Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIOL2500 > Unit 07: Chromosomal Alterations > Flashcards

Unit 07: Chromosomal Alterations Flashcards

(80 cards)

Start Studying
1
Q

chromosomal territories contain what?

A

a single chromosome within an arbitrary region not bound by any membranes

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

how many chromosomal shapes are found in most species?

A

3-4

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

what is a karyotype?

A

an image of all the chromosomes in an organisms ordered from biggest to smallest

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

what does the p arm of a chromosome represent?

A

the short end

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

what does the q arm of a chromosome represent?

A

the long end

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

what are metacentric chromosomes? how do p and q compare?

A

chromosomes where the centromere is found near the middle.

p = q

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

what are submetacentric chromosomes? how do p and q compare?

A

chromosomes where the centromere is nearer to one end. p<q

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

what are acrocentric chromosomes? how do p and q compare?

A

chromosomes where the centromeres are at the end (satellites)

p«q

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

what are telocentric chromosomes? how do p and q compare?

A

chromosome where the centromeres are terminal at the end

p = 0

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

rRNA genes are always in what form of chromatin? why?

A

euchromatin bc always being transcribed

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

what are large scale changes in chromosomes called?

A

chromosomal mutations

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

what type of mutations can be detected under a microscope?

A

chromosomal

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

what are changes in the numbers of the whole chromosome set called?

A

aberrant euploidy

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

what are changes in the numbers of part of the chromosome set called?

A

aneuploidy

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

what are euploids?

A

organisms with multiples of basic chromosome sets. ex. animals 2N and plants N

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

what are polyploids?

A

organisms with more than 2 chromosome sets

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

polyploidy is very common in ____

A

plants

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

what is the difference between autopolyploids and allopolyploids?

A

auto - chromosomes from a single species
allo - chromosomes from several species ex. wheat and canola

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

describe triploids as covered in the slides.

A
  • autopolyploid by spontaneous nondisjunction
  • usually sterile (ex bananas 3N = 33)
  • bivalents AND univalents
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what are some consequences of polyploidy?

A
  • increase in fruit and flower size
  • reduced fertility (seedless)
  • hybrids are more fit than true breeding plants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

allopolyploids are created by ____. give an example

A

hybridization of 2 or more species.

ex. canola

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

what are monosomic individuals?

A

individuals missing one chromosome copy (2n-1)

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

what are trisomic individuals?

A

individuals with an extra chromosome copy (2n+1)

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

what are nullisomic individuals?

