Cellular Energy Production


Hi, and welcome to this video where we continue to cover the basics of cellular anatomy as it relates to the membrane, energy production, and more.

The cell, or plasma, membrane, is a thin semipermeable membrane consisting of the phospholipid bilayer, with the hydrophilic ends of the outer layer facing the external environment, the inner layer facing the inside of the cell, and the hydrophobic ends facing each other. Cholesterol in the cell membrane adds stiffness and flexibility. Glycolipids help the cell to recognize other cells of the organisms. The proteins in the cell membrane help give the cells shape. Special proteins help the cell communicate with its external environment. Other proteins transport molecules across the cell membrane.

The cell membrane, has selective permeability with regard to size, charge, and solubility. With regard to molecule size, the cell membrane allows only small molecules to diffuse through it. Oxygen and water molecules are small and typically can pass through the cell membrane. The charge of the ions on the cell’s surface also either attracts or repels ions. Ions with like charges are repelled, and ions with opposite charges are attracted to the cell’s surface. Molecules that are soluble in phospholipids can usually pass through the cell membrane. Many molecules are not able to diffuse through the cell membrane, and, if needed, those molecules must be moved through by active transport and vesicles.

Ribosomes: Ribosomes are involved in synthesizing proteins from amino acids. They are numerous, making up about one quarter of the cell. Some cells contain thousands of ribosome. Some are mobile and some are embedded in the rough endoplasmic reticulum.
Golgi complex (Golgi apparatus): This is involved in synthesizing materials such as proteins that are transported out of the cell. It is located near the nucleus and consists of layers of membranes.
Vacuoles: These are sacs used for storage, digestion, and waste removal. There is one large vacuole in plant cells. Animal cells have small, sometimes numerous vacuoles.
Vesicle: This is a small organelle within a cell. It has a membrane and performs varying functions, including moving materials within a cell.
Cytoskeleton: This consists of microtubules that help shape and support the cell.
Microtubules: These are part of the cytoskeleton and help support the cell. They are made of protein.
Cytosol: This is the liquid material in the cell. It is mostly water, but also contains some floating molecules.
Cytoplasm: This is a general term that refers to cytosol and the substructures (organelles) found within the plasma membrane, but not within the nucleus.
Cell membrane (plasma membrane): This defines the cell by acting as a barrier. It helps keeps cytoplasm in and substances located outside the cell out. It also determines what is allowed to enter and exit the cell.
Endoplasmic reticulum: The two types of endoplasmic reticulum are rough (has ribosomes on the surface) and smooth (does not have ribosomes on the surface). It is a tubular network that comprises the transport system of a cell. It is fused to the nuclear membrane and extends through the cytoplasm to the cell membrane.
Mitochondrion (pl. mitochondria): These cell structures vary in terms of size and quantity. Some cells may have one mitochondrion, while others have thousands. This structure performs various functions such as generating ATP, and is also involved in cell growth and death. Mitochondria contain their own DNA that is separate from that contained in the nucleus.
Four functions of mitochondria are:

    - The production of cell energy 
    - Cell signaling (how communications are carried out within a cell 
    - Cellular differentiation (the process whereby a non- differentiated cell becomes transformed 
      into a cell with a more specialized purpose) 
    - Cell cycle and growth regulation (the process whereby the cell gets ready to reproduce and reproduces). 

Mitochondria are numerous in eukaryotic cells. There may be hundreds or even thousands of mitochondria in a single cell. Mitochondria can be involved in many functions, their main one being supplying the cell with energy. Mitochondria consist of an inner and outer membrane. The inner membrane encloses the matrix, which contains the mitochondrial DNA (mtDNA) and ribosomes.

I hope that helped answer some of your questions regarding cellular structure. Thanks for watching, and until next time, happy studying.


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