Answer:
Colchicine
Explanation:
Colchicine is an alkaloid derived from the autumn crocus (Colchicum autumnale).
The effect of colchicine, which inhibits microtubule polymerization and thus assembly of the mitotic spindle, demonstrates the presence of another checkpoint in the cell cycle. When colchicine is added to cultured cells, the cells enter mitosis and arrest with condensed chromosomes. With increasing time, a large fraction of the cells in a culture become arrested, thus permitting determination of the size, shape, and number of mitotic chromosomes — that is, the karyotype — in multiple cells. A checkpoint control somehow senses when the mitotic spindle has not assembled properly and prevents activation of the APC polyubiquitination system that normally leads to degradation of the anaphase inhibitor, required for onset of anaphase, and later to the degradation of mitotic cyclins, required for the exit from mitosis. As a result, MPF activity remains high, chromosomes remain condensed, and the nuclear envelope does not re-form.
Answer:
B
Explanation:
Great variations in temperature and pH from the optimum that an enzyme needs can affect its function. pH affects ionization of the functional groups of amino acids. The interaction of charges of these amino groups helps in stabilizing loops such as those of beta sheets and alpha helices and give the protein its an appropriate shape to function.
Temperatures, on the other hand, while it does not change the ionization of the functional side groups of amino acids, it breaks these bonds of the interactions by giving the molecules enough energy to break free from these bonds hence denaturing the protein.
Answer:
In reproductive or sexual cells
Explanation:
There are two principal types of cells in the organism: Somatic diploid cells (2n) that reproduce by the process of mitosis, and germ cells that are diploid reproductive cells in charge of gamete production. These germ cells suffer both mitosis (to form more sexual cells) and meiosis (giving place to haploid gametes: sperm and egg cells, through the gametogenesis process). Both somatic cells and germinal cells will end their cycle becoming two daughter cells with the same genetic dotation.
Gametes from each parent will merge in the process of fecundation, during which a new diploid cell called a zygote emerges through fertilization. The zygote is a complete cell from the structural point of view that suffers successive mitosis to form the new organism.
Any cell in the organism might suffer mutation.
- If the mutation occurs in the somatic cells, it will produce a population of identical mutated cells in that organism. However, this mutation in these cells is not inheritable. By definition, mutations in somatic cells do not inherit because these cells do not produce progeny.
- If the mutation occurs in the germinal line, in the germ cells, or the sexual cells, this <u>mutation will pass to the offspring</u>. The organism with mutated germinal cells might express a normal phenotype, but this mutation will be detected in the progeny.
The right answer is D
The stomata are at the level of the epidermis of the leaves and aerial stems, the place of passage of the gases (carbon dioxide, oxygen, water vapor) which play a fundamental role in the physiology of the plant. These structures (which can be considered as "mini-organs") interactively regulate these exchanges. They are the terrestrial plants that constitute the true interface between the external atmosphere and the internal gas network.
Answer:
They help scientists observe things that are very small.
Explanation:
Geologists use a lot of tools to aid their studies. Some of the most common tools used are compasses, rock hammers, hand lenses, and field books.
