lecture 13 Flashcards
what is a karyotype
An ordered, visual representation of the
chromosomes in a cell.
During what phase of mitosis are sister chromatids separated from one another?
anaphase
During what phase dose the mitotic spindle form?
prophase
During what phase do the replicated chromosomes line up along the metaphase
plate?
metaphase
Describe the end of G2 phase, as a precursor to Prophase
Chomosomes are replicated but uncondensed, two centrosomes are made from the one
describe prophase
Chromosomes condense, each chromosome is two chromatids.
The aster around the centrosome begins to form, the star shape thingy
Spindle fibres begin to form as the centrosomes move to the poles of the cell.
describe prometaphase
Nuclear envelope disintegrates
Centrosomes move to opposite poles of the cell
The spindle fibre microtubules continue to grow
These kinetochores connect the microtubule fibres to the centromere
In this phase non-kinetochore microtubules connect to each other
what makes kinetochores
Kinetochore proteins make a structure the kinetochore on the chromosomes
what type of microtubules touch the chromatids
, these spindle fibres that touch the kinetochore on the chromosomes are called kinetochore tubules
whats a non-kinetochore microtubule
, the spindle fibres that touch the kinetochore on the chromosomes are called kinetochore tubules
describe metaphase:
All pairs of sister chromatids line up at the metaphase plate, they may not be correctly oriented but the centromere of the sister chromatids are on the line exactly.
Centrosomes at this point have moved to opposite poles of the cell.
describe anaphase
Kinetochore microtubules lose tubulin subnits making the microtubules shrink, pulling the chromosomes toward the cell poles.
The sister chromatids are separated by this
The non-kinetochores get longer pushing the cells apart
describe telophase and cytokinesis
The spindle disappears and the nucleus starts to reappear
The clevage furrow forms between the two daughter cells
Cytokinesis occurs when the cells split at this line of clevage furrow. The furrow is made of a belt of actin microfilaments surrounding inside of cells circumference
describe the process to make the karyotype
take a blood sample, treat the sample with mitogen, then treat the sample with colchicine
define homologous chromosomes
a pair of the same chromosomes, one mum and one dad.
Each homologous chromosome is made of two strands, these are sister chromatids. The sister chromatids are attached at the centromere, the sister chromatids are identical to each other.
