lecture 21

Question 1

what are the two types of BALANCED chromosomal rearrangements?

Answer 1

inversions and translocations

Question 2

what is a balanced chromosomal rearrangement?

Answer 2

there is a change in the chromosome gene order but no duplication or deletion of DNA in the chromosome

Question 3

what type of chromosomal rearrangement involves an internal segment of a chromosome being broken twice(DSB), and rejoined?

Answer 3

inversion

Question 4

what type of chromosomal rearrangement involves fragments of two non-homologous chromosomes trading places?

Answer 4

translocation

Question 5

how do oncogenes form in an inversion?

Answer 5

if the break occurs in the middle of two genes, the resulting gene fusion once the ends have been flipped can be an oncogene(cancerous)

Question 6

what is it called when the centromere is OUTSIDE of the inversion?

Answer 6

paracentric

Question 7

what is it called when the centromere is INCLUDED in the inversion?

Answer 7

pericentric

Question 8

in order for alleles to line up after an inversion has taken place, what must form?

Answer 8

an inversion loop

Question 9

what is the result of an inversion loop?

Answer 9

crossing-over, resulting in decreased recombination

Question 10

in paracentric heterozygote inversions, what is the name of the fragment that is lost?

Answer 10

acentric fragment

Question 11

what is the name of the chromosome part that connects the two chromosomes in a paracentric heterozygote inversion?

Answer 11

paracentric bridge

Question 12

what is the RF for a paracentric heterozygote inversion?

Answer 12

0% because the recombinants are all lethals because the paracentric bridge gets cut in half during telophase I resulting in half the genetic material in the gametes

Question 13

what is the RF is pericentric heterozygote inversions?

Answer 13

0% because only the parental gametes survive because the recombinants have a genetic imbalance as they have double some genes and lack other genes

Question 14

what is it called when two non‐homologous chromosomes mutate by exchanging parts?

Answer 14

translocation

Question 15

what type of structure forms in prophase I in a reciprocal translocation?

Answer 15

cross-like structure of two chromosomes

Question 16

what are the results of alternate segregation in reciprocal translocation?

Answer 16

viable gametes with reduced fertility

Question 17

what are the results of adjacent-1 segregation in reciprocal translocation?

Answer 17

non-viable gametes

Question 18

what are the results of adjacent-2 segregation in reciprocal translocation?

Answer 18

non-viable gametes, doesn’t occur basically at all

Question 19

what are the two types of unbalanced chromosomal rearrangements?

Answer 19

deletions and duplications

Question 20

what is the double of genetic information on one part of a chromosome called?

Answer 20

duplication

Question 21

what is an intragenic deletion?

Answer 21

a small deletion WITHIN a gene that inactivates it

Question 22

how many chromosome breaks occur in an intragenic deletion?

Answer 22

two

Question 23

how is an intragenic deletion different than a single nucleotide mutation?

Answer 23

a single nucleotide mutation can be repaired

Question 24

what is multigenic deletion?

Answer 24

deletion on a chromosome resulting in the loss of multiple genes

Question 25

what is it called when alleles for recessive traits seem to show dominance over normal phenotypes?

Answer 25

pseudodominance

Question 26

how does pseudodominance occur?

Answer 26

if there is a deletion, there is only one allele that can be expressed, if it is recessive it may appear that it is masking the dominant allele that was actually deleted

Question 27

what happens in a tandem duplication?

Answer 27

the genetic material for a gene(s) is implanted into a chromosome next to where that gene(s) already resides

Question 28

what happens in an insertional duplication?

Answer 28

the genetic material for a gene(s) is implanted at some point in the chromosome that is not near where that gene(s) already resides

Question 29

what is it called when two non-homologous chromosomes mutate only by the exchange of genetic information going from one to the other?

Answer 29

non-reciprocal translocation

Question 30

what are the results of a non-reciprocal translocation?

Answer 30

an insertion in one chromosome and a deletion in the other