8 Questions
What is the thickness of the cell membrane?
75-100 Angstroms
Which of the following is correct about the phospholipid head?
It is hydrophilic.
What percentage of the cell membrane is composed of carbohydrates?
3%
Which type of protein occupies the whole thickness of the membrane?
Integral proteins
What is the role of cholesterol in the cell membrane?
It provides toughness and affects permeability.
What is the hydrophobic part of a phospholipid called?
Tail
What is the primary function of carbohydrates on the cell membrane?
Serving as recognition sites and aiding immune responses
Which is true about amphipathic molecules in the cell membrane?
One part is hydrophilic and the other part is hydrophobic.
Study Notes
Cell Membrane Characteristics
- Very thin, measuring 75-100 Angstroms
- Elastic in nature
- Semipermeable, allowing selective passage of substances
- Dynamic structure, constantly renewed
Cell Membrane Structure
- Composed of 55% proteins, 42% lipids, and 3% carbohydrates
- Phospholipids make up 25% of the lipids
- Cholesterol accounts for 13% of the lipids
- Other lipids and carbohydrates make up 4% and 3% respectively
Lipids
- Phospholipids consist of a phosphate group (head) and free fatty acids (tail)
- Head is hydrophilic, charged, and faces the exterior
- Tail is hydrophobic, uncharged, and faces the interior
- Phospholipids form a bilayer, important for flexibility and selective permeability
- Cholesterol is hydrophobic and embedded in the phospholipid bilayer
- Cholesterol affects membrane permeability and adds toughness
Proteins
- Two types: integral (globular) and peripheral (separate) proteins
- Integral proteins occupy the whole membrane thickness
- Integral proteins have an interior hydrophobic part and an outer hydrophilic part
- Peripheral proteins are separate at the sides of the membrane
Carbohydrates
- Present in combination with proteins and lipids as glycoproteins and glycolipids
- Function as recognition sites for self-differentiation and immune responses
- Help in attaching cells together
Learn about the composition and characteristics of the cell membrane, including its structure, lipids, and proteins. Discover the dynamic nature of the cell membrane and its importance in cellular functions.
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