• A level biology

    Cell Structure

    In the early days of microscopy an English scientist, Robert Hooke decided to examine thin slices of plant material. He chose cork as one of his examples. Looking down the microscope, he was struck by the regular appearance of the structure, and in 1665 he wrote a book containing the diagram shown in Figure. If you examine the diagram you will see the ‘porelike’ regular structures that Hooke called ‘cells’. Each cell appeared to be an empty box surrounded by a wall. Hooke had discovered and described, without realising it, the fundamental unit of all living things. Although we now know that the cells of cork are dead, further observations…

  • Q & A

    Q & A on Cell Structure

    Q: What is cell theory? Cell theory asserts that the cell is the constituent unit of living beings. Before the discovery of the cell, it was not recognized that living beings were made of building blocks like cells. The cell theory is one of the basic theories of Biology. Q:  Are there living beings without cells? Viruses are considered the only living beings that do not have cells. Viruses are constituted by genetic material (DNA or RNA) enwrapped by a protein capsule. They do not have membranes and cell organelles nor do they have self-metabolism. Q:  In 1665 Robert Hooke, an English scientist, published his book Micrographia, in which he…

  • A level biology,  Biology,  Cell biology

    Animal Cell

    All animal cells are multicellular. They are eukaryotic cells. Animal cells are surrounded by a plasma membrane and it contains the nucleus and organelles that are membrane-bound. Unlike the eukaryotic cells of plants and fungi, animal cells do not have a cell wall. This feature was lost in the distant past by the single-celled organisms that gave rise to the kingdom Animalia. Animal cells are of various sizes and have irregular shapes. Most of the cells size range between 1 and 100 micrometers and are visible only with the microscope. Trillions of cells are found in the human body. There are many different types of cells, approximately 210 distinct cell types…

  • Biochemistry,  Q & A

    Q & A ON CELL RESPIRATION

    1. How do cells obtain the energy they need to function? Cells obtain energy for their metabolic reactions from breaking down organic molecules with a high energy content. This energy is mostly stored as ATP molecules. The process of obtaining energy in order to produce ATP molecules is called cellular respiration. 2. What compound is phosphorylated for ATP formation? What is the resulting compound when ATP releases energy? ATP, or adenosine triphosphate, is formed after the binding of one phosphate molecule (phosphorylation) to one ADP (adenosine diphosphate) molecule. This is a process that stores energy in the produced ATP molecule. When ATP provides energy to the cellular metabolism, it releases…

  • Biochemistry,  Cell biology,  Q & A

    What is the function of the cell membrane?

    [vc_row][vc_column][/vc_column][/vc_row][vc_row][vc_column][vc_column_text] The cell membrane is otherwise called a Plasma membrane. It may be defined as the thin, elastic, semipermeable living membrane that serves as a boundary for the Cytoplasm. The Cell membrane is made up of glycoproteins and phospholipids. The Functions of the Cell membrane are as follows: Cell membrane or Plasma membrane is a semipermeable membrane present around the Protoplasm. It acts as a boundary to the cell. It gives a definite shape to the Cell. It gives Mechanical support to the Cell. It protects Cell contents. It regulates the exchange of materials into and out of the cell. The Sites for cell recognition are located on the surface of the…

  • Biology,  Cell biology

    WHAT IS CELL?

    [vc_row][vc_column][vc_column_text]The cell (meaning “small room”) is the basic structural, functional, and biological unit of all known living organisms. All living organisms are made up of building blocks we call the cell. Many living things consist of vast numbers of cells working in concert with one another. A number of cells in an organism varies. The cell is surrounded by a cell or plasma membrane. which contains many biomolecules such as proteins and nucleic acids. Cell consists of different organelles like cell nucleus, Mitochondria, Endoplasmic reticulum, Golgi apparatus, Lysosomes, Peroxisomes, centrosome, Vacuoles, Ribosome. In some organ­isms, the body is made up of many cells (multicellular) while in others it is made up of a single…

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