Cellular Membrane (copy)

cellular membranes

Phospholipids

A type of lipid found in cell membranes. It consists of a hydrophilic (water-loving) head and hydrophobic (water-fearing) tails.

sphingolipids

A type of complex lipid found in cell membranes. They consist of a sphingosine backbone attached to a fatty acid and a polar head group. They play essential roles in signaling, cell recognition, and membrane structure.

integral and peripheral proteins

Embedded within the cell membrane, help transport molecules across the membrane and provide structural support.

Found on the surface of the cell membrane, play a role in cell signaling, enzymatic activity, and cell recognition.

Singer and Nicholson

They proposed the fluid mosaic model of cell membrane structure. Described the membrane as a fluid bilayer of phospholipids. Embedded proteins float within the lipid bilayer. Proteins have various functions like transport and cell signaling.

phospholipid bilayer

A double layer of phospholipid molecules that forms the basis of cell membranes. It consists of two layers, with their hydrophilic (water-loving) heads facing outward and their hydrophobic (water-fearing) tails facing inward. This structure provides a barrier that controls the movement of substances in and out of the cell. This is also 8nm in thickness.

phospholipid fatty acids

The hydrophobic tails of phospholipids. They are composed of long hydrocarbon chains, typically containing 14-24 carbon atoms, with varying degrees of saturation. The fatty acids in phospholipids contribute to the fluidity and stability of the phospholipid bilayer in cell membranes.

Cholesterol

A type of lipid molecule that is an essential component of cell membranes. It helps maintain the fluidity and stability of the membrane structure. These molecules are interspersed within the phospholipid bilayer of the membrane, contributing to its integrity and regulating its permeability. Also plays a role in various cellular processes, including signal transduction and the synthesis of steroid hormones.

carbohydrates (membranes)

They are often found attached to proteins and lipids, forming glycoproteins and glycolipids respectively. In cell membranes, they contribute to cell recognition, cell adhesion, and cell signaling processes. They also provide structural support and help maintain the fluidity of the membrane.

polysaccharides (membranes)

Complex carbohydrates made up of multiple sugar units joined together. They play a crucial role in cell membranes, providing structural support and acting as a barrier. Examples include cellulose, which forms plant cell walls, and chitin, found in the exoskeletons of insects. They are essential for maintaining cell integrity and protecting against external factors.

oligosaccharides

Complex carbohydrates composed of a few (2-10) sugar units linked together. They play important roles in cell recognition, immune response, and energy storage. Examples include lactose, maltose, and sucrose.

glycoproteins

Proteins that have carbohydrate chains attached to them. These carbohydrate chains can play various roles in the structure and function of the protein. They are commonly found on the surface of cells and are involved in cell recognition, cell signaling, and immune response. Examples include antibodies, hormones, and enzymes

cell-cell recognition

Definition: ability of cells to identify and interact with each other through specific molecules on their surfaces. It allows cells to communicate, coordinate their activities, and form complex tissues and organs. It is essential for processes such as immune response, embryonic development, tissue repair, and maintaining homeostasis in multicellular organisms.

T-cells

A type of white blood cell that play a crucial role in the immune system. They are responsible for recognizing and attacking foreign substances, such as viruses or bacteria, in the body, also help regulate the immune response and can differentiate between healthy cells and infected or abnormal cells.

glycolipids

Type of lipid molecule that consists of a carbohydrate (sugar) attached to a lipid (fat) molecule. Found on the surface of cell membranes and play a role in cell recognition and signaling.

selectively permeable membrane

A membrane that allows certain substances to pass through while restricting the passage of others based on size, charge, or solubility.

diffusion

The process by which molecules or particles move from an area of higher concentration to an area of lower concentration. It occurs due to the random motion of particles and does not require any external energy input.

concentration gradient

The difference in concentration of a substance across a membrane or space, which drives the movement of molecules from an area of high concentration to an area of low concentration.

passive transport

Process of moving molecules across a cell membrane without the need for energy. It occurs along the concentration gradient, from an area of high concentration to low concentration.

osmosis

Process where solvent molecules pass through a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

aquaporins

Specialized proteins found in cell membranes that facilitate the transport of water molecules across the membrane.

intercellular fluid

The fluid found between cells in the body, providing a medium for the exchange of nutrients, waste products, and signaling molecules.

Lysed Cell

A cell that has ruptured or burst open, causing the release of its contents. This can occur due to various factors, such as physical damage, osmotic pressure, or the action of enzymes.

crenate cell

A cell with high concentration of solute causing the cell to have wavy or shriveled edges.

Contractile Vacuole

Organelle found in certain organisms, like protists, that regulates water balance by collecting and expelling excess water from the cell.

osmoregulation

Process by which organisms maintain a stable internal balance of water and solutes despite changes in their external environment.

Transport proteins

Proteins that facilitate the movement of molecules across cell membranes. They can transport ions, nutrients, and waste products. Examples include channel proteins, which form pores for passive transport, and carrier proteins, which undergo shape changes to transport molecules against their concentration gradient.

gated channels

Channels in cell membranes that open and close in response to specific signals or conditions, allowing the passage of ions or molecules.

Facilitated diffusion

Process by which molecules passively move across a cell membrane with the help of specific transport proteins. No energy is required as molecules move from an area of high concentration to an area of low concentration.

Active transport

Requires the expenditure of energy to move molecules or ions across a cell membrane against their concentration gradient. It is carried out by specific proteins called transporters or pumps. Allows cells to move substances from areas of lower concentration to areas of higher concentration.

chemical gradient

The difference in concentration of a chemical substance between two areas, which causes the substance to move from an area of higher concentration to an area of lower concentration.

electrochemical gradients

The difference in electrical charge and concentration of ions across a cell membrane, creating a driving force for ion movement.

voltage gradient

The change in electric potential per unit distance. It measures the rate at which the electric potential changes along a path.

Proton Pump

A membrane protein found in the stomach lining that releases hydrogen ions into the stomach, aiding in the production of gastric acid for digestion.

proton motive force

A form of potential energy that is generated by the movement of protons across a membrane. It is a key component in cellular processes such as ATP synthesis and active transport. This created by the difference in proton concentration (pH gradient) and the difference in electrical potential (membrane potential) across the membrane.

oxidative phosphorylation

Process in cellular respiration where electrons from NADH and FADH2 are passed through a series of protein complexes in the inner mitochondrial membrane, generating ATP.

cotransport

Process in which two substances are transported across a membrane simultaneously, using the energy from the movement of one substance down its concentration gradient to drive the movement of the other substance against its concentration gradient.

Phagocytosis

A process by which cells, such as white blood cells, engulf and digest foreign particles, such as bacteria or dead cells.

Pinocytosis

Process by which cells engulf fluids and particles by forming small pockets called vesicles. It is a type of endocytosis that allows cells to take in nutrients, remove waste, and regulate cell signaling.

Receptor-mediated endocytosis

Process by which cells internalize specific molecules, such as hormones or nutrients, through the binding of these molecules to specific receptors on the cell surface. This allows for selective uptake and regulation of substances into the cell.