Answer
I added 4 and 5 as an attachment due to time constraint.
Explanation:
1. at a steady state ca2+ taken by vesicle = 40n/mol
enclosed volume of CSR = 5μ/mg
concentration of ca2+ in vesicle =
40*10⁻⁶/5x10⁻⁶
= 0.008
= 8x10⁻⁹mol/L
2. radius of circle =75nM
volume = 150nm
volume of vesicle = 4/3 x pi x r³
= 1.33 x 3.14 x (75x10⁻⁹)³
= 1.77 x 10⁻²¹
when we convert this we get
1.77x10⁻¹⁸L since 1m³ is equal to 100oL
surface area =4x3.14x(75x10⁻⁹)²
= 12.56x5.625⁻¹⁵
= 7.065x10⁻¹⁴m²
this is 7.065x10⁻¹⁰cm²
3. number of vesicle/CSR
= 5x10⁻⁶/1.77x10⁻¹⁸
= 2.824x10¹²
surface are = 2.824x10¹² x7.06x10⁻¹⁰
= 19.95x10²
Answer:
The correct answers are option A. "tethering proteins to the cell cortex", B. "using barriers such as tight junctions", C. "tethering proteins to the extracellular matrix", D. "forming a covalent linkage with membrane lipids", E. "tethering proteins to the surface of another cell"
Explanation:
According to the fluid-mosaic model, the components of cell membranes are in constant movement forming a barrier to avoid unwanted exterior component internalization and to avoid the loss of precious internal components. This constant movement could cause that proteins move across the plasma membrane. But, this is avoided by several mechanisms including:
A. Tethering proteins to the cell cortex. The cell cortex is a rigid structure made of actin and actomyosin. Proteins found in the plasma membrane are tethered to this structure to restrict their movement.
B. Using barriers such as tight junctions. Tight junctions are barriers found in epithelia made of claudin and occludin proteins. These barriers are impenetrable, which avoid the movement of proteins in the cell membrane.
C. Tethering proteins to the extracellular matrix. The extracellular matrix is made of several proteins and macromolecules that provide a structural and biochemical support to cells that are nearby. Proteins could be tethered to this rigid structure as well.
D. Forming a covalent linkage with membrane lipids. The proteins in the cell membrane that form a covalent linkage with membrane lipids are known as lipid-anchored proteins, or lipid-linked proteins.
E. Tethering proteins to the surface of another cell. When cell-cell communication take place it is possible that proteins in the cell membrane got tethered to the surface of the other cell.
Answer:
Resolution
Explanation:
This phase proceeds organisms. The Sexual Response cycle phases are; excitement, Plateau, Orgasm, Resolution. Resolution is a recovery period after orgasm. In men, it is called the Refractory period and varies in lengths between men. The body returns to normal levels of functioning in this phase.
