Question

Answer Each Question with an Explanation.

1)Which protein in a fibroblast's plasma membrane attaches to the extracellular matrix on the outside if the cell and (through adapter molecules) to actin inside the cell?
a. Proteglycan
b. Cadherin
c. Fibronectin
d. Integrin

2)In the intestine, Wnt proteins:
a. promote the apoptosis of the stem cells at the base of each intestinal crypt
b. promote the proliferation of the stem cells at the base of each intestinal crypt
c. promote the destruction of precursor cells in each intestinal crypt
d. promote the secretion of mucus at the base of each intestinal crypt

3)Which of the following is not one of the traditional cancer treatments?
a. Surgery
b. Radiotherapy
c. DNA-damaging chemotherapy
d. stimulating cell migration

4)Which of the followings is not one of the new ways of cancer treatments?
a. Adult stem cells implantation
b. Inhibitors of DNA repair pathways
c. Vaccination with tumor specific molecules
d. Inhibitors for specific oncogene

5)Which of the following is NOT a key behavior of cancer cells?
a. They have a reduced dependence on signals from other cells for their growth, survival, and division
b. Most are genetically unstable, with a greatly increase mutation rate
c. They became more sensitive to the contact inhibition
d. They can often proliferate indefinitely

Answer 1

1) The macromolecules which comprised the extracellular matrix are mainly produced by the cells of the matrix. These cells helps in the organization of matrix and orientation of cytoskeleton inside the cell. Most of the matrix of connective tissues are secreted by fibroblast cells. Two main classes of extracellular macromolecules make up the matrix namely, polysaccharide chains of glycosaminoglycans (GAGs) which are linked to protein in the form of proteoglycans and fibrous proteins like collagen, fibronectin, etc which have both structural and adhesive functions. The proteoglycans are protein molecules that are heavily glycosylated. These not only form as secreted components of extracellular matrix but are also integral components of plasma membrane of fibroblasts. Some of the plasma membrane proteoglycans act as co-receptors that can bind to both extracellular matrix and also interact with intracellular domains inside the cells. Plasma membrane proteoglycans like Syndecans located at the cell surface of fibroblast act as receptors for matrix proteins where they attaches to the extracellular matrix by modulating integrin function interacting with fibronectin on the cell surface and with actin cytoskeleton and signaling molecule inside the cell. So the correct option is (a).

2) Wnt proteins are differentially expressed along the intestinal crypt villus and function as a potent stem cell precursors that regulate stem/progenitor cell self rejuvination, proliferation, differentiation and migration. So the correct option is (b).

3) Cancer treatment includes various methods like surgery, chemotherapy, radiotherapy, bone marrow transplant, immunotherapy, targeted drug therapy, etc. The traditional methods of cancer treatments includes chemotherapy that uses drugs to kill cancer cells, radiotherapy or radiation therapy that uses high power energy beams to destroy cancer cells, surgery that focuses on removal of cancer cells as much as possible. But, stimulating cell migration induces metastasis that is an inherent property of cancer cells that spread the cancerous cells to distinct sites via blood. So option (d) is correct one.

4) The new, modern approaches to cancer treatment includes adult stem cells implantation that uses stem cells graft to produce new cells and replace the cancerous cells, vaccination with tumor specific molecules that operates to destroy the specific tumor by the introduction of killed or disharmed pathogen, inhibitors of specific oncogene that specifically attack the oncogene and restrict its further propagation by disrupting its biosynthetic machinery. DNA repair pathways involve the restriction of cell cycle regulation by triggering the function of cyclin dependent protein kinase which is initiated by p53 tumor suppressor gene. If an inhibitor is introduced then it blocks the action of p53 gene along with deactivating the CDKs. So, option (b) s the correct answer.

5) Cancer cells do not depend on signals given by other cells and rely on the proteins that serve as chemical tiggers for blood vessel growth in tumor tissue. The cancer cells are highly mutated cells and are unstable because they have lost all the normal physiological properties of a normal cell. They can often proliferate indefinitely by uncontrolled cell division that led to a lump of cells inducing the formation of tumors. Normally cells show a property called contact cell inhibition by virtue of which contact with other cells inhibits their uncontrolled growth but cancer cells have lost this property. So option (c) is the correct answer.