During the
prophase
of mitosis, the chromatin in a cell compacts to form condensed chromosomes; this condensation is required in order for the cell to divide properly. … PCC results when an interphase cell fuses with a mitotic cell, causing the interphase cell to produce condensed chromosomes prematurely.
What causes chromosomes to condense?
Chromatin condensation is
driven by condensins and interactions between histones
. Chromatin decondensation requires the ATPases p97 and RuvBL1/2. During eukaryotic cell division, nuclear chromatin undergoes marked changes with respect to shape and degree of compaction.
What is the process of chromosome condensation?
Chromosome condensation is the dramatic reorganisation of the long thin chromatin strands into compact short chromosomes that occurs in
mitosis and meiosis
.
What proteins are involved in chromosome condensation?
It is possible that a combination of histone modifications promotes mitotic chromatin condensation (see Fig. 8.3). Two pentameric protein complexes,
condensin I and condensin II
are major regulators of mitotic chromosome architecture.
Why do chromosomes condense during mitosis?
Condensation of chromatin into sturdy chromosomes is also
necessary to establish proper physical properties
. Chromosomes must be stiff, resilient, and elastic enough to withstand forces coming from pulling microtubules and cytoplasmic drags during mitosis to prevent damage and breaks caused by external tensions.
Why do chromosomes condense before dividing?
Chromosome Condensation
This condensation is needed
to allow the chromosomes to move along the mitotic spindle without becoming tangled or broken during their distribution to daughter cells
. DNA in this highly condensed state can no longer be transcribed, so all RNA synthesis stops during mitosis.
Do chromosomes condense in mitosis?
Mitosis is the process of nuclear division, which occurs just prior to cell division, or cytokinesis. During this multistep process,
cell chromosomes condense
and the spindle assembles. … Each set of chromosomes is then surrounded by a nuclear membrane, and the parent cell splits into two complete daughter cells.
What happens if chromosomes fail to condense?
Chromosome segregation errors result
in aneuploid or polyploid cells
and are generally detrimental to both the cell and the organism. However, in some instances, changes in ploidy are programmed in normal development and physiology.
What is initiation of condensation of chromosomal material?
During interphase (1), chromatin is in its least condensed state and appears loosely distributed throughout the nucleus. Chromatin condensation begins
during prophase (2)
and chromosomes become visible. Chromosomes remain condensed throughout the various stages of mitosis (2-5).
What is the meaning of initiation of condensation of chromosomal material?
The cell division in somatic cells is known as mitosis which takes place in five different stages. After the interphase, during prophase, the
chromatin network
thickens and condenses and the chromosomes are visible as thickened threads pairs connected at the centromere.
What happens with more than 46 chromosomes?
A gain or loss in the number of chromosomes from the normal 46 is called aneuploidy. A common form of aneuploidy is
trisomy
, or the presence of an extra chromosome in cells. “Tri-” is Greek for “three”; people with trisomy have three copies of a particular chromosome in cells instead of the normal two copies.
What are chromosomes made up?
A chromosome is made up of
proteins and DNA organized into genes
. Each cell normally contains 23 pairs of chromosomes.
What phase is chromatin present?
S Phase
(Synthesis of DNA)
Throughout interphase, nuclear DNA remains in a semi-condensed chromatin configuration. In the S phase, DNA replication results in the formation of identical pairs of DNA molecules, sister chromatids, that are firmly attached to the centromeric region.
How many chromosomes do humans have?
In humans, each cell normally contains 23 pairs of chromosomes, for a
total of 46
. Twenty-two of these pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females.
Why do chromosomes condense during mitosis quizlet?
Why do chromosomes condense during mitosis?
Chromosomes condense in order to make chromosomes which consists of sister chromatids
.
Does chromatin condense during meiosis?
We found that, in the stationary phase, cells that undergo meiotic division have
condensed chromosomes prior
to the meiotic prophase.
