Cell Biology - Cell Theory & Organelles PDF

3 Points of Cell Theory: 1.​ All living organisms are made up of one or more cells. 2.​ The cell is the basic unit of structure and function in living organisms. 3.​ All cells arise from pre-existing cells. Spontaneous Generation Definition: Spontaneous generation is the outdated and dis...

3 Points of Cell Theory: 1.​ All living organisms are made up of one or more cells. 2.​ The cell is the basic unit of structure and function in living organisms. 3.​ All cells arise from pre-existing cells. Spontaneous Generation Definition: Spontaneous generation is the outdated and disproven hypothesis that living organisms can arise from non-living matter. Louis Pasteur’s Spontaneous Generation Experiment: ​ Experiment: Pasteur conducted an experiment using flasks with swan-necked tubes to prove that microorganisms did not arise spontaneously. He boiled broth to kill existing microbes, and only after exposure to air (through the swan neck) did microbes appear in the broth. ​ Conclusion: Microorganisms come from pre-existing microbes, not spontaneously from non-living matter. Francesco Redi’s Meat Experiment: ​ Experiment: Redi placed meat in jars, with some covered and others left open, to test whether maggots appeared spontaneously. ​ Conclusion: Maggots came only from eggs laid by flies, disproving spontaneous generation for larger organisms. Controlled, Manipulated, and Responding Variable Definitions: ​ Controlled Variable: A factor that is kept constant to ensure a fair experiment. ​ Manipulated (Independent) Variable: The factor that is deliberately changed or tested in the experiment. ​ Responding (Dependent) Variable: The factor that is measured or observed as a result of the change in the manipulated variable. Organelle Definitions/Functions (x12): 1.​ Nucleus: Contains genetic material (DNA); controls cell activities. 2.​ Mitochondria: Powerhouse of the cell; produces energy (ATP) through cellular respiration. 3.​ Ribosomes: Synthesize proteins. 4.​ Endoplasmic Reticulum (ER): ○​ Rough ER: Studded with ribosomes; involved in protein synthesis and transport. ○​ Smooth ER: Involved in lipid synthesis and detoxification. 5.​ Golgi Apparatus: Modifies, sorts, and packages proteins for secretion or use within the cell. 6.​ Lysosomes: Contain digestive enzymes to break down waste and cellular debris. 7.​ Chloroplasts (Plant Cells): Perform photosynthesis, converting sunlight into energy (glucose). 8.​ Vacuoles: Storage organelles for nutrients, water, and waste products (larger in plant cells). 9.​ Cell Membrane: Regulates the movement of substances into and out of the cell. 10.​Cytoskeleton: Provides structure, shape, and support to the cell; aids in movement. 11.​Centrosomes/Centrioles: Play a role in organizing microtubules during cell division. 12.​Peroxisomes: Break down fatty acids and detoxify harmful substances. Organelles Only in Plants: 1.​ Chloroplasts: Responsible for photosynthesis. 2.​ Cell Wall: Provides structure and rigidity to the cell. 3.​ Large Central Vacuole: Maintains cell turgor pressure and stores water, nutrients, and waste. 3 Types of Cell Research and Why They Are Important: 1.​ Microscopy (Light, Electron, Fluorescence): Allows visualization of cell structures and details not visible to the naked eye. Crucial for understanding cell anatomy and processes. 2.​ Cell Culture: Growing cells in a lab setting allows researchers to study cell behavior, genetics, and drug responses. 3.​ Molecular Biology Techniques (PCR, Gel Electrophoresis): These methods enable the study of genetic material and gene expression, essential for understanding diseases and developing treatments. 6 Points of the Cell as an Open System: 1.​ Exchange of Materials: Cells exchange gases, nutrients, and waste with their environment. 2.​ Energy Flow: Cells obtain energy (e.g., from food or sunlight) and release energy through metabolic processes. 3.​ Information Transfer: Cells communicate with each other through signals (e.g., chemical signals) to coordinate activities. 4.​ Homeostasis: Cells regulate their internal environment to maintain stability despite external changes. 5.​ Reproduction: Cells can reproduce (mitosis, meiosis) to create new cells, maintaining the population of the organism. 6.​ Response to Stimuli: Cells can respond to changes in their environment (e.g., temperature, light, or chemical signals). 