-
when its genetic codes are being expressed, DNA is in a threadlike form called
chromatin
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DNA is arranged to form a larger structure called
chromosome
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a person with a genotype expressed as AA is said to be
homozygous dominant
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both males and females need at least one normal
X chromosome
-
entire collection of genetic material in each tyupical cell of the human body
genome
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mutations are caused
- -spontaneously
- -by mutagens
- -by environmental agents that damage DNA
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Red-green color blindness is an example of an X-linked recessive condition. if X is normal, X1 is recessive, and Y is normal, an individual with the genotype XX1 will be
a normal female and a carrier
-
trisomy and monosomy result from
an error in meiosis called nondisjunction
-
-
person with the sex chromosomes XXY is afflicted with
Klinefelter syndrome
-
recessive X-linked genetic diseases
- -hemophilia
- -red-green color blindness
- -cleft palate
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disorders that involve trisomy or monosomy can be detected after a ___ is produced
karyotype
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the genes that cause albinism are
recessive
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during meiosis, matching pairs of chromosomes line up and exchange genes from their location to the same location on the other side; process called
crossing-over
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when a sperm cell unites with an ovum, a __is formed
zygote
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DNA molecules can also be called
- -a chromatin strand
- -a chromosome
-
sex-linked traits
are nonsexual traits carried on sex chromosomes
-
if a person has only X chromosomes, that person is
female
-
a karyotype
can detect trisomy
-
Osteogenesis imperfecta
group of connective tissue disorders is characterized by imperfect skeletal development that produces brittle bones
-
multiple neurofibromatosis
disorder is characterized by multiple, sometimes disfiguring benign tumors of the Schwann cells (neuroglia) that surround nerve fibers
-
Hypercholesterolemia (familial)
High blood cholesterol may lead to athersclerosis and other cardiovascular problems
-
Huntington disease (HD)
Degenerative brain disorder is characterized by chorea (purposeless movements) progressing to severe dementia and death generally by age 55 yrs
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Polycystic kidney disease, autosomal dominant form (ADPKD)
polycystic kidney disease or PKD (both dominant and recessive forms) is the most common single-gene disorder; clusters of fluid-filled sacs occur in kidneys and other organs causing kidney failure, hypertension, liver problems, and heart valve problems
-
sickle cell anemia
Blood disorder in which abnormal hemoglobin causes red blood cells to deform into a sickle shape; sickle cell anemia is the severe form, and sickle cell trait the milder form
-
Thalassemia
Group of inherited hemoglobin disorders is characterized by production in hypchromic, abnormal RBCs
-
Cystic Fibrosis (CF)
condition is characterized by excessive secretion of thick mucus and concentrated sweat, often causing obstruction of gastrointestinal or respiratory ducts
-
Tay-Sachs disease (TSD)
Fatal condition in which abnormal lipids accumulate in the brain and cause tissue damage leading to death by age 4 yrs
-
Phenylketonuria (PKU)
Excess of phenylketones in the urine is caused by accumulatino of phenylalanine in the tissues; it may cause brain injury and death if phenylalanine (amino acid) intake is not restricted
-
albinism (total)
lack of the dark brown pigment melanin in the skin and eyes results in vision problems and susceptibility to sunburn and skin cancer
-
severe combined immune deficiency (SCID)
failiuure of the lymphocytes to develop properly causes failure to the immune system's defense of the body; it is usually caused by adenosine deaminase (ADA) deficiency
-
Hemophilia
Group of blood clotting disorders is caused by failure to form clotting factors
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Duchenne muscular dystrophy (DMD)
muscle disorder is characterized by progressive atrophy of skeletal muscle without nerve involvement
-
red-green color blindness
inability to distinguish red and green light results from a deficiency of photopigments in the cone cells of the retina
-
Fragile X syndrome
Mental retardation results from breakage of X chromosome in males
-
Parkinson disease
Nervous disorder is characterized by involuntary trembling and muscle rigidity
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