Cell cycle Flashcards
What must happen before cytokinesis (cell splitting)
Karyokinesis (nucleus splitting)
What are the stages of the cell cycle
Interphase
Mitosis
Cytokinesis
What are the phases of mitosis
Prophase
Metaphase
Anaphase
Telophase
What are phases of meiosis
Early prophase 1 Late prophase 1 Metaphase 1 Anaphase 1 Telophase 1 Prophase 2 Metaphase 2 Anaphase 2 Telophase 2
When do mutations occur in the cell cycle
S phase of interphase
What is a proto-onco gene
Genes that start the cell cycle
What is a tumour-suppressor gene
Slows the cell cycle
What are chiasmata
Points of contact between chromatids which, in meiosis, causes variation through crossing over as genes are transferred from one chromatid to another
In what phase of meiosis do chiasmata occur
Late prophase 1
What is independent assortment
In meiosis, during metaphase 1, the chromosomes line up randomly, allowing for a random separation of chromosomes, causing variation
What happens in prophase in mitosis
The chromosomes condense making them visible
What happens in metaphase in mitosis
The chromosomes line up on the equator of the spindle
What happens in anaphase in mitosis
The centromere splits so the chromatids separate and are pulled to either end of the cell along the spindle
What happens in telophase in mitosis
Nuclear membranes appear around each group of chromatids at either end of the cell. The spindle fibres fade away
What happens in early prophase 1 in meiosis
The chromosomes condense making them visible
What happens in late prophase 1 in meiosis
Homologous chromosomes come together, forming two bivalents. Crossover points occur and genes can be transferred to different chromatids
What happens in metaphase 1 in meiosis
The bivalents line up on the equator of the spindle
What happens in anaphase 1 in meiosis
Bivalents separate and homologous chromosomes are pulled to either end of the cells. The centromere does not break.
What happens in telophase 1 in meiosis
The chromosomes arrive at either end of the cell and a nuclear membrane forms around each group and the cell splits.
What happens in prophase 2 of meiosis
The centrioles form new spindles at right angles to the original spindles
What happens in metaphase 2 of meiosis
The chromosomes line up on the equators of the spindles
What happens in anaphase 2 of meiosis
The centromeres split so the chromatids separate and travel to either end of the cells along the spindle fibres
What happens in telophase 2 of meiosis
Nuclear membranes form around all four groups of chromatids and the cells divide, producing four genetically unique daughter cells
