(6) Principles of Genetic Inheritance Flashcards
Define: Gene
Segments of DNA in a chromosome
Define: Chromatid
one of two identical copies of chromosome
Define: Centromere
Connects identical sister chromatids
Define: Telomere
Region at end of chromosome for stability
Human somatic cells are ________ cells
diploid
Homologous chromosomes refer to _________
pairs of chromosomes
Aa: what does the upper case and lower case letter represent?
A: wildtype
a: mutant
Describe AUTOSOMES
- Chromosomes common in both genders
- One from each parent
Banding and nomenclature:
What does the small arm represent?
p
Banding and nomenclature:
What does the long arm represent?
q
Entire set of a pt. chromosmes represents their _____
karyotype
How many chromosomes in pt’s diploid cells
46
What is LYONIZATION?
X-activation
*The choice of which X chromosome to be inactivated is random
What is MOSAICISM?
Condition in which cells from a pt. have different genotypes & karyotypes
What are examples of conditions that result from mosaicism?
- Downs syndrome
- Klinefelter syndrome
- Turner syndrome
What is Down’s syndrome caused by genetically?
Mosaicism:
46XX
47XX
Trisomy 21
What is Klinefelter syndrome caused by genetically?
Mosaicism:
46XY
47XXY
What is Turner syndrome caused by genetically?
Mosaicism:
46XX
45XO
Cell Cycle: Mitosis
What occurs during INTERPHASE?
Chromosome duplication
Cell Cycle: Mitosis
Unique about stem cells?
Undergo mitosis but divide asymmetrically, resulting in one stem cell and one daughter cell
Meiosis:
Goal?
Reduce the total number of chromosomes by half, producing four gametes (haploid)
Meiosis consists of:
- One round of DNA replication
- Two rounds of nuclear division
Meiotic errors:
Euploid=
Cells with a normal number of chromosomes
Meiotic errors:
Polyploidy=
presence of a complete set of EXTRA chromosomes in cells
*often seen in plants
Meiotic errors:
Aneuploidy=
Cells with a missing or additional individual chromsomes
TURNER SYNDROME:
What is the karyotype? Sx?
45, XO Karyotype
- Short stature
- Ovarian hypofunction
- Many do not undergo puberty
- Most infertile
- 30% webbed neck
- CV defects
- Normal intelligence