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Questions and Answers
What is the science that studies all aspects of the cell?
What is the science that studies all aspects of the cell?
Cytology
What do groups of cells form?
What do groups of cells form?
Tissues
What are the two main components of a cell?
What are the two main components of a cell?
The cell membrane is visible under a light microscope.
The cell membrane is visible under a light microscope.
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What model describes the arrangement of components in the cell membrane?
What model describes the arrangement of components in the cell membrane?
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What percentage of the cell membrane is made up of proteins?
What percentage of the cell membrane is made up of proteins?
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The part of the cell membrane that allows different cells to recognize each other is called the ______.
The part of the cell membrane that allows different cells to recognize each other is called the ______.
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What are the two types of endocytosis?
What are the two types of endocytosis?
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Which of the following is NOT a function of the cell membrane?
Which of the following is NOT a function of the cell membrane?
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Match the following organelles with their characteristics:
Match the following organelles with their characteristics:
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Study Notes
Cytology
- Cytology is the study of cells, encompassing their structure, function, division, and other aspects.
- Histology focuses on the structure and function of tissues and organs.
- Tissues are formed by groups of cells, organs by groups of tissues, systems by organs, and the body by systems.
The Cell
- The cell is the fundamental structural and functional unit of multicellular organisms.
- The cell is composed of protoplasm, divided into cytoplasm and the nucleus.
Cytoplasm
- The cytoplasm is an essential component of the cell containing:
- Cytoplasmic organelles: Living and permanent structures with specific functions.
- Cytoplasmic inclusions: Non-living components.
- Cytoplasmic matrix: The fluid component of the cytoplasm.
Cytoplasmic Organelles
- Classified based on the presence or absence of membranes:
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Membranous Organelles:
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Cell Membrane (plasma membrane/plasmalemma):
- Outer membrane of the cell.
- Acts as a barrier between the cell's internal and external environments.
- Invisible under light microscopy (8-10 nm thick).
- Visible with silver impregnation (dark brown line) or PAS staining (pink line).
- Exhibits a trilaminar structure under electron microscopy.
- Outer electron-dense lamina (2.5 nm)
- Intermediate electron-lucent lamina (3 nm)
- Inner electron-dense lamina (2.5 nm)
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Cell Membrane (plasma membrane/plasmalemma):
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Membranous Organelles:
Molecular Structure of the Cell Membrane
- Fluid mosaic model: Describes the arrangement of cell membrane components.
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Components:
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Lipids (30%):
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Phospholipids: Form the lipid bilayer
- Polar heads (hydrophilic): Attracted to water.
- Non-polar tails (hydrophobic): Repel water.
- Glycolipids
- Cholesterol
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Phospholipids: Form the lipid bilayer
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Proteins (60%):
- Peripheral or extrinsic proteins: Partially embedded in the membrane.
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Integral or intrinsic proteins: Firmly attached to the lipid bilayer.
- Transmembrane proteins: Span the membrane.
- Incomplete pass proteins: Partially embedded.
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Carbohydrates (10%):
- Glycocalyx (cell coat): Carbohydrates attached to the external surface of the cell.
- Glycoproteins: Carbohydrates attached to transmembrane proteins.
- Glycolipids: Carbohydrates attached to lipid polar heads.
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Lipids (30%):
Functions of the Cell Coat (Glycocalyx)
- Mechanical protection of the cell membrane.
- Chemical protection of the cell membrane.
- Induction of immunological responses.
- Binding for hormones.
- Intercellular adhesions.
- Formation of the basement membrane.
- Cell recognition.
Functions of the Cell Membrane
- Protection: Protects the cell from external threats.
- Regulation: Controls the passage of substances into and out of the cell.
- Recognition: Enables cells to identify each other and form connections.
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Modifications: Forms specialized structures for specific functions.
- Cell Junctions: Maintain cell-cell connections.
- Microvilli and cilia: Motility or increase cell surface area.
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Transportation: Transmits substances through the membrane.
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Endocytosis: Engulfing large particles or fluids.
- Phagocytosis: Engulfment of solid particles by pseudopodia.
- Pinocytosis: Engulfment of small droplets of fluid.
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Endocytosis: Engulfing large particles or fluids.
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Description
Test your knowledge on cytology, the study of cells, and understand the fundamental aspects like cell structure, cytoplasm components, and organelle classification. This quiz will help you grasp the relationships between cells, tissues, and organ systems.
