Fluid Mosaic Model of the Cell Membrane

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Questions and Answers

Which component is responsible for maintaining the fluidity of a cell membrane?

Cholesterol (correct)

Proteins

Carbohydrates

Phospholipids

What are the two layers of a cell membrane called?

Phospholipid bilayer

Cell membranes are impermeable to all substances.

False

The fluid mosaic model describes the cell membrane as a __________ of different components.

mosaic Signup and view all the answers

Match the type of membrane protein with its function:

Integral proteins = Transport substances across the membrane Peripheral proteins = Provide structural support Receptor proteins = Receive signals from outside the cell Enzymatic proteins = Catalyze chemical reactions Signup and view all the answers

The phospholipid bilayer is rigid and does not allow movement of its components.

False Signup and view all the answers

What is the primary function of the cell membrane?

Transporting nutrients and waste Signup and view all the answers

Name one function of cholesterol within the cell membrane.

To maintain membrane fluidity Signup and view all the answers

Cholesterol is not found in the lipid bilayer of cell membranes.

False Signup and view all the answers

What is the primary function of glycoproteins in the cell membrane?

Assist in cell to cell communication and transport of molecules Signup and view all the answers

Name two types of membrane proteins.

Integral proteins, Peripheral proteins Signup and view all the answers

The _____ regulates the fluidity of the cell membrane.

cholesterol Signup and view all the answers

Match the following types of membrane proteins with their functions:

Glycoproteins = Cell to cell communication Receptor proteins = Response to external signals Transport proteins = Molecule transport across membranes Structural proteins = Support and shape to the cell Signup and view all the answers

How do receptor proteins assist cells?

They communicate with external signaling molecules Signup and view all the answers

The carbohydrate chains attached to membrane proteins can be found on the inside surface of the lipid bilayer.

False Signup and view all the answers

Proteins are made up of building blocks called _____ joined by peptide bonds.

amino acids Signup and view all the answers

What are phospholipids primarily responsible for in the cell membrane?

Physical properties of biological membranes Signup and view all the answers

The hydrophilic region of a phospholipid is the 'water-fearing' tail.

False Signup and view all the answers

Which components are responsible for selective permeability in cell membranes?

Phospholipids and membrane proteins Signup and view all the answers

Carbohydrates are primarily found on the ______ surface of the plasma membrane.

outer Signup and view all the answers

Match the terms with their correct descriptions:

Phospholipid = Component that forms a bilayer in cell membranes Cholesterol = Molecule that helps maintain fluidity in membranes Selective Permeability = Ability of a membrane to control what enters and exits Carbohydrates = Biomolecules that often form glycoproteins and glycolipids Signup and view all the answers

What role does cholesterol play in cell membranes?

Maintains fluidity and stability of the membrane Signup and view all the answers

The lipid bilayer structure is impermeable to all substances.

False Signup and view all the answers

What did the Dutch scientists Gorter and Grendel propose about the nature of the plasma membrane?

The fluid mosaic model Signup and view all the answers

Study Notes

The Fluid Mosaic Model of the Cell Membrane

Proposed by S. Jonathan Singer and Garth Nicholson in 1972.
The membrane is a "mosaic" of different components, including phospholipids, cholesterol, proteins, and carbohydrates.
The lipid content of the membrane is responsible for its fluidity, preventing solidification at low temperatures.
The membrane is 5-10 nm thick.

Why is it called the Fluid Mosaic Model?

Many types of molecules float along the lipids.
It's called "fluid" because the phospholipid bilayer is viscous and individual phospholipids can move position.
It's called "mosaic" because the phospholipid bilayer is embedded with proteins, resulting in a mosaic of components.

Functions of the Cell Membrane

Protection
Cell Shape
Compartmentalization
Cell Recognition
Cell Function
Material Transport

Components of the Cell Membrane

Phospholipids:
- Amphipathic molecules with hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails.
- Form a bilayer structure, essential for the physical properties of biological membranes.
- First proposed in 1925 by Dutch scientists Evert Gorter and Francois Grendel.
Cholesterol:
- A lipid found alongside phospholipids in the core of the membrane.
- Regulates membrane fluidity as temperature varies.
- Serves as a base attachment for the cytoskeleton and cell wall in some organisms.
- Supports the cell and maintains its shape.
Proteins:
- Integral proteins: Embedded within the membrane.
- Peripheral proteins: Loosely attached to the membrane's inner or outer face.
- Monitor and maintain the chemical climate of the cell.
- Assist in transferring molecules across the membrane.
Carbohydrates:
- Only on the outer surface of the lipid bilayer or on peripheral proteins.
- Form glycoproteins when attached to proteins or glycolipids when attached to lipids.
- Serve as cell markers for cell recognition.

Types of Membrane Proteins

Glycoproteins: Embedded in the membrane, help with cell communication and molecule transport.
Receptor proteins: Facilitate communication with the external environment through hormones, neurotransmitters, and other signaling molecules.
Transport proteins: Transport molecules across cell membranes.
Structural proteins: Provide support and shape to the cell.

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Description

Explore the Fluid Mosaic Model of the Cell Membrane, proposed by Singer and Nicholson. This quiz delves into its components, functions, and the reasoning behind its nomenclature as 'fluid' and 'mosaic.' Test your knowledge of the critical roles played by the cell membrane in cellular processes.