A

individuals missing BOTH copies of a chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
how does nondisjunction occur in meiosis 1?
failure of homologous chromosome separation
26
how does nondisjunction occur in meiosis 2?
failure of sister chromatid separation
27
describe the chromosome alteration resulting in turner syndrome
a monosomy in mostly females where we are missing an X chromosome which is needed for development. the genes on the other X chromosome is not sufficient enough for normal development
28
in humans, monosomies in autosomal chromosomes causing what?
embryo abortion in utero
29
what trisomies are common in humans? why not others?
13, 18, 21 and sex chromosomes. others cause embryo abortion in utero.
30
describe the chromosome alteration resulting in triple X syndrome
trisomy of sex chromosomes X in females
31
describe the chromosome alteration resulting in klinefelter syndrome
trisomy of the sex chromosomes in males (XXY)
32
what is the most common autosomal aneuploidy in humans?
trisomy 21 (down syndrome)
33
describe meiosis in an egg cell throughout a mother's life.
- meiosis starts in fetal ovaries where it reaches synapsis in prophase 1 then stops. - at puberty, periods stimulate meiosis again and egg goes into fallopian tube after meiosis 1 - when egg is fertilized meiosis 2 occurs
34
90% of trisomy 21 cases were a result of disjunction at what stage of meiosis?
meiosis 1 in egg
35
individuals with down syndrome have how many copies of C21 from mom and how many from dad?
2 maternal copies 1 paternal copy
36
other than meiotic nondisjunction, how else can down syndrome occur?
Robertsonian translocation
37
what is the gene dosage of monosomic individuals?
50%
38
what is the gene dosage on trisomic individuals?
150%
39
are animals or plants more likely to be affected by gene dosage?
animals
40
what is uniparental disomy?
when both copies of the chromosome are from the same parent
41
describe the two ways a uniparental disomy can occur.
1. nondisjunction occurs in both the sperm and the egg (rare) (1 gamete gives XX other gives nothing) 2. nondisjunction in one gamete and the other is normal and then trisomy rescue occurs and the normal chromosome is thrown out
42
what are changes in chromosome structure called?
rearrangements
43
what type of break has to occur for a chromosome to break?
double stranded
44
what allows for broken chromosome ends to rejoin?
sticky ends!
45
what is unequal crossover?
crossover between repetitive DNA sequences
46
what is non allelic homologous recombination?
when in repetitive DNA sequences, they dont allign of the diff chromosomes. ex. ABCDA and ABCDA don't align perfectly rather the second only aligns at the second A on the first
47
only chromosomes that have ______ and _______ are viable
1 centromere and 2 telomeres
48
what are dicentric chromosomes?
chromosomes with 2 centromeres
49
why are dicentric chromosomes inviable?
because they will form an anaphase bridge where they will break and now both resulting chromosomes are lacking a telomere region to protect the genetic material
50
what are unbalanced rearrangements? which chromosome rearrangements fall under this category?
rearrangements that result in the changing of gene dosage. deletions and duplicaitons
51
what are balanced rearrangements? which chromosome rearrangements fall under this category?
rearrangements that change the gene order but do not alter gene dosage inversions and translocations
52
briefly describe what chromosomal deletions are and how they occur.
when we have parts of the genetic material being lost. double stranded break occurs at the chromosome break point and the cell cannot repair it so the genetic material there is lost. these broken ends can re adhere to either eachother or other chromosome bits.
53
what are intragenic deletions?
deletions within a gene which disrupts gene function.
54
what are multigenetic deletions?
where several genes are missing
55
are intragenic or multigenic mutations more severe?
multigenic
56
when are small deletions viable? what are individuals in this situation called?
when paired with a normal homolog. these individuals are called partial deletion heterozygotes
57
what happens when a small deletion homolog pairs up with a normal homolog in meiosis?
forms a deletion loop
58
what is pseudodominance?
when the recessive alleles on one homolog are unmasked because the dominant alleles on the other homolog were deleted
59
what chromosomal alteration causes cri du chat syndrome?
a terminal deletion of genes 15.2 and 15.3 on the p arm of chromosome 5
60
what is an interstitial deletion?
an internal deletion where there are 2 chromosome breaks so a whole internal chunk gets deleted. the internal ends get reattached resulting in a shorter than normal chromosome.
61
what are duplications?
repeated segments on a chromosome
62
what are tandem duplications?
where the duplicated region is adjacent to a gene
63
what is an insertional duplication?
duplications located elsewhere in the genome not adjacent to the gene
64
what are duplication heterozygotes?
individuals with one normal chromosome and one duplicated
65
what does unequal crossover result in?
partial duplication and partial deletion
66
describe the chromosome alteration resulting in williams-beuren syndrome
a partial deletion on chromosome 7 resulting in only one copy of the PMS gene on one chromosome while other has 3 copies
67
what is a chromosome inversion a result of?
sticky ends joining together but in the wrong orientation
68
what are paracentric inversions?
inversions that happen BESIDE the centromere and do not include it, therefore only occurring on one arm
69
what are pericentric inversions?
inversions that include the centromere. inversion rotates "around" centromere
70
what results of chromosome inversions are inviable?
- acentric/dicentric chromosomes - chromosomes with deletions/duplications
71
the probability of crossover within an inversion loop is linked to the size of ____
the loop
72
are there recombinant chromosomes in progeny of individual w inversion chromosomes? why?
no! bc viable gametes will contain either the WT chromosome or the inverted chromosome therefore we get crossover suppression.
73
how can fertility be suppressed in inversion heterozygotes?
if inversion is large enough we will always get only 2 viable gametes while 2 will be inviable
74
what is unbalanced translocation?
when a piece of one chromosome snaps off and attaches to another (one way event)
75
what is reciprocal translocation?
when a piece of each chromosome snaps off and they basically swap.
76
what is a robertsonian translocation?
where two nonhomologous chromosomes fuse together resulting in the loss of one of the centromeres
77
describe adjacent 1 segregation. are the products viable? why?
when one of the normal chromosomes gets translocated with a segregated chromosome. products not viable bc we are missing genetic material.
78
describe alternate segregation. are the products viable? why?
segregation of the translocated chromosomes together and the normal chromosomes together. viable bc gene dosage is normal.
79
where do robertsonian translocations generally occur in humans? why are these tolerated?
chromosomes 13, 14, 15, 20, 21. their p arms are not very important so we can tolerate the loss of the p arm
80
why do translocations matter?
- leads to cancer (leukemia) - genomic instabilities

BIOL2500 (10 decks)

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