The cell cycle Flashcards
(26 cards)
What is the M phase?
- mitosis
- cytokinesis
What is the S phase?
DNA replication
What is the G2 interphase?
- chromosomes condense
- nuclear envelope dissolves
- centrosomes replicate
What occurs during prophase?
- chromosomes fully condense
- spindle forms
What occurs during prometaphase?
chromosomes attach to spindle
What occurs during metaphase?
chromosomes align at equator
What occurs during anaphase?
- spindle contracts
- chromatids separate
What occurs during telophase and cytokinises?
- chromosomes reach poles of cells
- nucleus reforms
- cleavage furrow
What is the purpose of cohesion?
- joins chromosomes
- forms a multi subunit protein
- forms a loop between subunits - dimer loop
- multi subunit dimerises
- dimers loop around DNA, securing loops
- DNA loops through neck of the ring
What are structural maintenance of chromosomes (SMC) complexes?
- coordinated activity of cohesion and condensin enables chromatids to condense into fibres and looped domains
- cohesion and condensin are both descended from same bacterial protein and work together
What is the spindle?
- microtubules form a network, connecting poles of the cell with each other and cell membrane
- binds to chromosomes
- facilitates chromosome movement
- microtubules produced by centrioles
- 2 centrioles in a chromosome
Describe spindle interactions
- 3 sets of microtubules in the spindle
- bind to plasma membrane to fix spindle in place
- affix to chromosome
- affix to other microtubules in the spindle
What forms mitotic spindles?
polymerised tubulin molecules
How does the spindle interact with itself?
dynein - attaches astral microtubules to the plasma membrane
kinesin-14 - tightens the spindle
kinesin-5 - expands the spindle
kinesin-4-10 - moves the chromosomes to the poles of the microtubules
What is the centromere?
- the single point at which chromatids are joined together
- dense, tightly structured DNA
- devoid of genes
- structural condensed DNA
What is the kinetochore?
- attachment of the spindle
- consists of several proteins
3 layers: - collar - attaches to spindle
- outer - structural
- inner - binds to DNA
What is the purpose of separase?
allows chromatids to separate
What is meant by totipotent/omnipotent?
can differentiate into anything, zygote/very early embryo cells
What is meant by pluripotent?
can differentiate into most cell types
what is meant by multipotent?
can differentiate into specific related cell types
what is meant by oligopotent?
can differentiate into a few cell types
what is meant by unipotent?
specialised for only one cell type
What is the purpose of stem cell niches?
- specific locations that regulate participation in tissue generation, maintenance and repair
- protects stem cells
- restricts ‘over-active’ stem cells from proliferating across organism
- maintained by genetic and physiological cues
List the somatic stem cell types
adult –> bone marrow, mostly multipotent
foetal –> early differentiating organs, umbilical cord tissue
amniotic –> free-floating in amniotic fluid
