Download ANSWERS TO REVIEW QUESTIONS

ANSWERS TO REVIEW QUESTIONS
CHAPTER 8
1. Neurons transmit electrochemical messages. Neuroglial cells support neurons in
several ways.
2. Behavioral traits are multifactorial because they reflect the complex interaction of
genetic factors, responses to environmental stimuli, and learning.
3. Pathways involving neurotransmitters and signal transduction molecules affect
behavior when absent or abnormal.
4. The behavior of altered sleep phase is clearly identifiable, occurs in many individuals
across generations, and exhibits a clear mode of inheritance.
5. Drug addiction affects the nucleus accumbens, prefrontal cortex and ventral
tegmental area of the limbic system.
6. We must understand how a gene variant affects behavior, and how other genes and
the environment affect its expression.
7. Genetic heterogeneity; when a behavior is part of several disorders; behaviors that
fall within the range of normal, although they are extreme; ability to imitate a
behavior.
8. With age, the environment has had longer to affect gene expression than genetics.
Socioeconomic and racial biases affected studies of the inherited component of
intelligence.
9. Tolerance and dependence
10. Opiates bind receptors for endorphins and enkephalins, thereby relieving pain.
11. SSRls block reuptake of serotonin in synapses, correcting a deficit of the
neurotransmitter that presumably causes the symptoms.
12. Bipolar disorder affects mood and symptoms include depression alternating with
mania. Schizophrenia primarily affects thinking.
13. In humans, neurons have receptors for these drugs.
14. Maternal infection during pregnancy
15. A mutation in the cell surface receptor called hypocretin causes narcolepsy in dogs.
16. Autism may be subsumed by (part of) schizophrenia, separate from it, opposite it, or
overlap it.
17. Drug addiction. Adoption and twin studies indicated a strong inherited component.
GWAS point to variants in the dopamine D(2) receptor gene as well as candidate
genes at 51 other sites in the genome.
ANSWERS TO APPLIED QUESTIONS
1. a. The same neurotransmitter controls different behaviors. The differences arise
from which neurons are involved.
b. Dopamine
2. Identify what is abnormal in the Utah family, develop a drug to treat the condition,
and then try the drug on people who are having difficulty sleeping.
3. The IQ test could be flawed, culturally biased, or measure intelligence in a way that
does not compensate for differences in educational opportunities.
4. Mutations in genes for one subunit of the nicotinic receptor could affect functioning of
a different subunit.
5. Evaluate the individual for evidence of tolerance and dependence.
6. A SNP profile indicating increased risk could be helpful if the person can take action
to lower the risk of developing an addiction, but can be harmful if the person just
gives up, thinking the fate cannot be avoided. SNP profiling might also be used to
discriminate.
7. Depression and bipolar disorder each might actually be several conditions that have
similar symptoms.
8. Environmental component about equals genetic susceptibility.
9. a. Environmental
b. Chemical exposure, more children having their children evaluated for autistic
behaviors.
10. NRXN1 encodes a cell surface protein involved in synaptic function; CHRNA3 and
CHRNA5 are acetylcholine receptor genes, which also bind nicotine; CLCA1
encodes a calcium-activated chloride channel expressed in airway cells of smokers
differently than non-smokers; CTNNA3 encodes a cell adhesion catenin protein;
GABRA4 encodes the GABA receptor; KCNJ6 is a potassium channel. Variant ion
channels and neurotransmitter receptors affect neurotransmission.
ANSWERS TO WEB ACTIVITIES
1. Autism. Candidate genes encode neurexins and neuroligins. These proteins
strengthen neural connections as a child learns and consolidates memories.
2. a. Results of validation studies using large samples and different population
groups
b. Provides an objective source of data
c. Does not measure environmental effects
3. The participants were being treated for different conditions. Environmental factors
differ between the two groups. Therefore genes and environmental factors are different
between the two groups.
4. a. Small sample size
b. Genome-wide association study of responders and non-responders
c. Using the variant tryptophan hydroxylase-2 associated with calmness as a
potential therapy for anxiety
FORENSICS FOCUS
1. a. Opinion, but perhaps use genotyping if there is no other evidence, or as a way to
explain a behavior.
b. The high-activity allele for the enzyme MAO causes a deficiency of the three
neurotransmitters, which can affect behavior. In the Dutch family that can’t make the
enzyme, the levels of the neurotransmitters are too high. The levels of the three
neurotransmitters must be within a certain range for behavior to be “normal.”
c. Limitations are validity and generalizability
CASE STUDIES AND RESEARCH RESULTS
1. The fact that DISC1 underlies schizophrenia and bipolar disorder supports the
genetics approach because it indicates that the two disorders might not be as distinct as
traditional psychiatry has considered them. Distinctions based on genetics could refine
treatment choices. Perhaps a drug could be selected depending on genetics and the
type of therapist selected based on symptoms.
2. a. Environmental
b. Increased awareness and better screening
c. identification of a SNP pattern that children with specific subtypes of bipolar
disorder share.
3. Non-genetic cause. Genes may underlie the behavior which is modified by nongenetic influences on its expression.
4. Give the smoking cessation drug to a large number of people. Then determine
whether CYP2A6 fast-metabolizers are over-represented among the people who
respond. The participants should not know their genotypes.
5. The study cannot be evaluated without knowing the number of participants, and the
incidence of the repeat in the gene in the general population. The study doesn’t show if
the people who drank responded to the cues or just wanted the drinks.