60 years is three half life for the substance, so 40*1/2^3=5
Hi,
The rda is designed to be averaged over several days.
- true
(average across a number of days, because body is good at storing based on solid, reliable evidence and observations).
Answer:
With respect to the composition of DNA, in an analysis it can be found that the proportions of nucleotides are A + C = G + T (option a).
Explanation:
The proportion of nucleotides in a DNA molecule can be established according to the sequence of these nucleotides on both complementary strands, since the purinic bases of one strand are complemented by the pyrimidinic bases of another:
- <em>Adenine is complemented with Thymine A=T</em>
- <em>Guanine is complemented with Cytosine G=C</em>
From this we can deduce that in a DNA molecule with two chains there will be the same amount of adenine and thymine, as well as the same number of guanine with respect to cytosine, so:
<em> A + C = G + T</em>
An example of this would be a known DNA molecule (hypothetical), with 5 molecules of Adenine and 7 molecules of Guanine. In this case there are 5 Thymines, complementary with Adenine, and 7 Cytosines like Guanine:
<em> A + C = G + T</em>
<em> 5 + 7 = 7 + 5</em>
Answer:
The reflex arc follows this sequence of events
1. sensory receptor activation
2. sensory neuron activation
3.information processing
4. motor neuron activation
5. effector response
Explanation:
Reflex arc is the pathway of nerves during a reflex action. An example of a reflex arc is when we accidentally touch a hot object. First, the receptor in the skin detects a stimulus in this case the change in temperature. Second, the sensory neuron transmit the electrical impulses to the Central Nervous System for information processing. Then relay neurons connect sensory neurons to motor neurons. Third, motor neurons sends electrical impulses to an effector wherein the effector produces a response ( muscle contracts to move the hand away from the hot object. This happens in a split of seconds.
DNA is condensed by a certain amount just on its own, just by its own interactions within the DNA molecule,..but whne proteins get involved it gets condensed 30000 fold
<span>what happens is that proteins called histones are like hockey pucks, and DNA wraps around it 1.5 times and then goes to another histone and wraps around that so that it looks like beads on a string (i hope that makes sense, its the only way to describe it) </span>
<span>these histones condense this DNA a lot, and when the histones get methylated then the DNA packs together even closer to get heterochromatin (VERY densely packed DNA)...the theory here is that DNA has a net negative charge due to the phosphate groups in the DNA backbone and doesnt allow the DNA to come together as closely as it could (like charges repel like charges), but when histones are methylated, the negative charge on the DNA is masked by the methyl groups and DNA can come together closer </span>
