cell.pdf

BIOCHEMISTRY LABORATORY ACTIVITY DISCUSSION THE CELL HISTORY The Cells are the basic, fundamental unit of life. So, if we were to break apart an organism to the cellular level, the smallest independent component that we would find would be the cell....

BIOCHEMISTRY LABORATORY ACTIVITY DISCUSSION THE CELL HISTORY The Cells are the basic, fundamental unit of life. So, if we were to break apart an organism to the cellular level, the smallest independent component that we would find would be the cell. Who discovered cells? Robert Hooke discovered the cell in 1665. HISTORY Robert Hooke observed a piece of bottle cork under a compound microscope and noticed minuscule structures that reminded him of small rooms. Consequently, he named these “rooms” as cells. However, his compound microscope had limited magnification, and hence, he could not see any details in the structure. Owing to this limitation, Hooke concluded that these were non-living entities. HISTORY Later Anton Van Leeuwenhoek observed cells under another compound microscope with higher magnification. This time, he had noted that the cells exhibited some form of movement (motility). As a result, Leeuwenhoek concluded that these microscopic entities were “alive.” Eventually, after a host of other observations, these entities were named as animalcules. HISTORY In 1883, Robert Brown, a Scottish botanist, provided the very first insights into the cell structure. He was able to describe the nucleus present in the cells of orchids. CELL THEORY Cell Theory was proposed by the German scientists, Theodor Schwann, Matthias Schleiden, and Rudolf Virchow. The cell theory states that: All living species on Earth are composed of cells. A cell is the basic unit of life. All cells arise from pre-existing cells. A modern version of the cell theory was eventually formulated, and it contains the following postulates: Energy flows within the cells. Genetic information is passed on from one cell to the other. The chemical composition of all the cells is the same.  FUNCTIONS OF CELL A cell performs major functions essential for the growth and development of an organism. Important functions of cell are as follows: Provides Support and Structure All the organisms are made up of cells. They form the structural basis of all the organisms. The cell wall and the cell membrane are the main components that function to provide support and structure to the organism. For eg., the skin is made up of a large number of cells. Xylem present in the vascular plants is made of cells that provide structural support to the plants. Facilitate Growth Mitosis In the process of mitosis, the parent cell divides into the daughter cells. Thus, the cells multiply and facilitate the growth in an organism. Allows Transport of Substances Various nutrients are imported by the cells to carry out various chemical processes going on inside the cells. The waste produced by the chemical processes is eliminated from the cells by active and passive transport. Small molecules such as oxygen, carbon dioxide, and ethanol diffuse across the cell membrane along the concentration gradient. This is known as passive transport. The larger molecules diffuse across the cell membrane through active transport where the cells require a lot of energy to transport the substances. Energy Production Cells require energy to carry out various chemical processes. This energy is produced by the cells through a process called photosynthesis in plants and respiration in animals. Aids in Reproduction A cell aids in reproduction through the processes called mitosis and meiosis. Mitosis is termed as the asexual reproduction where the parent cell divides to form daughter cells. Meiosis causes the daughter cells to be genetically different from the parent cells. CHARACTERISTICS OF CELLS  FOLLOWING ARE THE VARIOUS ESSENTIAL CHARACTERISTICS OF CELLS: Cells provide structure and support to the body of an organism. The cell interior is organized into different individual organelles surrounded by a separate membrane. The nucleus (major organelle) holds genetic information necessary for reproduction and cell growth.  FOLLOWING ARE THE VARIOUS ESSENTIAL CHARACTERISTICS OF CELLS: Every cell has one nucleus and membrane-bound organelles in the cytoplasm. Mitochondria, a double membrane-bound organelle is mainly responsible for the energy transactions vital for the survival of the cell. Lysosomes digest unwanted materials in the cell. FOLLOWING ARE THE VARIOUS ESSENTIAL CHARACTERISTICS OF CELLS: Endoplasmic reticulum plays a significant role in the internal organization of the cell by synthesizing selective molecules and processing, directing and sorting them to their appropriate locations.  TYPES OF CELLS Prokaryotes Eukaryotes  PROKARYOTIC CELLS 1. Prokaryotic cells have no nucleus. Instead, some prokaryotes such as bacteria have a region within the cell where the genetic material is freely suspended. This region is called the nucleoid. 