8 Matching Annotations
- Mar 2024
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bio.libretexts.org bio.libretexts.org
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at three main cell cycle checkpoints at which the cell cycle can be stopped until conditions are favorable. These checkpoints occur near the end of G1, at the G2–M transition, and during metaphase (see figure below).
important: These cell checkpoints are super important for the cell to regulate and ensure that it can undergo cellular division. Without these checkpoints, the cell could have mutations, and it would not be able to fix them before moving to the next stage.
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The cell is accumulating the building blocks of chromosomal DNA and the associated proteins, and accumulating enough energy reserves to complete replicating each chromosome in the nucleus.
important: The G1 phase is the longest phase because it prepares the cell for division and gains all of the neccessary resources for the replication of each chromosomes in the nucleus.
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Cytokinesis then occurs, dividing the cytoplasm and cell body into two new cells. Note
Is cytokinesis count as a major process because it is the most visual and the actual creation of the two cells, even if mitosis is the process that matters the most?
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This process of DNA replication is typically occurring at the same time as a growth in the physical dimensions of the cell. Therefore, as the cell elongates, the growing membrane aids in the transport of the chromosomes towards the two opposite poles of the cells. After the chromosomes have cleared the midpoint of the elongated cell, cytoplasmic separation begins.
question: is there any signal or anything that tells the bacteria to go into binary fission, or is it just a spontaneous reaction?
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bio.libretexts.org bio.libretexts.org
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Some deleterious mutations are null or knock-out mutations which result in a loss of function of the gene product. These mutations can arise by a deletion of the either the entire gene, a portion of the gene, or by a point mutation in a critical region of the gene that renders the gene product non-functional.
Will these mutations cause issues to the chromosomes or just create mutations in the protein synthesis?
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no longer binds to the ribosome and inhibits protein synthesis.
important This example of antibiotic resistance is a great representation of how mutations can occur and multiply when there is diversity and change in the ratio of mutants and wild-type cells.
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Why did so many mechanisms evolve to repair errors in DNA? By contrast, similar proof-reading mechanisms did NOT evolve for errors in transcription or translation.
real-world-application I think that DNA is the overall structure of everything, and it acts as the template for all functions in the cell. It is the professor, and the RNA is the student's notes. They might have errors in them, but you can go back and fix them. It is way more important to have the right information in the DNA than the RNA, so that is why it has evolved to repair these errors so frequently.
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Such mutations may be of two types: induced or spontaneous. Induced mutations are those that result from an exposure to chemicals, UV rays, x-rays, or some other environmental agent.
important induced mutations significantly increase changes of mutations and cancerous mutations. It is well known that if you use tanning beds or are in the sun without sunscreen, you increase your chances of skin cancer, which is an induced mutation.
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