【多选题】How do cell-surface receptors relay extracellular signals via intracellular signaling pathways?
A.
The majority of extracellular signal molecules are proteins, peptides, or small, hydrophilic molecules that bind to cell-surface receptors that span the plasma membrane. Transmembrane receptors detect a signal on the outside and relay the message, in a new form, across the membrane into the interior of the cell.
B.
The receptor protein performs the primary step in signal transduction: it recognizes the extracellular signal and generates new intracellular signals in response.
C.
The resulting intracellular signaling process usually works like a molecular relay race, in which the message is passed “downstream” from one intracellular signaling molecule to another, each activating or generating the next signaling molecule in the pathway, until a metabolic enzyme is kicked into action, the cytoskeleton is tweaked into a new configuration, or a gene is switched on or off.
D.
This final outcome is called the response of the cell.
【单选题】听力原文: Students sitting the National College Entrance Exam are likely to see cell phone signals blocked inside exam sites this year to prevent cheating. While education authorities said they would use ...
A.
To increase the number of exam supervisors.
B.
To ban handsets from exam rooms.
C.
To equip exam sites with cell phone signal shielding facilities.
【单选题】There are more than _____ visibly different cell types in the body of a vertebrate. The majority of these are organized into epithelia—multicellular sheets in which adjacent cells are joined tightly t...
【简答题】从A、B、C、D中选择最恰当的选项填进文章中去,你会读到一个有意思的故事。 Do you like pop music? Most people do. One of the best 1 on the music scene is the New Ocean Waves. In the 2 twelve months, they've had three major 3 and made a h...
【简答题】请写出以下单词的中文意思 journalist circle meet therefore blame breathe combine nervous direction personal spoon without major symbol accurate cancel bury tendency hesitate average