Cell Division Flashcards
To understand how cells divide and the different types of cell division
What is mitosis?
Mitosis is cell division that produces genetically identical cells.
What is mitosis needed for?
Mitosis is needed for growth of multicellular organisms and for repairing damaged tissues.
What are the stages of the cell cycle?
Mitosis- cycle starts and ends here
Gap Phase 1- cell grows and new organelles and proteins are made.
Synthesis- cell replicates its DNA, ready to divide by mitosis.
Gap Phase 2- cell keeps growing and proteins needed for cell division are made
What are the four stages of mitosis?
Interphase
Prophase
Metaphase
Anaphase
Telophase + cytokinesis
What happens during interphase?
The cell carries out normal functions, but also prepares to divide
Cell’s DNA is unravelled and replicated, to double its genetic content. The organelles are also replicated and its ATP content is increased.
What happens during prophase?
Chromosomes condense, getting shorter and fatter.
Tiny bundles of protein called centrioles start moving yo opposite ends of the cell, forming a network of protein fibres across it called a spindle
The nuclear envelope breaks down and chromosomes lie free in cytoplasm.
What happens during metaphase?
The chromosomes =, each with 2 chromatids, line up along the middle of the cell and become attached to the spindle by their centromeres.
What happens during anaphase?
The centromeres divide, separating each pair of sister chromatids. The spindles contract, pulling chromatids to opposite poles of the spindle
Makes chromatids appear v shaped.
What happens during telophase?
Chromatids reach opposite poles on the spindle. They uncoil and become long and thin again. They’re now called chromosomes again.
A nuclear envelope forms around each group of chromosomes, so there are now two nuclei.
Cytokinesis- division of the cytoplasm
Two daughter cells that are genetically identical.
What is cancer?
If there’s a mutation in the gene that controls cell division, the cells can grow out of control. The cells keep on dividing to make more and more cells, which form a tumor.
Cancer is a tumor that invades surrounding tissue.
What do some cancer treatments do?
Some chemical drugs (chemotherapy) prevent the synthesis of enzymes needed for DNA replication. If these aren’t produced, the cell is unable to enter the synthesis phase, forcing the cell to kill itself.
Radiation and some drugs damage DNA. Just before and during the S phase, DNA in the cell is checked for damage. If severe damage is detected, the cell will kill itself, preventing further tumor growth.
How do you calculate the mitotic index?
Mitotic index=
number of cells with visible chromosomes / total number of cells observed.
