changes to a chromosome number, dele-
chromosomal mutation or aberration
tion, addition, rearrangement
two types of deletions terminal and intercalary
deletion at the end terminal
deletion in the middle of a chromosome intercalary
deletion in chromosome 5 that causes
mental delays Cri du Chat Syndrome
deformed larynx and glottis
Which is more tolerated -- duplications or
duplications
deletions?
Genes are thought to be indispensable
and every gene does something. If a
gene is to get mutated then that would be
How can duplications within genes en-
negative...BUT if the gene is duplicated
hance evolution?
and THEN mutated and the mutation is
beneficial, then now this is advantageous
to the cell and could become a new gene
genes in multiple locations gene redundancy
ribosomes require a large amount of
rRNA bc they are constantly used in
Why is lots of rRNA advantageous? cells. There need to be a lot of copies of
rRNA so there is constant transcription of
these genes...gene redundancy
an uneven crossover event where homo-
How does a duplication usually happen?
logues don't split correctly
Large sequences of DNA are duplicated
very often and vary a to between individ- CNV - copy number variation
uals
can lead to things like autism, diabetes,
CONS to copy number variation
cancers
can be associated w protection from dis-
PROs to Copy number variation ease
- CCL3L1: protects from HIV
1/5
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- High EGFR is responsive to non small
cell lung cancer
translocation
two chromosomes exchange info. by
- at ends requires 2 breaks
breaking and coming together
- in middle required 4 breaks
duplication
deletion
types of aberrations and mutations
translocation
inversion
addition or loss of one autosomal chro-
aneuploidy
mosome
(2n-1)
- you are missing one chromosome from
a set of two
monosomy
- not really viable in humans
- possibly seen in X chromosome in ani-
mals
(2n + 1)
- addition of chromosome to a pair
trisomy
- smaller the chromosome, the more like-
ly organism is to survive
Results from NONDISJUNCTION dur-
Why does Trisomy 21 happen? ing meiosis I, when chromosomes don't
come apart (occurs in ovum)
- amniocentesis (amniotic fluid)
- chorionic villus sampling (placental
3 types of genetic testing chorion)
- noninvasive prenatal genetic screening
(maternal blood)
- 3 copies of chromosome 21
Types of causes of Trisomy 21 - familial
- mosaic of chromosome
Normal + balanced carrier
1 normal chromosome 21 and EXTRA familial trisomy 21
21 on chromosome 14
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