2A Mitosis Flashcards
What is mitosis?
> the DIVISION 1 parent cell divides to produce 2 GENETICALLY IDENTICAL daughter cells
What are the 2 key reasons that mitosis is required in organisms?
> growth
> repairing damaged tissue
Describe the 4 stages of the cell cycle.
1) Mitosis
2) G1 - cell GROWS and new ORGANELLES and PROTEINS are MADE
3) S - DNA REPLICATES in preparation for cell division
4) G2 - Cell continues to GROW and produces PROTEINS that are required for the DIVISION of the cell
Which stages of the cell cycle occupy interphase?
G1, S and G2
What 3 things happen during interphase?
> DNA is UNRAVELLED and REPLICATED which doubles the genetic content
Organelles are REPLICATED
ATP CONTENT INCREASED - provides the ENERGY needed for cell division
What are the 4 stages of mitosis?
Prophase, metaphase, anaphase, telophase
What happens during prophase?
> Chromosomes CONDENSE and protein bundles called CENTRIOLES move to OPPOSITE POLES of the cell
Centrioles then produce a NETWORK OF FIBRES called SPINDLE FIBRES
The NUCLEAR MEMBRANE DISINTERGRATES
What happens during metaphase?
> Chromosomes line the EQUATOR of the cell and become ATTACHED to the spindle by their CENTROMERES
What happens during Anaphase?
> CENTROMERE DIVIDE - separates chromosomes into SISTER CHROMATIDS
SPINDLES CONTRACT and chromatid pairs are pulled to OPPOSITE POLES of the cell, centromeres first (making the chromosomes appear V-SHAPED)
What happens during telophase?
> Chromatids REACH OPPOSITE POLES of the cell on the spindle and UNCOIL to become LONG and THIN again (they are now referred to as CHROMOSOMES again)
NUCLEAR ENVELOPES form around each GROUP of chromosomes so there are now TWO NUCLEI
CYTOPLASM DIVIDES to form two GENETICALLY IDENTICAL DAUGHTER CELLS to the original cell and each other
INTERPHASE then begins in each of the newly formed cells
What is cancer?
> UNCONTROLLABLE CELL DIVISION caused by a gene MUTATION which forms a tumour
Cancer is a TUMOUR that INVADES surrounding tissue
Describe how cancer treatments work.
> They can control the RATE of CELL DIVISION in tumour cells by DISRUPTIONG the cell cycle
However, they CAN’T DISTINGUISH between cancerous and healthy cells so can KILL HEALTHY BODY CELLS too
However, tumour cells divide MORE QUICKLY than normal cells so treaments are more likely to kill these
In what stage of the cell cycle does all the DNA unravel?
Interphase
What is cytokinesis?
Division of the CELL CYTOPLASM
