11. CHROMOSOMAL ABNORMALITIES Flashcards
(23 cards)
1
Q
- What do Large Scale Chromosomal Alterations often lead to?
A
- they often lead to spontaneous abortions and
miscarriages - they can also cause a variety of developmental disorders
2
Q
- What are the two types of Chromosomal Abnormalities?
A
- Chromosomal Abnormalities due to the Chromosome
Number - Chromosomal Abnormalities due to the Chromosome
Structure
3
Q
- Are most of the genes in our body linked or unlinked?
A
- most of the genes in our body are unlinked
4
Q
- What are the two types of Chromosomal Conditions caused by Chromosome Number?
A
- Aneuploidy
- Polyploidy
5
Q
- What is Aneuploidy?
A
- this is the presence of an abnormal chromosome
number - it is a condition in which the number of chromosomes
in a cell is NOT the exact multiple of the monoploid
number of a particular species - the cell does not have the correct diploid number of its
particular species
6
Q
- What causes Aneuploidy?
A
- it is caused by the nondisjunction of gametes
- this happened during the fertilisation of the gametes
7
Q
- What happens to the offspring who have aneuploidy?
A
- they have an abnormal number of a particular
chromosome - this makes their karyotype abnormal
8
Q
- Provide a definition for Nondisjunction.
A
- this is the abnormal separation of homologous
chromosome pairs - this happens during Meiosis I
IT CAN ALSO HAPPEN DURING MEIOSIS II:
- this would be caused by the abnormal separation of
the sister chromatids
9
Q
- What happens when Nondisjunction of the homologous chromosomes occurs during Meiosis I?
A
- one gamete will receive both of the homologous
chromosomes from a pair - the other gamete will receive none of the
chromosomes from a pair
(0 chromosomes)
10
Q
- What happens when Nondisjunction of the sister chromatids occurs during Meiosis II?
A
- this is the result of the absence of separation of the
sister chromatids during Meiosis II - this means that half of the gametes will have either 1
extra chromosome or have 1 less chromosome at the
end of Meiosis II - the other half of the gametes will have the normal
amount of chromosomes at the end of Meiosis II
11
Q
- What is a Monosomic Zygote?
A
- this is a zygote that has only 1 copy of a particular
chromosome
12
Q
- What is a Trisomic Zygote?
A
- this is a zygote that has 3 copies of a particular
chromosome
13
Q
- Does this diagram make sense?
A
- yes
14
Q
- Which kind of Nondisjunction results in more serious effects in the individual?
A
- Nondisjunction of the Homologous Chromosomes
during Meiosis I
15
Q
- What is Polyploidy?
A
- this is a condition in which an organism has more than
2 complete sets of chromosomes
16
Q
- Provide 2 examples of Polyploidy.
A
- TRIPLOIDY (3n):
- this is three sets of chromosomes
- TETRAPLOIDY (4n):
- this is four sets of chromosomes
17
Q
- In which species is Polyploidy common?
A
- Polyploidy is common in plants
- it is not common in animals
- it is more normal in its appearance than Aneuploidy
18
Q
- What are the 4 types of Chromosomal Abnormalities caused by alterations to the Chromosome Structure?
A
- Deletion
- Duplication
- Inversion
- Translocation
NB:
- all of these are caused by the breaking of the
chromosome
19
Q
- What is Deletion?
A
- this is the removal of a chromosomal segment
20
Q
- What is Duplication?
A
- this is the repetition of a chromosomal segment
21
Q
- What is Inversion?
A
- this is the reversal of the chromosome segment
- this happens within the chromosome
22
Q
- What is Translocation?
A
- this is the exchange of segments between non-
homologous chromosomes - it is the movement of a segment from one chromosome
to another
23
Q
- Does this image make sense?
A
- yes
