Topic 2 -14 Flashcards
(16 cards)
What are chromosome mutations?
Changes in the structure or number of chromosomes
What is translocation in the context of chromosome structure?
Genes break off one chromosome and join onto another
What is non-disjunction?
Failure of homologous chromosomes or sister chromatids to separate during anaphase
What can result from non-disjunction during gamete formation?
Gametes may have an extra chromosome or none at all
What is trisomy?
A form of polysomy where there is one extra chromosome
What is monosomy?
A condition where there is one chromosome missing
What is Down’s syndrome?
A condition caused by trisomy of chromosome 21 affecting mental and physical development
What is the incidence rate of Down’s syndrome?
Occurs in about 1 in every 1000 babies born
How does maternal age affect the incidence of Down’s syndrome?
The frequency increases with the increasing age of the mother
What is Turner’s syndrome?
A condition in females with a missing X chromosome (XO) leading to infertility
What is a karyotype?
A micrograph showing all the chromosomes in an organism in their pairs
How many chromosomes do human cells have?
46 chromosomes in 23 pairs
True or False: Chromosome mutations are common events.
False
Fill in the blank: Non-disjunction at anaphase I gives rise to a gamete with an extra chromosome, one with a chromosome missing, and _______.
two normal gametes
What does the presence of an extra chromosome 21 indicate in a zygote?
It indicates Down’s syndrome
What are the consequences of Turner’s syndrome?
Females are infertile and do not mature without sex hormone treatment
