Karyotypes & Chromosome Mutations
Look at the karyotype for the mutation
A karyotype is an organized profile of a person's chromosomes. In a karyotype, chromosomes are arranged and numbered by size, from largest to smallest.
Karyotypes are done by doctors to diagnose some genetic disorders
A normal human karyotype has 46 chromosomes (23 pairs): #1-22 are called autosomes #23 are called sex chromosomes
XX~ female XY~ male
RECALL…What is a mutation? Any mistake or change in DNA sequence Mutations can only be inherited if they occur in sex cells Two types: Gene or chromosomal
Chromosomal mutation: affects whole or part of a chromosome Gene mutation: Changes to the bases in the DNA of ONE gene
Chromosomal Mutations Change in # of chromosomes OR structure of the chromosome Abnormality detected on karyotype Five types
Can YOU spot the chromosomal mutation??
1) Deletion Loss of all or part of a chromosome
2) Duplication Produce extra copies of parts of a chromosome.
3) Inversion Part of a chromosome breaks out and reinserts backwards.
4) Translocation Part of a chromosome breaks off & attaches to another chromosome
5) Nondisjunction Improper separation of homologous chromosomes during meiosis Results in extra or missing chromosomes in gametes
Remember—normally have 2 copies of each Types of Nondisjunction Trisomy~ 3 copies of a chromosome Monosomy~ 1 copy of a chromosome Remember—normally have 2 copies of each
Can you spot the mutation?
Down Syndrome – Trisomy 21 Intellectual and developmental disabilities may have heart defects and respiratory problems
Look at the karyotype for the mutation
Trisomy on Sex Chromosomes XYY Syndrome – Extra Y XXX Syndrome – Triple X
What is the mutation? Boy or Girl?
Trisomy 13 (Patau syndrome) Extra fingers or toes Cleft lip or palate (deformed lips) Heart and brain structure problems Die within 1-2 years of age
What is the mutation? Boy or Girl?
Turner’s Syndrome 45,X Webbed neck Infertile Swollen hands & feet at birth Heart defects
Chromosomal Mutations Videos Visualizing Nondisjunction