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:
CELLS! Living things use energy, move, consume water and food, etc. Any individual form of life that is capable of growing and reproducing is considered an organism. All organisms get water and other materials from the environment.
Explanation:
Answer:
Direct and indirect sunlight is the main cause for the 4 different seasons
Explanation:
Answer:
fluids we drink.
Explanation:
Most body water comes from fluids we drink such as water, juices etc. Our body obtains water by absorbing it directly from the digestive tract. A small amount of water is produced in the metabolism of food particles. Our body loses excess amount of water by excreting it in the form of urine from the body. Kidney is the organ that filters waster materials and excess water from the blood and remove it from the body.
Answer:
Operons afford the organism the opportunity to simultaneously regulate transcription of multiple genes, whose products are active in the same process.
Explanation:
Operon is the group of related genes and the operator and promoter sequences that regulate their expression. All the genes in an operon are expressed together and are under the regulation of the same promoter and operator sequences.
Operons consist of the genes that are involved in related metabolic pathways. For example, the genes that code for the enzymes of lactose catabolism are expressed together as lac operon. It allows simultaneous expression of the genes of lactose catabolism only when lactose is present in the medium. Similarly, these genes are inhibited simultaneously in absence of lactose by binding of repressor protein to the operator sequence.
