Cell Division - Mitosis Flashcards
What are the two types of cell division in eukaryotes?
- Mitosis
2. Meiosis
In mitosis, the parent cell divides to produce what?
Two genetically identical daughter cells
Why is mitosis needed?
Mitosis is needed got the growth of multicellular organism and for repairing damaged tissue
What is the cell cycle
The cell cycle consists of a period of cell growth and DNA replication called interphase. Mitosis happens after that. Interphase can be divided into three separate growth stages - G1, S and G2
Explain the 4 stages of the cell cycle
- Mitosis - the cycle starts and ends here
- G1 (gap phase 1) - cell grows and new organelles and proteins are made
- Synthesis - cell replicates its DNA, ready to divide by mitosis
- G2 (gap phase 2) - cell keeps growing and proteins needed for cell division are made
What are the four stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telephase
Describe interphase
The cell carries out normal functions, but also prepares to divide. The cell’s DNA is unravelled and replicated, to double its genetic content. The organelles are also replicated so it has spare ones, and its ATP content is increased (ATP provides the energy needed for cell division)
Describe prophase
The chromosomes condense, getting shorter and fatter. Tiny bundles of protein called centrioles start moving to opposite poles of the cell, forming a network of protein fibres called the spindle. The nuclear envelope breaks down and chromosomes lie free in the cytoplasm
Describe metaphase
The chromosome (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere
Describe anaphase
The centromeres divide, separating each pair of sister chromatids. The spindles contract, pulling chromatids to opposite poles of the spindle, centromere first. This makes the chromatids appear v-shaped
Describe telophase
The chromatids reach the opposite poles on the spindle. They uncoil and become long and thin again. They’re now called chromosomes, so there are now two nuclei. The cytoplasm divides - cytokinesis. There are now two daughter cells that are genetically identical tot he original cell and each other. Mitosis is finished and each daughter cell starts the interphase part of the cell cycle to get ready for the next round go mitosis
Describe the chromosomes at the beginning and end of mitosis
As mitosis begins, the chromosomes are made of two strands joined in the middle by a centromere. The separate strands are called chromatids. There are two strands because each chromosome has already made an identical copy of itself during interphase. When mitosis is over, the chromatids end up as one-strand chromosomes int he daughter cells
What are mitosis and the cell cycle controlled by?
Genes
What happens to cells if there is a mutation in the gene?
Normally, when cells have divided enough times to make enough new cells, they stop. If there is a mutation in the gene that controls cell division, the cells can grow out of control. The cells keep on dividing which forms a tumour. Cancer is a tumour which invades surrounding tissue
What are some treatments for cancer designed to control?
They are designed to control the rate of cell division in tumour cells by disrupting the cell cycle. This kills the tumour cells