The Cell Cycle Flashcards
What is the cell cycle?
The process that all body cells in multicellular organisms use to grow and divide.
What are the checkpoints in the cell cycle?
Metaphase checkpoint (M PHASE)
G1 checkpoint (GAP PHASE 1)
S checkpoint (SYNTHESIS)
G2 checkpoint (GAP PHASE 2).
What happens at the M PHASE?
Mitosis and Cytokinesis.
What happens at the GAP PHASE 1?
The cell grows and new organelles and proteins are made.
What happens at the Synthesis?
The cell replicates it’s DNA, ready to divide by mitosis.
What happens at GAP PHASE 2?
The cell keeps growing and proteins needed for cell division are made.
What happens at the G1 Checkpoint?
The cell check that the chemical needed for replication are present and for any damage to the DNA before entering S-phase.
What happens at the G2 Checkpoint?
The cell checks whether all the DNA has been replicated without any damage. If it has, the cell can enter mitosis.
What is mitosis and why is it needed?
Mitosis is one continuous process, but it’s described as a series of division stages - Prophase, Metaphase, Anaphase and Telophase.
Mitosis is needed for the growth of multicellular organisms and for repairing damaged tissues. It is also a method of asexual reproduction for some plants, animals and fungi.
What is Interphase?
Interphase comes before mitosis in the cell cycle. It’s when cells grow and replicate their DNA ready for division.
What happens during Interphase?
During interphase the cell prepares to divide. The cells DNA is unravelled and replicated, to double its genetic content. The organelles are also replicated so it has spare ones, and it’s ATP content is increased.
What happens during Prophase?
The chromosomes condense, getting shorter and fatter. Tiny bundles of protein called centrioles start moving to opposite ends of the cell, forming a network of protein fibres across it called the spindle. The nuclear envelope (membrane around the nucleus) breaks down and chromosomes lie free in the cytoplasm.
What happens during Metaphase?
The chromosomes line up along the middle of the cell and become attached to the spindle by the centromere. At the metaphor checkpoint, the cell checks that all the chromosomes are attached to the spindle before mitosis can continue.
What happens during Anaphase?
The centromeres divide, separating each pair of sister chromatids. The spindles contract, pulling chromatids to opposite ends of the cell, centromere first.
What happens during Telophase?
The chromatids reach the opposite piles on the spindle. The 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 2 nuclei.
What happens during Cytokinesis?
The cytoplasm divides. In animal cells, a cleavage furrow forms to divide the cell membrane. There are now two daughter cells that are genetically identical to the original cell and to each other. Cytokinesis usually begins in anaphase and ends in telophase. It’s a separate process to mitosis.
List the order of the four stages of mitosis.
PMAT
Prophase, Metaphase, Anaphase, Telophase.
At what stage in mitosis does the nuclear envelope break down?
Prophase.
What is a haploid?
A copy of each chromosome (three non-homologous chromosomes).
What is a diploid?
Two copies of each chromosome (three pairs of homologous chromosomes of maternal and paternal origin).
What is the importance of the cell cycle?
It produces genetically identical daughter cells.
Replacement of worn out/damaged cells.
Repair of body tissues (bone, muscles).
Asexual reproduction/cloning.
What might happen if the DNA is not checked in the cell cycle?
Mutations in the DNA sequence.
Faulty DNA produced.
Error in cpoying daughter cells.
Proteins not made or don’t function properly.
What are sister chromatids?
Chromosomes that are identical, carry the same version of all their genes because one was produced as an exact copy of the other.
How is chromatin produced?
During interphase DNA combines with proteins called histones to form a dense complex called chromatin.
