L5 - L6 Morphology of chromosomes and Karyotyping Flashcards
chromosomes
rod shaped
filamentous bodies present
carriers of the gene or unit of heredity
not visible in active nucleus due to high water content.
Chromosome size
interphase - longest/ thinnest
prophase- decrease in length and increase thickness
anaphase- smallest chromosomes
metaphase- very thick / shortt
which phase is measurement usually taken
metaphase
identifying chromosomes
size/ shape/ banding patterns
karyotypes
standard arrangement of chromosome pairs in order of decreasing length.
chromosome classification
metacentric
submetacentric
acrocentric
metacentric
both arms are of equal length
submetacentric
one arm is longer than the other
acrocentric
centromere close to one end
euchromatin
dark stained regions/ less gene/ active region
heterochromatin
light stained region/ more gene
constitutive heterochromatin
the chromosome remains in the heterochromatin
eg- skin/ can not be turned on or off
facultative heterochromatin
can develop characteristics of heterochromatin during some phase of development.
centromere
required for segregation of the chromatids during meiosis and mitosis.
telomere
provide terminal stability to the chromosome and ensure its survival.
To maintain integrity and stability
telomeric repeat TTAGGG
At birth there are 8000 repeats but during the growth stage the repeats are cut short to 20-200.
