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AP Bio Sherrill - Chapter 15 Chromosomal Genetics

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chromosomal theory of inheritance
Mendelian genes have specific positions on chromosomes, and it is the chromosomes that undergo segregation and independent assortment.
wild-type
An individual with the normal (most common) phenotype.
mutant
an individual whose DNA or chromosomes differ from some previous or normal state
linked genes
genes located on the same chromosome that tend to be inherited together
genetic recombination
the production of offspring with combinations of traits differing from those found in either parent
parental types
Offspring with a phenotype that matches one of the parental phenotypes
recombinant types
when offspring display phenotypes that are different than parents
crossing over
process in which homologous chromosomes exchange portions of their chromatids during prophase I of meiosis
linkage map
A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes
map unit
A unit of measurement of the distance between genes. One map unit is equivalent to a 1% recombination frequency.
sex-linked genes
A gene located on a sex chromosome
Duchenne muscular dystophy
Progressive weakening of the muscles and loss of coordination - caused by a lack of muscle protein called dystophin. Inheritance pattern: X-linked recessive
hemophilia
sex-linked recessive disorder defined by the absence of one or more proteins required for blood clotting
color blindness
A sex-linked recessive trait in which an individual cannot perceive certain colors
Barr body
Inactivated X in females
aneuploidy
abnormal number of chromosomes
trisomic
extra chromosome (caused by nondisjunction)
monosomic
missing chromosome (caused by nondisjunction)
polyploidy
condition in which an organism has extra sets of chromosomes
deletion
change to a chromosome in which a fragment of the chromosome is removed
duplication
change to a chromosome in which part of the chromosome is repeated
inversion
a kind of mutation in which the order of the genes in a section of a chromosome is reversed
translocation
change to a chromosome in which a fragment of one chromosome attaches to another nonhomologous chromosome
Down syndrome
A human genetic disease resulting from having an extra chromosome 21, characterized by mental retardation and heart and respiratory defects
Klinefelter syndrome
XXY - males that are characterized by small testes and long legs and enlarged breasts and reduced sperm production
Turner syndrome
Girl with underdeveloped sex organs, girl with only one X
cri du chat
a chromosomal deletion in chromosome 5 that results in children who are mentally retarded, have small heads, and have a cry that sounds like a loud cat; they die at a young age
PKU(phenylketonuria)
A genetic abnormality in which a child cannot metabolize phenylalanine, an amino acid, which consequently builds up in the body and causes mental retardation
Tay Sach's Disease
human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accomidation of a certain lipid in the brain. Most common in Ashkenazic Jews.
Cystic fibrosis
genetic disorder caused by a recessive allele for a chloride channel protein; characterized by an excessive secretion of mucus and consquent vulnerability to infection
Huntington's disease
caused by a dominant allele. genetic disorder that causes progressive deterioration of brain cells. symptoms do not appear until the age of 30 or so
Multiple X syndrome
embyros with triple X chromosomes. individuals are phenotypically normal
Sickle-cell anemia
a recessive genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape. Most common in African Americans.