Where do microtubules attach to chromosomes?
Centrioles begin moving to opposite ends of the cell, and microtubules extend from the centrioles and begin to attach to the centromeres of chromosomes . Eventually, the microtubules extending from centrioles on opposite poles of the cell attach to every centromere and develop into spindle fibers.
Which of the following microtubules are attached to chromosomes?
Mitosis and the Cell Cycle
|Region where identical DNA molecules are most tightly attached to each other||centromere|
|Microtubules attach to chromosomes at _______||kinetochore|
|most of cell’s growth occurs here||interphase|
|cell structure consisting of microtubules that forms during early mitosis||mitotic spindle|
Where are chromosomes attached during cell division?
During metaphase, the cell’s chromosomes align themselves in the middle of the cell through a type of cellular “tug of war.” The chromosomes , which have been replicated and remain joined at a central point called the centromere, are called sister chromatids.
Which type of microtubules attach to and separate the chromosomes during cell division?
Kinetochore microtubules attach the chromosomes to the spindle pole; interpolar microtubules extend from the spindle pole across the equator, almost to the opposite spindle pole; and astral microtubules extend from the spindle pole to the cell membrane.
How do microtubules attach to kinetochores?
In prometaphase, kinetochores appear at the centromeres and mitotic spindle microtubules attach to kinetochores . In metaphase, chromosomes are lined up and each sister chromatid is attached to a spindle fiber. In anaphase, sister chromatids (now called chromosomes) are pulled toward opposite poles.
Are microtubules and spindle fibers the same?
They are the same thing. As the others have written, microtubules are a “track” that can move organelles around when “motor” proteins (that cleave ATP) pull those organelles. The spindle is what moves the chromosomes during mitosis and meiosis. Spindle fibers are used in cell division, and are made of microtubules .
What happens to chromosomes in mitosis?
During mitosis , the chromosomes , which have already duplicated, condense and attach to spindle fibers that pull one copy of each chromosome to opposite sides of the cell. The result is two genetically identical daughter nuclei.
What is the relationship between chromatin and chromosomes?
As mentioned above, chromatin is composed of DNA and histones that are packaged into thin, stringy fibers. The chromatin undergoes further condensation to form the chromosome . So the chromatin is a lower order of DNA organization, while chromosomes are the higher order of DNA organization.
Are the organizing centers for microtubules?
The centrosome, also referred to as the microtubule organizing center (MTOC), is an organelle that regulates the cell cycle via assembly of microtubules . Specifically, spindle assembly is controlled by the centrosome. Each cell has a single centrosome that is copied, or duplicated, during S phase.
What can happen if cells do not duplicate correctly?
If a cell has not properly copied its chromosomes or there is damage to the DNA, the CDK will not activate the S phase cyclin and the cell will not progress to the G2 phase. The cell will remain in S phase until the chromosomes are properly copied, or the cell will undergo programmed cell death.
What is the role of chromosome in cell division?
The fundamental importance of chromosomes is that they contain DNA, or deoxyribonucleic acid, the substance that contains every organism’s genetic code. When a cell divides, its chromosomes must first replicate. Cells divide in two basic ways – mitosis and meiosis. The latter type of division incorporates the former.
What does it mean when two sets of chromosomes are homologous?
The two chromosomes in a homologous pair are very similar to one another and have the same size and shape. Most importantly, they carry the same type of genetic information: that is, they have the same genes in the same locations. However, they don’t necessarily have the same versions of genes.
What are the two main stages of cell division?
The mitotic phase of the cell cycle in an eukaryotic cell occurs in two major steps: mitosis, when the nucleus divides; and cytokinesis , when the cytoplasm divides and two daughter cells form.
How do dividing cells distribute chromosomes to daughter cells?
Daughter chromosomes result from the separation of sister chromatids occuring in anaphase of mitosis and anaphase II of meiosis. Sister chromatids are eventually separated during the division process and equally distributed among newly formed daughter cells . Each separated chromatid is known as a daughter chromosome .
What is it called when chromosomes appear?
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).