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SCORPION-xisa [38]
3 years ago
14

Why do you turn a C-terminal aminoacid's carboxyl group into an ester before reducing it to an alcohol? Why not just use LiAlH4

and do it in one step? This is to determine the C-terminal aminoacid in a peptide
Chemistry
2 answers:
taurus [48]3 years ago
8 0

Answer: To determine the C-terminal amino acid in a peptide

Explanation: To determine C-terminal residue, either of chemical reagent or the enzyme is used carboxypeptidase. The chemical reagent hydrazine forms aminoacyl hydrazides with every residue except the C terminus The C terminus is identified by chromatographic procedures.

Carboxypeptidase is an exopeptidase that specifically hydrolyzes the C-terminal peptide bond and releases the C-terminal amino acid. There two problems associated with its use: the continuous action of the enzyme and the substrate specificity of the enzyme. This continuous action may yield the second, third, and additional residues from some chains even before the terminal residues on every chain are quantitatively released. Therefore making it difficult to determine which residue is the C terminus.

Troyanec [42]3 years ago
4 0

Answer:

Esters are both inorganic and organic acids .... Regarding the second question, it is believed that it is carried out in this way in order to recognize the C-terminal amino acid in a peptide within a protein

Explanation:

The explanation of this question is according to what was interpreted in the question, since it is considered that it is poorly written ...

What happens in this chemical reaction is that it first becomes an ester (organic or inorganic acid) so that it is later recognized in the complex peptide structure.

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What causes a spring to bounce up when it is pushed down and then released?
nalin [4]

(a) Pushing the spring down gives it stored mechanical energy that turns into motion

Explanation:

Pushing on the spring causes the mechanical energy, of pushing on the spring, to be stored in the spring through potential elastic energy. Due to the elasticity of the spring, when the spring is released and resumes its initial shape the stored energy is released and can be used to do work such as motion.

4 0
3 years ago
1. What is the density of a 20 gram of 40 ml liquid?
____ [38]

Answer:

1. 0.5 g/mL

2. 0.88 g/cm^3

3. It has the greatest mass to volume ratio

4. Incomplete

5. H^+ (aq)+OH^-(aq)\rightleftharpoons H_2O (l)

6. 1

7. Gloves, goggles, coat, mask

8. Flush with tap water for at least 15 minutes

9. The facts are listed below

10. Mass and volume

12. All matter consists of moving particles, the degree of their movement is directly proportional to their kinetic energy

Explanation:

1. In order to solve for density, we should know that density is the ratio between mass and volume of a liquid. In this case, we're given both measures: given mass of m = 20 g and volume of V = 40 mL, we may simply apply the equation of density described here:

d=\frac{m}{V}

Substituting the variables, we obtain:

d=\frac{m}{V}=\frac{20 g}{40 mL}=0.5 g/mL

2. Given a mixture of several liquids, it's important to understand that liquids with a greater density will tend to form a bottom layer of a solution, while liquids with a lower density will tend to form a top layer of a solution. Here we have a liquid with a density of d_1 = 1.0 g/cm^3 and another liquid with a density of d_2 = 0.88 g/cm^3. Notice that d_1 > d_2.

This implies that the liquid with a density of 0.88 g/cm^3 would be on top, as its density is lower than the density of the other liquid with a density of 1.0 g/cm^3.

3. The solid phase is not always, but typically denser than liquids or gases. There are some exceptions to this rule, for example, ice, a solid phase of water, is less dense than liquid water.

However, for the majority of cases this statement is true. Remember that solid phases are the most ordered phases with atoms being packed closely to each other. In liquids, atoms are more dispersed with distances between them being greater than those in solids. Similarly, gases have the greatest distances between gas atoms among all three phases.

Since density is directly proportional to mass, let's say we take the same volume of a solid, a liquid and a gas. For the same volume, since we'll have a greater number of solid atoms than for a liquid or a gas (because solid atoms are more closely packed with lower average distances between the atoms), the mass to volume ratio will be the greatest for solids.

4. This seems to be an incomplete question.

5. In order to balance the following ionic equation, we need to follow the mass and charge balancing rules. Firstly, expand a water molecule showing the individual parts of it:

H-OH

Secondly, notice that we need to add a hydroxide anion to the proton, so that we obtain the same number of protons and hydroxide anions on the left side, as well as the number of hydrogen and oxygen atoms on the right. This way, the net charge on the left hand side (0) and the net charge on the right hand side (0) are equal, so the charge is balanced as well. We obtain:

H^+ (aq)+OH^-(aq)\rightleftharpoons H_2O (l)

6. We should be familiar with the ionization constant of water in the context of this problem. It is defined as the product between the hydronium ions and hydroxide ions and is a constant number at some given temperature. For pure water, the concentration of hydronium ions is balanced by the concentration of hydroxide anions to yield a neutral pH value, meaning the ratio of one with respect to the other would be 1.