1. Identify Controlled, Manipulated, and Responding Variables: ​ Controlled Variable: This is the factor that remains constant throughout the experiment. For example, if you’re testing the effect of light on plant growth, the type of soil used would be a controlled variable because it doesn't change. ​ Manipulated (Independent) Variable: This is the factor you intentionally change to test its effect. For example, if you are testing how different light intensities affect plant growth, light intensity is the manipulated variable. ​ Responding (Dependent) Variable: This is the factor that changes as a result of the manipulated variable. For the plant growth experiment, the height of the plant or the number of leaves would be the responding variable, as these would change depending on the light intensity. 2. Calculate Total Magnification: ​ Formula: Total magnification = ocular lens magnification × objective lens magnification. ○​ Example: If your ocular lens is 10x and you are using a 40x objective lens, the total magnification would be: ​ 10x × 40x = 400x total magnification. 3. Estimating Specimen Size Using FOV Diameter × Number of Specimens Across Diameter:  ​ Formula: Estimating specimen size = FOV diameter ÷ number of specimens across the field of view. ○​ Example: If the field of view (FOV) is 100 micrometers and there are 5 specimens across the FOV, the size of each specimen would be: ​ 100 µm ÷ 5 = 20 µm per specimen. 4. Use A = IM (Actual Size = Image Magnification × Magnification): ​ Formula: A = I × M (where A = Actual Size, I = Image Size, M = Magnification). ○​ Example: If the image size is 200 µm and the magnification is 400x, the actual size would be: ​ A = 200 µm ÷ 400 = 0.5 µm. 5. Use M1D1 = M2D2 to Find FOV: ​ Formula: M1 × D1 = M2 × D2 (where M = magnification, D = field of view diameter). ○​ This equation helps you compare the FOV at different magnifications. ○​ Example: If you know the FOV at 40x magnification (D1 = 2 mm) and want to find the FOV at 100x magnification, use: ​ (40x) × (2 mm) = (100x) × (D2) ​ D2 = (40x × 2 mm) ÷ 100x = 0.8 mm. 6. Compare Prokaryotes and Eukaryotes: ​ Prokaryotes: ○​ Single-celled organisms (e.g., bacteria). ○​ No membrane-bound nucleus. ○​ Lack membrane-bound organelles. ○​ Smaller size (~1-5 µm). ○​ Have a simple structure with DNA typically in a nucleoid region. ​ Eukaryotes: ○​ Can be single-celled or multicellular organisms (e.g., animals, plants, fungi). ○​ Have a membrane-bound nucleus. ○​ Contain membrane-bound organelles (e.g., mitochondria, endoplasmic reticulum). ○​ Larger size (~10-100 µm). ○​ More complex structure with compartmentalized functions. 7. Label Organelles of a Plant Cell: ​ Key Plant Cell Organelles: 1.​ Nucleus – Controls the cell’s activities and contains genetic material (DNA). 2.​ Cell Wall – Provides structure and protection. 3.​ Chloroplasts – Carry out photosynthesis to make food for the plant. 4.​ Vacuole – Stores water, nutrients, and waste; helps maintain turgor pressure. 5.​ Mitochondria – Produce energy (ATP) through cellular respiration. 6.​ Endoplasmic Reticulum (ER) – Synthesizes and transports proteins (Rough ER) and lipids (Smooth ER). 7.​ Golgi Apparatus – Modifies, sorts, and packages proteins and lipids for transport. 8.​ Ribosomes – Protein synthesis. 8. Label Organelles of an Animal Cell: ​ Key Animal Cell Organelles: 1.​ Nucleus – Controls the cell’s activities and contains genetic material (DNA). 2.​ Mitochondria – Powerhouse of the cell; produces ATP (energy). 3.​ Endoplasmic Reticulum (ER) – Synthesizes and transports proteins (Rough ER) and lipids (Smooth ER). 4.​ Golgi Apparatus – Packages proteins for export from the cell. 5.​ Lysosomes – Digest waste materials and cellular debris. 6.​ Ribosomes – Protein synthesis. 7.​ Cytoplasm – Gel-like substance where organelles are suspended. 9. Discuss Why Extra Organelles Are in Plant Cells: ​ Plant-Specific Organelles: 1.​ Cell Wall: Provides structural support and protection against mechanical stress and water loss. 2.​ Chloroplasts: Allow plants to perform photosynthesis, producing their own food using sunlight, carbon dioxide, and water. 3.​ Large Central Vacuole: Helps maintain turgor pressure, stores water, nutrients, and waste, and contributes to overall plant cell rigidity. These organelles are crucial for the plant's ability to perform photosynthesis, maintain structural integrity, and store water, all of which are essential for a plant's survival. 