Answer:
Sometimes molecules cannot move through the cell membrane on their own. These molecules need special transport proteins to help them move across the membrane. Facilitated diffusion is the diffusion of substances with the help of transport proteins in the plasma membrane. These special proteins are called channel proteins or carrier proteins, and they are attached to the cell membrane. In fact, they go through the cell membrane, from the inside of the cell to the outside. Facilitated diffusion is used for molecules that cannot diffuse rapidly through cell membranes on their own, even when the molecules are moving from high to low concentration areas. An example is the sugar plants and animals use for energy, called glucose. Even though facilitated diffusion involves transport proteins, it is still passive transport because the solute is moving down the concentration gradient so it does not require the use of cellular energy.
Answer:
Transitional epithelium has dome shaped cells on the apical surface.
both alleles in the heterozygous
genotype are exhibit in the phenotypes. Allele
is completely dominant over the other, and it is the phenotype is a blend of the two
homozygous phenotypes, there are more than two forms of the same gene, and
there maybe one more superior form and several different phenotypes
Answer:
C. The enzyme with mutation 1 has decreased affinity for pyridoxal phosphate, whereas the enzyme with mutation 2 has lost the ability to bind to the substrates.
Explanation:
A coenzyme is an organic cofactor that binds with an enzyme in order to initiate or aid the function of the enzyme. A coenzyme binds to the active site of the enzyme (where the reaction occurs), thereby triggering its activation by modifying protein structure during the reaction. Some examples of coenzymes include Coenzyme A and Adenosine triphosphate (ATP). Pyridoxal phosphate is a coenzyme (it is the active form of vitamin B6) that is required for the function of cystathionase. Moreover, cystathionase is an enzyme that enables cells the synthesis of cysteine from methionine (transsulfuration pathway). The binding of pyridoxal phosphate to the enzyme increases the binding affinity of the enzyme for the substrate, thereby influencing its activity. In this case, it is expected that mutation 1 reduces the binding affinity of the enzyme to the cofactor, and thereby the cofactor is required at a higher concentration to restore normal enzyme activity.
