Genetics

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47 Cards. Created by Liisia ().
 
Term  
Definition
Mitosis
The one-step process of cellular division in a somatic cell. 1. Produces two genetically identical cells, each with the same number of chromosomes as in the parent 2. Process does not shuffle the genes, producing chromosomes pairs identical to those in the parent cell.
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Meiosis
The two-step cellular division of the original germ cells. 1. Produces four genetically unique cells, each with half the number of chromosomes as in the parent. 2. Shuffles the genes between the two chromosomes in each pair (one received from each parent), producing chromosomes with new genetic combinations in every gamete generated.
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Dominant
A trait or characteristic that is expressed when it is carried by only one of a pair of homologous chromosomes (chromosome pairs of approximately the same length, centromere position, and staining pattern, with genes for the same characteristics at corresponding loci)
Recessive
A trait or characteristic that is manifested clinically with a double gene dose in autosomal chromosomes
Molecular chromosomal abnormalities
• Occur at the DNA level • Not detectable microscopically • Most inherited disorders are at the level of one or both allelic genes
Gross chromosomal abnormalities
Can be observed in a karyotype: A photographic representation of a person’s chromosomal constitution - Alterations in number: • Non-disjunction -the failure of chromosome pairs to separate properly during meiosis in the anaphase. - Alterations in structure: • Deletion – loss of part • Translocation – a portion attached to another • Inversion – a portion is upside down • Duplication – larger than normal
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Trisomy 21: Down Syndrome
Nondisjunction of 'autosomal' chromosomes; Gross chromosomal abnormality
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Trisomy 13
Nondisjunction of 'autosomal' chromosomes; Gross chromosomal abnormality
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Turner Syndrome
Nondisjunction of 'sex chromosomes'; Gross chromosomal abnormality
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Klinefelter Syndrome
Nondisjunction of 'sex chromosomes'; Gross chromosomal abnormality
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Patterns of Inheritance
Inheriting a disease, condition, or trait depends on the type of chromosome affected (autosomal or sex chromosome). It also depends on whether the trait is dominant or recessive.
• Autosomal dominant inheritance
• Autosomal recessive inheritance
• X-linked inheritance
       • Lyon hypothesis and X-linked recessive traits
• Genetic heterogeneity

Penetrance
The number of individuals affected
• Lack of penetrance: When an individual carries a 
gene without presenting any clinical manifestation
• Complete penetrance - all individuals who have 
the disease-causing mutation have clinical symptoms of the disease.
• Highly penetrant -the trait it produces will almost always be apparent in an individual carrying the allele.
• Incomplete penetrance or reduced penetrance -some individuals fail to express the trait, even though they carry the allele.
• Low penetrance - will only sometimes produce the symptom or trait with which it has been associated at a detectable level. In cases of low penetrance, it is difficult to distinguish
Expressivity
The degree to which an individual is affected 

Autosomal Dominance 
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Autosomal Recessive 
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X-Linked Inheritance

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Genetically Heterogeneous
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Molecular Chromosomal Abnormalities
• Inherited disorders affecting the gingiva and periodontium
• Inherited disorders affecting the jawbones and facies
• Inherited disorders affecting the oral mucosa
• Inherited disorders affecting the teeth

Cyclic Neutropenia
Inherited Disorder Affecting the Gingiva and Periodontium
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Papillon-Lefèvre Syndrome
Inherited Disorder Affecting the Gingiva and Periodontium
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