NUR 239 Study Guide - Midterm Guide: Dominance (Genetics), Quantitative Trait Locus, Marfan Syndrome
21 May 2018
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1. DNA Repair
a. Mutations are caused by substitution of one base pair for another, the loss or addition of
one or more base pairs, or rearrangement of base pairs. Many can occur spontaneously
through normal endogenous processes, whereas others occur because of exogenous or
environmental agents such as chemical and radiation. Mutations may arise in somatic
cells or in germ cells. Only those DNA changes that occur in germ cells can be inherited.
Most are corrected by DNA repair mechanisms.
2. Patterns of Inheritance
a. Phenotype: the set of observable characteristics resulting from the interaction of its
genotype with the environment
b. Genotype: the genetic constitution of an individual organism
c. Polygenic: Involves multiple genes at different loci with each gene exerting a small
additive effecting in determining a trait; most human traits are determined by multiple
pairs of genes, many with alteration codes, accounting for some dissimilar forms that
occur with certain genetic disorders.
d. Multifactorial: Similar to polygenic inheritance in that multiple genes at different loci
affect the outcome; however, environmental effects on the genes also affect the
outcome
e. Mendel Laws: A main feature of inheritance is predictability given certain conditions, the
likelihood of the occurrence or recurrence of a specific trait is remarkably predictable;
Parents chromosomes separate and form gametes with each ½ of chromosome (Meosis);
Chromosome halves combine in 1 of 4 combinations (Punnet square)
i. Human Genome Project: International effort to match each human gene and
completely sequence human DNA, study legal, ethical, and social dilemmas of gene
research & therapy
3. Autosomal Dominant Disorders: A single mutant allele from an affected parent is transmitted
to an offspring regardless of sex; affected parent has 50% chance of transmitting the disorder
to each offspring; Ex: Marfan Syndrome or Neurofibromatosis; If you get the trait, you get
the disease (there are no carriers). If you have the genotype with the trait, you automatically
have the disease ad hae a 5% of passig it o. You usuall dot fid out if ou hae it
util oue olde.
4. Autosomal Recessive Disorders → Parents of an individual with an autosomal recessive
disode eah a oe op of the utated gee; dot sho “&“ of the condition, shows
early within age, cystic fibrosis, sickle cell anemia; Manifested only when both members of
the gene pair are affected; both parents may be unaffected but are carriers or the defective
gene; affect both sexes
5. X-Linked Disorders → Male offspring has the disorder but females are the carrier; Examples:
Duhees Musula Dstoph, Heophilia A; Glucose 6 Deficiency; Almost always
associated with the X, female, chromosome and the inheritance pattern is predominantly
recessive; female heterozygotes rarely experience the effects, whereas all males who receive
the gene are affected
6. Chromosomal Disorders
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a. Down Syndrome: Chromosome 21 is affected; possible birth defects include heart
defects, vision problems, hearing loss, infections, hypothyroidism; Risk of having a child
with Down Syndrome increases once the female is over 30 years old; Causes a
combination of birth defects including some degree of intellectual disability characteristic
facial features, and other health problems
b. Turner Syndrome: Absence of all or part of one of a feales to X hoosoes; Some
women may display a mosaicism with 1+ additional cell lines; short, absence of ovaries,
no menstruation
c. Klinefelter Syndrome: Condition of testicular dysgenesis accompanied by the presence of
one or more extra X chromosomes in excess of the normal male XY complement. Most
males with Klinefelter syndrome have one extra X chromosome. Features: small testes,
inability to produce sperm, large breasts; noticed in puberty
7. Disorders Due to Environmental Influences (also called teratogenic agents)
a. Teratogenic Agents: Radiation, environmental changes and illicit drugs, alcohol, infectious
agents, nutritional deficiencies (folic acid)
i. Radiation: heavy doses of radiation have been shown to cause microcephaly, skeletal
malformation, and intellectual disability.
ii. Environmental Changes: Can cross the placenta and cause damage to the developing
embryo and fetus
1. Medication and Illicit Drugs: Thalidomide has been shown to give rise to a full
range of malformations, including phocomelia (short flipper like appendages) of
all extremities; Lipid-soluble drugs cross the placenta; molecular-weight of drug
influences the rate of transfer; antimetabolites are used in treatment of cancer,
warfarin, ethyl alcohol & cocaine; Acutane → cleft palate, heart deficits, CNS
malformations, nerve abnormalities
2. Alcohol: Alcohol exerts harmful effects on the fetus in the placenta and
throughout gestation; abnormalities include
a. Fetal Alcohol Syndrome: Mental retardation, malformations of skeletal and
organ systems, motor skills, inhibited growth, CNS complications, attention
span, mortality; small eyes, thin upper lip, small chin, short nose, microcephaly
8. What part of the brain is responsible for respirations? The medulla (brain stem) becomes
quite large and acts in vital reflexes controlling respiration, CV function, swallowing, and
vomiting.
