Cell Structure and Division- Mitosis Flashcards
What are the two types of cell division in eukaryotes?
Mitosis and meiosis
What happens in mitosis?
A parent cell divides to produce two genetically identical daughter cells
What is mitosis needed for?
Growth of multicellular organisms and repairing damaged tissues
What does the cell cycle consist of?
A period of cell growth and DNA replication called interphase, mitosis happens after this
What happens in G1?
Cell grows and new organelles and proteins are made
What happens in S?
Cell replicates its DNA
What happens in G2?
Cell keeps growing and proteins needed for cell division are made
What are the three growth stages in interphase?
G1, S and G2
What happens in interphase?
Cell’s DNA is unravelled and replicated, organelles are also replicated, ATP content is increased
What happens in prophase?
- Chromosomes condense and get shorter and fatter
- Centrioles start moving to opposite ends of cell
- Form spindle
- Nuclear envelope breaks down
What happens in metaphase?
- Chromosomes line up along equator of cell
- Attach to spindle by centromere
What happens in anaphase?
- Centromeres divide
- Each pair of sister chromatids separate
- Spindles contract
- Chromatids pulled to opposite poles of cell
- Chromosomes appear V-shaped
What happens in telophase?
- Chromosomes reach opposite poles on spindle
- Uncoil and become long and thin
- Nuclear envelope forms
- Division of cytoplasm (cytokinesis)
- Forms two daughter cells that are genetically identical
How can you calculate how long each stage of mitosis lasts?
eg. 100 cells undergoing mitosis, 10 in metaphase, one complete cell cycle= 15 hours, how long do cells spend in metaphase?
10/100th of cell cycle in metaphase
15 x 60= 900 minutes
10/100 x 900= 90 minutes in metaphase
What are mitosis and the cell cycle controlled by?
Genes
How can cells grow out of control?
If there’s a mutation in a gene that controls cell division
How is a tumour formed?
Cells keep on dividing to make more and more cells
What is cancer?
A tumour that invade surrounding tissue
What are treatments for cancer designed to do?
Control the rate of cell division in tumour cells by disrupting the cells cycle which kills the tumour cells
What is the problem with cancer treatments?
They don’t distinguish tumour cells from normal cells so they also kill normal body cells that are dividing
Why would cancer treatments target G1?
This would prevent the synthesis of enzymes needed for DNA replication and if these aren’t produced the cell can’t enter the S phase so the cell cycle is disrupted which forces the cell to kill itself
Why would cancer treatments target the S phase?
This is the stage of DNA replication and the cell is checked for damage so if severe damage is detected then the cell will kill itself and prevent further tumour growth
