Mitosis and Cell Cycle Flashcards
Why do Multiorganisms depend on cell division
Growth (development from an embryo into an adult)
Renewal (cells die naturally and need to be replaced)
Repair (cell are destroyed and need to need to be replaced)
What is binary fission
prokaryotes reproduce by a type of cell division (asexual)
How does binary fission work
the chromosome replicates at the ori and the two daughter chromosomes actively move apart
What is the genome in a prokaryotes
A single DNA molecule
What is the genome in a eukaryotic
Multiple DNA molecules
What are the 2 main events of the cell cycle
Mitotic (M) phase: consisting of mitosis and cytokinesis
Interphase (cell growth, copying of DNA on chromosomes, synthesizing proteins and new organelles in preparation for cell division)
What are the phases of interphase
G1,S,G2
What is G1
cells undergo major portion of growth
What is S phase?
it replicates DNA
What is the G2 phase?
chromosomes coil more tightly using motor proteins, centrioles replicate
How do chromatids stay attached?
at the centromere by cohesion proteins
What are the phases of mitosis
prophase, prometaphase, metaphase, anaphase, telophase
What is the purpose of the mitotic spindle?
It physically separates the chromosomes during mitosis
What happens during prophase?
The chromosomes condense and become visible
the spindle apparatus assembles (asters assemble)
the nuclear envelope breaks down
The golgi and ER are dispersed
What is an aster
a radial array of microtubules in animals (not in plants)
What happens in prometaphase
Occurs after nuclear envelope disassembles
The chromosomes are attached to microtubules at the kinetochore and move to the equator of the cell via motor proteins at the kinetochores
How are the chromosomes connected to microtubules?
Each sister chromatid must be connected to microtubules from opposite poles at their kinetochores
What is metaphase
The chromosomes align along the metaphase plate and are under tension from the microtubule attachment from opposite poles
What does the mitotic spindle include
Centrosomes, Spindle, Microtubules, and asters
What is anaphase
the centromeres are spilt and pulled apart with the removal of cohesion proteins from all chromosomes
the sister chromatids are pulled to opposite poles
what are the two movements of anaphase
Anaphase A and Anaphase B
What is anaphase A
kinetochores are pulled toward poles
what is anaphase B
poles move apart and the spindle lengthens
What is telophase
the spindle apparatus disassembles, the nuclear envelope forms around each set of sister chromatids
chromosomes decondense
a nucleolus reappears in each nucleus
Golgi complex and ER reform
What are the sister chromatids called when the nuclear envelope reforms during telophase
chromosomes
when does the nuclear envelope disassemble and reform
prophase and telophase
When does cytokinesis occur
it overlaps with telophase
it cleaves the cell into two
how does cytokinesis occur in animals
constriction of actin filaments produces a cleavage furrow
how does cytokinesis occur in plants
a cell plate forms between the nuclei
how does cytokinesis occur in fungi and protists
the nuclear membrane does not dissolve and mitosis rather occurs in the nucleus, the division of the nucleus occurs with cytokinesis
What are the irreversible points of the cell cycle
replication of genetic material
separation of the sister chromatids
What are the three check points for cell division
G1/S checkpoint, G2/M checkpoint, Late metaphase (spindle checkpoint)
G1/S checkpoint
The cell decides whether or not to divide
most important signal, primary point for influence of external signal
What is the G2/M checkpoimt
the Cell commits to mitosis and assesses accuracy of DNA replication
What is the late metaphase (spindle) checkpoint?
the cell ensures that all chromosomes are attached to the mitotic spindle
Which checkpoint is the most important
G1, usually a cell will complete S, G2, and M phases if it recieves the go ahead signal at G1
What happens if a cell does not receive a go-ahead signal at the G1 phase?
It exits the cycle and switches to a nondividing state called the G0 phase
What is G1
It is cell growth and the synthesis of new organelles and the cytoskeleton
what is the order of the cell cycle
Interphase: G1, S, G2
Mitosis +Cytokinesis
what is the S phase
DNA replication
what is a chromatid
it is one of the identical halves of a duplicated chromosome created in DNA replication
G2 Phase
cell growth, chromosomes condense more,centrosomes replicate, and microtubulin synthesis occurs
Centrosome
structure of cell division and the mitotic spindle, it moves to polar ends during prophase
organizes microtubules
Sister chromatid
One of the duplicated chromosomes attached by cohesion proteins
Interphase
involved in cell growth, copying of DNA, synthesizing proteins, and creating new organelles in preparation for cell division
Mitosis
division of a genome, divided into 5 phases
Mitotic (M) phase:
consisting of mitosis and cytokinesis