9. Spinal cord and brain
a. Spinal Reflexes: Response mediated by cells in the spinal cord, bypassing any conscious
effot fo the ai; jekig efle that ou dot hae to thik aout; Highly
predictable relationship between a stimulus and a motor response. It is a response
mediated by the cells in the spinal cord, bypassing any conscious effort from the brain. It
may involve neurons at a single spinal cord segment, several or many reflexes, or
structures in the brain. It involves a sensory receptor, an afferent pathway, an integrating
center in the spinal cord, an efferent pathway, and an effort muscle/gland. Ex: knee-jerk
or patellar reflex
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b. What does the parietal lobe do? Perceives the meaningfulness of integrated sensory
ifoatio fo aious seso sstes, espeiall the peeptio of hee the
stimulus is in spae ad i elatio to od pats
c. What does the limbic system control? → This region of the brain is involved in emotional
experience and is in the control of emotion-related behavior.
10. Coordination of Movement
a. Cerebellar System: Loss of function can result in total incoordination of the functions
such as running, typing and even talking; even though paralysis does not occur
i. One movement cannot be followed quickly by its opposite movement; movements are
slow, irregular, clumsy, unsteady, and inappropriately varying in their speed, force, and
direction. Dysdiadochokinesia – failure to accurately perform rapid alternating
movements
ii. Ataxia: Characterized by wide-based staggering, lurching, and uncontrolled gait; visual
monitoring of movement cannot compensate for cerebellar defects, and these
abnormalities occur whether the eyes are closed or open
b. Basal Ganglia Disorders: The basal ganglia are thought to be particularly important in
starting, stopping, and monitoring movements executed by the cortex, especially those
that are relatively slow and sustained, or stereotyped; disorders disrupt these
i. Chorea: abnormal writhing movements
ii. Dystonia: abnormal simultaneous contractions of agonist/antagonist, muscles, leading
to abnormal posture
iii. Tremor: rhythmic movements of particular body parts
iv. Bradykinesia: slowness of movement
v. Myoclonus: involuntary jerking movement
vi. Basal ganglia are a group of deep, interrelated subcortical nuclei that play an essential
role in control of movement that function in the organization of inherited and highly
learned and rather automatic movement programs, especially those affecting the trunk
ad poial lis; thee thought to e patiulal ipotat i statig, stoppig,
and monitoring movements executed by the cortex, especially those that are relatively
slow and sustained or stereotyped.
11. Disorders of the Cerebellum:
a. Ataxia, smooth movements
12. Disorders of Basal Ganglia
a. Pakisos disease: Progressive degenerative disorder that results in variable
combinations of tremor, rigidity, and bradykinesia, difficulty walking. It is the second
most common neurodegenerative disease after Alzheies disease. It egis afte 5
years of age, with the prevalence increasing 4-5% in those older than 85 yrs. The clinical
syndrome arising from the degenerative changes in basal ganglia function often is
efeed to as pakisois. Pakisos disease, the most common form of parkinsonism
is named after James Parkinson, a British physician who first described the disease in a
paper he published in 1817 on the shaking palsy.
13. Oeie of Pakisos Disease
a. Drugs associated with the development: Drugs that deplete dopamine stores/block
dopamine receptors, including the older antipsychotic drugs, reserpine, and
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Document Summary
Dna repair, mutations are caused by substitution of one base pair for another, the loss or addition of one or more base pairs, or rearrangement of base pairs. Many can occur spontaneously through normal endogenous processes, whereas others occur because of exogenous or environmental agents such as chemical and radiation. Mutations may arise in somatic cells or in germ cells. Only those dna changes that occur in germ cells can be inherited. Parents chromosomes separate and form gametes with each of chromosome (meosis); If you have the genotype with the trait, you automatically have the disease a(cid:374)d ha(cid:448)e a 5(cid:1004)% of passi(cid:374)g it o(cid:374). Most males with klinefelter syndrome have one extra x chromosome. It is a response mediated by the cells in the spinal cord, bypassing any conscious effort from the brain. It may involve neurons at a single spinal cord segment, several or many reflexes, or structures in the brain.
