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Cell Division and Diseases (Cell Cycle (G1 - Includes cell growth and…
Cell Division and Diseases
Mitosis
Process which copies cells and repairs tissue/ allows growth
Has four processes, PMAT (Prophase, Metaphase, Anaphase, Telophase)
Copied daughter cells are genetically identical
Meiosis
Creates mature haploid gametes
Goes through PMAT 2x
Has a process for genetic variation, crossing over (same chromosomes, one mom and one dad, exchange parts)
The four haploid daughter cells produced have half the number of chromosomes as parent
Cell Cycle
G1 - Includes cell growth and makes proteins and organelles
G1 Checkpoint - Checks cell size and nutrient levels, p53 also checks for mistakes in DNA
S - DNA is replicated and copied (there are now 2 copies of each chromosome)
G2 - Includes more organelles (microtubules, centrosomes, centrioles) needed for mitosis
G2 Checkpoint - DNA is checked for mistakes and proteins and organelles needed for mitosis are checked
M - Mitosis where PMAT occurs and produces two identical daughter cells
M Checkpoint - Checks Metaphase and that chromosomes are aligned at the middle of the cell properly to split evenly into two daughter cells
Disease
Cancerous cells are smaller than normal cells and move through the cell cycle faster than normal (cancer cells continue to replicate unceasingly)
To form, cancer cells either ignore cell signals or receive incorrect signals
Some cancer cells form when genes are muted that affect the function of the cell cycle in a major way
Cell cycle uses cyclins and CDK kinases to phosphorylate proteins to move through the checkpoints of the cell cycle
CDK Kinase levels are always the came but Cyclin levels rise to push cells into the next phase of the cell cycle
Proto-Oncogenes control the rate of cell cycle and Tumor Suppressor Genes slow down the cell cycle
When mutated a proto-oncogene becomes an oncogene which causes a cell to go through the cell cycle faster than normal (only takes one mutation)
When mutated a Tumor Suppressor gene no longer slows down the cell cycle at all and doesn't function and the cell cycle goes faster (requires two mutations)
DNA repair genes act to repair the DNA and are most active when the DNA is being copied in the S phase (these are p53 genes)
Stem Cells
Stem cells are immortal cells that can turn into any cell type that is needed
There are two main types of stem cells, somatic and embryonic which help to regenerate cells
Somatic stem cells come from in the body and are used to replace worn out cells. With medicine they are used as bone marrow transplants to treat Leukemia but its not very effective
Embryonic stem cells come from very young and immature embryos (cannot be produced by adults) and have been used to treat diseases like Parkinson's, Arthritis, Diabetes, Paralisis, and can create new neurons (Couples consent to donate Embryos)
Stem Cell niches interact with stem cells to give signals to differentiated them into a specific cell and to do a specific task.