Genetic Disorders Flashcards
Errors in Meiosis are known as -
Nondisjunction
Nondisjunction occurs in..
Anaphase 1 - Homologous pairs don’t separate.
Anaphase 2 - Chromatids don’t separate.
An abnormal number of chromosomes is known as…
Aneuploidy
N+1
Trisomy
N-1
Monosomy
Errors can also be caused by:
Alterations in chromosomal structure.
Alterations in chromosomal structure can be:
Deletions, Insertions or translocations
In Trisomy, which 3 will survive?
15, 18 & 21
Aneuploidy of sex chromosomes can lead to…
XXY
XYY
XXX
XO
XXY is known as:
Klinefelter Syndrome
Barr bodies in males
Characteristics of Klinefelter?
Small testes & sterile
XYY characteristics?
No syndrome, but tend to be taller
XXX characteristics?
Super Female!
2 Barr Bodies
XO characteristics?
Single sex chromosome. More prone to recessive X linked traits.
YO?
No such thing. Male can’t survive without X!
Euploidy =
Right amount
Partial Aneuploidy =
Deletions, duplications & translocations.
Partial Aneuploidy can result from:
Errors in crossovers
Unequal or non-reciprocal events
Unequal expression, caused by neighbouring genes or hot spots is an example of the
Dose effect - sometimes it doesn’t matter and we’ll never know.
If someone has double the amount of hemoglobin as a result of dose effect.
Never know, does them no harm.
Assuming fertilization is normal we can have:
Half or extra of the amount of a gene
ABCDE->ADCBE
Inversion
MNOCDE->ABPQR
Translocation
Areas of high expression or low-transcribed regions?
Hot Spots
If you move a gene from low to high…
Start producing more of that gene, therefore more expression
ABCDE->ACDE
Deletion
ABCDE->ABBCDE
Duplication
Genes outside of the nucleus are called..
Extranuclear genes
How many genes in mitochondria?
34-97
How many genes in Chloroplasts?
99-115
Where do all mitochondria come from?
Maternal - none in sperm. Maternal inheritance.
Do extranuclear genes follow Mandelian inheritance?
No.
