Explain how genetic mutations that cause neurodegenerative disorders such as Huntington disease and Alzheimer
disease can also cause abnormal behavior. What will be an ideal response?
ANSWER: Because the nervous system receives and processes stimuli and generates behavioral
responses, it is the focus of behavior genetics. The central nervous system (CNS) includes the
brain and spinal cord; the peripheral nervous system (PNS) includes the nerves that radiate
from the CNS and the sense organs. This emphasis is reinforced by the finding that many
disorders with a behavioral phenotype—including Huntington disease, Alzheimer disease,
and Charcot-Marie-Tooth disease—alter the structure and/or function of the brain and the
nervous system.
When a nerve impulse travels to the axon of one cell (neuron A), it must cross the synapse to
neuron B in order to continue its journey. Axon tips contain membrane-bound vesicles
enclosing packets of chemicals called neurotransmitters. These chemicals are an important
component of human behavior. When a nerve impulse arrives at the axon, neurotransmitters
are released into the synaptic cleft. These chemical signals diffuse across the cleft and bind to
receptors on the membrane of the postsynaptic neuron. Neurotransmitter binding triggers a
new nerve impulse in the postsynaptic cell. Changes in the timing or duration of
neurotransmitter action can affect someone’s behavior. In addition to mediating behavior,
neurotransmitters can affect our mood, memory, and our sense of well-being. Endorphins are
one type of neurotransmitter. When endorphins are released, often during exercise, stress, or
excitement, we feel a rush of exhilaration. Many drugs, such as cocaine, that change our
moods also bind to endorphin receptors and mimic the effect of our own neurotransmitters,
creating a similar feeling.
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A. the transfer of viral genes to a bacteria by a virus. B. the transfer of bacterial genes to another bacteria by a virus. C. the use of bacterial replication machinery to produce viral particles. D. the transfer of bacterial genes from one bacteria to another. E. the transfer of bacterial genes to another via a pilus.
Explain why epithelial cells are the source of 80% to 90% of all cancers. Then list at least two types of epithelial cells, and at least four types of cancer for which they are the source
What will be an ideal response?
It is hypothesized that the high diversity of rock-dwelling species within the cichlids is due to:
a. allopolyploidy. b. poor water quality. c. polyploidy coloration. d. disruptive sexual selection. e. macroevolution
What is selective toxicity?
A) The level of resistance bacteria displays to a specific chemotherapeutic agent. B) The ability of a chemotherapeutic agent to target all strains of bacteria. C) The ability of a chemotherapeutic agent to target only the pathogen, leaving other bacteria unaffected.