Unit 11

Question 1

What are the general types of genetic disorders

Answer 1

-whole chromosome disorders=syndromes
-single gene diseases=defect due to gene mutation

Question 2

How are whole chromosome disorders formed

Answer 2

Non disjunction: meiosis fails during anaphase 1 or 2, resulting in a gamete with the wrong number of chromosomes, called aneuploidy

Question 3

Show non-disjunction in a drawing during both meiosis

Answer 3

Aj

Question 4

Does non disjunction always happen in both meiosis

Answer 4

Rarely, one or the other

Question 5

What is the difference in effect of non-disjunction in meiosis 1 and 2

Answer 5

-M1 affects all gametes
-M2 affects half the gametes

Question 6

What is the effect of non disjunction

Answer 6

-one extra chromosome=trisomy
-missing one chromosome=monosomy
Both are called syndromes

Question 7

What is caused by non-disjunction in automsome chromosomes?

Answer 7

Trisomy 21-down syndrome

Question 8

What is caused by non disjunction in X-chromosomes?

Answer 8

-turner syndrome X0
-klinefelter syndrome XXY
-metafemale syndrome XXX

Question 9

What is caused by non-disjunction in Y-chromosomes during meiosis II

Answer 9

Jacobs syndrome XYY

Question 10

What are the characteristics of trisomy 21

Answer 10

-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

Question 11

What are the characteristics of turner syndrome

Answer 11

-genetically female
-98% die before birth
-affect 1 in 2,500 females
-short stature, webbed neck, non-functioning ovaries

Question 12

What are the characteristics of klinefelter syndrome

Answer 12

-1 in 599 males
-taller than average
-feminine body type
-incomplete breast development
-absent, delayed or incomplete puberty

Question 13

What are the characteristics of trisomy X

Answer 13

-1 in 1000 females
-taller
-problems with spoken language and processing spoken words
-coordination problems, weaker muscles
-normal sexual development and fertility

Question 14

What are the characteristics of Jacobs syndrome

Answer 14

-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

Question 15

Why does Y0 not exist?

Answer 15

Because genes on X chromosomes are necessary for survival

Question 16

When do you risk chromosomal problems?

Answer 16

Adults age 35 or older have a higher risk of conceiving a child with a chromosomal abnormality because aging affects the meiosis process

Question 17

How can you detect syndromes before brith

Answer 17

-check the mothers blood during the second trimester to check for 3 markers
If they are present, a karotype is ordered

Question 18

What is a karotype

Answer 18

Fetal cells are examined to see chromosome numbers and length

Question 19

How do you prepare a karotype

Answer 19

-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

Question 20

How do you collect fetal cells for a karotype

Answer 20

-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

Question 21

What is polyploidy

Answer 21

One whole extra set of chromosomes, affects animals but lead to miscarriage
Plants are less affected and used in the food industry