What are the three reasons why cells divide to make identical copies of themselves?
asexual reproduction
growth and development
wound repair
What are the steps of binary fission?
circular chromosome attaches to the plasma membrane
the chromosome is duplicated
the cell grows and fibers for a contractile ring
fibers contract to pinch the cell into two
What is mitosis?
asexual reproduction that results in two identical cell s
What are the three primary stages of the eukaryotic cell cycle?
Interphase
Mitosis (M-phase)
Cytokinesis
What are the three stages of Interphase and their function?
G-1: first growth phase and is used to grow the cell and create more organelles for later division
S phase: chromosomes are duplicated or “synthesized”
G-2: second growth phase in order for last minute protein synthesis and a checkpoint
What were the 2 major steps in DNA replication?
unwind the parental strands
synthesize the new daughter strands
When chromosomes are duplicated in S-phase what do they create?
sister chromatids
What are sister chromatids connected at?
a centromere
What is the main function of mitosis?
to separate sister chromatids into their respective daughter cells
What are G0 cells?
cells that are not preparing for division
What are the stages of Mitosis?
prophase
prometaphase
metaphase
anaphase
telophase
cytokinesis
What occurs during prophase?
duplicated chromosomes begin moving to opposite poles
nuclear membrane and nucleolus both begin breaking down
centrosomes move to opposite poles
What occurs during Prometaphase?
the nuclear envelope is completely broken down
chromosomes are easily visible
centrosomes begin moving via spindle fibers
What does the mitotic spindle do?
organizes and separates the replicated chromosomes
What is the mitotic spindle comprised of?
Centrosomes (organize the spindle)
microtubules (form the spindle)
What are kinetichores?
regions of the centromere where microtubules attach to sister chromatids
Define Centromere
region that holds the sisters together
Define centrosome
where microtubules grow out of
Define chromosome
condensed DNA
What occurs during Metaphase?
sister chromatids are lined up at the equatorial plate
centrosomes are at the poles of the cell
What occurs during Anaphase?
sister chromatids are pulled apart at the centromere
How are sister chromatids pulled apart during Anaphase?
motor proteins move the daughter chromosomes toward the pole using ATP hydrolysis
the kinetochore microtubules are shortened towards the poles
What occurs during telophase?
cleavage furrow develops
nucleolus returns
nucelar envelopes reform
What occurs during cytokinesis of an animal cell?
the cleavage furrow creates a contractile ring which separates the two cells
What occurs during cytokinesis of a plant cell?
vesicles form a cell plate which separates into two new cells
Where are cell cycle checkpoints?
G1
G2
M
What is the role of cell cycle check points?
they detect errors in order to stop the cell cycle
How is the cell cycle regulated?
protein kinases (cyclin-dependent kinases). cyclin is accumulated throughout the cell cycle and is degraded during M phase. Cdk must be at a lower concentration for a cell to go back through the cycle
Does replication change the ploidy of a cell?
No it does not, chromosomes are duplicated and then split in half during cytokinesis.
What is the restriction point of the cell cycle?
The restriction point of the cell cycle is G1. If a cell moves past this stage they will go through the entire cell cycle. its the “point of no return”
What checked at the first check point in G1?
size, nutrients, molecular signals, and DNA integrity is checked to see if the cell is capable of division later on
What is checked at the second check point in G2?
DNA damage and DNA replication completeness in order to see if repairs are needed before division
What is checked at the third check point in M?
chromosome attachment to the spindle at metaphase in order to ensure that division goes smoothly