DNA model given by Watson and Creek in the year of 1953 gave a very detailed study regarding the structure of B DNA which is valid till date and is essentially corroborating with Chargaff's data and Xray diffraction pattern.
<h3><u>Explanation:</u></h3>
The DNA is the most common nucleic acid found in the living organisms as a genetic material. As stated by Watson and Creek, this DNA contains a double helical structure with two sugar phosphate backbones and the nitrogen bases getting projected from it inwards. The backbones are formed of ribose sugar and phosphate and joined together with a phosphodiester bond. The ribose sugar is attached to phosphates at its 3' and 5' Carbon atoms. The nitrogen bases found in DNA are Adenine, Guanine, Thymine and Cytosine. The Adenine has two hydrogen bonds with thymine and guanine has 3 hydrogen bonds with cytosine.
Each full turn of a helix is 34A and each base pair is 3.4A apart. The distance between two strands of DNA is 20A.
Chargaff's rule regarding the equal amount of adenine and thymine as well as guanine and cytosine is matching with this structure. All the other rules also do match with this DNA structure.
Answer:
Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the limitations imposed by practicality, regulation, safety and cost.
Or,
the person who design and builds or maintain machines or structure..
Answer:
Stabilizing selection
Explanation:
The process of natural selection selects a species in one of the three ways: stabilizing selection, directional selection and disruptive selection.
During the process of stabilizing selection, nature does not favour the extreme phenotypes of the population but the intermediate phenotype with the maximum number of population.
In the given question, the Robin laid four eggs, neither more than four nor less than four which could have more disadvantages than the advantages. Since the intermediate number of eggs is favoured by nature therefore the stabilizing pattern is observed.
Thus, Stabilizing selection is correct.
Answer: Anterograde direction.
Explanation:
Choline acetyltransferase is an enzyme made in the body of a neuron and that needs to be transferred to the axon terminal to perform its function. Its function is to bind acetyl-CoA to choline to form the neurotransmitter acetylcholine.
The movement toward the cell body is called retrograde transport and the movement toward the synapse is called anterograde transport. So, since it is produced in the body of the cell and it has to go to the axon terminals, the choline acetyltransferase is transported in the anterograde direction.
This type of transport is responsible for the movement of organelles such as mitochondria, lipids, synaptic vesicles, proteins from a neuron cell body through the cytoplasm of its axon called the axoplasm. <u>Because axons can sometimes be meters long, neurons cannot rely on diffusion to carry products to the end of their axons</u>. Dynein is a motor protein involved in this retrograde axonal transport. Its light chains bind cargo, and its globular head regions bind the microtubule, "moving forward" along it.
<span>Pacinian corpuscles are rapidly adapting mechanoreceptors so they respond only at the onset and offset of the stimulus. The Pacinian corpuscle has a single afferent nerve fiber. Its end is covered by a sensitive receptor membrane whose sodium channels will open when the membrane is deformed in any way. Pressure thus causes sodium to enter the neuron and create a generator potential. If this potential reaches a certain threshold nerve impulses are formed. This impulse is now transferred along the axon with the use of sodium channels and sodium/potassium pumps in the axon membrane. The magnitude of the stimulus is encoded in the frequency of impulses generated in the neuron. So the more massive or rapid the deformation of a single corpuscle, the higher the frequency of nerve impulses generated in its neuron.</span>
