3.2.2 Cell Cycle Flashcards
Do all cells retain the ability to divide?
No
What happens in interphase?
Gap 1
DNA synthesis
Gap 2
What is the prophase stage of mitosis?
- chromosomes become visible -> condense and become short and fat
- centrioles move the poles
- nuclear envelope breaks down
- nucleolus dissapears
- spindle fibres develop
What is metaphase in mitosis?
- the chromosomes line up along the equator
- the spindle fibres attach to the centromeres
What is anaphase in mitosis?
- the spindle fibres contract, pulling the centromere
- this causes the separation of each sister chromatid to opposite ends of the cell
What is telophase in mitosis?
- chromatids reach the opposite poles on the spindle
- they uncoil, becoming long and thin
- nuclear envelope forms around each group of chromosomes, there are now two nuclei
What is cytokinesis?
the division of the cytoplasm, creating two separate cells
Made by constriction from the edge of the cell
cell membrane forms a cleavage furrow that eventually pinches the cell into two parts, each part containing its own nucleus
What is binary fission?
4 steps
1) circular DNA and plasmids replicate
- the main DNA loop is only replicated once, however plasmids can replicate multiple times
2) cell gets bigger and DNA moves to either side
3) the cytoplasm begins to divide
4) cytoplasm divides and two daughter cells are produced
- each daughter cell has one copy of the circular DNA but can have a variable number of plasmid copies
How to viruses replicate?
viruses use their attachment proteins to bind to complementary receptor proteins on the surface of host cells.
they then inject their DNA or RNA into the host cell
the host cell then replicated the viral particles
What is a somatic cell?
A typical body cell with twice the number of chromosomes as the gamete
How do you calculate the mitotic index?
Mitotic cells
—————– X 100
Total cells
What happens in Gap 1?
- the cell grows and organelles and proteins are made
- cell carries out normal functions
What happens in Gap 2?
- cell keeps growing
- proteins needed for division are made
What happens in S1 (synthesis) in interphase?
-cell replicates it’s DNA
How is a tumour formed?
a tumour is formed is formed when there is uncontrollable replication/cell division
