Unit 8- Chromosome Variation

Question 1

Chromo Rearrangement

Answer 1

alter the structure of chromo

Question 2

duplication

Answer 2

a seg of chromosome duplicated (can be inverted)
- tatem: duplicate next door
- displaced: duplicate elsewhere
*detected by looping

Question 3

deletion

Answer 3

loss of a chromo seg
- large deletions easily detected; during pairing, normal chromo loops out

Question 4

effects of deletions

Answer 4

• imbalances in gene product
• expression of a normally recessive gene (pseudodominance)
• haploinsufficiency: when a single copy of a dom allele is not enought to produce wild-type alleles

Question 5

inversion

Answer 5

seg of chromo turned 180 degrees
- paracentric or pericentric

Question 6

translocation

Answer 6

seg moves from chromo to a nonhomologous chromo or to another place on same chromo

Question 7

inversions in meiosis

Answer 7

• homozygous: no problems arise
• heterozygous:
  
  • homol seq align only if the 2 chromo form an inversion loop

Question 8

nonreciprocal translocation

Answer 8

segment from ONE chromo goes to another

Question 9

reciprocal translocation

Answer 9

segment from EACH chromo goes to the other

Question 10

Robertsonian translocation

Answer 10

the entire long arms of two different chromosomes become fused (short arms fuse together too)

Question 11

aneuploidy

Answer 11

inc or dec in # of indiv chromos
causes:
- deletion of centromere during mitosis/meiosis
- robertsonian translocation
- nondisjunction

Question 12

Aneuploidy: nullisomy

Answer 12

loss of both members of a homologous pair of chromos; 2n-2

Question 13

Aneuploidy: monosomy

Answer 13

loss of a single chromo; 2n-1

Question 14

Aneuploidy: trisomy

Answer 14

gain of a single chromo; 2n+1

Question 15

Aneuploidy: tetrasomy

Answer 15

gain of 2 homologous chromos; 2n+2

Question 16

effects of aneuploidy

Answer 16

sex chromos:
- turners syndrome: XO
- Klinefelter Syndrome: XXY

autosomes
- trisomy 21: down syndrome (primary: 75% nondisjunction and familial: 25% robertsonian translocation)

uniparental disomy: both chromos inherited from same parent

Question 17

Polyploidy

Answer 17

prescence of more than 2 SETS of chromos

significance:
- inc in cell size
-evolution

Question 18

polyploidy: autoploidy

Answer 18

2+ sets from single species

Question 19

polyploidy: allopolyploidy

Answer 19

2+ sets from 2 diff species

Question 20

paracentric inversion

Answer 20

inversions that do not include centromere
- no recomb (nonviable offspring: chromo breaks off)

Question 21

pericentric inversions

Answer 21

inversion that INCLUDE the centromere
- abnormal gametes

Question 22

position effect

Answer 22

genes are expressed at wrong times or produce the wrong tissues due to inversion

Question 23

uniparental disomy

Answer 23

both chromosomes are inherited from the same
parent (some cystic fibrosis and willi syndrome)