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Cell Cycle
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Need help preparing for the Biology section of the MCAT? MedSchoolCoach expert, Ken Tao, will teach everything you need to know about Cell Cycle of Mitosis. Watch this video to get all the MCAT study tips you need to do well on this section of the exam!
The cell cycle is a series of processes that take place in a cell that results in the production of two identical daughter cells. The cell cycle is a 4-stage process that all actively dividing eukaryotic cells undergo. In the stages of the cell cycle, there are the G1 phase, the S phase, the G2 phase, and the M phase. Another way to categorize the phases of the cell cycle is to use the terms interphase and M phase. Interphase consists of the G1, S, and G2 phases. During interphase, the cell will undergo a series of changes that will prepare it for cell division. It is also known as the preparatory phase. The M phase is when the cell undergoes mitosis and divides. It is essential to understand each stage in more detail for the MCAT exam.
G1 Phase
The G1 phase is the first stage of interphase. It is also called the first growth phase. During this stage, there is a high rate of cellular activities, which may include the production of both proteins and cell organelles, such as mitochondria and ribosomes, and an increase in cell size. During the G1 phase, the cell is preparing for DNA replication. Also, at this point, the cell has a choice. It can either continue in the cell cycle and enter into the S phase. Alternatively, it can exit the cell cycle and enter into the G0 phase.
G0 Phase
The G0 phase is outside of the normal cell cycle. It is also known as quiescence and is a cycle for non-dividing cells. During this phase, cells are in a stable state, and the cellular processes in the cell are continuing as usual. Several mature cells that are fully differentiated, such as neurons, do not need to undergo cell division any longer. Therefore, neurons will enter into the G0 phase. It is important to note that in this phase, cells are continuing to produce proteins and organelles to carry out their functions.
S phase
If a cell chooses to enter the S phase from the G1 phase, it will undergo DNA replication. The S phase is also known as the synthesis phase. Recall that DNA replication will result in the formation of two identical copies of DNA. At the end of this phase, all the chromosomes of the cell will have been replicated. Recall that each chromosome consists of two sister chromatids. Although the amount of DNA doubles, the number of chromosomes stays the same.
G2 phase
After DNA replication in the S phase, the cell enters the G2 phase. The G2 phase is also called the second growth phase. Similar to the G1 phase, in the G2 phase, there is a high rate of cellular activities. However, unlike the G1 phase, which prepped the cell for DNA replication, the G2 phase preps the cell for mitosis. Also, before entering mitosis, the cells are checked for DNA damage by a checkpoint protein called p53. If the DNA is damaged, p53 will either trigger DNA repair or apoptosis (cellular death). It is important to note that p53 is also known as a tumor protein, because if mutated, p53 will be unable to repair or destroy damaged DNA. In this way, the cell will continuously divide with damaged DNA, which can lead to several forms of cancer.
M phase
The last phase of the cell cycle is the M phase or the mitotic phase. Two processes occur during this phase. First, there is mitosis, which involves the division of the nucleus into two identical nuclei. Recall that mitosis consists of several events divided into different phases: prophase, metaphase, anaphase, and telophase. The second process in the M phase is cytokinesis, which involves the division of the cell into two identical daughter cells. In cytokinesis, the cell divides all of its components, such as its nuclei, cytoplasm, organelles, and cell membrane, into two cells. In this way, the M phase is the combination of both mitosis and cytokinesis.
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The cell cycle is a series of processes that take place in a cell that results in the production of two identical daughter cells. The cell cycle is a 4-stage process that all actively dividing eukaryotic cells undergo. In the stages of the cell cycle, there are the G1 phase, the S phase, the G2 phase, and the M phase. Another way to categorize the phases of the cell cycle is to use the terms interphase and M phase. Interphase consists of the G1, S, and G2 phases. During interphase, the cell will undergo a series of changes that will prepare it for cell division. It is also known as the preparatory phase. The M phase is when the cell undergoes mitosis and divides. It is essential to understand each stage in more detail for the MCAT exam.
G1 Phase
The G1 phase is the first stage of interphase. It is also called the first growth phase. During this stage, there is a high rate of cellular activities, which may include the production of both proteins and cell organelles, such as mitochondria and ribosomes, and an increase in cell size. During the G1 phase, the cell is preparing for DNA replication. Also, at this point, the cell has a choice. It can either continue in the cell cycle and enter into the S phase. Alternatively, it can exit the cell cycle and enter into the G0 phase.
G0 Phase
The G0 phase is outside of the normal cell cycle. It is also known as quiescence and is a cycle for non-dividing cells. During this phase, cells are in a stable state, and the cellular processes in the cell are continuing as usual. Several mature cells that are fully differentiated, such as neurons, do not need to undergo cell division any longer. Therefore, neurons will enter into the G0 phase. It is important to note that in this phase, cells are continuing to produce proteins and organelles to carry out their functions.
S phase
If a cell chooses to enter the S phase from the G1 phase, it will undergo DNA replication. The S phase is also known as the synthesis phase. Recall that DNA replication will result in the formation of two identical copies of DNA. At the end of this phase, all the chromosomes of the cell will have been replicated. Recall that each chromosome consists of two sister chromatids. Although the amount of DNA doubles, the number of chromosomes stays the same.
G2 phase
After DNA replication in the S phase, the cell enters the G2 phase. The G2 phase is also called the second growth phase. Similar to the G1 phase, in the G2 phase, there is a high rate of cellular activities. However, unlike the G1 phase, which prepped the cell for DNA replication, the G2 phase preps the cell for mitosis. Also, before entering mitosis, the cells are checked for DNA damage by a checkpoint protein called p53. If the DNA is damaged, p53 will either trigger DNA repair or apoptosis (cellular death). It is important to note that p53 is also known as a tumor protein, because if mutated, p53 will be unable to repair or destroy damaged DNA. In this way, the cell will continuously divide with damaged DNA, which can lead to several forms of cancer.
M phase
The last phase of the cell cycle is the M phase or the mitotic phase. Two processes occur during this phase. First, there is mitosis, which involves the division of the nucleus into two identical nuclei. Recall that mitosis consists of several events divided into different phases: prophase, metaphase, anaphase, and telophase. The second process in the M phase is cytokinesis, which involves the division of the cell into two identical daughter cells. In cytokinesis, the cell divides all of its components, such as its nuclei, cytoplasm, organelles, and cell membrane, into two cells. In this way, the M phase is the combination of both mitosis and cytokinesis.
MEDSCHOOLCOACH
To watch more MCAT video tutorials like this and have access to study scheduling, progress tracking, flashcard and question bank, download MCAT Prep by MedSchoolCoach
#medschoolcoach #MCATprep #MCATstudytools
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