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Define Genes Answer: a unit of heredity that is transferred from a parent to offspring and is
held to determine some characteristic of the offspring.
Define Genotype Answer: Specific genetic makeup of an individual
Define Allele Answer: one or two or more alternative versions of gene at a given position or
locus on a chromosome that imparts the same characteristic of that gene
Define phenotype Answer: the observed, outward characteristics of an individual
Define Homozygous Answer: Alleles the same for the characteristic
Define Heterozygous Answer: Alleles different for the characteristic
Define mutations Answer: change in gene structure which may alter the type and amount
of protein produced
Define karyotype Answer: Pictorial analysis of the number, form, and size of the
individual's chromosomes
Genetics
Pattern of Inheritance
Single Gene Disorders: Describe Autosomal Dominant (5) Answer: The abnormal gene
overshadows the normal gene
Can also be a new mutation never seen before in the family
Affected person usually has affected parent
Offspring of parent will have 50% change of inheriting two normal genes and 50% inheriting
one abnormal and one normal
NF1, achondroplasia, Huntington's disease
Genetics
Pattern of Inheritance
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, Single Gene Disorders: Describe Autosomal recessive (4) Answer: Both parents must be
carriers of the recessive trait for the child to have it
50% of children will be carriers, 25% will be normal, 25% chance of each pregnancy
producing a child with the disease
ALL children born to these parents are at risk
Sickle cell, Cystic Fibrosis, PKU
Genetics
Pattern of Inheritance
Single Gene Disorders: Describe X-linked recessive Answer: Trait carried on the X
chromosome
Usually effects males (XY)
25% chance of each pregnancy producing a child with the disease
Male child: 50% chance if Mom is a carrier
Female child: 50% chance she will be a carrier if Mom is a carrier
Hemophilia, Duchenne muscular dystrophy, color blindness
X-linked recessive Answer: X linked inheritance disorders are directly attached to the X
chromosome. Males are typically affected because they only get one X chromosome. XY
Female will need 2 abnormal chromosomes to exhibit the disease. There is no male to
male transmission (Males always donate the Y to the male)
Any male who is affected, will produce carrier daughters - because the X they donated is
the one the daughter gets
Genetics
Patterns of Inheritance
Single Gene Disorders: Describe X- linked dominant Answer: Occurs when male has
abnormal X chromosome and mom has at least one abnormal chromosome
All of the daughters and none of the sons of an effected father will inherit the disorder
Both female and male offspring of an affected woman have 50% chance of inheriting the
condition
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