Answer:
1. Verdadero
2. Falso
3. Falso
4. Falso
5. Verdadero
Explanation:
Los seres humanos, como así también la mayoría de los mamíferos, poseen dos cromosomas sexuales: un cromosoma X y un cromosoma Y. Las hembras poseen 2 cromosomas X (un cromosoma X es heredado de la madre y el otro cromosoma X es heredado del padre); mientras que los hombres tienen un cromosoma X y un cromosoma Y (el cromosoma X es heredado de la madre, mientras que el cromosoma Y es heredado del padre). La hemofilia es una enfermedad recesiva monogénica ligada al cromosoma X, la cual está caracterizada por cuadros hemorrágicos causados por el déficit parcial y/o total de factores de coagulación. Los hombres expresan el fenotipo recesivo con mayor frecuencia que las mujeres para aquellos genes que se encuentran en el cromosoma X y poseen un mecanismo de herencia recesivo, esto debido a que los hombres sólo poseen una copia del alelo ligado al X (lo que hace que el alelo recesivo se exprese con mayor frecuencia en el fenotipo). De este modo, los hombres manifiestan hemofilia con mayor frecuencia que las mujeres porque en mujeres el gen recesivo necesita la presencia de dos copias del alelo defectuoso recesivo para que se exprese en el fenotipo hemofílico (es decir, las mujeres heterocigotas son portadoras de un alelo defectuoso pero no expresan la condición en el fenotipo), mientras que en los hombres la presencia de un sólo alelo defectuoso localizado en su único cromosoma X es suficiente para la expresión del fenotipo recesivo. En hombres, los genes ligados al cromosoma X son siempre heredados de la madre (los hombres heredan del padre el cromosoma Y). Finalmente, la herencia de caracteres ligados al cromosoma Y es muy rara porque los genes localizados en la región diferencial del cromosoma Y son escasos y estos genes solamente pueden ser trasmitidos de padres a hijos varones (ya que se encuentran en el cromosoma Y).
Green house gases gives out. Carbon dioxide more than oxygen.... nitrogen stays the same as greenhouses gas does take in or give out
Answer:
The correct answer is c) The first statement is true; the second is false.
Explanation:
To be able to perform its role, a hormone must bind a specific receptor in its target cell. The receptor can be located inside the cell (in cytosol) or in the surface of the cell (transmembrane receptor). By regulating the expression of the receptor, the target cell regulates the hormonal activity.
The number of hormone receptors in a cell is not constant, it can vary depending on sereral factors, such as the age of the organisms, the effect of several drugs, mutations or diseases.
Answer:
TNF-alpha is expressed as a homotrimer that exerts its activities through binding to two types of receptors: TNFR1 and TNFR2, which are transmembrane glycoproteins characterized by having an extracellular domain with 4 cysteine-rich domains (CRD 1-4) , each with 3 cysteinecysteine disulfide bonds.
Explanation:
TNF-alpha (Tumor Necrosis Factor), which has the characteristic of being a paracrine signaling ligand, is a pleiotropic cytokine that functions as a mediator of immune regulation, the inflammatory response and apoptosis in some cell types. Receptors in this family are involved, with some exceptions, in juxtacrine signaling; that is, both the ligand and the receptor are membrane proteins with extracellular domains through which signaling is established. The cellular responses promoted by TNF are initiated by its interaction with two different types of cell receptors, the type I receptor (55 kDa) and the type II receptor (75 kDa). Both types of receptors are part of the TNF receptor family, members of which include Fas antigen (apoptosis inducer, also called Apo-1 or CD95), CD27 (T-cell activation antigen), CD30 (lymphoma marker Hodgkin) and CD40 (B-cell antigen), which share the characteristic of cysteine-rich sequences in their extracellular domains. This family of cytokines generate cellular responses that include differentiation, proliferation, activation of NFκB and cell death, promoting the aggregation of receptor monomers, that is, they have a transmembrane domain that participates in the solubilization of the receptor and a domain of intracellular death that is involved in signal transduction. The binding of TNF to TNF-R1 induces a signaling cascade through its intracellular death domain, which subsequently leads to the activation of complex I (or inflammatory) of NFkB and proceeds to the transcription of anti-apoptotic genes, pro- inflammatory diseases and apoptosis complex II (caspases).
