A phospholipid bilayer
Explication
The cell membrane's fundamental structure is a phospholipid bilayer, which consists of two layers of phospholipids with hydrophilic heads facing outward and hydrophobic tails inward, forming the basic framework of the membrane.
A double layer of phospholipids with embedded proteins, where hydrophilic heads face outward and hydrophobic tails inward.
Explication
The fluid mosaic model describes the membrane as a double layer of phospholipids with embedded proteins; hydrophilic heads face outward to interact with water, while hydrophobic tails face inward, forming a flexible yet selective barrier.
Sodium-Potassium Pump
Explication
The sodium-potassium pump is an active transport mechanism that moves 3 Na+ ions out of the cell and 2 K+ ions into the cell, using ATP. It is essential for maintaining cellular ion balance and resting potential, as explicitly described in the content.
Integral protein
Explication
Integral proteins are embedded fully within the phospholipid bilayer and can span across the membrane, playing roles in transport and signaling. Peripheral proteins attach temporarily to membrane surfaces.
To facilitate the passive movement of substances and water, maintaining cell homeostasis
Explication
Diffusion and osmosis primarily serve to passively move molecules and water across cell membranes, helping maintain homeostasis by balancing internal and external environments. They do not require energy and are essential for nutrient intake, waste removal, and water regulation.
It maintains ion balance by actively transporting sodium out and potassium into the cell.
Explication
The sodium-potassium pump actively transports sodium ions out of the cell and potassium ions into the cell, consuming energy, and is vital for nerve impulses and cell volume regulation.
Osmosis
Explication
Osmosis is the passive movement of water molecules from a region of lower solute concentration (hypotonic) to higher solute concentration (hypertonic) across a semi-permeable membrane.
Facilitated diffusion involves specific carrier or channel proteins, while simple diffusion does not.
Explication
Facilitated diffusion is mediated by specific proteins that assist molecules across the membrane without energy expenditure, unlike simple diffusion which depends solely on concentration gradients.
To repair damaged tissues and grow new cells.
Explication
Cells divide primarily to facilitate growth, repair tissues, and reproduce, ensuring the maintenance of healthy tissues and organism development.
Metaphase
Explication
During metaphase, chromosomes align at the cell's equatorial plane, preparing for separation in the following stage, anaphase.
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Cell membrane — structure?
Phospholipid bilayer with embedded proteins.
Cell membrane — key components?
Phospholipid bilayer and embedded proteins.
Membrane transport — types?
Diffusion, osmosis, facilitated diffusion, active transport.
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