Should RGS (regulator of G protein signaling) proteins be classified as GEFs (guanine nucleotide exchange factors) or GAPs (GTPase activating proteins) Explain what role this activity plays in modulating G-protein-mediated responses in animals and yeasts.

问答题Transport by carrier proteins can be either active or passive, whereas transport by channel proteins is always passive. Explain your answer.

问答题The signaling mechanisms used by a steroid-hormone(固醇激素) receptor and by an ion-channel-linked receptor have very few components(组分). Can either mechanism lead to an amplification of the initial signal If so, how

问答题The basic structure of biological membranes is determined by the lipid bilayer, but their specific functions are carried out largely by proteins. Explain your answer.

判断题电镜的波长与电压有关，电压越高，波长越短，分辨率越高。

判断题Because prokaryotic cells have neither mitochondria nor chloroplasts, they cannot carry out either ATP synthesis or photosynthesis.

问答题Discuss the following analogy(相似): “The differences between transporting a ligand by a channel or a carrier protein are like the differences between crossing a river by a bridge or a ferry(摆渡).

问答题EGTA chelates(螯合) Ca2+ with high affinity and specificity. How would microinjection(微注射) of EGTA affect glucagon-triggered breakdown of glycogen (糖原) in liver

问答题What functional roles do the ECM (细胞外基质)and cell wall share in common

判断题Atrial natriuretic peptides(心钠肽) bind to a receptor that activates a G protein,which in turn activates guanylyl cyclase(鸟苷环化酶) to produce cyclic GMP which then activates a cyclic GMP-dependent protein kinase (PKG).

判断题It is thought that extracellular ligand binding to a receptor tyrosine kinase activates the intracellular catalytic domain by propagating a conformational change across the lipid bilayer through the single transmembrane a helix.