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Questions and Answers
What is the primary effect of osmosis in a hypotonic solution on a cell?
What is the primary effect of osmosis in a hypotonic solution on a cell?
- The cell will swell and may burst. (correct)
- The cell will become more rigid.
- The cell will remain unchanged.
- The cell will shrink and lose function.
Which transport method uses energy to move substances against their concentration gradient?
Which transport method uses energy to move substances against their concentration gradient?
- Simple diffusion
- Active transport (correct)
- Facilitated diffusion
- Osmosis
What occurs to a cell placed in a hypertonic solution?
What occurs to a cell placed in a hypertonic solution?
- The cell shrinks and crenates. (correct)
- Water enters the cell rapidly.
- The cell maintains its normal shape.
- The cell swells and becomes larger.
Which statement is true regarding simple diffusion?
Which statement is true regarding simple diffusion?
What term describes the process when the cell membrane engulfs material from outside the cell?
What term describes the process when the cell membrane engulfs material from outside the cell?
What is the primary function of the plasma membrane?
What is the primary function of the plasma membrane?
Which part of the cell contains the DNA?
Which part of the cell contains the DNA?
What is cytosol primarily composed of?
What is cytosol primarily composed of?
Which model describes the arrangement of molecules in the plasma membrane?
Which model describes the arrangement of molecules in the plasma membrane?
What role do integral proteins play in the plasma membrane?
What role do integral proteins play in the plasma membrane?
What are chromosomes made up of?
What are chromosomes made up of?
What substance acts as a barrier to certain substances within the plasma membrane?
What substance acts as a barrier to certain substances within the plasma membrane?
Which type of protein is most likely to span the entire lipid bilayer?
Which type of protein is most likely to span the entire lipid bilayer?
What is the outcome of meiosis 1?
What is the outcome of meiosis 1?
During which phase are two identical nuclei formed?
During which phase are two identical nuclei formed?
What is the primary purpose of cytokinesis?
What is the primary purpose of cytokinesis?
How many chromosomes do gametes contain?
How many chromosomes do gametes contain?
What restores the diploid number of chromosomes after fertilization?
What restores the diploid number of chromosomes after fertilization?
What distinguishes active diffusion from passive diffusion?
What distinguishes active diffusion from passive diffusion?
What is the end result of meiosis 2?
What is the end result of meiosis 2?
Which of the following statements about haploid cells is correct?
Which of the following statements about haploid cells is correct?
Which of the following correctly describes isotonic solutions?
Which of the following correctly describes isotonic solutions?
Which process occurs in the gonads to produce gametes?
Which process occurs in the gonads to produce gametes?
What is the main process through which water moves across a selectively permeable membrane?
What is the main process through which water moves across a selectively permeable membrane?
What type of endocytosis involves the engulfing of large particles or cells?
What type of endocytosis involves the engulfing of large particles or cells?
What is the role of aquaporins in cellular transport?
What is the role of aquaporins in cellular transport?
Which of the following correctly describes the sodium-potassium pump?
Which of the following correctly describes the sodium-potassium pump?
What is the primary function of ribosomes in the cell?
What is the primary function of ribosomes in the cell?
Which cytoskeletal component is involved in providing structural support and intracellular transport?
Which cytoskeletal component is involved in providing structural support and intracellular transport?
Which process involves the fusing of vesicles with the plasma membrane to release their contents?
Which process involves the fusing of vesicles with the plasma membrane to release their contents?
What type of facilitated diffusion specifically involves the movement of potassium ions?
What type of facilitated diffusion specifically involves the movement of potassium ions?
What is transcytosis?
What is transcytosis?
Which cellular component is primarily responsible for moving fluids along the cell surface?
Which cellular component is primarily responsible for moving fluids along the cell surface?
What is the main function of ribosomes in the cytosol?
What is the main function of ribosomes in the cytosol?
Which organelle is primarily involved in the modification and packaging of proteins?
Which organelle is primarily involved in the modification and packaging of proteins?
What is the primary role of lysosomes?
What is the primary role of lysosomes?
Which structure is mainly responsible for detoxifying harmful substances, including alcohol?
Which structure is mainly responsible for detoxifying harmful substances, including alcohol?