2. They all are single-celled microorganisms. Examples include archaea, bacteria, and cyanobacteria. 3. The cell size ranges from 0.1 to 0.5 µm in diameter 4. The hereditary material can either be DNA or RNA.  PROKARYOTIC CELLS 4. reproduce by binary fission, a form of asexual reproduction. They are also known to use conjugation – which is often seen as the prokaryotic equivalent to sexual reproduction (however, it is NOT sexual reproduction).  EUKARYOTIC CELLS 1. Eukaryotic cells are characterized by a true nucleus. 2. The size of the cells ranges between 10–100 µm in diameter. 3. This broad category involves plants, fungi, protozoans, and animals. 4. The plasma membrane is responsible for monitoring the transport of nutrients and electrolytes in and out of the cells. It is also responsible for cell to cell communication.  EUKARYOTIC CELLS 5. They reproduce sexually as well as asexually. 6. There are some contrasting features between plant and animal cells. For eg., the plant cell contains chloroplast, central vacuoles, and other plastids, whereas the animal cells do not.  CELL STRUCTURE The cell structure comprises These components include: individual components with 1. cell wall, specific functions essential to 2. cell membrane, carry out life’s processes 3. cytoplasm, 4. nucleus, 5. cell organelles.  CELL MEMBRANE The cell membrane The cell membrane is By structure, it is a supports and protects outer covering porous membrane supports and protects the outer covering of porous membrane the cell. It controls the a cell within which all (with pores) which movement of other organelles, such permits the movement substances in and out as the cytoplasm and of selective substances of the cells. It nucleus, are enclosed. in and out of the separates the cell It is also referred to cell. Besides this, the from the external as the plasma cell membrane also environment. The cell membrane. protects the cellular membrane is present component from in all the cells. damage and leakage.  CELL MEMBRANE It forms the wall- Plants are immobile wall-like like structure immobile, so their between two cells cell structures are as well as well-adapted to between the cell protect them from and its external factors. surroundings. The cell wall helps to reinforce this function.  CELL WALL prominent part outermost layer of plant cells The cell wall is the The cell wall is most prominent part present exclusively in of the plant’s cell plant cells. It protects structure. It is made the plasma up of cellulose, membrane and other hemicellulose and cellular components. pectin. The cell wall is also the outermost layer of plant cells.  CELL WALL rigid and stiff provides shape structure and support It is a rigid and It provides stiff structure shape and surrounding the support to the cell membrane. cells and protects them from mechanical shocks and injuries.  CYTOPLASM The cytoplasm Most of the The cell thick, clear, jelly-like chemical reactions organelles are suspended is a thick, chemical organelles clear, jelly-like reactions such as substance within a cell endoplasmic present inside take place in reticulum, the cell this cytoplasm. vacuoles, membrane. mitochondria, ribosomes, are suspended in this cytoplasm.  NUCLEUS The nucleus is The nucleus The nucleus It sends surrounded protects contains signals to by the the DNA the the cells to nuclear and is an hereditary grow, envelope integral material mature, that component of the cell, divide and separates of a the DNA. die. the DNA plant’s cell from the structure. rest of the cell.  CELL ORGANELLES “Cells are composed of various cell organelles that perform certain specific functions to carry out life’s processes. The different cell organelles, along with its principal functions, are as follows:”  CELL ORGANELLES Golgi Bodies Ribosome Mitochondria Golgi bodies are Ribosomes are The mitochondrion called the cell’s the protein is called “the post office as it synthesizers of powerhouse of the is involved in the the cell. cell.” It is called so transportation of because it produces ATP – the materials within cell’s energy the cell currency.  CELL ORGANELLES Lysosomes Chloroplast Vacuoles Lysosomes protect the cell Chloroplasts are the Vacuoles store food, by engulfing the foreign primary organelles for water, and other waste bodies entering the cell photosynthesis. It materials in the cell. and help in cell renewal. contains the pigment Therefore, they are called chlorophyll. known as the cell’s suicide bags.  CELL ORGANELLES Lysosomes Chloroplast Vacuoles Lysosomes protect the cell Chloroplasts are the Vacuoles store food, by engulfing the foreign primary organelles for water, and other waste bodies entering the cell photosynthesis. It materials in the cell. and help in cell renewal. contains the pigment Therefore, they are called chlorophyll. known as the cell’s suicide bags.