Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIO207 > Chromosomal Rearrangements > Flashcards

Chromosomal Rearrangements Flashcards

1
Q

What are the two types of events that reshape genomes?

A

Rearrangements and changes in chromosome numbers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are rearrangements?

A

DNA sequences reorganized within one or more chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is nondisjunction?

A

The failure of chromosomes and sister chromatids to properly separate during cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the euploid number?

A

Number of complete sets of chromosomes in an individual (e.g., n, 2n, 3n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is aneuploid number?

A

When cells contain a number of chromosomes that are not euploid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the result of nondisjunction in germ-line cells?

A

Aneuploid gametes that can produce aneuploid zygotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What causes nondisjunction in meiosis I?

A

Failure of homologs to separate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What gametes are produced from nondisjunction of meiosis I?

A

n+1 or n-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What kind of offspring does fusion of n+1 or n-1 gametes with normal (n) gametes produce?

A

Trisomic (2n+1) or monosomic (2n-1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What causes nondisjunction in meiosis II?

A

Failure of sister chromatids to separate normally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Among the 4 gametes produced by meiosis, how many are affected by nondisjunction of meiosis II?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the characteristics of gametes produced by meiosis II nondisjunction?

A

2 are normal (n), one is n+1, one is n-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What type of offspring can be produced by meiosis II nondisjunction

A

50% normal diploid, 25% trisomic, 25% monosomic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What do changes in gene dosage cause?

A

Imbalance of gene products from the affected chromosome relative to the unaffected chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How are humans affected by aneuploidy?

A

Humans are very sensitive to gene dosage and aneuploids usually don’t survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What type of aneuploidies do we see in humans?

A

Autosomal trisomies of chromosomes 13, 18, 21; no autosomal monosomies
Multiple sex-chromosome trisomies and one sex-chromosome monosomy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What syndrome is caused by trisomy 13?

A

Patau syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the characteristics of patau syndrome ?

A

Mental retardation and developmental delay, possible deafness, major organ abnormalities, early death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What syndrome is caused by trisomy 18?

A

Edwards syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the characteristics of Edwards syndrome?

A

Mental retardation and developmental delay, skill and facial abnormalities, early death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What syndrome is caused by trisomy 21?

A

Down syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the characteristics of down syndrome?

A

Mental retardation and developmental delay, characteristic facial abnormalities, short stature, variable life span

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What syndrome is caused by XYY?

A

Jacob syndrome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the characteristics of Jacob syndrome?

