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Reil [10]
2 years ago
6

An epithelial cell with Celia would have them on the ______ surface.

Biology
1 answer:
JulijaS [17]2 years ago
6 0

Answer: C) Apical

Explanation: An epithelium has a free surface, the apical surface, exposed to the outside, and an attached surface, the basal surface, resting on the underlying connective tissue.

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Explain why serine proteases do not catalyze hydrolysis if the amino acid at the hydrolysis site is a D-amino acid. Trypsin, for
kotykmax [81]

Answer:

Explanation:

A protease is an enzyme that catalyzes the hydrolysis of the peptide bonds that tie polypeptide chains together, releasing individual amino acid subunits. The L and D nomenclature for amino acids defines the structure of the glyceraldehyde isomer through which the amino acid can be produced.

SEE BELOW FOR THE APPROPRIATE STRUCTURES.

We need to figure out why swine proteases hydrolyze L-amino acids but not D-amino acids in any way. we know that enzymatic catalysts act as polypeptides if you can recall. They must retain a very precise three-dimensional structure for a catalytic activity to occur. Substrates that do not quite match the required configuration at the active site will not be reacted to — this is a "lock and key" style.

The present exercise may be explained by the fact that the configuration and structure of D-amino acids prevent them from binding properly to the active site of the protease enzyme. Perhaps they're pointed in the wrong direction, or perhaps there happens to be missing electrical interaction that's needed to keep the substrate in position.

Nonetheless, L-amino acids, on the other hand, seem to have the right configurational aspects in the active site and are hydrolyzed.

5 0
2 years ago
Can someone answer this pls??
Lunna [17]

Answer:

75% brown, 25% white

Explanation:

This question involves a single gene coding for color in chickens. The allele for brown color (B) is dominant over the allele for white color (b).

According to this question, a brown rooter with genotype 'BB' was crossed with a white hen (bb). The offsprings in the F1 generation will all possess the 'Bb' genotype and be brown colored. However, if these F1 offsprings are self-mated i.e Bb × Bb, the proportion of F2 offsprings will be 1BB, 2Bb, 1bb.

Since BB, Bb and Bb offsprings are Brown in color and bb is white in color, this means that the expected phenotypic appearance of the F2 offsprings will be:

¾ or 75% brown and ¼ or 25% white

8 0
3 years ago
How do temperature and concentration of monounsaturated phospholipids change the rate at which molecules permeate the plasma mem
Nikitich [7]

Answer: At low temperatures the fluidity of the membrane decreases and it favors fluidity. The higher the concentration of unsaturated fatty acids, the less tightly the phospholipids can bind and the more fluid (more permeable).

Explanation:

The plasma membrane is a lipid layer that delimits the entire cell, dividing the extracellular medium from the intracellular (the cytoplasm of a cell). They are composed of phospholipids, which are molecules composed of glycerol, a phosphate group and two lipid chains (such as fatty acids). Glycerol is a three-carbon molecule that functions as the backbone of this membrane. A geometry is formed that allows the phospholipids to line up side by side to form broad sheets. They are insoluble in water, but their unique geometry causes them to aggregate in layers without any energy input, as they possess a hydrophilic phosphate head and a hydrophobic tail consisting of the two fatty acid chains. The hydrophilic heads of the phospholipids in a bilayer membrane face outward and are in contact with the aqueous fluid inside and outside the cell. Because water is a polar molecule, it readily forms electrostatic (charge-based) interactions with the phospholipid heads.

Selective permeability is a property of the plasma membrane and other semipermeable membranes that allow only certain particles to pass through them. In this way,<u> those particles that are needed by the cell can enter the cell and those that are not useful to the cell are prevented from entering</u>. In the same way, the cell can eliminate the particles it has produced as waste. In this way, the entry and exit of substances through the membrane is regulated and the correct functioning of the cell is achieved.

For a particle to be able to cross the plasma membrane it must have a size equal to or smaller than the pores of the membrane, it must have the opposite charge to the charge of the membrane or simply have a neutral charge, and if it is larger than the pores it must be dissolved in a solution, decreasing its size and thus be able to enter the cell through the membrane.  

Plasma membranes are fluid and this fluidity depends on their lipid composition and temperature. Depending on the temperature, membrane lipids can be found in two different states or phases: gel (solid-like, with more rigid hydrocarbon chains) and liquid crystal (more fluid, with more mobile hydrocarbon chains). At low temperatures the fluidity of the membrane decreases and in these conditions the increase of its concentration favors fluidity. The temperature at which the transition from one state to the other occurs is the phase transition temperature (Tc). At values below Tc, the bilayer is in the gel state and at higher values it passes to the liquid crystal. It should be noted that there is an equilibrium between the gel state and the liquid crystal state and that the characteristics of the lipids of the bilayer condition the transition temperature. In the case of bilayers consisting of only one type of lipid, the Tc is well defined. But biological membranes are complex lipid mixtures and the transition from one state to another occurs over a range of temperatures. The presence of short-chain or unsaturated fatty acids reduces the transition temperature, while saturated fatty acids and the increase in the length of the hydrocarbon chains cause this temperature to rise. <u>Then, phospholipids with unsaturated fatty acid tails cannot bind as tightly due to the bent structure of their tails. For this reason, a membrane of unsaturated phospholipids remains fluid at lower temperatures than a membrane of saturated phospholipids</u>.  

The fluidity of a membrane is the ability of a molecule to move through it.<u> In short, the higher the concentration of unsaturated fatty acids, the less tightly the phospholipids can bind and the more fluid (more permeable) the membrane will be even at low temperatures</u>. However, <u>at low temperatures the fluidity of the membrane decreases (lower permeability) but the effect will depend on the composition of the fatty acids</u>. To determine the exact permeability, it is necessary to relate the concentration of unsaturated bonds and the length of the fatty acids in the phospholipids and the temperature.

8 0
3 years ago
Which of the following lists the reactants (raw materials) needed for photosynthesis to occur? *
Evgen [1.6K]

Answer:

carbon dioxide and water

Explanation:

carbon dioxide and water are the raw materials needed to start the reaction. They are on the left side of the equation so that is how you know.  

5 0
3 years ago
Read 2 more answers
Which level of organization completes a series of task?
tia_tia [17]
Option C would be correct. The organ system can plays many parts at one time. Also, it is the only system listed.

Hope this helps!
7 0
3 years ago
Read 2 more answers
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