chapter 6 (Part 3) Flashcards
Nondisjunction
Incorrect separation of chromosomes as germ cells divide during either meiosis I or meiosis II
what does nondisjunction lead to?
aneuploidy (abnormal chromosome number) in gametes and zygotes
Down syndrome (Trisomy-21)
These individuals have delayed development and mental impairment
XXX (Trisomy X)
Female. Taller than average, long legs, wide-set eyes, delayed speech, learning disabilities, problems with fine motor skills. May have problems with fertility.
X0 (Turner Syndrome)
Female. Short stature, wide neck, heart problems, sex organs don’t mature, usually infertile
XXY (Klinefelter Syndrome)
Male. Severity varies. Smaller than normal testicles → reduced testosterone, lower muscle mass, reduced body hair, breast development. Usually infertile.
XYY
normal male
T/F - mutations that occur in the DNA of germ cells cannot be passed onto future generations
False
a carrier
person who is heterozygous for a recessive trait but does not exhibit the traits
Sickle-cell anemia
an autosomal recessive disease where the hemoglobin gene is mutated, causing abnormal red
blood cell formation and reduced capacity to carry oxygen
Tay Sachs
an autosomal recessive disease caused by the absence of an enzyme that breaks down fatty substances in
the brain and spinal cord
a mutated HEXA gene results in the absence of…
lysosomal enzyme
tay sachs typically leads to death before…
adolesence
Cystic fibrosis
an autosomal recessive disease where the gene that codes for a chloride channel is mutated
Cystic fibrosis results in…
thick, sticky mucus in the respiratory,
digestive and reproductive systems, as well as increased salt in sweat.
Huntington’s disease
an autosomal dominant disease where CAG nucleotide repeats are inserted into a gene on chromosome 4.
Huntington’s disease results in…
- Basal ganglia associated with coordinated movements
- HD patients exhibit ‘chorea’ and ‘ballistic movements’
- Movement, cognitive (thinking), and psychiatric effects
Hemophilia
a recessive X-linked disease that affects a gene involved in blood clotting. A lack of any of the blood
clotting factors can lead to an inability to stop bleeding
Duchenne muscular dystrophy
a recessive X-linked disease that involves an important muscle protein, called dystrophin, that holds myofibrils together
without the proper function of dystrophin…
muscles degenerate
