Mitosis Flashcards
What is the cell cycle?
an ordered series of events involving cell growth and division that produces two new daughter cells
What are the two major parts of the cell cycle?
interphase, mitotic phase
What is interphase in cell divison
phase of the cell cycle during which a eukaryotic cell grows, replicates its DNA, and prepares for cell division
What does interphase consist of?
Consists of G1 , S (synthesis), and G2
What is the longest part of the cell cycle?
interphase
What parts of cell division does interphase encompass?
the period between cell divisions, where the cell grows, carries out its normal functions, and replicates its DNA
What is the mitotic phase
also known as the M phase, is the phase of the cell cycle during which a eukaryotic cell divides into two identical daughter cells
What does the mitotic phase include?
includes mitosis (nuclear division) and cytokinesis (cytoplasmic division)
What is the name for nuclear divison and what step is it?
karyokinesis; the first step
What is karyokinesis?
Process by which duplicated chromosomes are sorted and separated to form two identical nuclei for daughter cells
What happens when G2 is complete?
the cell will enter mitosis
How many phases are in mitosis? What are they in order?
5 phases; Prophase, Pro-metaphase, Meta phase, Anaphase, Telophase (Cytokinesis)
What are the qualities of the phases in mitosis besides the metaphase and anaphase transition?
not discrete and happen as a continuous process
What is cytokinesis?
the final stage of the cell cycle during which the cytoplasm and organelles of a parent cell are divided into two identical daughter cells. (second part of mitotic phase)
Describe the G1 Phase (first gap)
- Change is not evident (“gap”) but the cell is biochemically active.
- S Phase is when DNA synthesis/replication occurs:
- Identical copies of the DNA molecules (sister chromatids) are joined at the centromere.
Describe the G2 Phase (second gap)
- Energy is replenished, organelles reproduce, and cytoskeleton breaks down.
What is the Mitotic Spindle?
- Microtubules and associated proteins
- Organizes chromosomes during mitosis
- Microtubules (spindle fibers) arise from centrosomes
What happens is the Mitotic Spindle?
- Kinetochore microtubules attach to chromosomes
- Polar microtubules attach to each other
Describe Prophase
- Nuclear envelope breaks down.
- Chromosomes condense and are now visible.
- Membranous organelles (e.g. Golgi complex, endoplasmic reticulum) disperse toward edges of the cell.
- The nucleolus disappears.
- Spindle fibers start to appear.
- Centrosomes begin migration to opposite poles
What happens in pro-metaphase?
- Sister chromatids develop a protein kinetochore in the centromere region which attaches the chromatids to the spindle microtubules.
- Centrosomes continue to move towards opposite poles.
- mitotic spindle microtubules from opposite poles attach to each sister chromatid at the kinetochore
What is the basic definition of Pro-metaphase?
Chromosome Attachment and Centrosome Movement
How is anaphase related to pro-metaphase?
In anaphase, the connection between the sister chromatids breaks down, and the microtubules pull the chromosomes toward opposite poles
What is the basic definition of metaphase?
Chromosome Alignment and Cohesion
What happens in metaphase?
- The mitotic spindle is fully developed, and centrosomes are at opposite poles.
- Chromosomes are aligned at the “equatorial plate” and each sister chromatid rests on one side of the plate, with spindle fibers attached to them.
- Sister chromatids remain attached by cohesion proteins.
What happens in chromosome alignment at the metaphase plate?
- The microtubule spindle has completed the alignment of chromosomes at the metaphase plate in preparation for the separation of sister chromatids during anaphase.
What is the basic definition of anaphase?
Sister Chromatid Separation and Cell Elongation
What happens in anaphase?
- Cohesion proteins degenerate allowing chromatids to separate.
- Sister chromatids move in opposite directions toward the centrosomes to which their microtubules are attached.
- Each chromatid is now a chromosome.
- The cell elongates.
- Shortest phase of mitosis
What is the basic definition of telophase?
Chromosome De-condensation and Nuclear Envelope Formation
What happens in telophase?
- Chromosomes reach opposite poles and begin to decondense (unravel).
- Spindles depolymerize into tubulin monomers that will form cytoskeletal components for the daughter cells.
- Nuclear envelopes form around the chromosomes, and nucleosomes appear within the nuclear area.
What is the relationship between cytokinesis in plants and animals?
They differ
How does cytokinesis happen in animal cells?
Animal cell cleavage: contraction of actin filaments by myosin pull the “equator” of the cell causing an invagination of the cell (a fissure called a cleavage furrow). The cleavage furrow gets continuously deeper until it eventually divides the cell into two new, independent daughter cells.
How does cytokinesis happen in plant cells?
Plant cell wall formation: a mixture of enzymes, proteins, and glucose molecules are transported via vesicles to the center of the cell. These vesicles continuously build upon each other known as ‘Cell plate’ until a completely new cell wall has emerged, and two new cells are formed, independent of one another.