In which phase of the cell cycle does DNA replication occur?
In which phase of the cell cycle does DNA replication occur?
What cellular structure is known as the 'powerhouse' of the cell?
What cellular structure is known as the 'powerhouse' of the cell?
What distinguishes somatic cells in humans?
What distinguishes somatic cells in humans?
Which part of the nucleus allows for the movement of substances between the nucleus and cytoplasm?
Which part of the nucleus allows for the movement of substances between the nucleus and cytoplasm?
During which mitotic phase do the chromatin fibers condense into visible chromosomes?
During which mitotic phase do the chromatin fibers condense into visible chromosomes?
What is the purpose of the cytoskeleton within the cell?
What is the purpose of the cytoskeleton within the cell?
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Study Notes
The Cellular Level of Organization
- Plasma membrane acts as the outer boundary of the cell, separating internal and external environments while being selectively permeable.
- Cytoplasm contains all cell contents between plasma membrane and nucleus, including cytosol (fluid portion) and organelles (subcellular structures).
- Fluid mosaic model describes the membrane's structure, with lipids forming a barrier and proteins acting as gatekeepers for substances.
Nucleus
- The nucleus is a large organelle housing DNA and chromosomes, which contain genes, the hereditary units of the cell.
- The nuclear envelope consists of a double membrane with nuclear pores regulating transport in and out.
Membrane Structure
- Composed of a lipid bilayer featuring phospholipids, cholesterol, and glycolipids.
- Integral proteins (transmembrane and peripheral) are embedded within or attached to the membrane surface.
Transport Mechanisms
- Transport through membranes can occur via:
- Facilitated Diffusion: Channel-mediated or carrier-mediated for diffusing molecules.
- Active Transport: Uses energy to move substances against concentration gradients (e.g., Na+/K+ pump).
- Osmosis: Movement of water across a selectively permeable membrane from high water concentration to low water concentration.
- Vesicular Transport: Involves endocytosis (intake of materials), exocytosis (release of materials), and transcytosis (combined transport).
Types of Endocytosis
- Receptor-mediated Endocytosis: Selective uptake following ligand binding.
- Phagocytosis: Cell “eating” to incorporate larger particles.
- Bulk-phase Endocytosis (Pinocytosis): Non-specific uptake of fluid.
Organelles
- Centrosome: Contains centrioles and pericentriolar material, plays a role in cell division.
- Cilia and Flagella: Hair-like structures aiding in movement; cilia move fluids, while flagella facilitate the movement of entire cells.
- Ribosomes: Sites for protein synthesis, either free or attached to endoplasmic reticulum (ER).
- Endoplasmic Reticulum (ER):
- Rough ER is involved in protein production due to ribosomes.
- Smooth ER synthesizes lipids and detoxifies drugs.
- Golgi Complex: Modifies, sorts, and packages proteins using cisternae.
- Lysosomes: Contain digestive enzymes, involved in breaking down waste.
- Peroxisomes: Detoxify harmful substances such as alcohol.
- Proteasomes: Degrade damaged or unneeded proteins.
Mitochondria
- Known as the cell’s powerhouses, generating ATP through cellular respiration.
- Feature double membranes with inner folds called cristae and a central matrix.
Cell Division
- Somatic Cell Division (Mitosis): Divides a body cell into two identical daughter cells containing the same chromosome number (diploid, 46 chromosomes).
- Interphase consists of G1, S (DNA replication), and G2 phases.
- The mitotic phase involves prophase, metaphase, anaphase, and telophase.
- Reproductive Cell Division (Meiosis): Reduces chromosome number by half to create haploid gametes (23 chromosomes), occurring in gonads.
- Includes two rounds: meiosis I and II.
Solutions and Tonicity
- Isotonic Solution: Equal solute concentrations, maintaining cell shape and size.
- Hypotonic Solution: Lower external solute concentration, leading to cell swelling and potential lysis.
- Hypertonic Solution: Higher external solute concentration, causing cell shrinkage (crenation).
Diffusion Types
- Passive Diffusion: No energy required, movement driven by concentration gradients.
- Active Transport: Energy-dependent movement against gradients, utilizing ATP for ion transport (e.g., sodium/potassium exchange).
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