15 terms

C. Classical genetics - patterns to recognize and D. Pedigree basics

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Phenotypic ratio 3:1
We use a monohybrid cross for heterozygous parents
Phenotypic ratio 9:33:1
We use a dihybrid cross
Phenotypic ratio 1:1
We use a monohybrid cross for a heterozygous parent and a homozygous recessive parent.
Phenotypic ration 4:0
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Pedigree Chart
A chart which shows several generations of related families and how traits are passed down through the offspring. Pretty much a family tree.
What does a square mean in a pedigree chart?
Males
What does a circle mean in a pedigree chart?
Female
What does a shaded square of shaded circle mean in a pedigree chart?
It means the person is carrying the gene. They are affected.
What does a half shaded circle or square mean in a pedigree chart?
It means they are carrying the trait but do not show it.
Autosomal dominant
Individuals with autosomal dominant diseases have a 50-50 chance of passing the mutant gene and therefore the disorder on to each of their children.
While studying several generations of a particular family, a geneticist observed that a certain disease was found equally in males and females and that all children who had the disease had parents who also had the disease. The gene coding for this disease is probably
Autosomal dominant
Autosomal recessive
In autosomal recessive inheritance, both genes of interest (i.e., one from each parent) on a paired chromosome have the same defect; if both parents have the recessive gene of interest, the likelihood of expression in progeny is 1:4. Men and women are affected equally.
X-Linked dominant
sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome. As an inheritance pattern, it is less common than the X-linked recessive type.
X-Linked Recessive
A mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed in males who are hemizygous for the gene mutation (i.e., they have only one X chromosome) and in females who are homozygous for the gene mutation (i.e., they have a copy of the gene mutation on each of their two X chromosomes). Carrier females who have only one copy of the mutation do not usually express the phenotype, although differences in X-chromosome inactivation can lead to varying degrees of clinical expression in carrier females
Y-Linked
A gene on the Y chromosome. A Y-linked gene is by necessity passed from father to son, since the Y chromosome can only be transmitted by a man to his male progeny.