DN) cells. DN cells first travel to the region under the thymic capsule, a region referred to as the ________, where they proliferate and begin to generate their T-cell receptors. Thymocytes that successfully express TCRs begin to express both CD4 and CD8, becoming double positive (DP) cells, and populate the cortex, the site where most (85% or more) immature T cells are found.

TLS Online TPP Program

#Question id: 16954

#Unit 4. Cell Communication and Cell Signaling

match the following

Component	Description
A. endosteal niche	1. versatile cells that both generate bone and control the differentiation of HSCs
B. osteoblasts	2. line the blood vessels and also regulate HSC differentiation
C. reticular cells	3. send processes connecting cells to bone and blood vessels, and unexpectedly
D. sympathetic neurons	4. can control the release of hematopoietic cells from the bone marrow.

TLS Online TPP Program

#Question id: 16953

#Unit 4. Cell Communication and Cell Signaling

The ability of any stem cell to self-renew and differentiate depends on the structural organization and cellular function of specialized anatomic microenvironments known as stem cell niches. These sequestered regions are typically populated by a supportive network of stromal cells. Stem cell niche stromal cells express soluble and membrane-bound proteins that regulate cell survival, proliferation, differentiation, and trafficking. Which statements is true about HSCs?

TLS Online TPP Program

#Question id: 16148

#Unit 4. Cell Communication and Cell Signaling

 Which statement is not true for NKT Cells?

TLS Online TPP Program

#Question id: 16147

#Unit 4. Cell Communication and Cell Signaling

 Which statement is not true for Natural killer (NK) cells?