There are few millions to billions of cells in an animal body based weight and size of the animal.
Animal cells are quite unique than plant cells.
Unlike in plants, there are many different types of cells with diverse functions.
They are vary based on the organ and tissue they form.
Animal Cell Facts
1. Lack of nucleus: Animal cells are eukaryotic and hence have a nucleus. Not all cells have the nucleus in them. Red blood cells have no nucleus. Hence, they are called as red blood corpuscles. But they are formed from the bone marrow tissue. These RBC cells do not need a nucleus as they are not going to multiply by mitosis or meiosis. Also, the hemoglobin inside them occupies most of the space.
2. Totipotency: This means the cells can convert into any required cell in the body. Stem cells are the one which is totipotent. They can be found in dental growth tissue, placenta, umbilical cord blood of newborn babies.
3. Ability to swim: Some animal cells can swim when required. Protozoans are examples of the cell which can swim. Besides male gamete containing sperm cells are also able to swim towards the ova in the uterus. They have a tail which enables them to swim and reach to ova to fertilize.
4. Receptors: Most cells have plasma or cell membranes which have receptors. Receptors are the protein structures which receive a signal and pass it on to the cell. This is the way the drugs we take act at the cellular level and bring required effects. There are four types of receptors with diverse functions.
5. Telomer decides lifespan: Cells divide by mitosis and multiply in numbers. For each cell division, the telomere length goes down and it decides the lifespan of a cell. Cell life also decides on the stress, health, nutrition and other conditions.
6. Self-repair: During the process of physiology and daily life activities, the cell tends to have some malfunction like in DNA strand, RNA strand, protein arrangement, etc. The cells immediately correct the malfunction for stability.
7. Self-destruction: The cells when they are injured or their DNA is a defect, they go for self-destruction to avoid damage to other cells. This self-destruction occurs by a process called as apoptosis.
8. Lack of multiplication and division: Animals cells undergo either mitosis or meiosis to multiply their numbers. But nerve cells are an exception. They never divide or multiply once formed during birth. There is damage; they try to innervate the surrounding area by plasticity.
9. Chemotaxis activity: This a mechanism wherein cells move towards one part of the body due to chemical guidance. This is seen in white blood cells. When there is an infection or wound in one part of the body, the WBC cells migrate to that point for defense and repair. Hence you will notice pus in the area of wounds or infection.
10. Cell eating: Cells can eat by themselves. Macrophages are a type of white blood cells which engulf any harmful bacteria or toxins in the body. This cell eating is called as phagocytosis.
11. Cell drinking: Cell drink link material or substances by a process known as pinocytosis. This seen mostly in protozoa like the amoeba.
12. Cell content: Almost 70% of cell matter is made of water, the remaining portion is made of proteins, carbohydrates, lipids, micro-elements, etc.
13 Vision: Cells like rods and cone in the eye make it possible to view light and color.
14. Organelle location: The location or organelles varies based on the requirement other factors. In nerve cells, the mitochondria are concentrated at the nerve endings to generate the energy required for signal transduction.