cell biology flashcards | IB - Wyatt's Notes
Cell Biology Flashcards
20 flashcards covering IB Biology cell biology — cell theory, prokaryotic vs eukaryotic cells, organelles, membrane structure and transport, and cell division.
Key Concepts
Cell Theory: All living things are made of cells; cells are the basic unit of life; all cells arise from pre-existing cells. This is the foundation of modern biology and was established by Schleiden (plants), Schwann (animals), and Virchow (cell division) in the 19th century. Cell theory explains how organisms grow, repair, and reproduce. It also implies that all life shares fundamental cellular processes.
Prokaryotic vs Eukaryotic Cells: Prokaryotes (bacteria, archaea) have no membrane-bound nucleus or organelles, circular DNA (in a nucleoid region), 70S ribosomes, cell walls (peptidoglycan in bacteria), and are smaller (0.1-5 μm). Eukaryotes (plants, animals, fungi, protists) have a true nucleus with linear DNA, membrane-bound organelles (mitochondria, ER, Golgi, lysosomes), 80S ribosomes, and are larger (10-100 μm). Plant cells additionally have chloroplasts, large central vacuoles, and cellulose cell walls.
Fluid Mosaic Model: The cell membrane is a phospholipid bilayer with embedded proteins (integral — span the membrane; peripheral — on the surface), cholesterol (modulates fluidity), and carbohydrates (cell recognition). The “fluid” refers to the ability of lipids and proteins to move laterally within the bilayer. This structure allows selective permeability — small non-polar molecules pass freely; ions and large polar molecules require transport proteins.
Membrane Transport: Passive transport (no energy required) includes simple diffusion (small non-polar molecules through the bilayer), osmosis (water movement through aquaporins), and facilitated diffusion (polar molecules through channel or carrier proteins). Active transport requires energy (ATP) to move substances against the concentration gradient (e.g., sodium-potassium pump). Endocytosis (phagocytosis, pinocytosis) and exocytosis move large molecules in bulk.
Intuition
Think of a cell as a factory. The nucleus is the CEO’s office (directs operations by controlling gene expression), mitochondria are the power stations (generate ATP through cellular respiration), the ER is the production line (rough ER makes proteins, smooth ER makes lipids), the Golgi is the packaging department (modifies and ships proteins), and the cell membrane is the security gate (controls what enters and leaves). Prokaryotic cells are like small start-up workshops — efficient but limited. Eukaryotic cells are large factories with specialised departments.
Why it matters: Cell biology is the foundation of all biology. Understanding cell structure and function is essential for medicine (disease mechanisms), biotechnology (genetic engineering), and ecology (understanding how organisms interact with their environment). Every living process ultimately occurs at the cellular level.
Common Pitfalls
- Confusing active and passive transport. Passive = no energy required, moves down the concentration gradient (from high to low concentration). Active = requires energy (ATP), moves against the gradient (from low to high concentration). The type of transport determines what the cell can and cannot do.
- Assuming all eukaryotic cells have the same organelles. Plant cells have chloroplasts and large central vacuoles; animal cells have centrioles and lysosomes. Red blood cells lack a nucleus entirely (to maximise haemoglobin space). Fungal cells have chitin cell walls, not cellulose.
- Forgetting that the fluid mosaic model describes structure, not just function. The “mosaic” of proteins in the lipid bilayer is what allows selective permeability — without the proteins, the membrane would be a poor barrier. The fluidity is essential for membrane function.
- Confusing pinocytosis (“cell drinking” — taking in fluid) with phagocytosis (“cell eating” — taking in solid particles). Both are forms of endocytosis but involve different particle types and mechanisms.
Cross-References
- Genetics: Genetics covers DNA structure and protein synthesis, which occur within the cell structures described here.
- Ecology: Ecology studies populations and communities, which are built from cells with the structures and functions described here.
- Molecular Biology: Molecular biology explores DNA, RNA, and protein synthesis at the molecular level within cells.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.
Advanced Content
This section provides detailed coverage of advanced concepts, including full derivations, proofs, and extended examples.
Derivations and Proofs
Complete mathematical derivations and proofs are provided where appropriate. Each step is explained to ensure understanding of the underlying reasoning.
Extended Examples
Advanced examples demonstrate the application of concepts to complex problems. These examples go beyond standard exam questions to develop deeper understanding.
Research Connections
This material connects to current research and advanced applications in the field. Understanding these connections provides context for the study material.
Prerequisites
Ensure you have mastered the prerequisite material before attempting this advanced content.