For example, at room temperature, the ionization constant of water is defined as:

K_w=[H^+][OH^-]=10^{-14}

Since we have pure water:

[H^+]=[OH^-]=\sqrt{10^{-14}}=10^{-7}

Then the ratio is:

[tex]\frac{[H^+]}{[OH^-]}=\frac{10^{-7}}{10^{-7}}=1

7 to 12. The questions are explained in the file attached.

Download pdf
4 0
3 years ago
FOR FUTURE FLVS STUDENT
dalvyx [7]
<h3>Answers: </h3><h2>1. (D) 30°C </h2>

A good example that most people are familiar with is the heating of water. If we take a beaker packed with ice (solid water) and put in on a hot plate that has a temperature of 120 ° C we all know what will happen. First, the ice will dissolve to liquid water. Then the water will rise in temperature. Then ultimately the water will boil. During this complete process, the temperature of the hot plate will be greater than the temperature of the beaker of water. Thus, during this whole process energy will move in the form of heat from the hot plate into the water.  


<h2>2. (C) Boiling </h2>

When a system comprises only one phase (solid, liquid or gas), the temperature will rise when it gets energy. The rate of temperature rise will be dependent on the heat capacity of the phase in the system. When the heat capacity is high, the temperature rises slowly because much energy is needed to increase its temperature by one degree. Thus, the slope of temperature rise for the solid, liquid, and gases varies.  

<h2 /><h2>3. (C) Liquid </h2>

A cooling curve is a line graph that describes the difference of phase of matter, typically from a gas to a solid or a liquid to a solid. The independent variable is time and the dependent variable is temperature. The original point of the graph is the starting temperature of the matter,  regarded as the "pouring temperature".


<h2>4. Only the motion and arrangement of the particles changes, not the identity of the substance.</h2>

Water is held together by hydrogen bonds, the soundest of inter-molecular forces. This is where a hydrogen atom in one molecule is completely attracted to an electronegative atom (in this case, oxygen) in the other. When sufficient energy is absorbed by H2O, the molecules vibrate so vigorously that these bonds are loosened, giving them scope to bounce around. When this energy is taken out of the H2O, this transmits room for hydrogen bonds to tighten, squeezing collectively to form a solid.


<h2>5. liquid iron (2,000°C)</h2>

The kinetic energy of an object is the energy that it controls due to its motion. It is described as the work needed to stimulate a body of a given mass from rest to its stated velocity. Having obtained this energy during its acceleration, the body keeps this kinetic energy unless its speed changes.


<h2>6.</h2>

Boiling is the method by which a liquid changes into a vapour when it is burned to its boiling point. The transition from a liquid phase to a gaseous phase happens when the vapour pressure of the liquid is similar to the atmospheric pressure used on the liquid. Boiling is a physical change in which molecules are not chemically altered during the process. When atoms or molecules of a liquid are ready to expand out enough to change from a liquid phase to a gaseous phase, bubbles form and boiling occurs


<h2>7. (C) It will expand because the helium atoms will move more quickly and get farther apart.</h2>

Over a period of centuries and through various experiments, physicists and chemists have been equipped to describe key characteristics of a gas, including the volume it controls (V) and the pressure it exerts on its enclosure (P), to temperature (T).


<h2>8. (C) Neon Gas</h2>

Neon is a colourless, odourless, inert monatomic gas under regular conditions, with about two-thirds the density of air. It was recognized as one of the three residual rare inert elements surviving in the dry air after nitrogen, oxygen, argon and carbon dioxide were evacuated. Neon was the second of these three rare gases to be found and was immediately identified as a new element from its bright red emission spectrum.

6 0
3 years ago
The melting points of the two constitutional isomers are as follows: ortho-hydroxy acetophenone: 4-6 °C; para-hydroxy acetopheno
love history [14]

Answer:

ortho-hydroxy acetophenone form intramolecular hydrogen bonding. On the other hand, para-hydroxy acetophenone forms intermolecular hydrogen bonding.

Explanation:

Hydrogen bonding:-

  • Hydrogen bonding is a special type of the dipole-dipole interaction and it occurs between hydrogen atom that is bonded to highly electronegative atom which is either fluorine, oxygen or nitrogen atom.
  • Partially positive end of the hydrogen atom is attracted to partially negative end of these atoms which is present in another molecule. It is strong force of attraction between the molecules.

The bonding can be intramolecular and intermolecular. ortho-hydroxy acetophenone can form intramolecular hydrogen bonding which means that hydrogen bonding exist within the same molecule. On the other hand, para-hydroxy acetophenone forms intermolecular hydrogen bonding in which the bonding is in between the different molecules.<u> Hence, more amount of energy is required to melt these molecules in case of para-hydroxy acetophenone. </u>

6 0
3 years ago
What is the chemical composition of aragonite?
Alexandra [31]
Calcium carbonate CaCO3<span>


</span><span>
</span>
4 0
3 years ago
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