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:
all cells so the last one
It was the trip that Charles Darwin went on in attempt to find the answer of how animals got on earth in the first place and how they changed over time. This later on helped him discover evolution and natural selection. The most significant find on this voyage was that he found that different types of finches evolved to the food around them. Smaller beaks meant the finch ate more small nutrients but larger beaks meant the finch ate more harder prey such as fish and worms.
What are the nephron?
Nephrons are the functional unit of the kidney. There are about two million nephrons in each of our kidneys. Each nephron has a network of glomelural capillaries called glomerulus where blood filtration occurs, and the renal tabule which is where the filtered fluid is converted to urine.
How they work?
The nephrons act as a filter, cleaning our blood. Unwanted metabolites like urea and creatinine are taken from the blood, as well as high amounts of sodium. The filtered fluid flows from inside Bowman's capsule (epithelial cells surrounding the glomerulus) and from there into the proximal tubule (see attached figure at the end). From the tubule, fluid flows into several other ducts until it reaches the ducts where collectors will empty into the renal pelvis.
