Cell physiology

Source: Wikipedia, the free encyclopedia.

Cell physiology is the biological study of the activities that take place in a

Animal cells, plant cells and microorganism cells show similarities in their functions even though they vary in structure.[2][page needed
]

General characteristics

There are two types of cells: prokaryotes and eukaryotes.

Prokaryotes were the first of the two to develop and do not have a self-contained

eukaryotes, which contain a nucleus that envelops the cell's DNA and some organelles.[3]

Prokaryotes

Typical prokaryotic cell structure

Prokaryotes have DNA located in an area called the nucleoid, which is not separated from other parts of the cell by a

flagella (threadlike structures that aid movement).[2]

Eukaryotes

Typical eukaryotic animal cell structure

Eukaryotes have a nucleus where DNA is contained. They are usually larger than prokaryotes and contain many more organelles. The nucleus, the feature of a eukaryote that distinguishes it from a prokaryote, contains a

mitochondria, metabolic processes such as cellular respiration occur. The cytoskeleton is made of fibers that support the structure of the cell and help the cell move.[2]

Physiological processes

There are different ways through which cells can transport substances across the cell membrane. The two main pathways are passive transport and active transport. Passive transport is more direct and does not require the use of the cell's energy. It relies on an area that maintains a high-to-low concentration gradient. Active transport uses adenosine triphosphate (ATP) to transport a substance that moves against its concentration gradient.[4][page needed]

Movement of proteins

The pathway for proteins to move in cells starts at the ER.

plasma membrane. The cell releases secretory proteins known as exocytosis.[2]

Transport of ions

Ion Transport: Direction of Na/K flow

Ions travel across cell membranes through channels, pumps or transporters. In channels, they move down an electrochemical gradient to produce electrical signals. Pumps maintain electrochemical gradients. The main type of pump is the Na/K pump. It moves 3 sodium ions out of a cell and 2 potassium ions into a cell. The process converts one ATP molecule to adenosine diphosphate (ADP) and Phosphate.[clarification needed] In a transporter, ions use more than one gradient to produce electrical signals.[3]

Endocytosis in Animal Cells

Endocytosis in animal cells

Endocytosis is a form of active transport where a cell takes in molecules, using the plasma membrane, and packages them into vesicles.[2]: 139–140 

Phagocytosis

In phagocytosis, a cell surrounds particles including food particles through an extension of the

hydrolytic enzymes, then fuses with the food vacuole. Hydrolytic enzymes, also known as digestive enzymes, then digest the particles within the food vacuole.[2]
: 139–140 

Pinocytosis

In pinocytosis, a cell takes in ("gulps") extracellular fluid into vesicles, which are formed when plasma membrane surrounds the fluid. The cell can take in any molecule or solute through this process.[2]: 139–140 

Receptor-mediated endocytosis

Receptor-mediated endocytosis is a form of pinocytosis where a cell takes in specific molecules or solutes. Proteins with receptor sites are located on the plasma membrane, binding to specific solutes. The receptor proteins that are attached to the specific solutes go inside coated pits, forming a vesicle. The vesicles then surround the receptors that are attached to the specific solutes, releasing their molecules. Receptor proteins are recycled back to the plasma membrane by the same vesicle.[2]: 139–140 

References

  1. ISBN 978-1-938168-13-0. Archived from the original
    on November 1, 2020. Retrieved October 23, 2019.
  2. ^
    OCLC 956379308
    .
  3. ^
    OCLC 70047489
    .
  4. ISBN 978-1-947172-51-7
    .

External links
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