A neuron sends information across a chemical synapse by
a. movement of sodium ions from the first cell through the membrane of the second.
b. electrons from the first cell that induce permeability changes in the second.
c. neurotransmitter molecules that penetrate into the second cell.
d. fusion of the plasma membrane of the first cell with the membrane of the second.
e. neurotransmitter molecules that bind to membrane receptors on the second cell.
E; Chemical synapses conduct information by releasing a neurotransmitter from the end of the button-shaped structures at the terminal branches of the axon. The neurotransmitter then binds to the membrane of the next cell. There is a small gap between the cells, which prevents sending an electrical signal (choices a and b) or fusing membranes directly (choice d). The neurotransmitter functions at the surface, and is usually either destroyed or taken back up by the original cell that released it (choice c).
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A scientist does not have an antibody to detect the protein of interest, but wants to know if the gene is expressed at low levels. What technique could the researcher use to detect, but not quantify the expression of the gene of interest?
A. Western Blotting B. real-time PCR C. cloning D. reverse transcriptase PCR
A polysome is ____
a. the combination of a large and a small ribosomal subunit b. the complex where mRNA splicing occurs c. the promoter assembly at the site of transcription initiation d. an mRNA transcript to which multiple ribosomes are attached e. the complex that adds a poly(A) tail onto an mRNA
Which of the following statements is false?
a. Many fossils have not been discovered, whereas others may have been destroyed. b. Some types of organisms are more likely to be preserved than others. c. Pressure and mineralization lead to fossil formation. d. Aerobic environments favor fossilization. e. Most fossils form in sedimentary rock.
Which laboratory finding is associated with multiple sclerosis?
A.) Antibody to acetylcholine receptors B.) Several bands on electrophoresis of cerebrospinal fluid C.) Antibody to thyroglobulin D.) Presence of antinuclear antibodies