Chapter 2 Flashcards
Down syndrome is the most commonly known example of an ______ aneuploidy
a. autosomal aneuploidy
b. sex chromosome aneuploidy
a. autosomal aneuploidy
which chromosome is affected in down syndrome?
21
all or part of a third copy of the 21st chromosome. “Trisomy 21”
risk of down syndrome increases with maternal age above 35. why?
older eggs have a greater risk of improper cellular division
what are some characteristics of trisomy 21?
Mentally challenged, low nasal bridge, epicanthic folds, protruding tongue, low-set ears, poor muscle tone
Klinefelter syndrome chromosomes
at least two X’s and one Y
can be: XXY and XXXY
abnormalities increase with each additional X
what are some characteristics of Klinefelter syndrome?
- Male appearance
- Tall stature
- Develop female-like breasts
- Small testes—usually sterile
- Sparse body hair
- Long limbs
which of the following are examples of sex chromosome aneuploidy? (select all that apply)
a. Klinefelter syndrome
b. Turner syndrome
c. down syndrome
d. Duchenne muscular dystrophy
a. Klinefelter syndrome & b. Turner syndrome
What is turner syndrome?
a condition that affects only females, when one of the X chromosomes is missing or partially missing. This is usually inherited by the mother
what are some characteristics of turner syndrome?
- underdeveloped ovaries (infertility)
- short stature (~4’7”)
- webbing of the neck
- underdeveloped breasts; wide nipples
- risk for development of cardiac defect (coarctation of aorta)
- high number of fetuses that do not survive gestation
What is Autosomal dominant inheritance?
genes that are in the autosomal chromosome.
- affected offspring/children usually produced by a union of a normal parent with an affected heterozygous parent
-allele may be disease-causing or normal
– the condition is represented by a capitalized letter
EX: Huntington’s disease, polycystic kidney disease
what is autosomal recessive inheritance?
Condition is represented by lower case letter
○ In most cases, both parents of affected individuals are heterozygous carriers
○ Recurrence risk/ inheritance risk for offspring/children is 25%
○ Males and females equally affected
○ Examples: Sickle cell anemia/ disease, Cystic fibrosis, Tay Sach’s disease
what is a single-gene disorder? examples?
disorders caused by one abnormal gene and are inherited in the traditional mendelian patterns
single gene disorder can be autosomal dominant, autosomal recessive, x-linked recessive, and x-linked dominant
ex: cystic fibrosis, sickle cell anemia
what are euploid cells?
euploid (normal) cells have a multiple of the normal number (23) of chromosomes
example: Haploid (egg and sperm) and diploid cells (somatic cells) are euploid forms
What is a polyploid cell?
When a euploid cell has more than the diploid number
EX:
Triploidy: a zygote having three copies of each chromosome (69 total)
Tetraploidy: four copies of each (92 total)
What is aneuploidy?
a somatic cell (any cell except for sex cells) that does not contain a multiple of 23 chromosomes
