Cell Biology Overview Quiz

Key Area 1: Laboratory Techniques for Biologists

• Health and Safety: Laboratory hazards include toxic chemicals, heat, flammable substances, pathogenic organisms, and mechanical equipment.
• Risk Assessment: Risk is the likelihood of harm arising from exposure to a hazard. Risk assessment identifies control measures to minimize risk. These include appropriate handling techniques, protective clothing and equipment, and aseptic techniques.
• Learning Activities: Students should learn standard lab rules and risk assessment procedures.

Key Area 1: Liquids and Solutions

• Dilution Types: Linear dilutions have equal intervals (e.g., 0.1, 0.2, 0.3...). Log dilutions have constant proportions (e.g., 10⁻¹, 10⁻², 10⁻³...).
• Equipment: Students should become familiar with measuring cylinders, pipettes, burettes, autopipettes, and syringes.

Key Area 2: Production of a Standard Curve

• Determining an Unknown: Plotting measured values for known concentrations creates a line or curve; this allows determination of the unknown concentration.
• Use of Buffers: Maintaining a constant pH (e.g., using buffers) during experiments is important to control the reaction mixture.
• Colorimeters and Spectrophotometers: Calibration with a blank provides a baseline; absorbance measures concentration of colored solutions; percentage transmission gauges turbidity (e.g., in cells).

Key Area 3: Separation Techniques

• Centrifugation: More dense components settle at the bottom (pellet), while less dense ones remain on top (supernatant).
• Chromatography: Techniques like paper and thin layer chromatography separate substances based on differing solubilities in solvents.

Key Area 4: Principle of Affinity Chromatography

• Separating Proteins: A solid matrix or gel column is created with specific molecules. Target proteins with high affinity attach; other molecules are washed out.

Key Area 4: Principle of Gel Electrophoresis

• Separating Substances: Charged molecules move through an electric field applied to a gel matrix. Used to separate proteins and nucleic acids.
• Native Gels: Do not denature molecules, separating based on shape, size, and charge.
• SDS-PAGE: Denatures molecules resulting in separation by size only.
• Isoelectric Point (IEP): A pH where a protein has no net charge and readily precipitates out of solution. Electrophoresis in an IEP gradient stops a protein at its IEP.

Key Area 5: Detecting Proteins

• Immunoassay: Techniques use antibodies to detect and identify specific proteins.
  • Monoclonal Antibodies (MAbs): Stocks of antibodies with identical specificity, linked to a chemical label.
• ELISA (Enzyme-linked immunosorbent assay): A technique to detect specific antigens using enzyme-linked antibodies.
• Western Blotting: Separated proteins from SDS-PAGE are transferred to a solid medium for detection.

Key Area 6: Microscopy

• Bright-field Microscopy: Used to observe whole organisms, sections of dissected tissue, or individual cells.
• Fluorescence Microscopy: Specific fluorescent labels bind to and visualize molecules or structures within cells or tissues.

Key Area 7: Aseptic Techniques and Cell Culture

• Sterilization: Aseptic techniques eliminate unwanted microbes by sterilising equipment and culture media.
• Contaminants: Proper techniques prevent contamination.
• Culture Media: Growth of specific microbes is promoted.

Key Area 8: Animal Cells in Culture

• Growth Factors: Proteins promoting cell growth and proliferation are essential for animal cell culture.
• Cell Lines: Primary cell lines divide a limited number of times; tumor cell lines divide indefinitely.
• Plating and Counting: Plating out microbial cultures on solid media; counting colony-forming units estimates cell density.
• Haemocytometer: A tool for estimating cell numbers in liquid culture.

Key Area 9: Proteins

• The Proteome: The entire set of proteins expressed by a genome. The proteome is larger than the number of genes, especially in eukaryotes.

Key Area 9 (b): Intracellular and Transport of Proteins

• Intracellular Membranes: Eukaryotic cells have internal membranes increasing the total membrane surface area used for various functions

Key Area 9 (ii): Synthesis of Membrane Components

• Lipids and Proteins: Synthesised in the ER.
• Rough ER vs Smooth ER: Rough ER has ribosomes; smooth ER lacks ribosomes.
• Vesicles: Transport materials between organelles.

Key Area 10: The Secretory Pathway

• Secreted Proteins: Synthesized on ribosomes, enter the RER lumen, travel through Golgi, packaged into secretory vesicles, and released from the cell.
• Proteolytic Cleavage: Many secreted proteins are inactive precursors requiring cleavage to become active proteins.

Key Area 11: Amino Acid Sequence

• Peptide Bonds: Amino acids are linked by peptide bonds to form polypeptide chains.
• R Group Differences: Diversity in R groups account for the diversity of protein function.

Key Area 11 (ii): Ligand Binding

• Ligands and Conformational Change: Ligands, substances that bind to a protein, cause conformational changes in the protein to initiate a function.
• Allosteric Interactions: Interactions between spatially distinct sites, including binding sites, that can influence protein function.
• Allosteric Proteins: Exhibit cooperativity in binding/function. Protein changes shape when a binding site ligand binds.

Key Area 12: Post-Translational Protein Modifications

• Enzyme Phosphorylation: Phosphorylation cascades, triggered by protein kinases and phosphatases, modify protein activity.
• Conformation Changes: Phosphorylation alters the protein's three-dimensional structure, enabling or inhibiting some functions.

Key Area 13: Membrane Proteins

• Fluid Mosaic Model: Membranes are fluid structures with proteins embedded within a phospholipid bilayer.
• Types of Proteins: Integral proteins extend through the membrane; peripheral proteins are bound to the surface.

Key Area 14: Transport Across Membranes

• Passive Transport: Movement along the concentration gradient, exemplified by simple and facilitated diffusion.
• Active Transport: Requires energy (often ATP hydrolysis) to move substances against their concentration gradient.
• Ion Channels and Gradients: Channels allow ion passage; ion pumps maintain ion gradients.

Key Area 15: Membrane proteins, communication and signalling

• Cell signalling: Communication between cells through extracellular signalling molecules.
• Hormones, peptide & neurotransmitters: Examples of extracellular signalling molecules.
• Hydrophilic vs. hydrophobic signalling: Hydrophobic signalling molecules (e.g., steroid hormones) can pass directly through cell membranes binding to intracellular receptors; hydrophilic ones (e.g., peptide hormones) bind to transmembrane receptors which triggers signal transduction.
• Receptor Molecules: Specific proteins on target cells, binding to signalling molecules eliciting a response (like insulin to GLUT4).
• Signal Transduction: Binding of the ligand changes the receptor conformation triggering responses within the cell.

Key Area 16: Other Processes

• Nerve Impulse Transmission: Resting membrane potential; action potential is a wave of electrical excitation across a neuron, involving changes in ion permeability through membrane ion channels.
• Neurotransmitters: Initiate responses by binding to receptors.
• Post-Translational Modification: Process after the protein has been made, that causes changes to its structure and/or activity.

Key Area 17: Co-Evolution

• Symbiotic Relationships: Co-evolution occurs between species interacting intimately, with positive (+/+), negative (-/-) or neutral (+/0) consequences.

Key Area 18: Cell Cycle and Apoptosis

• Cell Cycle Phases: Sequence of events leading to cell division; includes interphase, mitosis and cytokinesis, with specific checkpoints.
• Metaphase Checkpoint: Progression is halted until chromosomes are aligned and attached to spindle microtubules.
• Apoptosis: Triggered by external or internal signals leading to programmed cell death by activating caspases (proteases).