cells have checkpoints to regulate when the cell can move on to the next stage of the cycle. true or false

Biology

1 answer:

Kisachek [45]2 years ago

6 0

Answer:

True

Explanation:

Cell cycle checkpoints are an important layer of control of the cell cycle. The cell cycle is a process by which cells divide.

There are 4 stages of the cell cycle G1, G2, S and M.

When the cell goes through the cell cycle, each stage has different processes that must occur for the cell to properly divide. During G1, the cell must grow to sufficient size and the environment must be favorable for cell division. During S phase, all the DNA must be properly replicated. during G2 the cell must prepare for division. During M, the cell actually divides.

There are 3 checkpoints throughout the cell cycle. The G1 checkpoint ensures the cell has reached sufficient size. The G2 checkpoint ensures the DNA has been properly replicated. The M checkpoint makes sure the chromosomes are properly attached to the spindles to split the DNA between 2 new cells.

Without these checkpoints, the cell can divide uncontrollably which can lead to cancer.

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At what point do the pulmonary and systemic circulation systems meet up?

Hitman42 [59]

Answer: The Heart

Explanation:

The blood circulatory system (cardiovascular system) delivers nutrients and oxygen to all cells in the body. It consists of the heart and the blood vessels running through the entire body. The arteries carry blood away from the heart; the veins carry it back to the heart. The system of blood vessels resembles a tree: The “trunk” – the main artery (aorta) – branches into large arteries, which lead to smaller and smaller vessels. The smallest arteries end in a network of tiny vessels known as the capillary network.

There are two types of blood circulatory system in the human body, which are connected: The systemic circulation provides organs, tissues and cells with blood so that they get oxygen and other vital substances. The pulmonary circulation is where the fresh oxygen we breathe in enters the blood. At the same time, carbon dioxide is released from the blood.

Blood circulation starts when the heart relaxes between two heartbeats: The blood flows from both atria (the upper two chambers of the heart) into the ventricles (the lower two chambers), which then expand. The following phase is called the ejection period, which is when both ventricles pump the blood into the large arteries.

In the systemic circulation, the left ventricle pumps oxygen-rich blood into the main artery (aorta). The blood travels from the main artery to larger and smaller arteries and into the capillary network. There the blood drops off oxygen, nutrients and other important substances and picks up carbon dioxide and waste products. The blood, which is now low in oxygen, is collected in veins and travels to the right atrium and into the right ventricle.

This is where pulmonary circulation begins: The right ventricle pumps low-oxygen blood into the pulmonary artery, which branches off into smaller and smaller arteries and capillaries. The capillaries form a fine network around the pulmonary vesicles (grape-like air sacs at the end of the airways). This is where carbon dioxide is released from the blood into the air inside the pulmonary vesicles, and fresh oxygen enters the bloodstream. When we breathe out, carbon dioxide leaves our body. Oxygen-rich blood travels through the pulmonary veins and the left atrium into the left ventricle. The next heartbeat starts a new cycle of systemic circulation. Below is an attachment of a diagram that explains the connection between pulmonary and systemic circulation from google.