6| CHROMOSOME MUTATIONS: VARIATION IN NUMBER AND ARRANGMENT

Question 1

a change in the total number or chromosomes, deletion or duplication of genes or segments of a chromosome, rearrangements of the genetic material either within or among chromosomes

-passed to offspring in a predictable manner, resulting in many unique genetic outcomes

TERMED AS:

Answer 1

chromosome mutations or aberrations

Question 2

an organism gains or loses one or more chromosomes but not a complete set, can be termed as a

Answer 2

Aneuploidy

Question 3

the loss of a single chromosome (2n-1)

Answer 3

Monosomy

Question 4

the gain of one chromosome (2n+1)

Answer 4

Trisomy

Question 5

complete haploid sets of chromosomes are present, can be defined as an

Answer 5

Euploidy

Question 6

more than two sets of chromosomes are present, termed as an

Answer 6

Polyploidy

Question 7

paired homologs fail to disjoin during segregation, termed

Answer 7

non-disjunction

Question 8

a single copy of a recessive gene due to monosomy may be insufficient to provide life-sustaining function for the organism, can be termed as

Answer 8

Haploinsufficiency

Question 9

The only human autosomal trisomy in which a significant number of individuals survive longer than a year past birth
-1/800 births

Answer 9

Down syndrome

Question 10

Why does down syndrome occur

Answer 10

Nondisjunction of chromosome 21 during meiosis

Question 11

Only two human trisomies that survive to term

Answer 11

Patau and Edwards syndromes

Question 12

2 ways polyploidy originates

Answer 12

1) the addition of one or more extra sets of chromosomes, identical to the normal haploid compliment of the same species, resulting in autoploidy
2) the combination or chromosome sets from different species occurring as a consequence of hybridization resulting in alloploidy

Question 13

repressed when ploidy increases– facilitate the cell’s movement through G1 of the cell cycle, which is thus delayed when expression of these genes is repressed, can be defined as

Answer 13

G1 Cyclins

Question 14

The result of unequal crossing over between synapsed chromosomes during meiosis or through replication error prior to meiosis, is caused by

Answer 14

Duplications

Question 15

Three aspects of duplications

Answer 15

1. may result in gene redundancy
2. may produce phenotypic variation
3. source of genetic variability during evolution

Question 16

Bar phenotype in flies, is a result of

Answer 16

duplications

Question 17

the centromere is not part of the rearranged chromosome segment

Answer 17

paracentric; the centromere is part of the inverted segment is pericentric

Question 18

inversion heterozygotes

Answer 18

organisms with one inverted chromosome and one non inverted homolog

Question 19

a sequence of three nucleotides is repeated many ties, expanding the size of the gene

ex: huntingtons disease

Answer 19

Trinucleotide repeats

Question 20

the number of repeats continues to increase in future generations, age of onset happens latter but the mutation becomes more sever as its passed down; termed as

Answer 20

Genetic anticipation

Question 21

Unequal crossing over, can cause both,

Answer 21

duplications or deletions

Question 22

Heterozygous deletions can lead to, name three;

Answer 22

1. imbalanced gene products
2. pseudodominance
3. haploinsufficiency

Question 23

How do polyploidy arise. name three;

Answer 23

1. errors in meiosis
2. events at fertilization
3. errors in mitosis following fertilization

Question 24

four types of dna damage are;

Answer 24

1. deletion
2. duplication
3. inversion
4. translocation

Question 25

The fusion of 2 chromosomes into 1 (monocentric), can be termed as

Answer 25

Robertsonian translocation (chromosomes 21 & 14)

Question 26

In Autopolypolidy, the origin is due to an addition of

Answer 26

one complete haploid set of chromosomes

Question 27

A Trisomy (2n+1), 47 (XXY); causing rudimentry, tall/long, enlarged breasts. more dominant in males than females

Answer 27

Klinfelters syndrome

Question 28

23. A trisomy (2n+1), 47 (XYY); 96% are phenotypically normal, behavioral problems because of the extra Y

Answer 28

Jacobs syndome

Question 29

47, XXX

females > males

having an additional copy or missing copy of every X-linked gene is temerd

Answer 29

Triplo-X- Aneuploidy

Tall/ menstrual irregularities

Question 30

Rare Aneuploidies

Answer 30

48, XXXX tetra- x
49,XXXXX penta-x

acne, reading, speech, aggressiveness

Question 31

A chromosomal aberration +/- chromosomes individually not a complete set is termed

Answer 31

Aneuploidy

Question 32

parental diagnostic techniques in which fetal cells are isolated and cultured

Answer 32

amniocentesis and CVS, chronic villus sampling

; fetal cells are obtained from the placenta or amniotic fluid

Question 33

fetal cells and DNA are derived directly from the maternal blood circulation causing no risk to the fetus is termed

Answer 33

NIP-GD, non invasive parental genetic testing

Question 34

trisomy 47, 21+

Answer 34

down syndrome, #21

Question 35

2n-1

Answer 35

monosomy

Question 36

45, X0

Answer 36

monosomy 2n-1

turners, females>

short/external genitalia

Question 37

46, 5p

Answer 37

monosomy 2n-1

chiduchat syndrome (not genetically linked); partial monosomy from segmental deletion

Question 38

The four types of aberrations

Answer 38

duplications
deletions
inversions
reciprocal translocations

;aneuploidy is a change in chromosome number

Question 39

why do monosomics most often fail to survive

Answer 39

because complete lack of expression of a particular gene effects metabolism or expression of other developing genes

Question 40

an individual has a heterozygous condition for a particular gene and one copy is lost to non dissjunction, termed

Answer 40

haploinsufficiency

Question 41

the movement of chromosomal segment to a new location in the genome (no loss or gain); rearrangement that doesn’t alter viability directly

Answer 41

translocation;

reciprocal translocation involves exchange between two non homologous chromosomes

Question 42

type of deletion remaining in the centromere region

Answer 42

intercalary

Question 43

for synapsis to occur between a chromosome with a large intercalary deletion and a normal homolog, what must the unpaired normal homolog do

Answer 43

“buckle out” into deletion or compensation loop

Question 44

Gene amplification can be termed as

Answer 44

a large amount of expression in essential genes, rDNA

Question 45

translocation occur at what regions of the chromosome

Answer 45

rDNA regions

Question 46

semisterility, causes a decrease in reproductive fitness. It is a result of

Answer 46

heterozygote translocations

partial monosomy or trisomy

less than 50% will be viable, 1:1

Question 47

the three types of deletions are

Answer 47

1. terminal
2. intercalary
3. compensation loop, “buckle out”

Question 48

Why do duplications occur?

Answer 48

because of a replication error causing unequal crossing over during recombination, “line-up offset

Question 49

The effect of inversions pairing between 1 non inverted and 1 inverted chromosome

Answer 49

inversion heterozygote

inversion; forms chromosomal loop prior to breakage with newly created sticky ends brought together, no loss or gain

Question 50

name the two types of inversions

Answer 50

paracentric and pericentric (centrome involved in p and q breakage)

Question 51

an evolutionary advantage of inversions

Answer 51

balanced chromosomes

Question 52

an evolutionary advantage of duplications

Answer 52

adaptation over time creating unique homology function (gives rise to new genes)