B.) Name two specific chemokines and the cells that respond to them. CCL13 is a
ID: 60808 • Letter: B
Question
B.) Name two specific chemokines and the cells that respond to them.CCL13 is a homeostatic chemokine and monocytes/macrophages and eosinophils respond to them. CCL2 is an inflammatory chemokine and T-lymphocytes, monocytes/macrophages and mast cells respond to them.
C.) Pick one of your choices in B.) and describe the signaling pathway, beginning with the chemokine and its receptor and ending with the cytoskeleton, that connects the chemokine with cellular movement.
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#4 The contractile ring is the structure that forms the cleavage furrow during cytokinesis of animal cells.
A.) What is the contractile ring made of?
The contractile ring is made up of microfilaments and actin filaments. These two filaments are concentrated at the cleavage region of the cell. Cleavage is driven by actin and myosin motor proteins, which are the same proteins involved with muscle contraction. During cytokinesis, the contractile ring tightens around the cytoplasm of the cell until the cell membrane is pinched off into two daughter cells.
B.) How does the contractile ring get positioned correctly during mitosis? (I.e., what cellular structures or molecules guide the formation of the contractile ring?)
C.) Describe the actions of Rho, ROCK, actin, and myosin-2 at the contractile ring and how the cell regulates cytokinesis through these proteins. Need to answer B, C and B B.) Name two specific chemokines and the cells that respond to them.
CCL13 is a homeostatic chemokine and monocytes/macrophages and eosinophils respond to them. CCL2 is an inflammatory chemokine and T-lymphocytes, monocytes/macrophages and mast cells respond to them.
C.) Pick one of your choices in B.) and describe the signaling pathway, beginning with the chemokine and its receptor and ending with the cytoskeleton, that connects the chemokine with cellular movement.
(see next page)
#4 The contractile ring is the structure that forms the cleavage furrow during cytokinesis of animal cells.
A.) What is the contractile ring made of?
The contractile ring is made up of microfilaments and actin filaments. These two filaments are concentrated at the cleavage region of the cell. Cleavage is driven by actin and myosin motor proteins, which are the same proteins involved with muscle contraction. During cytokinesis, the contractile ring tightens around the cytoplasm of the cell until the cell membrane is pinched off into two daughter cells.
B.) How does the contractile ring get positioned correctly during mitosis? (I.e., what cellular structures or molecules guide the formation of the contractile ring?)
C.) Describe the actions of Rho, ROCK, actin, and myosin-2 at the contractile ring and how the cell regulates cytokinesis through these proteins. Need to answer B, C and B B.) Name two specific chemokines and the cells that respond to them.
CCL13 is a homeostatic chemokine and monocytes/macrophages and eosinophils respond to them. CCL2 is an inflammatory chemokine and T-lymphocytes, monocytes/macrophages and mast cells respond to them.
C.) Pick one of your choices in B.) and describe the signaling pathway, beginning with the chemokine and its receptor and ending with the cytoskeleton, that connects the chemokine with cellular movement.
(see next page)
#4 The contractile ring is the structure that forms the cleavage furrow during cytokinesis of animal cells.
A.) What is the contractile ring made of?
The contractile ring is made up of microfilaments and actin filaments. These two filaments are concentrated at the cleavage region of the cell. Cleavage is driven by actin and myosin motor proteins, which are the same proteins involved with muscle contraction. During cytokinesis, the contractile ring tightens around the cytoplasm of the cell until the cell membrane is pinched off into two daughter cells.
B.) How does the contractile ring get positioned correctly during mitosis? (I.e., what cellular structures or molecules guide the formation of the contractile ring?)
C.) Describe the actions of Rho, ROCK, actin, and myosin-2 at the contractile ring and how the cell regulates cytokinesis through these proteins. Need to answer B, C and B
Explanation / Answer
C) CCL13 induces cell migration of monocytes, T-lymphocytes, eosinophills and basophills. They act by binding to the receptors that are bound to GTP-bunding Rho proteins (Rho is an entire family of proteins). The Rho proteins get activated by an exchange of GDP by GTP which in turn then activates Rho-Kinase. Rho-kinase now phosphorylates myosin light chains. Rho also inhibits the Myosin light chain phosphatase. Both of the process cause cytoskeleton remodeling which results cell movement. (microinjection of fibroblasts with Rho proteins induces production of cell surface protrusions).
B) The position of contractile ring is guided by the position of the spindle. They form at the posotion at which spindle is perpendicular to the Metaphase plate.
C) Rho is a family of GTP-binding proteins which regulate cytoskeleton organization and induce cell movement. Rho family members are activated by cytokines and chemokines. Rho activates Rho kinases phosphorylate myosin light chain and inhibit myosin light chain phosphatase. This leads to the cytoskeleton remodeling.
ROCK - Short for Rho-associated Coiled-coil forming protein kinase, is one of the targets of Rho-GTP-binding proteins. When activated by Rho, they phosphorylate myosin light chain and inhibit myosin light chain phosphatase. This leads to the cytoskeleton remodeling and cell migration.
Contractile ring consists of actin and myosin II filaments beneath the plasma membrane. Its contraction pulls the plasma membrane inwards, dividing the cell into two. The thickness of the contractile ring remains constant as it contracts which indicates that actin filaments disassemble during the process. It then disperses after cell division.
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