Cell division - mitosis Flashcards
what happens in mitosis?
parent cell divides into 2 genetically identical daughter cells
What is mitosis needed for?
Growth of multicellular organisms and repairing damaged tissue
Interphase
- cell carries out normal function
- DNA is unravelled and replicated
- number of organelles double
- ATP content is increased
Phase 1- Prophase
- chromosomes condense, get shorter and fatter
- bundles of protein called centrioles start to move to opposite ends, forming a network of spindle fibres
- nuclear envelope starts to break down
Phase 2 - Metaphase
•chromosomes line up and get attached to the spindles by the centromere
phase 3 - Anaphase
- centromeres divide, along with the chromatids
* spindles contract pulling the chromatids, with the centromeres first
phase 4-Telophase
- chromatids reach the opposite poles of the spindle, becoming long and thin again
- nuclear envelope forms again and this becomes the nuclei
- cytoplasm divides (cytokinesis)
- now 2 genetically identical daughter cells are made.
scientists finds 100 cells in mitosis, 10 are in metaphase, one complete cycle lasts about 15 hours. How long do the cells spend in metaphase?
1) 10/100th cells are in metaphase
2) cell cycle lasts around 15 hours. (15 x 60 = 900)
3) 10/100 (x900) = 90 minutes in metaphase.
What is cancer?
It is the result of uncontrolled cell division, a mutation in a gene can result in the cells growing out of control, cells keep dividing and form a tumour, CANCER IS A TUMOUR THAT INVADES SURROUNDING TISSUES
How do cancer treatments work?
control the rate of cell division, by disrupting the cell cycle
Why are cancer treatments effective despite harming body cells?
Tumour cells divide more frequently so the treatment is more likely to kill tumour cells than bodily cells.
How does cancer treatment effect the G1 phase(cell growth and protein production)?
some chemicals(chemotherapy) prevent the synthesis of enzymes required for DNA replication, without this the cell cant enter the synthesis phase(S), forcing the cell to kill .
How does cancer treatment affect the S (DNA replication) phase?
Radiation + other drugs cause damage to the DNA, at several points in the cell cycle the DNA is detected for damage, severe damage causes the cell to kill itself- preventing further tumour growth.
