Exam 1: Lecture 11

Question 1

inversion depends on the involvement of the _ in the inversion

Answer 1

centromere

Question 2

paracentric inversion

Answer 2

does not include centromere (confined to one arm of a chromosome)

Question 3

pericentric inversion

Answer 3

change in position of centromere; occur on both arms of a chromosome and spans the centromere

Question 4

an inversion in mitosis, if balanced usually no problems in mitosis, t/f?

Answer 4

true

Question 5

an inversion in meiosis: homozygous individuals

Answer 5

no problems arise during meiosis

Question 6

an inversion in meiosis: heterozygous individuals

Answer 6

para- or peri- centric inversion often have nonfcnal gametes due to loss of large amounts of genetic material during meiosis

Question 7

an indiv heterozygous for a para/pericentric inversion, what occurs?

Answer 7

the chromosomes form an inversion loop during pairing in prophase I

Question 8

in a heterozygous indiv, a single crossover within a paracentric inversion leads to

Answer 8

abnormal gametes

Question 9

crossing over within para inversion leads to (het)

Answer 9

unusual structure, one of the 4 chromatids now has 2 centromeres and 1 lacks a centromere

Question 10

what happens in anaphase I of meiosis during paracentric inversions (het)

Answer 10

centromeres separate, stretching the dicentric chromatid (from crossing over) which breaks. The chromosome lacking a centromere is lost

Question 11

what happens in anaphase II of meiosis during paracentric inversions (het)

Answer 11

2 gametes contain non-recombinant chromosomes: one WT (normal) and one with inversion. The other 2 contain recombinant chromosomes that are missing some genes; these gametes will not produce viable offspring

resulting recombinant gametes are nonviable bc they are missing some genes

Question 12

what happens in crossing over of a peri inversion (het)

Answer 12

2 of the resulting chromatids have too many copies of some genes and no copies of others

Question 13

what happens in anaphase I of peri inversion (het)

Answer 13

chromosomes separate in anaphase I

Question 14

what happens in anaphase II of peri inversion (het)

Answer 14

sister chromatids separate in anaphase II forming 4 gametes; recombinant gametes are nonviable bc genes are either missing or present in too many copies

Question 15

translocations are caused by:

Answer 15

rearrangement of segments between nonhomologous chromosomes

Question 16

a translocation can be balanced if:

Answer 16

in an even exchange of material with no genetic information duplicated or lost, and usually fully functioning

Question 17

a translocation can be unbalanced if:

Answer 17

the exchange of genetic material is unequal resulting in extra or missing genes

Question 18

reciprocal translocation

Answer 18

an exchange of material btwn nonhomologous chromosomes

Question 19

nonreciprocal translocation

Answer 19

transfer of genes from one chromosome to another nonhomologous chromosome

Question 20

robertsonian translocation

Answer 20

recombining with acrocentric chromosomes that allow the short arms to be lost and the long arms creating metacentric chromosome

Question 21

translocation in meiosis infertility:

Answer 21

gametes resulting from adjacent-I and adjacent-2 segregation are nonviable bc of the loss or gain of large amts of DNA (missing or 2 copies)

Question 22

it is thought that humans and chimpanzees are more closely related than chimpanzees and gorillas or orangutans.

how can you explain that chimpanzees, gorillas and orangutans all have 2 chromosomes that contain the genes on chromosome 2 of humans?

Answer 22

the human chromosome combined and formed one singular stable chromosome that may be similar to the 2 chromosomes in chimpanzees, gorillas, and orangutans, but the genes on human chromosome 2 are not used the exact same way/amount they are used in the 2 chromosomes of primates

Question 23

chromosome 4 differs in humans and chimpanzees due to a

Answer 23

pericentric inversion; genes around centromeres is rearranged differently

Question 24

cen

Answer 24

centromere

Question 25

del

Answer 25

deletion

Question 26

der

Answer 26

derivative chromosome (translocation)

Question 27

fra

Answer 27

fragile site

Question 28

dic

Answer 28

dicentric chromosome

Question 29

dup

Answer 29

duplication

Question 30

what are the causes of aneuploidy

Answer 30

• deletion of centromere during mitosis and meiosis
• robertsonian translocation
• nondisjunction during mitosis/meiosis

Question 31

types of aneuploidy: 2n - 2

Answer 31

nullisomy: loss of both members of a homologous pair of chromosomes

Question 32

types of aneuploidy: 2n - 1

Answer 32

monosomy: loss of a single chromosome

Question 33

types of aneuploidy: 2n + 1

Answer 33

trisomy: gain of a single chromosome

Question 34

types of aneuploidy: 2n + 2

Answer 34

tetrasomy: gain of 2 homologous chromosomes

Question 35

effects of aneuploidy in plants

Answer 35

trisomies product different seed cases for a different plant (mutants could actually be trisomics)

Question 36

effects of aneuploidy in humans

Answer 36

sex-chromosome aneuploids:

• turner syndrome XO
• klinefelter syndrome XXY

Question 37

autosomal trisomy in humans

Answer 37

trisomy 21 down syndrome

Question 38

what is primary down syndrome

Answer 38

nondisjunction in egg formation

Question 39

what is familial down syndrome

Answer 39

robertsonian translocation

Question 40

translocation carriers are at an increased risk for what

Answer 40

producing children with down syndrome

Question 41

autopolyploidy

Answer 41

from single species

Question 42

allopolyploidy

Answer 42

from 2 or more species

Question 43

the significance of polyploidy

Answer 43

increase in cell size, larger plant attributes, evolution (give rise to new species)

Question 44

autopolyploidy do not segregate in anaphase and result in

Answer 44

unreduced cell (common in cancer) also happens in meiosis