A

Tall stature, possible reduction but not loss of fertility, no impact on mental capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What syndrome is caused by XXX?
Triple X syndrome
26
What are the characteristics of triple X syndrome?
Tall stature, possible reduction of fertility, menstrual irregularity, no impact on mental capacity
27
What happens to the risk of down syndrome as a mother gets older?
Increases
28
A portion of chromosome 21 is correlated with the majority of Down syndrome symptoms?
DSCR (down syndrome critical region)
29
What gene makes a major contribution to Down syndrome?
DYRK, has a homolog known to produce dosage-sensitive learning defects in mice
30
How is Turner syndrome explained?
In XO embryos, the single copy of the gene SHOX, which is not inactivated by dosage compensation, is insufficient to direct normal development
31
What is chromosomal mosaicism?
When someone has two or more genetically different sets of cells
32
What is uniparental disomy?
When both copies of a homologous chromosome pair arise from the same parent.
33
What two conditions was uniparental disomy first identified in?
Angelman syndrome, Prader-Willi syndrome
34
What is a rare mechanism for uniparental disomy?
The same chromosome undergoes nondisjunction in both sperm and egg. Fertilization occurs with one of the gametes contributing two copies of the chromosome and the other gamete does not contribute a copy.
35
What is a more common mechanism for uniparental disomy?
Nondisjunction occurs in one parent, resulting in an n+1 gamete. This unites with a normal gamete to produce a trisomic zygote. Trisomy rescue occurs. If the two copies retained by the zygote are from the same parent, uniparental disomy results.
36
What is trisomy rescue?
One copy of the trisomy chromosome is randomly ejected in one of the first mitotic divisions after fertilization
37
What is polyploidy?
Presence of three or more sets of chromosomes in the nucleus of an organism
38
What is autopolyploidy?
Polyploidy resulting from duplication of chromosome sets within a species
39
What is allopolyploidy?
Polyploidy resulting from combining the chromosome sets of different species
40
What two mechanisms most commonly cause autopolypoloidy?
Meiotic nondisjunction leading to a diploid rather than haploid gamete Mitotic nondisjunction that doubles chromosome number
41
What are some consequences of polyploidy?
Decreased fertility, hybrid vigor?
42
What is hybrid vigor?
More rapid growth, increased fruit and flower production, improved disease resistance
43
What is a chromosome break point?
The location at which both DNA strands are severed during chromosome breakage.
44
What can lead to a terminal deletion?
Detachment of all or part of one chromosome arm
45
When might a broken chromosome fragment be lost during cell division?
If it is acentric (i.e., lacks a centromere)
46
What are partial deletion heterozygotes?
Organisms with one normal and one terminally deleted chromosome
47
What is cri-du-chat syndrome?
Infants have a cat-cry sound
48
What causes cri-du-chat syndrome?
Partial deletion heterozygotes who lost 5p15.2-5p15.3
49
What is an interstitial deletion?
The loss of an internal portion of a chromosome
50
What causes interstitial deletion?
Two chromosome breaks
51
What causes WAGR syndrome?
Interstitial deletion of multiple genes on chromosome 11
52
What does unequal crossover cause?
Partial duplication on one homolog and partial deletion on the other?
53
What is a partial duplication heterozygote?
An organism with one normal and one duplication homolog
54
What is a partial deletion heterozygote?
An organism with one normal and one deleted homolog.
55
When does unequal crossover most commonly occur?
When repetitive regions of homologs misalign.
56
What causes Williams-Beuren syndrome?
Partial deletion heterozygotes for the segment of chromosome 7 that contains duplicated copies of a gene called PMS (PMSA and PMSB). Unequal crossover leads to one nonfunctional hybrid PMSA- PMSB gene
57
How can large deletions or duplications be detected?
By microscopy that reveals altered chromosome banding patterns
58
How can microdeletions and microduplications be detected
Molecular techniques like FISH
59
What is another microscopic approach to detect regions of chromosome duplication or deletion?
Microscopic observation during prophase I
60
What causes an unpaired loop?
A large deletion or duplication creates an area of mismatch
61
What is pseudodominance?
When a recessive allele is unmasked by a deletion that removes the dominant allele on the homolog
62
What is chromosome inversion?
Reattachment at the wrong end
63
What is chromosome translocation?
Reattachment to a nonhomologous chromosome
64
What are the two possible types of chromosome inversion?
Paracentric and pericentric
65
What is paracentric inversion?
Centromere is outside of the inverted region
66
What is pericentric inversion?
Centromere is within the inverted region
67
What are inversion heterozygotes?
Individuals with one normal and one inverted homolog
68
What does the alignment of a normal chromosome with its inverted homologs result in?
Inversion loop
69
What does crossing over within the inversion loop result in?
Deletions and duplications in the recombinant chromosomes
70
What does crossing over within a paracentric inversion result in?
Dicentric chromosome and an acentric fragment (which is lost)
71
What does crossing over within a pericentric inversion result in??
Duplicated and deleted regions in both of the recombinants
72
What are the three genetic implications of recombination in inversion heterozygotes?
1. The probability of crossover within the inversion loop is proportional to the size of the loop 2. Inversion suppresses the production of recombinant chromosomes (crossover suppression) 3. Fertility may be altered if an inversion heterozygote carries a very large inversion
73
What is chromosome translocation?
When broken ends of nonhomologous chromosomes are reattached
74
What are nonreciprocal translocations?
A piece of one chromosomes is translocated to a nonhomolog and there is no reciprocal event
75
What are reciprocal balanced translocations?
Pieces of two nonhomologs switch places
76
What are Robertsonian translocations?
Fusion of two nonhomologous chromosomes
77
What happens in heterozygotes for reciprocal balanced translocations?
None of the four chromosomes has a fully homologous partner. A cross-like structure is formed as metaphase I of meiosis and two patterns of segregation are possible.
78
What is alternate segregation?
The two normal chromosomes move to one pole of the cell and the two translocated chromosomes to the other.
79
What is adjacent-1 segregation?
One normal and one translocated chromosome move to each pole of the cell
80
What is the very rare adjacent-2 segregation?
Homologous centromeres move together to each pole of the cell
81
Describe the gametes produced by alternate segregation?
Have a full haploid set of genes
82
Describe the gametes produced by adjacent segregation.
Each gamete contains two copies of some genes and the complete absence of others.
83
Where are translocation heterozygotes semi-sterile?
Only alternate segregation leads to normal gametes.
84
What happens if two pairs of chromosomes fuse by Robertsonian translocation?
Number of chromosomes drops to 2n-2

BIO207 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions