Cells as basic unit of living organisms - Session 2

Cells are the basic units of life, and they are the building-blocks of all living organisms. All living organisms, from bacteria to plants and animals, are composed of cells. Each cell is a self-contained unit with its own membrane and genetic material.

Some organisms are unicellular. Unicellular organisms are made up of only one cell. An example of unicellular organism is Escherichia coli bacteria. It is found in the lower intestine of some organisms.

Some organisms are multicellular. Multicellular organisms are made up of more than one cell. One example of multicellular organisms are monkeys. In addition to the role of cells as the basic building-blocks of life, cells also have many other important functions. Cells maintain the body's internal environment, also known as homeostasis. Homeostasis refers to the equilibrium and stability of the internal environment of the body.

Have you ever wondered why we sweat during a hot summer day? This is because cells in the skin help to regulate body temperature by sweating. During winter, when the body becomes cold, cells help to retain heat by constricting blood vessels and reducing sweat production. How does our body get rid of waste? In other words, how does our body remove toxic substances? Cells in the liver eliminate toxins from the body. Cells in the kidneys filter waste products from the blood and excrete them in the urine. Cells in the immune system help to protect the body against foreign invaders.

To be more specific, the cells in the immune system help protect the body against foreign invaders such as bacteria, viruses, and parasites. These cells can identify and attack harmful pathogens to prevent infection and illness. Pathogens are microorganisms such as viruses and bacteria that cause disease or illness. Phagocytes are the cells that eat these pathogens and remove them out of the body of living organism.

As we know each cell is a self-contained unit with its own membrane and genetic material. Genetic material is the information that is passed on from one generation to the next in living organisms. This information is stored in molecules called nucleic acids. They include DNA and RNA. Traits from parents to children are passed on through this genetic material.

What are the information seen in genetic material ? All of the information like height, skin color, gender, eye color, shape of different parts of body is seen in genetic material. This information is passed on from one generation to another generation. Defects in the genetic material also causes diseases.

Cells are enclosed by a membrane. This membrane is called plasma membrane. Lets discuss the basic structure and important functions of plasma membrane. The plasma membrane is a thin barrier that encloses the contents of a cell and separates it from the external environment. The membrane is selectively permeable, allowing some substances to pass through while keeping others out. It is made up of lipids and proteins. It is arranged in two layers of fat molecules. These fat molecules are called phospholipids. Plasma membrane controls the movement of substances in and out of the cell.

Organelles are like tiny organs inside a cell that have specific functions to help the cell survive and carry out its tasks. The organelles are enclosed by a membrane. An example of organelle is the nucleus which contains genetic material. Cytoplasm is a substance that fills the inside of a cell and surrounds the cell's organelles. Cytoplasm is a gel-like substance. It helps in movement of organelles in a cell.

Prokaryotes are simple, single-celled organisms that lack a true nucleus and other membrane-bound organelles. They are the smallest and most ancient forms of life. They can be found in a wide range of environments. For example they can be found in soil, water and the human body. Prokaryotes are divided into two main groups, bacteria and archaea. Bacteria are the most familiar type of prokaryote and can be found in a wide range of habitats, including soil, water, and living organisms. Archaea are less well-known and are found in extreme environments such as hot springs, salt flats, and deep-sea vents.

Eukaryotic cells are cells that make up the bodies of all living organisms except for bacteria and archaea. They are more complex than prokaryotic cells and contain membrane-bound organelles such as nucleus. Eukaryotic cells are larger than prokaryotic cells. More examples of eukaryotic cells include cells in plants, animals, fungi and protists.

Animal cells are eukaryotic cells that are found in animals and have a variety of functions. For example, nerve cells transmit information through the body, while muscle cells enable movement. As we know animal cells and plant cells are eukaryotic cells. There are some differences between plant cells and animal cells. One of the major differences is that, plant cells have a cell wall while animal cells lack a cell wall. A cell wall is a tough membrane that surrounds the plasma membrane.

Plants have cell walls because a cell wall provides strength and support to the cell. The cell wall is a rigid layer that surrounds the plasma membrane of plant cells. The cell wall undertake several important roles in plant cells. Firstly, it provides mechanical support and helps maintain the shape of the cell. This is especially. important in plants, which are exposed to external pressures and need to maintain their structure and integrity. The cell wall also acts as a barrier, preventing the entry of pathogens and toxins into the cell.