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
Define autosomal aneuploidy
chromosome abnormalities that do NOT involve the sex chromosomes
define sex chromone aneuploidy
chromosome abnormalities that involve sex chromosomes
define sex-linked inheritance
-traits/genes located on sex chromosomes
-Most sex-linked traits/genes are located on the X chromosome and are said to be X-linked
-Most are recessive
EX: Duchenne Muscular Dystrophy, Fragile X, Hemophilia, Red-green color-blindness
genotype vs. phenotype
genotype: the composition of genes at a given locus (what they have)
phenotype: the outward appearance of the genetics of an organism (what they demonstrate)
mitosis vs. meiosis
mitosis: process in which somatic cells are replicated -each with a pair of 23 chromosomes
meiosis: process in which germ cells are replicated (haploid cells from diploid cells) - results in the formation of gametes (ovum and sperm). each with a single set of 23 chromosomes
what are pedigree charts used for?
-Used to study specific genetic disorders within families
-Begins with the proband/ first person diagnosed with the genetic condition/ inherited health concern
define multifactorial inheritance
variation in traits caused by genetic and environmental factors
ex: IQ
cells that line the Gi tract replicate by which process?
a. meiosis
b. mitosis
b. mitosis
Which of the following are examples of single gene disorders (Select all that apply)
a. Klinefelter syndrome - sex chromosomal
b. Cystic Fibrosis - recessive
c. Down syndrome - autosomal chromosomal
d. Sickle cell anemia/ disease - recessive
b & C
_____ is the study of biological inheritance while ___ helps determine which of an individual’s genes are active in which cells
a. genomics; genetics
b. genetics; genomics
b. genetics; genomics
a cell that does not contain a multiple of 23 chromosomes is a(n) ______ cell
a. autosomal
b. gamete
c. aneuploidy
d. polyploid
c. aneuploidy
gamete cells replicate through the process of ________ while autosomal cells replicate through the process of _______
a. meiosis; mitosis
b. mitosis; meiosis
a. meiosis; mitosis
cells with a multiple of the normal number of chromosomes are _______ cells
a. euploid
b. polyploid
a. euploid
turner syndrome and Klinefelter’s syndromes are examples of _________
a. autosomal polyploidy
b. sex-chromosome aneuploidy
c. autosomal aneuploidy
d. sex-chromosome polyploidy
b. sex-chromosome aneuploidy
an allele whose effects are observable is said to be _____ while an allele whose effects are hidden is said to be ________
a. heterozygous; homozygous
b. dominant; recessive
c. recessive; dominant
d. homozygous; heterozygous
b. dominant; recessive
the outward appearance of an individual is the ________. However, the actual composition of genes at a given locus is the ________
a. genotype; phenotype
b. phenotype; genotype
b. phenotype; genotype
the outward appearance of an individual is the ________. However, the actual composition of genes at a given locus is the ________
a. genotype; phenotype
b. phenotype; genotype
b. phenotype; genotype
A(n) _________ chart summarizes family relationships and shows which members of a family are affected by a genetic disease
a. pedigree
b. lineage
c. inheritance
d. growth
a. pedigree
when environmental factors influence the expression of a trait, it’s known as ______.
a. single gene inheritance
b. multifactorial inheritance
b. multifactorial inheritance
