CSF (Cell Division & Cancer) Flashcards
G1 name and description
Growth or Gap Phase 1
Cellular activities. Duration depends on the cell.
S name and description
Synthesis of DNA
DNA replication with DNA poly. Each new strand is the opposite of the old strand.
G2 Name and description
Growth or gap phase 2
Checks that DNA synthesis is ok. Prepares mitotic phase (gathers proteins, enzymes, reactants). Replication of centrosomes.
G0 description
Non-dividing cell. Most nerve cells.
Interphase
DNA replicates.
Chromatin.
Phophase
DNA condensed further into 2 identical chromatids per chromosome, called sister chromatids. Spindles form. Nuclear envelope disappears.
Cyclin
G2
A protein that fluctuates throughout the cell cycle.
Cdk
G2
Cyclin dependent kinase. A kinase that is activated when attached to a cyclin.
MPF
A cyclin / Cdk complex which is the key for the G2 checkpoint. Phosphorylation many other proteins, allowing mitosis to commence.
What signals are required to pass the G1 checkpoint?
Is DNA undamaged? Is cell size and nutrition ok? Appropriate signals present?
If not, may exit to G0.
What 2 types of changes are responsible for DNA changes?
Acquired changes (effects specific cells). Inherited changes (effects all cells).
How does a tumor suppressor gene cause a tumor?
Deactivated = loss of brakes. Creates a defective non-functioning protein instead of a normal growth-inhibiting protein. Causes uncontrolled cell decision and growth.
How does a proto-oncogene cause cancer?
If it mutates, it’s becomes an oncogene which produces a hyperactive growth-stimulating protein.
If multiple copies of the gene, or new promotor, produces: growth-stimulating protein in excess.
Meiosis 1 Prophase 1
Synapsis: 2 sister chromatids of each pair of homologous chromosomes join. The 4 chromatids are called a tetrad.
Tetrads form. Recombination (non sister chromatids with these tetrads can cross over.)
Meiosis 1 Metaphase 1
Pairs of homologous chromosomes lines up. Kinetochore microtubules at centromeres. Metaphase plate at the bottom.
