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Questions and Answers
What primarily composes the plasma membrane of a cell?
What primarily composes the plasma membrane of a cell?
- Cholesterol molecules
- Protein layers
- Carbohydrate chains
- Phospholipid bilayer (correct)
Which of the following components is NOT part of the cell's anatomy?
Which of the following components is NOT part of the cell's anatomy?
- Chloroplast (correct)
- Nucleus
- Cytoplasm
- Plasma membrane
What role does the cytoplasm serve within the cell?
What role does the cytoplasm serve within the cell?
- Protects the nucleus from damage
- Activates cellular transport
- Stores genetic information
- Suspends organelles in a gel-like substance (correct)
How is the plasma membrane described in terms of its structure?
How is the plasma membrane described in terms of its structure?
Which type of transport does NOT require energy?
Which type of transport does NOT require energy?
What is the main function of the nucleus in a cell?
What is the main function of the nucleus in a cell?
What feature characterizes the phospholipid bilayer?
What feature characterizes the phospholipid bilayer?
Active transport in a cell requires which of the following?
Active transport in a cell requires which of the following?
What is the term for the movement of water across a semi-permeable membrane?
What is the term for the movement of water across a semi-permeable membrane?
If red blood cells are in a hypertonic solution, what effect is observed?
If red blood cells are in a hypertonic solution, what effect is observed?
What describes a situation where RBCs are in an isotonic solution?
What describes a situation where RBCs are in an isotonic solution?
Which of the following best describes the movement of water in a hypotonic solution for red blood cells?
Which of the following best describes the movement of water in a hypotonic solution for red blood cells?
What defines a solution that has a higher solute concentration compared to another solution?
What defines a solution that has a higher solute concentration compared to another solution?
What characteristic of the plasma membrane allows some substances to pass while preventing others?
What characteristic of the plasma membrane allows some substances to pass while preventing others?
How do water-soluble materials primarily cross the plasma membrane?
How do water-soluble materials primarily cross the plasma membrane?
In the context of tonicity, what is an isotonic solution?
In the context of tonicity, what is an isotonic solution?
If Side A of a beaker has a higher concentration of solutes than Side B, what term describes Side A?
If Side A of a beaker has a higher concentration of solutes than Side B, what term describes Side A?
What does a concentration gradient refer to?
What does a concentration gradient refer to?
What would occur if a cell is placed in a hypertonic solution?
What would occur if a cell is placed in a hypertonic solution?
Which materials are likely to cross the plasma membrane without assistance?
Which materials are likely to cross the plasma membrane without assistance?
What is the primary function of a semi-permeable membrane in a biological system?
What is the primary function of a semi-permeable membrane in a biological system?
What is the electrical gradient in nerve cells relative to their extracellular environment?
What is the electrical gradient in nerve cells relative to their extracellular environment?
What process involves the transport of substances into the cell by surrounding them with a portion of the cell membrane?
What process involves the transport of substances into the cell by surrounding them with a portion of the cell membrane?
Which type of endocytosis is specifically aimed at large particles to be digested?
Which type of endocytosis is specifically aimed at large particles to be digested?
What is the purpose of receptor-mediated endocytosis?
What is the purpose of receptor-mediated endocytosis?
What is the role of exocytosis in a cell?
What is the role of exocytosis in a cell?
Which component is NOT part of the cytoplasm?
Which component is NOT part of the cytoplasm?
What best describes the intracellular environment of a cell?
What best describes the intracellular environment of a cell?
Which of the following correctly describes active transport?
Which of the following correctly describes active transport?
What substance does the nucleolus manufacture that is necessary for ribosome construction?
What substance does the nucleolus manufacture that is necessary for ribosome construction?
Which type of cytoskeletal fiber is primarily involved in muscle contraction?
Which type of cytoskeletal fiber is primarily involved in muscle contraction?
What is the primary function of cilia in the respiratory tract?
What is the primary function of cilia in the respiratory tract?
Which part of the cytoskeleton helps resist tension and forms cell-to-cell junctions?
Which part of the cytoskeleton helps resist tension and forms cell-to-cell junctions?
What is the main structure of microvilli?
What is the main structure of microvilli?
Which structure assists with the separation of DNA during cell division?
Which structure assists with the separation of DNA during cell division?
Which of the following is NOT a function of the cytoskeleton?
Which of the following is NOT a function of the cytoskeleton?
What is the primary structural component of microtubules?
What is the primary structural component of microtubules?
What ultimately drives sperm cell movement?
What ultimately drives sperm cell movement?
Which type of fiber in the cytoskeleton is primarily used for structural integrity and resisting compression?
Which type of fiber in the cytoskeleton is primarily used for structural integrity and resisting compression?
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Study Notes
Cellular Level of Organization Overview
- The cell is the basic unit of life, organized into various structures and compartments.
- The plasma (cell) membrane is a phospholipid bilayer that separates the cell from its environment.
Main Components of a Cell
- Plasma Membrane: Fluid structure that controls substance movement.
- Cytoplasm: Gel-like substance consisting of organelles and cytosol.
- Nucleus: Membranous structure containing genetic material, located near the cell's center.
Plasma Membrane Characteristics
- Selectively permeable, allowing certain substances to pass while blocking others.
- Water moves through protein channels or between phospholipid tails.
- Small nonpolar molecules and gases can easily penetrate; water-soluble substances are restricted.
Movement Across Membranes
- Semi-permeable membranes allow selective movement of substances.
- Concentration gradients dictate movement, influencing diffusion and osmosis.
Tonicity Definitions
- Isotonic Solution: Equal solute concentration compared to another solution.
- Hypotonic Solution: Lower solute concentration (higher water concentration).
- Hypertonic Solution: Higher solute concentration (lower water concentration).
Effects of Tonicity on Red Blood Cells (RBCs)
- In isotonic solutions, water balance is maintained; RBCs remain stable.
- In hypertonic solutions, water exits RBCs, causing shrinkage (crenation).
- In hypotonic solutions, water enters RBCs, leading to swelling or potential lysis.
Electrical Gradient
- Nerve cells maintain an electrical gradient of -70 mV relative to their environment, crucial for impulse transmission.
Active Transport Mechanisms
- Endocytosis: Material intake through vesicle formation from the cell membrane.
- Phagocytosis: Engulfing of large particles.
- Pinocytosis: Uptake of fluids and solutes.
- Receptor-mediated Endocytosis: Specific uptake via binding to cell surface receptors.
- Exocytosis: Export of materials like hormones from the cell via vesicles.
Cytoplasm and Organelles
- Cytoplasm: Contains cytosol and organelles, providing the internal environment of the cell.
- Nucleoplasm: Gel-like substance within the nucleus housing nucleic acids.
- Nucleolus: Synthesizes RNA required for ribosome formation.
Cytoskeleton Structure and Function
- Composed of fibrous proteins, maintaining cell structure and motility.
- Microfilaments: Thin structures that aid in cell contraction and division.
- Intermediate Filaments: Provide resistance to tension and anchor organelles.
- Microtubules: Thickest fibers that resist compression and organize cellular components.
Cell Extensions
- Cilia: Composed of microtubules, found in respiratory tract, assist with movement of particles.
- Microvilli: Projections increasing surface area for enhanced nutrient absorption in the small intestine.
- Flagellum: Propels sperm cells towards the egg, structured with microtubules.
- Centriole: Located in dividing cells, aids in DNA separation during cell division.
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