C4 Missed Questions Flashcards
Which of the following provides molecular evidence that signal transduction pathways evolved early in the history of life on Earth?
The mechanisms of cell signaling are similar in organisms whose last common ancestor lived a billion years ago
Which of the following best describes processes that take place during cell communication to produce a cellular response?
A series of changes takes place in relay molecules through a signal transduction pathway.
A patient is given antihistamines due to an allergic reaction where vascular permeability is increased, causing watery eyes. Which of the following describes how antihistamines affect a signal transduction pathway?
Antihistamines block histamine from binding to the appropriate receptor.
Acetylcholine is found in the synapse between muscles cells and neurons. It can be broken down by the enzyme acetylcholinesterase. Which of the following describes what happens if acetylcholinesterase is inhibited?
Acetylcholine will continue to be activated.
The cholera bacterium Vibrio cholerae produces an enzyme toxin that chemically modifies a G protein involved in regulating salt and water secretion in intestinal cells. Stuck in its active form, the modified G protein stimulates the production of a high concentration of cAMP, which causes the intestinal cells to secrete large amounts of salts into the intestines, with water following by osmosis. An infected person quickly develops profuse diarrhea and, if left untreated, can soon die from the loss of water and salts. What is the basic effect of the cholera toxin?
The basic effect of the cholera toxin is signal amplification.
Which of the following is not a way in which antihistamines may affect transduction pathways?
They reduce histamine in the blood by binding to and destroying it.
Which of the following organisms can only use behavioral controls to maintain its body temperature?
Rattlesnake
What happens in diabetes
Our cells have a signaling pathway that begins with an insulin receptor and results in the cell taking in glucose through a specific channel in the cell membrane. Individuals with type 1 diabetes do not produce insulin, which means there is no signaling molecule to bind to the receptor and initiate this pathway.
What are antihistamines
Histamines increase vascular permeability, causing fluid to escape from capillaries into tissues. This leads to the classic symptoms of an allergic reaction, such as a runny nose and watery eyes. Normally, when an antigen binds to an appropriate receptor, it causes the immune system to produce and release histamines from the mast cell granules. Antihistamines are a group of pharmaceutical drugs that interfere with the production or function of histamines, to prevent or decrease the symptoms associated with allergic reactions. Some antihistamines block this signal transduction, preventing the release of histamines. Others block the histamine from binding to the appropriate receptor, while still others inhibit the enzyme that normally catalyzes the transformation of histidine into histamine.
G1 Phase
The G1 phase is the longest stage of interphase. During this time the cell grows in size and performs its particular jobs and functions within the organism. For example, liver cells in your body work to store sugar from your food and the leaf cells in a tree perform photosynthesis to harness energy from the sun. Cells in this phase will work and grow until they get too large to continue normal daily activity. When they reach that point, a chemical signal is activated to send them into the S phase.
S Phase
In the S stage, or the synthesis phase, the cell will make a copy of the chromatin in its nucleus. The chromatin contains the cell’s DNA. Once this genetic material has been copied, the cell moves on to the G2 phase.
G2 Phase
Now in the G2 phase, the cell grows a bit and makes final preparations for cell division. At the end of this phase, the cell is ready to divide.
Prophase
The duplicated chromatin inside the nucleus condenses into chromosomes, becoming more visible under a microscope. These identical copies of chromosomes, called sister chromatids, are held together at the center by a centromere. This is why each pair of sister chromatids resembles the letter “x.”
The nuclear membrane and the nucleolus begin to break down and disappear.
Spindle fibers, fanlike structures of very thin fibers, begin to form from one end of the cell to another. Centrioles, tiny structures within the cell’s cytoplasm, organize the spindle fibers.
Metaphase
The sister chromatid pairs line up across the middle of the cell.
Spindle fibers attach to the centromeres at the center of each chromatid pair.
Anaphase
The centromeres that are holding the sister chromatids together divide, and the individual chromosomes are pulled apart.
The individual chromosomes move along the spindle fibers to opposite ends of the cell. Each resulting set of chromosomes contains an exact copy of the original genetic information.
