Human genetics Flashcards
determine the pattern of inheritance of man’s traits, the construction of family
history is performed
pedigree analysis
By doing this, one can determine the possible genotypes and phenotypes of the individuals, and can predict if the trait can be possibly transmitted to the next generation.
pedigree analysis
involve the careful compilation of phenotypic records of
the family over several generations
Family histories or pedigrees
affected individual whom the pedigree is discussed is called the ____ (____ if male, ___ if female).
proband;
propositus;
proposita
Analyzing pedigrees can reveal the following: (4)
(a) whether a trait is dominant or recessive
(b) the type of chromosome (autosomal or sex) to which the trait is linked
(c) genotypes of family members
(d) probabilities of phenotypes in future generations
show the presence or absence of a trait as it relates to the relationship among parents, offspring, and siblings.
Pedigrees
If the trait is __, one of the parents must have the trait. ___ traits will not skip a generation. If the trait is ___, neither parent is required to have the trait since they can be heterozygous.
dominant;Dominant
recessive
Common pattern of inheritance in man (5)
-Autosomal dominance
-Autosomal recessive
-Sex-linked dominance
-Sex-linked recessive
-Sex-influenced
The trait for this type of inheritance never skips a generation Affected individual may either be homozygous or heterozygous
Autosomal dominance
Marriage between 2 affected individuals produce affected offspring; May also be produced by both unaffected person heterozygous for the character
Autosomal recessive
Affected male with unaffected wife transmit the trait to daughter only
Sex-linked dominance
Affected female with unaffected husband transmits the trait to sons only; the daughters serve as carrier of the trait
Sex-linked recessive
Gene exhibits high penetrance or expressivity in one sex
Sex-influenced
Give tehir example/s:
Autosomal recessive:
Sex-linked dominance:
Sex-linked recessive: (2)
Sex-influenced: men (2), women
Autosomal recessive: inability to roll tongue
Sex-linked dominance: defective teeth enamel
Sex-linked recessive: colorblindness, hemophilia
Sex-influenced: men (harelip, baldness), women (spina bifida)
One mutated copy of the gene in each cell is sufficient for a person to be affected
Autosomal dominant
an affected person inherits the condition from an affected parent; condition may result from a new mutation in the gene and occur in people with no history of the disorder
Autosomal dominant
both copies of the gene in each cell have mutations.
Autosomal recessive
The parents of an individual with an ____condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition
Autosomal recessive
typically not seen in every generation of an affected family.
Autosomal recessive
In female, a mutation in one of the two copies of the gene in each cell is sufficient to cause the disorder
X-linked dominant
In males, a mutation in the only copy of the gene in each cell causes the disorder.
X-linked dominant
males experience more severe symptoms of the disorder than females
X-linked dominant disorder
In females, a mutation would have to occur in both copies of the gene to cause the disorder
X-linked recessive
Because it is unlikely that females will have two altered copies of this gene, males are affected by ___ disorders much more frequently than females.
X-linked recessive disorders
mutation can only be passed from father to son
Y-linked
two different versions (alleles) of a gene are expressed, and each version makes a slightly different protein.
Co-dominant inheritance
Both alleles influence the genetic trait or determine the characteristics of the genetic condition.
Co-dominant inheritance
Conditions resulting from mutations in ______ can appear in every generation of a family and can affect both males and females, but fathers do not pass these disorders to their daughters or sons.
mitochondrial DNA
Give their example/s:
Autosomal dominant: (2)
Autosomal recessive: (2)
X-linked dominant:
X-linked recessive:
Y-linked:
Co-dominant: (2)
Mitochondrial:
Autosomal dominant: Huntington disease; Marfan syndrome
Autosomal recessive: Cystic fibrosis; Sickle cell disease
X-linked dominant: Fragile X syndrome
X-linked recessive: Hemophilia
Y-linked: Y chromosome infertility
Co-dominant: ABO blood group; alpha-1 antitrypsin deficiency
Mitochondrial: Leber hereditary optic neuropathy (LHON)
, , a type of euploidy has not been observed in humans, and is considered lethal
polyploidy
