Answer: We are evolving to the environment, and the changes around us. And those that don't die
Explanation:
They put pressure on us to adapt in order to survive the environment we are in and reproduce. It is selection pressure that drives natural selection ('survival of the fittest') and it is how we evolved into the species we are today. Genetic studies have demonstrated that humans are still evolving.
<span>If some of the synapses onto a cell have been highly active and others have not, only the active ones become strengthened. This is known as the property of specificity.
Synapse allows the neuron to pass electrical and chemical signals to other neuron. A specificity of synaptic connection between neurons and target cells is known as synaptic specificity.</span>
Answer and Explanation:
Ribosomes are the primary structure for protein synthesis. They can be found in the rough endoplasmic reticulum or floating in the cytosol.
Free ribosomes are not attached to any cytoplasmic structure or organelle. They synthesize proteins only for internal cell use. Other ribosomes are attached to the membrane of the endoplasmic reticulum and they are in charge of synthesizing membrane proteins or exportation proteins. Free and attached ribosomes are identical and they can alternate their location. This means that although free ribosomes are floating in the cytosol, eventually, they can get attached to the endoplasmic reticulum membrane.
Synthesis of proteins that are destined to membrane or exportation starts in the cytoplasm with the production of a molecule portion known as a <u>signal aminoacidic sequence</u>. This signal sequence varies between 13 and 36 amino acids, is located in the <u>amino extreme</u> of the synthesizing protein, and when it reaches a certain length, it meets the <u>signal recognizing particle</u>. This particle joins the signal sequence of the protein and leads the synthesizing protein and associated ribosome to a specific region in the Rough endoplasmic reticulum where it continues the protein building. When they reach the membrane of the endoplasmic reticulum, the signal recognizing particle links to a receptor associated with a pore. Meanwhile, the ribosome keeps synthesizing the protein, and the enlarged polypeptidic chain goes forward the reticulum lumen through the pore. While this is happening, another enzyme cuts the signal sequence, an action that requires energy from the ATP hydrolysis. When the new protein synthesis is complete, the polypeptide is released into the reticulum lumen. Here it also happens the protein folding (which is possible by the formation of disulfide bridges of proteins are formed) and the initial stages of glycosylation (the oligosaccharide addition).
Once membrane proteins are folded in the interior of the endoplasmic reticulum, they are packaged into vesicles and sent to the Golgi complex, where it occurs the final association of carbohydrates with proteins. The Golgi complex sends proteins to their different destinies. Proteins destined to a certain place are packaged all together in the same vesicle and sent to the target organelle. In the case of membrane proteins, they are packaged in vesicles and sent to the cell membrane where they get incrusted.
There are certain signal sequences in the <u>carboxy-terminal extreme</u> of the protein that plays an important role during the transport of membrane proteins. A signal as simple as one amino acid in the c-terminal extreme is responsible for the correct transport of the molecule through the whole traject until it reaches the membrane.
The correct answer is: None of the above
Soil formation is affected by many factors that include time, climate (temperature, precipitation), relief, mineral organic materials.
• Precipitation is part of the climatic factors. Precipitation refers to the amount of water (in the form of rain, snow) that a soil gets. Thus, it is one of the most important factor that determinates the formation and characteristics of soil. Precipitation affects both, the amount of erosion and weathering (breakdown of rocks and soil) that occurs.
• Time. It refers to changes of soil as it age. For example, older soils contain more organic matter and are more exposed to moisture and other environmental factors that may change their features.
• Erosion is removal and transportation of material from the Earth’s crust as a consequence of natural processes such as wind or rainfall. Because it includes the removal of the soil it affects its formation.