Mitosis Flashcards
Describe the process of interphase?
Interphase is split into three separate stages:
G1- the cell grows and organelles and proteins are made.
S- the DNA is unraveled and then replicated.
G2- proteins needed for cell division are made.
Describe the process of prophase?
The chromosomes condense becoming shorter and thicker. Centrioles move to opposite poles forming a network of protein fibres called the spindle. The nuclear envelope breaks down and the chromosomes lie free in the cytoplasm.
Describe the process of metaphase?
Chromosomes visible as pairs of sister chromatids joined at the centromere, arrange themselves at the equator and become attached to the spindle fibres at the centromere.
Describe the process of anaphase?
The centromere divides and the spindle fibres contract and shorten and pull the separated chromatids to opposite poles.
Describe the process of telophase?
The chromatids reach the opposite poles and uncoil and lengthen to become chromatin. A new nuclear envelope forms around each group of chromosomes, so there are two new nuclei.
Describe the process of cytokinesis?
The cytoplasm divides to form two genetically identical cells.
How does cytokinesis occur in animal cells?
Occurs by cleavage of the cell membrane, the cytoplasm splits to form two genetically identical daughter cells.
How does cytokinesis occur in plant cells?
Cell plates form across the equator and a new cell wall is made.
Describe how some cancer treatments work by targeting the cell cycle?
-During G1, some chemical drugs, like chemotherapy, prevent the synthesis of enzymes needed for DNA replication. If they aren’t produced the cell is unable to enter the synthesis phase forcing the cell to kill itself.
-During S phase, radiation and some drugs damage DNA. At several point during the cell cycle the DNA is checked for damage and if severe damage is detected the cell will kill itself.
