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:
The correct option is B) a pattern of biological functioning that occurs on a 24-hour cycle.
Explanation:
Biological rhythm is defined as the regular variation of an organic function related to the course of time, circadian biological phenomena (around the day), are those with a period of approximately 24 hours.
Circadian rhythms are physical, mental and behavioral changes that follow a daily cycle (the biological rhythm), and that respond primarily to light and darkness in an organism's environment. This cycle close to 24 hours, allows to recognize the sleep-wake phenomena and their homeostatic action, in the systemic processes of every living being. The circadian system is composed of photoreceptors, pacemakers and efferent pathways that allow a regular functioning of the sleep and wakeful state.
Answer:
<u><em>Seeds are found in both flowering and non-flowering plants. Both plants reproduce, the difference being that the former reproduces through blossoms, whereas the latter reproduces through seeds or spores. Because both flowering and non-flowering plants have chlorophyll, they can both photosynthesise.</em></u>
Explanation:
