Sabemos que la vida comenzó hace al menos 3.500 millones de años, porque esa es la edad de las rocas más antiguas con evidencia fósil de vida en la tierra. Estas rocas son raras porque los procesos geológicos posteriores han remodelado la superficie de nuestro planeta, a menudo destruyendo rocas más viejas y creando otras nuevas (lo siento si es un amor incorrecto, marque como más inteligente si es correcto).
Answer:
Aa would be ur answer:)))
Answer:
The C. elegans embryo is a powerful model system for studying the mechanics of metazoan cell division. Its primary advantage is that the architecture of the syncytial gonad makes it possible to use RNAi to generate oocytes whose cytoplasm is reproducibly (typically >95%) depleted of targeted essential gene products via a process that does not depend exclusively on intrinsic protein turnover. The depleted oocytes can then be analyzed as they attempt their first mitotic division following fertilization. Here we outline the characteristics that contribute to the usefulness of the C. elegans embryo for cell division studies. We provide a timeline for the first embryonic mitosis and highlight some of its key features. We also summarize some of the recent discoveries made using this system, particularly in the areas of nuclear envelope assembly/ dissassembly, centrosome dynamics, formation of the mitotic spindle, kinetochore assembly, chromosome segregation, and cytokinesis.
1. The C. elegans embryo as a system to study cell division
The C. elegans embryo is a powerful model system for studying the mechanics of metazoan cell division. Its primary advantage is that the syncytial gonad makes it possible to use RNA interference (RNAi) to generate oocytes whose cytoplasm is reproducibly (>95%) depleted of targeted essential gene products. Introduction of dsRNA rapidly catalyzes the destruction of the corresponding mRNA in many different systems. However, depletion of pre-existing protein is generally a slow process that depends on the half-life of the targeted protein. In contrast, in the C. elegans gonad, the protein present when the dsRNA is introduced is depleted by the continual packaging of maternal cytoplasm into oocytes (Figure 1). Since depletion relies on the rate of embryo production instead of protein half-life, the kinetics tend to be similar for different targets. By 36-48 hours after introduction of the dsRNA, newly formed oocytes are typically >95% depleted of the target protein.
Explanation:
The type of glial cells are particularly at risk from the disease are the Schwann cells. This disease is caused by a bacterium, Corynebacterium diphtheriae, and is caused when the bacteria releases a toxin, or poison, into a person's body. The Schwann cells produces insulating myelin sheath that covers the axons of many neurons. These cells may suffers immune or toxic attacks with diphtheria infection.
