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Questions and Answers
The cell membrane is primarily composed of ______, which makes up 55% of its structure.
The cell membrane is primarily composed of ______, which makes up 55% of its structure.
proteins
The cell membrane exhibits ______ which allows it to maintain its integrity while still being flexible.
The cell membrane exhibits ______ which allows it to maintain its integrity while still being flexible.
flexibility
Osmosis specifically refers to the movement of ______ across a semi-permeable membrane.
Osmosis specifically refers to the movement of ______ across a semi-permeable membrane.
water
Phagocytosis is a process in which a cell engulfs ______ such as bacteria and dust.
Phagocytosis is a process in which a cell engulfs ______ such as bacteria and dust.
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The cell membrane's lipid component is mainly composed of ______, which forms a bilayer.
The cell membrane's lipid component is mainly composed of ______, which forms a bilayer.
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Study Notes
Cell Membrane Structure
- Composed primarily of proteins (55%), lipids (42%), and carbohydrates (3%).
- Major lipid components include phospholipids (25-35%), cholesterol, glycolipids.
- Proteins can be either peripheral (on the surface) or integral (embedded within the membrane).
Cell Membrane Properties
- Consists of two layers, providing flexibility.
- Selectively permeable, allowing some substances to pass through while blocking others.
- Carbohydrates attached to the membrane act as recognition sites, aid in self-differentiation, and contribute to cell adhesion.
Cell Membrane Functions
- Serves both physical (protection) and physiological (transport, communication) roles.
- Facilitates transport mechanisms including diffusion, osmosis (water transport), filtration (salt transport), and active transport (e.g., Na+-K+ pump).
- Engages in processes like pinocytosis (cell drinking) where dissolved proteins are taken into the cell via vesicles.
- Participates in endocytosis (exocytosis) where large particles are transported into the cell within vesicles, further dividing into smaller components like hormones and neurotransmitters.
- Utilizes phagocytosis (cell eating) to engulf bacteria, dust, etc. within a vesicle called a phagosome.
- Employs vesicles (endosomes) to release substances into the cytoplasm.
Cell Membrane Characteristics
- Extremely thin and elastic.
- Exhibits semi-permeability, allowing selective passage of substances.
- Demonstrates dynamic structure, constantly changing and adapting.
- Facilitates transport of gases and nutrients (e.g., O2, CO2, lipid-soluble substances, fatty acids, glucose).
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Description
Test your knowledge on the structure, properties, and functions of the cell membrane. This quiz covers the main components such as lipids, proteins, and carbohydrates, along with their roles in transport and communication. Understand selective permeability and mechanisms like diffusion and osmosis.
