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EXAM 1: Pathophysiology > Genetics (CHP 5) > Flashcards

Genetics (CHP 5) Flashcards

Define basic terms used in genetics. Compare and contrast single-gene, chromosomal, and multifactorial disorders. Summarize causes and manifestations of autosomal recessive, autosomal dominate, X-linked inheritance disorders, and mitochondrial gene disorders. Differentiate how environmental influences (such as teratogens) can affect embryo and fetal development.

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What is a mutation/mutagen?

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A biochemical event, such as nucleotide change, deletion, or insertion that produces a new allele for a particular gene.

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4
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Define locus in genetics.

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A specific location that one gene occupies.

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5
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What is an allele?

A

Two members of a gene pair, one inherited from the mother and the other from the father.

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6
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Differentiate between homozygous and heterozygous.

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  • Homozygous: members of gene pair are identical
  • Heterozygous: two members are different.
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7
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Define expressivity in genetics.

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How much a trait is expressed in a person.

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8
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What is penetrance?

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The percentage of people with a gene who have the associated trait.

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9
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True or False: A 50% penetrance indicates that a person who inherits the defective gene has a 50% chance of expressing the disorder.

A

True.

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10
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Differentiate between dominant and recessive traits.

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  • Dominant: trait is phenotypically seen in the heterozygote
  • Recessive: phenotypically seen only in the homozygote.
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11
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What is a carrier in genetics?

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An individual who possesses one copy of a mutated gene associated with a disease but does not exhibit symptoms.

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12
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Define autosomal in genetics.

A

A specific gene that is not on a sex chromosome and is a numbered chromosome.

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13
Q

What are chromosomes?

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Thread-like structures located inside the nucleus of a cell, composed of DNA and proteins, which carry genetic information.

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14
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What are gametes?

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Reproductive cells of an animal or plant.

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15
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Define somatic cells.

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Any cell of a living organism other than the reproductive cells.

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16
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What is mitosis?

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A type of indirect cell division that occurs in somatic cells resulting in the formation of two daughter nuclei containing identical complements of chromosomes.

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17
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Define meiosis.

A

The division of a sex cell as it matures, so that each daughter nucleus receives one half of the number of chromosomes characteristic of the somatic cells.

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18
Q

What is a karyotype?

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The total chromosomal characteristics of a cell, or the micrograph of chromosomes arranged in pairs in descending order of size.

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19
Q

What is a pedigree?

A

A systematic presentation of an individual’s ancestors used in human genetics to analyze inheritance.

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20
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Define genogram.

A

A visual diagram that depicts a person’s family relationships across multiple generations.

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21
Q

What are single-gene disorders?

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Disorders caused by a defective or mutant allele at a single gene locus that follow Mendelian patterns of inheritance.

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22
Q

What is the etiology of autosomal dominant disorders?

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A single mutant allele from an affected parent is transmitted to offspring regardless of sex.

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23
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What is reduced penetrance?

A

When an individual inherits a dominant mutant gene but fails to exhibit the phenotype.

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24
Q

Give an example of an autosomal dominant disorder.

A

Marfan Syndrome.

