1. Explain why neither cyclins nor kinases alone can cause a cell to progress through the cell cycle.
As cyclin accumulates, it activates their kinases that turn on the pathway to mitotic spindle formation, and so on.
2. How do controls of the cell cycle protect multi-cellular organisms from accumulating large numbers of damaged or defective cells?
The checkpoint control is responsible for multi-cellular organisms for not accumulating large numbers of damaged or defective cells. Checkpoint controls consist of proteins that detect mistakes and damage and quickly halt the cell cycle until repairs are made. When this occurs, the cell is said to be in cell-cycle <span>arrest.
</span>3. What is the difference between a cancerous tumor and metastasis?
Cancer is cause by mutations in the genes that encode these proteins can lead to uncontrolled growth. Cancer is when there is uncontrolled cell growth and reproduction. Metastasis is caused by tumors when they grow and interfere with the surrounding tissue or cells and break off and spread around the body. Cancerous tumors cause metastasis, and tumors are caused by mutations in genes that lead to uncontrolled growth.
4. What are the functions of tumor-suppressor genes and protoncogenes in noncancerous cells?
The genes that encode the checkpoint proteins are called tumor suppressors because they suppress the development of cells into tumors. If mutations inactivate these genes, the cell-cycle break is removed with or without a signal from the outside. Proto-oncogene’s are involved in promoting cell division, mutations can cause them to become oncogenes, or cancer genes which stimulate cells to leave G0 and divide whether or not it is a signal.
Answer:
The cell body of a neuron is called SOMA. The soma or pericarion contains the nucleus surrounded by the cytoplasm; Inside them we find different types of organelles:
-Mitochondria
-A Golgi apparatus
-Smooth endoplasmic reticulum (REL)
-Nissi's body
-Cytoskeleton, formed by neurofibrils.
I think the the ribs are not a solid sheet because they need to be able to expand so the lungs can get an adequate amount of air in the lungs. The brain just needs to be protected and doesn’t need to expand so it’s a solid sheet. The skull seems to be the better protector at first because the ribs can break and puncture a lung, harming your breathing but if you do hit your head your brain can start swelling and the skull doesn’t allow any room for expansion. Head injuries are much more dangerous, especially if the brain starts swelling. Rib injuries seem much simpler to fix and less dangerous.
<span>Water heats up, changes to water vapor and evaporates, rises into the sky. It cools, condenses, turns back into liquid water forming clouds. Then it falls back to earth as precipitation and runs down hills or mountains during runoff and returns to lakes and oceans.
I think i`m not sure :)</span>