1. HeLa Cells:  ​ What They Are: HeLa cells are a famous line of human cancer cells that were derived from a woman named Henrietta Lacks in 1951. Her cells were taken without her consent, but they have been used extensively in scientific research since then. ​ Why They Are Important: HeLa cells are immortal (they continue to divide and grow indefinitely in culture), which makes them valuable for medical and biological research. They have been used to study cancer, test drugs, and investigate diseases such as AIDS and Parkinson’s disease. ​ Applications: These cells have contributed to the development of vaccines (such as the polio vaccine), cancer treatments, and gene therapy. 2. Viruses: ​ What They Are: Viruses are microscopic infectious agents that cannot reproduce or carry out metabolic processes on their own. They require a host cell to replicate. ​ Structure: Viruses consist of a protein coat (capsid) that surrounds their genetic material (either DNA or RNA). Some viruses also have an outer lipid envelope. ​ How They Work: Viruses infect host cells by binding to specific receptors on the cell surface. Once inside, the virus hijacks the host cell’s machinery to replicate its genetic material and assemble new viral particles, often killing the host cell in the process. ​ Examples: The flu virus, the coronavirus (COVID-19), and HIV are all examples of viruses. 3. Stem Cells: ​ What They Are: Stem cells are undifferentiated cells with the ability to develop into various specialized cell types. They are crucial for growth, development, and tissue repair. ​ Types of Stem Cells: ○​ Embryonic Stem Cells: Found in early-stage embryos, these cells are pluripotent, meaning they can differentiate into almost any cell type in the body. ○​ Adult (Somatic) Stem Cells: Found in various tissues in the body, these are multipotent, meaning they can differentiate into a limited number of cell types (e.g., blood stem cells can become various types of blood cells). ○​ Induced Pluripotent Stem Cells (iPSCs): These are adult cells that have been genetically reprogrammed to act like embryonic stem cells, giving them the ability to differentiate into many different cell types. ​ Applications: Stem cells are used in regenerative medicine to treat diseases such as leukemia, spinal cord injuries, and even in experimental treatments for conditions like heart disease and neurodegenerative disorders. 4. Gene Editing: ​ What It Is: Gene editing refers to the techniques used to modify an organism’s DNA, allowing for the precise insertion, deletion, or alteration of genetic material. ​ CRISPR-Cas9: One of the most widely used gene-editing technologies. It uses a guide RNA to target specific parts of the genome and an enzyme (Cas9) to cut the DNA at the desired location, allowing for the insertion of new genetic material or the removal of faulty genes. ​ Applications: Gene editing holds great promise for treating genetic disorders, such as sickle cell anemia and cystic fibrosis, by correcting mutations at the DNA level. It is also used in research to study genes and their functions and has potential applications in agriculture to create crops with desirable traits. 5. HIV (Human Immunodeficiency Virus): ​ What It Is: HIV is a virus that attacks the immune system, specifically the CD4+ T cells (a type of white blood cell), which are crucial for the body's defense against infections. ​ How It Works: HIV binds to and enters CD4 cells, using the cell’s machinery to replicate. Over time, this weakens the immune system, leaving the body vulnerable to opportunistic infections and certain cancers. If untreated, HIV can progress to AIDS (Acquired Immunodeficiency Syndrome), the final stage of HIV infection, where the immune system is severely compromised. ​ Transmission: HIV is primarily spread through blood, semen, vaginal fluids, and breast milk, often through unprotected sexual contact, sharing needles, or from mother to child during childbirth or breastfeeding. ​ Treatment: While there is no cure for HIV, it can be managed with antiretroviral therapy (ART), which involves taking a combination of medications to lower the viral load and maintain immune function. Early diagnosis and treatment can help people with HIV live long, healthy lives.