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What is neurofibromatosis?
A disorder that causes tumors to develop from schwann cells due to a genetic defect in a tumor suppressor gene.
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What are the characteristics of Type 1 Neurofibromatosis?
* Cutaneous and subcutaneous neurofibromas * Pigmented nodules of iris (Lisch nodules) * Café au lait spots.
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What are autosomal recessive disorders?
Disorders where both members of the gene pair are affected, and parents could be unaffected but carriers.
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What is phenylketonuria (PKU)?
A disorder caused by a deficiency of the liver enzyme phenylalanine hydroxylase.
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What is Tay-Sachs disease?
A lysosomal storage disease caused by the accumulation of GM2 ganglioside in neurons.
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What are X-linked disorders?
* X-linked recessive disorders: almost always affect males * X-linked dominant disorders: affected females transmit the disorder to 50% of offspring.
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What is Fragile X syndrome?
A genetic disorder that causes intellectual disability, primarily affecting males.
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What are inherited multifactorial disorders?
Disorders caused by multiple genes along with environmental factors that do not follow clear-cut patterns of inheritance.
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What is a teratogen?
An environmental factor that can cause malformation of an embryo.
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What is aneuploidy?
Having an abnormal number of chromosomes.
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Define non-disjunction.
Failure of the chromosomes to separate during oogenesis or spermatogenesis.
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What is monosomy?
Presence of only one member of a chromosome pair.
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What is polysomy?
Presence of more than 2 chromosomes to a set.
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Give an example of a trisomy disorder.
Down syndrome (trisomy 21).
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What is Turner syndrome?
A condition in females characterized by short stature and loss of oocytes, leading to no menstruation.
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What is Klinefelter syndrome?
A condition in males caused by testicular dysgenesis and the presence of one or more extra X chromosomes.
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What is a mitochondrial gene disorder?
Disorders caused by mutations in mitochondrial DNA that affect tissues dependent on oxidative phosphorylation.
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What is organogenesis?
The process of differentiation and development of organs occurring from day 15 to day 60 after conception.
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What are common disorders of the neuromuscular system?
Encephalopathies, myopathies, retinal degeneration, loss of extraocular muscle function, deafness ## Footnote These disorders can significantly affect motor and sensory functions.
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What are teratogens?
Environmental influences that can adversely affect embryo and fetal development ## Footnote Teratogens can lead to various developmental disorders or malformations.
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What is organogenesis?
The process of differentiation and development of the organs ## Footnote This process occurs from day 15 to day 60 after conception.
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What is the period of vulnerability in embryonic development?
Each organ has a critical period where it is highly susceptible to damage ## Footnote This means that certain stages of development are more sensitive to environmental influences.
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What may influences during the first 2 weeks of pregnancy result in?
Interference with implantation, resulting in abortion or early resorption ## Footnote This highlights the importance of early prenatal care.
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How can teratogenic agents affect an embryo?
Through direct exposure of the mother and fetus, exposure of soon-to-be pregnant females, or mutagenic effects before pregnancy ## Footnote These pathways can lead to permanent reproductive cell damage.
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What are some disorders caused by radiation exposure during pregnancy?
Microcephaly, skeletal malformations, mental retardation ## Footnote Radiation can cause inheritable changes in genetic materials.
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What factors affect placental drug transfer?
* Rate at which the drug crosses * Duration of exposure * Stage of placental/fetal development * Molecular weight ## Footnote These factors influence the potential risks to the developing embryo.
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What does the FDA classification system (ABCDX) signify?
A = least dangerous, X = contraindicated ## Footnote This system helps assess the risk of drug use during pregnancy.
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What are the effects of thalidomide on fetal development?
Full range malformations including phocomelia ## Footnote Phocomelia refers to short, flipper-like appendages on all four limbs.
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What is Fetal Alcohol Syndrome (FAS)?
A condition caused by alcohol exposure during pregnancy leading to growth retardation and CNS abnormalities ## Footnote FAS is characterized by distinct facial features and varying severity based on exposure.
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What are the characteristic facial features of Fetal Alcohol Syndrome?
* Small palpebral fissures * Thin vermillion border * Elongated, flattened midface and philtrum ## Footnote These features become more subtle in adulthood.
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What does the acronym TORCH represent in terms of infections?
* Toxoplasmosis * Other (e.g., Listeriosis, Leptospirosis) * Rubella * Cytomegalovirus * Herpes ## Footnote These infections can cross the placenta and affect fetal development.
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What are potential disorders caused by maternal infections during pregnancy?
Growth retardation, brain abnormalities, eye and ear abnormalities, hematopoietic system issues ## Footnote These can lead to severe developmental complications.
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What is the etiology of folic acid deficiency during pregnancy?
Not enough folic acid intake ## Footnote This deficiency can lead to neural tube defects (NTDs) in the developing fetus.
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What is the recommended daily intake of folic acid for pregnant women?
0.4 mg daily ## Footnote This is crucial for the prevention of neural tube defects.
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Fill in the blank: The effects of folic acid deficiency in embryonic development lead to _______.
neural tube defects ## Footnote This underscores the importance of adequate folic acid during pregnancy.
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EXAM 1: Pathophysiology (9 decks)

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