Cell cycle Flashcards
What are the reasons for cell division? Provide examples.
The three reasons why cells divide are: growth, reproduction, and repair.
An example of growth is a zygote becoming an embryo.
An example of repair is a scar forming after getting a cut.
An example of reproduction is asexual reproduction, which is mitosis or binary fission.
Describe binary fission.
Binary fission is the division/reproduction of prokaryotic cells into two new cells.
Describe the phases of binary fission.
The cell elongates and DNA is replicated. The cell wall and membrane then begin to divide, and a cross-wall (septum) forms completely around the divided DNA. The cell then separates into two new bodies.
Briefly describe the eukaryotic cell cycle.
The eukaryotic cell cycle is the replication/reproduction of eukaryotic cells. It is a 3 step process, which includes interphase (gap 1, synthesis, gap 2) mitosis, and cytokinesis.
What is interphase?
Interphase is the longest and most important phase of the eukaryotic cell cycle, where the cell is in a non-dividing state . There are three stages in this phase, which are gap 1, gap 0, synthesis, gap 2).
Explain the first stage of interphase.
Gap 1 is the first stage in interphase. In this stage, the cell grows and increases cytosol, then the cell synthesises proteins for DNA replication. The mitochondria and chloroplast will then divide.
Gap 1 is where the cell will decide whether it will commit to continuing on with the cell cycle, or drop out and not divide.
Explain the second stage of interphase.
Gap 0 (G0) is the second stage, where the cell will carry out normal cell functions.
This is a temporary stage, as the cell normally re-enters gap 1. Some specialised (cells that have specific jobs) will remain permanently in the G0 phase and will not replicate.
Explain the third stage of interphase.
Synthesis is the third stage of interphase. This is where the parent cell synthesises/replicates its DNA (chromosomes). By the end of this stage, the parent cell will have two identical copies of its original DNA.
Explain the fourth stage of interphase.
The fourth and last stage of interphase is the second stage of growth. This stage prepares for mitotic division by synthesising proteins and acquiring energy. By the end of interphase, the cell has doubled in size and DNA has been synthesised.
What is mitosis?
Mitosis is the process by which a cell replicates its chromosomes and then separates them, producing two identical nuclei in preparation for cell division.
What are the phases of mitosis?
The phases of mitosis are prophase, metaphase, anaphase, and telophase.
Describe prophase.
Prophase is the first stage. It is a process in which the duplicated genetic material (chromosomes) in the nucleus of a parent cell are separated/divided into two identical daughter cells. The proteins contained in the nucleus (known as chromatin) are condensed.
Describe metaphase.
Metaphase is the second stage. The individual chromosomes are spread out in the cell nucleus and the nucleus dissolves. The cell’s chromosomes condense and move together, aligning in the centre of the dividing cell.
Describe anaphase.
Anaphase is the third stage. It is a process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells.
Describe telophase.
Telophase is the fourth and last stage. The chromatids move to opposite ends of the cell and two new nuclei form.
