Answer:
The correct answer is 7.68
Explanation:
Isoelectric point (pI) is the pH at which the amino acid has net a charge of zero. We have to choose the two values of pKa at which the neutral form of the amino acid is predominant. Histidine (Hys) is a basic amino acid. From pKa's data, we deduce:
pKa1 = 2.3 (corresponds to α- carboxyl group)
pKa2= 6.04 (corresponds to R group)
pKa3= 9.33 (corresponds to α- amino group)
Since it is a basic amino acid, the neutral form will exist between the higher pKa's values. Thus, the pI will be in a pH value between 6.3 and 9.33.
So, we have to calculate the average of pKa2 and pKa3:
pI= (pKa2+pKa3)/2= (6.04+9.33)/2= 7.68
Therefore, the pI of Hys is 7.68.
Answer:
The cells need water to maintain their metabolic functions, the way water enters through cells membranes is by osmosis.
Explanation:
The cell membrane is a lipidic bilayer composed of phospholipids and embedded proteins. Phospholipids have the characteristic of being amphiphilic which means that possess hydrophilic and lipophilic characteristics. The most common way is by osmosis, that is a mechanism that moves water from high concentration to less concentration of water. In the cell membrane, there are is channels of proteins called aquaporins that facilitate the pass of water through the membrane. Also, as water is a very small molecule without charge, this characteristic allows passing a limit amount of water molecules through the hydrophilic characteristic of membranes.
Answer:
the answer is B. C horizon
Explanation:
AP3X
_____A_______Adductor A. Action (type of movement)
magnus B. Shape
Vastus lateralis C. Site of origin or insertion (Points of attachment)
lateralis D. Number of origins
E. Location to a nearby bone
Biceps femoris
Biceps F. Direction the muscle fibers are oriented
femoris G. Size of muscle
Fibularis longus H. Location to a superficial area
一Fibularis
longus
Popliteus
Popliteus
Answer:
Explanation:
Brachii: H - It means of the arm.
Palmaris: H - It means of the palm of hands.
Longus : G - Longus means long
Brachio: C - It refers to origin on the upper arm.
Radialis: C - It refers to insertion on the radius of the forearm.
Pronator: A - Pronation is inward rotation of part of the body towards middle of the body.
Teres: B - meaning round or cylindrical shape
Deltoid: B - meaning triangular shape
Cold-blooded animals change their body temperature to match the environment.
Mammals and birds are usually cold blooded.
All of the above.
Answer:
Explanation:
Cold blooded animal did not have cold blood.
Cold blooded animals can’t change their body temperature to match the environment.
Mammals and birds are not cold blooded.
Endotherms, such as mammals and birds, are able to maintain a constant body temperature in the face of changing environmental conditions. In contrast, cold-blooded animals, or ectotherms, have a body temperature that matches their environment and varies with it.
An animal that maintains a constant body temperature in the face of environmental changes is called an endotherm. These animals are able to maintain a level of activity that an ectothermic animal cannot because they generate internal heat that keeps their cellular processes operating optimally even when the environment is cold.
Mammals and birds evolved endothermy, meaning they regulate their body temperature from the inside through metabolic or physical changes. This allows them to maintain a relatively stable body temperature regardless of the outside temperature.
Cold-blooded animals, also known as ectotherms, rely on external temperatures to set their body temperature. Their body temperature varies with the environment.
Answer:
enzyme RuBisCO
(im not sure but i think its this)
Answer:
Explanation:
The scenario is the following.
A population of yellow lizards lives on an island where there is no natural predator. Males of the species use the yellow color to attract females in reproductive seasons. The brighter the males are, the better their genetic quality is. Females are also yellow, but not as bright as males.
A new hawk species was introduced into the island to control some farm pests. But this hawk species prefer to feed on the lizards. The yellow color of these animals contrasts with the dark background and can be easily seen from the air. So the lizard population suffers from significant predation affecting its size sharply.
Some of the lizards then suffer from a mutation and change their color from yellow to greyish brown, which turns to be better to camouflage on the rocks and get to survive. Individuals with greyish brown color get to reproduce at a higher rate than yellow individuals, who keep being hunted by the hawk.
Eventually, after many generations, the yellow individuals decrease to near zero in the population, while greyish brown individuals increase significantly, with males still being brighter than females.
------------------------------------------------------------------------------------------------------
Natural selection is an evolutive force that can act favoring an allele or against it, according to how it affects the fitness of individuals. Natural selection selects beneficial alleles and increases their frequency in the population.
When many organisms in a population sharing the same trait die, it is because they did not have good fitness, so they were not adapted to the environment and its pressures. The alleles coding for that trait were not good for the fitness of the animals, so they do not get to survive.
These individuals die before reproducing, so they could not transfer their genetic charge to the following generation. Eventually, the alleles coding for the trait will decrease in the population, probably near zero. Natural selection is acting against this phenotype. Other alleles will be beneficiated, and their frequency in the population will increase.
This change in alleles frequency is what we call adaptation.
Natural selection results in adaptation, which means the increase of the aptitude phenotype. Aptitude is the contribution of each genotype to the next generation.
In many cases, adaptations can be correlated to environmental factors or selective pressures applied by other organisms or habitats.
Let us remember that a mutation is a change or alteration in DNI sequences that introduce new variants. Many of these are eliminated, but some of them might succeed and be incorporated into each individual. These mutations are the ones that have been selected by natural selection.
So, in the exposed example, we are focussing on the lizards population.
• The selective pressure or modeling environmental factor is predation by the introduced hawk.
• The lizards´ response to predation is the survival of only those that carry mutations ⇒ greyish brown color
• Natural selection benefits these mutations.
• Greyish brown lizards survive and increase their fitness.