4/15/2025 chromosomal mutations

Question 1

what are chromosomal aberrations

Answer 1

they are changes in chromosomal structure that typically affect more than one gene

Question 2

what is a deficiency/deletion?

Answer 2

it is the loss of a chromosomal segment, it typically results in a major loss of genes

Question 3

when a deletion occurs, what can this cause?

Answer 3

a partial monosomy snce we only have 1/2 of the proper gene dosage of a particular gene

Question 4

deletions and duplications typically affect:

Answer 4

gene dosages

Question 5

what is a recessive lethal allele?

Answer 5

when there is a deletion on one homologous chromosome, certain alleles that were previously repressed become active and may be lethal

Question 6

what is pseudodominance?

Answer 6

deletions that make previously recessive alleles now active, as if they were dominant

Question 7

what does the consequence of a deletion depend on?

Answer 7

the size of the deletion

the type of chromosomal material that was deleted

Question 8

if a nonessential portion of a chromosome is deleted, will this have a large phenotypic effect?

Answer 8

no

Question 9

what is cri-du-chat syndrome caused by?

Answer 9

it is caused by the deletion in chromosome 5

Question 10

what is a duplication?

Answer 10

the repetition of a chromosomal segment due to gene misalignments during recombination

Question 11

if a chromosome undergoes a duplication event, and now has three copies of a particular gene, what is it referred to as?

Answer 11

a partial trisomy

Question 12

compared to deletions, how harmful are duplications?

Answer 12

duplications tend to be less harmful than deletions

the phenotypic effect depends on the size and placement of the duplication

Question 13

what generally causes duplications?

Answer 13

misalignment during homologous recombination

Question 14

if a chromosome undergoes a misalignment during recombination, what is an additional side effect?

Answer 14

one chromosome will undergo a duplication while the other will have a deletion

Question 15

when a gene undergoes a duplication event, what might occur over time?

Answer 15

they will differ overtime and may subspecialize as they develop mutations

Question 16

are duplications always harmful?

Answer 16

no, sometimes they can be beneficial

Question 17

why is the gene family of globin helpful in development?

Answer 17

different globins may be expressed during different phases of development to meet the needs of embryos, fetuses, and adults

Question 18

what is the role of myoglobin? how is its affinity for oxygen and CO2

Answer 18

myoglobin stores oxygen in muscle cells by having a higher O2 affinity and low CO2 affinity

Question 18

what is the role of hemoglobin? how is its affinity for oxygen and CO2

Answer 18

hemoglobin binds and transports oxygen in blood cells by having a lower O2 affinity and higher CO2 affinity

Question 19

what is copy number variation

Answer 19

segments of DNA that may vary in copy number among members of the same species

Question 20

what is an inversion? does the amount of genetic information change?

Answer 20

a segment of DNA has been flipped but the amount of genetic material does not change so it may not have a detrimental consequence in the host

Question 21

what is the breakpoint effect?

Answer 21

the inversion occurs in the middle of the gene

Question 22

what is the position effect?

Answer 22

a gene is repositioned in a way that it affects gene expression

Question 23

if an inversion results in a gene being relocated in a heterochromatic region, what is the effect?

Answer 23

it will be a positon effect where there is less gene expression

Question 24

true or false, an inversion will not have any effects in the host and their children

Answer 24

false, it will likely affect their child

Question 25

what is an inversion heterozygote

Answer 25

it is an individual with with a normal chromosome and an inverted chromosome

Question 26

do people with inversion heterozygotes form normal gametes?

Answer 26

no, they have a high probability of forming abnormal gametes due to cross-overs in the inverted segments

Question 27

what is an inversion loop?

Answer 27

it is a loop that forms so the normal and inverted chromosomes can align properly in homologous recombination

Question 28

if homologous recombination occurs in the inversion loop region of a chromosome, will it affect the gametes?

Answer 28

yes, it may result in inversions or deletions

Question 29

if homologous recombination occurs in a region outside of the inversion loop, will it be abnormal?

Answer 29

no, it will be normal

Question 30

what is a translocation

Answer 30

when a segment of one chromosome becomes attached to another

Question 31

what is a reciprocal/balanced translocation?

Answer 31

two non-homologous chromosomes exchange genetic material

Question 32

what is an unbalanced/simple translocation

Answer 32

transfer of genetic material in one direction on one chromosome

Question 33

for a translocation, where might the phenotype be observed?

Answer 33

in the gametes

Question 34

when a reciprocal or simple translocation occurs, what effects may be seen?

Answer 34

break point effects or position effects

Question 35

true or false, in order for a translocation to occur, the chromosomes must be homologous

Answer 35

false, they must be non-homologous

Question 36

what is familial down syndrome

Answer 36

it is a translocation where the majority of chromosome 21 is attached to chromosome 14. This results in an individual with 3 copies of chromosome 21 so they exhibit characteristics of down syndrome (trisomy 21)

Question 37

how is familial down down syndrome similar and different to trisomy 21?

Answer 37

they have the same phenotype but trisomy 21 is not familial and is inherited through nondisjunction while famial down syndrome is familial and results from a robertsonian translocation

Question 38

why is it not considered a deletion when the p arm of chromosome 14 and 21 are lost?

Answer 38

these portions were not essential

Question 39

for a person who is a carrier for familial down syndrome, how many chromosomes do they have and why does this not affect them

Answer 39

they only have 45 chromosomes but this has no effect since they still have two copies of every gene, its just 21 and 14 are translocated into one

Question 40

what types of gametes can carriers of non familial down syndrome have?

Answer 40

they can have normal children, carrier children, children with familial down syndrome, and non functional gametes

Question 41

translocations and inversions most often have effects in:

Answer 41

their gametes

Question 42

when homologous chromosomes with translocations align, what types of gamates might they form

Answer 42

normal children, unbalanced or semi-sterile gametes, or disfunctional gametes

Question 43

what is semisterility

Answer 43

an individual with reciprocal translocations will produce 1/2 viable gametes and 1/2 non viable gametes

Question 44

what is the blending theory of inhertiance

Answer 44

it is where traits are belnded to form co-dominance

Question 45

what is true breeding

Answer 45

it is where two homozygous individuals for their respective traits are crossed (both are homo YY and yy)

Question 46

what did mendel's work with the single trait cross reveal

Answer 46

when two pure bred individuals are crossed, the dominant trait is the one that will be observed while the recessive trait will be completely absent

Question 47

what is a self cross? what did it reveal in mendels work

Answer 47

a self cross is where an inidvidual is crossed with itself in mendels work, he crossed his F1 generation (hybrid) which created a dominant phenotype in a 3:1 ration

Question 48

what law did mendel's law of segregation support?

Answer 48

it supported the law of segregation where 1.2 of the gametes will recieve one factor while the other half will recieve the other factor

Question 49

for Li2, Be2, B2, C2, and N2, what is different about the molecular orbital diagram

Answer 49

the σ g (2p) is now higher energy than the π u (2p)