Mitosis Flashcards
What type of asexual cell division occurs in eukaryotes
Mitosis
What type of cell division occurs in prokaryotes
Binary fission
What type of cell division creates gametes
Meiosis
In prokaryotes what are the three categories of sexual reproduction cell division
Transformation, transduction, conjunction
What is transformation in prokaryotes
Takes up DNA found within environment from other prokaryotes
Transduction
Prokaryote is infected by virus which injects short pieces of chromosomal DNA from one bacterium to another
Conjugation
DNA is transferred between prokaryotes by a sex pilus
All DNA in a cell constitutes its
Genome
DNA molecules are packaged into
Chromosomes
When cell is not dividing the chromosome takes the form of a
Chromatin fiber
Chromosome DNA is wrapped around what
Proteins called histones
What are somatic cells
Non reproductive cells with two sets of chromosomes, formed by mitosis
What are gametic cells
Reproductive cells like sperm and eggs with half as many chromosomes, formed by meiosis
Each replicated chromosome has two what
Sister chromatids
Where are sister chromatids most closely attached
The centromere
Sister chromatids are held together with what
rings of proteins called cohesins
What are condensins
Protein rings along the length of chromosomes to compact chromosomes before cell division
What are the two phases of the cell cycle
Mitotic (M) phase
Interphase
The mitotic phase consists of
Mitosis and cytokinesis
Interphase consists of
G1 phase (first Gap)
S phase (synthesis)
G2 phase (second gap)
What is the Mitotic spindle
Apparatus of microtubules which controls the movement of chromosomes during mitosis
The mitotic spindle consists of
The centrosomes, spindle microtubules, and asters
The centrosome is
The organelle that serves as a microtubules organizing center (MTOC)
What are asters or astral microtubules
Short microtubules that go to the closest cell wall to the centrosome
What are the two main types of spindle microtubules
Kinetochore microtubules and Non-kinetochore microtubules
What does the kinetochore microtubules attach to
Sister chromatids on the kinetochore which is found at the centromere
What do non-kinetochore microtubules attach to
Other non kinetochore microtubules
What happens during G2 phase
Centrosomes are duplicated
What happens in S phase
DNA replicated
What happens in prophase
Nucleolus disappears and chromatin fibers form chromosomes, centrosomes begin to move away from each other
Prometaphase
Nuclear envelope breaks down and chromosomes completely condense, microtubules enter nuclear space and attach to chromosomes
What are the phases of mitosis
Prophase prometaphase metaphase anaphase telophase
Metaphase
Centrosomes fully at opposite ends, chromosomes are held in the middle of the cell on the metaphase (equatorial) plate, spindle apparatus complete
Anaphase
Chromosomes pulled apart and non-kinetochore grow to elongate cell
Telophase
Chromosomes decondense into chromatin, nucleolus and nuclear envelope reappear and spindle microtubules disappear.
Cytokinesis
In animal cells uses a cleavage furrow to separate the 2 daughter cells
In plant cells they use a cell plate
What seems to be the most important checkpoint in the cell cycle
G1 checkpoint
What happens if a cell does not succeed the G1 checkpoint
It enters G0 phase
What is the G2 checkpoint
Checkpoint after G1 and before the M checkpoint, checks if the chromosomes have replicated and the DNA is undamaged and MPF is present
What does the M phase checkpoint check for
Chromosomes have attached to spindle apparatus, chromosomes have properly segregated and MPF is absent
What does the G1 checkpoint look for
Cell size adequate
Nutrients are sufficient
Social signals are present
DNA undamaged
M-phase checkpoints occur between
Metaphase and anaphase, and anaphase and telophase
The two types of regulatory proteins involved in cell cycle are
Cyclins and cyclin-dependent kinases CDKs
Does cyclins or CDKs fluctuate during the cell cycle
Cyclin
What does MPF mean
Mitotic phase promoting factor
MPF is a
Cyclin-CDK complex
What is density dependent inhibition
An external signal which tells cells to stop dividing
What is anchorage dependence
An external signal which requires a cell to be attached to a substratum to divide
Does cancer exhibit density dependent inhibition or anchorage dependence
NAH
Cancer forms a
Tumor
If a tumor stays in one place it is a
Benign tumour
What does a malignant tumour do
Invades surrounding tissue and metastasizes
What internal signal occurs during the third checkpoint
Until all kinetochores are attached the anaphase-promoting complex is inactive. When everything is attached APC activates and breaks down securin which activates separase which degrades the cohesins which hold the sister chromatins together.
What activates APC
The attachment of all kinetochores
What does APC do
Breaks down securin
What does securin do
Keeps separase inactive until it is broken down
What does separase do
Degrades the cohesion proteins
