Unit 11 Flashcards
What are the general types of genetic disorders
-whole chromosome disorders=syndromes
-single gene diseases=defect due to gene mutation
How are whole chromosome disorders formed
Non disjunction: meiosis fails during anaphase 1 or 2, resulting in a gamete with the wrong number of chromosomes, called aneuploidy
Show non-disjunction in a drawing during both meiosis
Aj
Does non disjunction always happen in both meiosis
Rarely, one or the other
What is the difference in effect of non-disjunction in meiosis 1 and 2
-M1 affects all gametes
-M2 affects half the gametes
What is the effect of non disjunction
-one extra chromosome=trisomy
-missing one chromosome=monosomy
Both are called syndromes
What is caused by non-disjunction in automsome chromosomes?
Trisomy 21-down syndrome
What is caused by non disjunction in X-chromosomes?
-turner syndrome X0
-klinefelter syndrome XXY
-metafemale syndrome XXX
What is caused by non-disjunction in Y-chromosomes during meiosis II
Jacobs syndrome XYY
What are the characteristics of trisomy 21
-affects the development of the brain, immune system, heart and skeleton
-mentally challenged
-broad face with flat nasal bridge, wide set eyes, transverse simian crease in hands
What are the characteristics of turner syndrome
-genetically female
-98% die before birth
-affect 1 in 2,500 females
-short stature, webbed neck, non-functioning ovaries
What are the characteristics of klinefelter syndrome
-1 in 599 males
-taller than average
-feminine body type
-incomplete breast development
-absent, delayed or incomplete puberty
What are the characteristics of trisomy X
-1 in 1000 females
-taller
-problems with spoken language and processing spoken words
-coordination problems, weaker muscles
-normal sexual development and fertility
What are the characteristics of Jacobs syndrome
-1 in 1000 males
-delayed motor skill development (ex. Writting)
-delayed or difficult speech
-emotional or behavioral issues
-hand trembling or involuntary muscle movements
-weak muscle tone
-no abnormal physical appearances
Why does Y0 not exist?
Because genes on X chromosomes are necessary for survival
When do you risk chromosomal problems?
Adults age 35 or older have a higher risk of conceiving a child with a chromosomal abnormality because aging affects the meiosis process
How can you detect syndromes before brith
-check the mothers blood during the second trimester to check for 3 markers
If they are present, a karotype is ordered
What is a karotype
Fetal cells are examined to see chromosome numbers and length
How do you prepare a karotype
-fetal cells are cultured to increase their number and promote cell division
-cell growth is stopped during mitosis
-metaphase cell is collected and squished between two slides
How do you collect fetal cells for a karotype
-amniocentesis: collecting from the amniotic fluid at 9 to 15 weeks.
Results take 3-5 weeks
-chorionic villi sampling: collecting from the placental tissue at 8 weeks.
Results in 48 hours
What is polyploidy
One whole extra set of chromosomes, affects animals but lead to miscarriage
Plants are less affected and used in the food industry
