Indicate whether each of the following statements is likely to be true or false. Integrins are transmembrane components of “adhesion belts”.   [1] Tight junctions seal the plasma membrane of adjacent epithelial cells together, which makes it possible for directional membrane transport across the epithelial sheet to occur. [2] Gap junctions are important structures for coupling the electrical and metabolic activities of adjacent cells. Gap junctions are always open. [3] Extracellular matrix plays an important role in tissue formation and regeneration.  [4]

Complete the following statements by selecting one of the options provided.  A genetic change that inhibits the production of S-cyclin will lead to  [1] It usually takes a few [2] for the initial abnormal cell to develop into a tumor detectable by X-ray. A mutation that increases the activity of the monomeric GTPase Ras will lead to [3] of cells. A mutation that [4] the activity of CDI (Cdk inhibitor) will lead to accumulation of DNA damages. A mutation that [5] the activity of the anaphase promoting complex (APC/C) will cause cell-cycle arrest. The inactivation of cell cycle checkpoints will lead to [6] 

Determine, for each individual case listed below, whether a certain genetic change will result in high activity of the gene product of a proto-oncogene. Answer Yes or No for each case. Gain of a chromosome that contains the proto-oncogene. [1] A mutation that introduces a stop codon 10 amino acids after the codon for the initiator methionine. [2] A mutation within the coding sequence that makes the protein less active. [3] A change in the promoter of the proto-oncogene, causing the normal protein to be transcribed and translated at an abnormally high level. [4]

The actin subunits at the minus end of a rapidly shrinking actin filament most likely contain___

 Indicate whether each of the following statements regarding skeletal muscle contraction is likely to be true or false.   After receiving a stimulating signal from a motor neuron, an action potential is generated and propagated across the plasma membrane of the muscle cell. This causes an influx of Ca2+ into the sarcoplasmic reticulum, triggering a muscle contraction. [1] When the cytoplasmic [Ca2+] increases, a change in the conformation of troponin leads to changes in tropomyosin such that it blocks the binding of myosin heads to the actin filament. [2] During muscle contraction, the Z discs move closer together as the myosin heads walk toward the minus ends of the actin filaments. [3] The T-tubule membrane in the muscle cell contains voltage-gated calcium channels. [4]

Indicate whether the following statements are true or false. An antibiotic that inhibits protein synthesis of a bacterium will likely inhibit protein synthesis in mitochondria. [1] The mitochondria are thought to have evolved by invagination and pinching off from the plasma membrane of an ancient eukaryotic cell. [2] Most mitochondrial proteins are translated in the cytosol. [3] Reovirus enters into the target cell by engaging with the surface receptor on the target cell, which in turns triggers the assembly of clathrin coat on the cytoplasmic side. [4] Reovirus is activated when an outer shell viral protein is attacked by an intestinal protease.[5] Per pumping cycle, the sodium-potassium antiporter transports one sodium ion into the cell and one potassium ion out of the cell. [6] The electrical potential of a charged molecule is not zero if the membrane potential is not zero.  [7]

For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below.  Not all words or phrases will be used; each word or phrase should be used only once. There are several ways that membrane proteins can associate with the cell membrane.  Membrane proteins that extend through the lipid bilayer are called [1] proteins and have [2] regions that are exposed to the interior of the bilayer. Some other proteins are [3] attached to lipid molecules that are inserted in the membrane.  [4] membrane proteins are associated with the membrane through noncovalent interactions with other membrane-bound proteins. In animals, proteins constitute ~ [5] of the total mass of the plasma membrane. Transmembrane proteins that are destined for the plasma membrane are first inserted into the membrane of the [6]. 

For a cargo protein to be delivered to the nucleus, which of the following statements regarding its nuclear localization sequence is true?

In the textbox, compose your rough draft for Paragraph 2.  You should consult your outline (a printed copy) as you work on the paragraph. 

Find (fg)(x).​\(\style{font-family:Times New Roman}{f(x)=x^2,\;g(x)=\text{7}x-\text{7}}\)​