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Questions and Answers
What is the primary function of the cell membrane?
Which of the following is NOT a characteristic of a cell?
What is the primary function of epithelial tissue?
Which type of tissue is responsible for transmitting nerve impulses?
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What is the term for the group of cells with similar function?
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What is the term for the structure formed by two or more primary types of tissues?
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Which of the following cells do not reproduce by division?
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What is the term for the process by which cells respond to their environment?
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What is the function of cholesterol in the lipid layer of the cell membrane?
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What type of proteins pass through the entire thickness of the cell membrane?
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Which of the following is NOT a function of integral proteins?
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What is the term for proteins that are partially embedded in the outer and inner surfaces of the cell membrane?
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What is the purpose of the lipid layer in the cell membrane?
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What is the term for carbohydrate molecules attached to proteins in the cell membrane?
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Which of the following is an example of an integral protein?
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What is the function of peripheral proteins in the cell membrane?
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What is the term for the arrangement of phospholipid molecules in the lipid layer of the cell membrane?
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What is the function of carrier proteins in the cell membrane?
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What is the function of glycocalyx in cell membranes?
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How do carbohydrate molecules contribute to the selective permeability of the cell membrane?
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Which of the following is NOT a function of the cell membrane?
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How does the cell membrane contribute to the exchange of gases?
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Which of the following is NOT a function of carbohydrates in the cell membrane?
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Which of these statements BEST describes the role of the cell membrane in maintaining the cell's shape and size?
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Which organ system is primarily responsible for digestion of food particles?
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What is the primary function of the respiratory system?
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How are proteins, lipids, and carbohydrates proportionally composed in the cell membrane?
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What structure of the cell membrane was first proposed by James F Danielli and Hugh Davson?
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Which model of the cell membrane proposed that proteins float in the lipid layer?
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What is the thickness range of the cell membrane mentioned in the content?
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What is the role of the endocrine system in the body?
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Which type of lipid is primarily found in the lipid layer of the cell membrane?
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What distinguishes the fluid mosaic model from the Danielli-Davson model?
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What are the two parts of the cell body?
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Study Notes
Introduction to Cells and Tissues
- Cells are the fundamental units of life, essential for all living organisms.
- Each cell requires nutrition and oxygen, produces energy, eliminates waste, maintains its environment, responds to invaders, and can reproduce, with exceptions like neurons.
- Tissues consist of groups of similar cells and are classified into four primary types: muscle, nervous, epithelial, and connective tissues.
Organs and Organ Systems
- Organs are structures formed from two or more primary tissue types that perform specific functions.
- Types of organs include tubular (hollow) organs and compact (parenchymal) organs.
- Organ systems are groups of interconnected organs that work together for specific bodily functions, such as:
- Digestive system: processes food.
- Excretory system: removes waste.
- Cardiovascular system: transports substances.
- Respiratory system: exchanges gases.
- Reproductive system: facilitates reproduction.
- Endocrine system: regulates growth and bodily functions.
- Musculoskeletal system: provides stability and movement.
- Nervous system: controls activities and intellectual functions.
Structure of the Cell
- Every cell consists of a cell body, a nucleus, and surrounding cytoplasm, all encased by a cell membrane.
Cell Membrane
- The cell membrane, or plasma membrane, is a protective and semi-permeable barrier between extracellular fluid (ECF) and intracellular fluid (ICF).
- Thickness ranges between 75 to 111Å.
- Composed of 55% proteins, 40% lipids, and 5% carbohydrates.
Models of Cell Membrane Structure
- Danielli-Davson Model: Proposed a lipid "sandwich" covered with protein layers.
- Unit Membrane Model: Replaced the previous model, indicating structured layers based on electron microscopy.
- Fluid Mosaic Model: Current model recognizing a dynamic arrangement of proteins floating within a fluid lipid bilayer.
Lipid Layer and Phospholipids
- The lipid layer is bilayered, consisting mainly of phospholipids which have hydrophilic heads and hydrophobic tails.
- Cholesterol is interspersed among phospholipids, maintaining membrane integrity and fluidity.
- The lipid layer's semi-permeability allows fat-soluble substances (e.g., oxygen, carbon dioxide) to pass, while being impermeable to water-soluble substances (e.g., glucose).
Protein Layers in the Cell Membrane
- Composed of integral (transmembrane) proteins that span the membrane and peripheral proteins that are loosely associated.
- Functions of proteins include:
- Structural integrity, transport, and as channels for molecules.
- Serving as receptors for hormones and neurotransmitters.
- Acting as enzymes for metabolic reactions.
Carbohydrates in the Cell Membrane
- Carbohydrates form glycoproteins and glycolipids, contributing to the glycocalyx, a protective layer on the membrane.
- Functions include:
- Restrictions on negatively charged substances.
- Facilitating cell adhesion and signaling through receptor functions.
Functions of the Cell Membrane
- Protective barrier safeguarding the cytoplasm and organelles.
- Selectively permeable to certain substances, enabling nutrient absorption and waste excretion.
- Facilitates gas exchange (oxygen and carbon dioxide).
- Maintains the cell's shape and size.
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Description
Learn about the characteristics of cells, the basic units of life. Discover how cells obtain nutrition, produce energy, and maintain their environment.