Science Techniques Flashcards
What are the main differences between in vivo, in vitro, and ex vivo experiments?
In Vivo refers to experiments performed on whole, living organisms. This method is used in disease models, behavioral studies, and testing drug safety and efficacy.
In Vitro involves tests performed on isolated cells, tissues, or organs outside of a living organism, such as in cell culture.
Ex Vivo involves studying tissues outside the body, maintaining the tissue’s natural state with minimal alteration. This is useful in pharmacology and investigating issues not observed in vivo.
What is the purpose of using humanized animal models in research?
Humanized animal models are immunodeficient animals transplanted with human cells, such as peripheral blood mononuclear cells (PBMCs) or human hematopoietic stem cells. These models are primarily used for cancer, infectious disease, and autoimmune disease research, as they allow researchers to study human-like immune responses and disease processes in a living organism.
What is the significance of the Genetically Engineered Mouse Model (GEMM)?
The Genetically Engineered Mouse Model (GEMM) is used in research to study gene functions and disease mechanisms. These mice are genetically modified by integrating foreign genes into their genomes (transgenic) or altering existing genes (knockout or knock-in). This model helps to investigate the role of specific genes in diseases, including cancer, cardiovascular diseases, and neurological disorders.
How does flow cytometry work and what are its applications?
Flow cytometry measures the physical and chemical characteristics of cells or particles by passing them through a laser beam. The scattered light and fluorescence emitted by cells labelled with fluorescent markers are measured. Flow cytometry is used for cell counting, diagnosing health disorders, biomarker detection, and analysing cellular functions, including protein expression and cell activation.
What is the difference between ELISA and Western Blot techniques?
ELISA (Enzyme-Linked Immunosorbent Assay) detects proteins in liquid samples using antibodies that bind to specific antigens, producing a detectable signal like a color change.
Western Blot separates proteins by size using gel electrophoresis and transfers them onto a membrane, where specific proteins are detected using primary and secondary antibodies. The main difference is that ELISA is used for liquid samples, whereas Western Blot is typically used for tissue homogenates or cell extracts.
How does immunohistochemistry (IHC) help in cancer research?
Immunohistochemistry (IHC) is a technique used to identify specific proteins in tissue samples by using antibodies that bind to antigens. In cancer research, IHC helps detect tumor markers and the presence of certain proteins associated with cancer progression. It can be performed using chromogenic methods (which produce color reactions) or immunofluorescence (which uses fluorescent markers), allowing detailed visualization of proteins in cancerous tissues.
What is the Langendorff technique and its purpose in cardiovascular research?
The Langendorff technique involves isolating a heart and perfusing it with a saline solution to sustain it for several hours outside the body. This method allows researchers to measure the heart’s contraction, heart rate, coronary flow, and electrical properties in a controlled environment. It is often used in cardiovascular research to study heart function, drug effects, and cardiac disease mechanisms.
What is an immunocompetent animal model and how is it different from an immunodeficient model?
An immunocompetent animal model has a fully functional immune system and is capable of mounting normal immune responses after exposure to antigens. This model is used to study immune system interactions and responses.
In contrast, an immunodeficient model lacks a functional immune system, meaning it cannot reject foreign cells. This model is often used in cancer research, where human cells or tissues are transplanted into these animals without being rejected by the immune system.
How does a xenograft animal model contribute to cancer research?
A xenograft animal model involves transplanting human tumor cells or tissues (often patient-derived) into an immunodeficient animal. These models are valuable in cancer research as they mimic the growth of human tumors in a living organism, allowing researchers to study tumor biology, test potential treatments, and understand how human cancers behave in vivo.
What is the role of hepatocytes in the liver’s functions?
Hepatocytes are the primary functional cells of the liver, making up about 60% of the liver’s cell population. They are involved in a wide range of metabolic processes, including protein synthesis, detoxification, bile production, and nutrient storage. Hepatocytes play a critical role in drug metabolism and the regulation of blood glucose, cholesterol, and fatty acids.
How does the liver’s dual blood supply contribute to its metabolic functions?
he liver receives blood from two distinct sources: approximately 75% of the blood comes from the portal vein, carrying nutrient-rich blood from the gastrointestinal tract, while 25% is supplied by the proper hepatic artery, which provides oxygenated blood from the heart. This dual blood supply allows the liver to process absorbed nutrients from the intestines and also receive oxygen and other essential molecules required for its metabolic and detoxification functions.
What is the significance of bile production in the liver?
Bile is produced by hepatocytes in the liver and plays a key role in fat digestion and absorption. It contains water, electrolytes, bilirubin, cholesterol, and bile salts. Bile is secreted into the duodenum, where it emulsifies fats, aiding in their digestion. The liver also uses bile to eliminate waste products, such as bilirubin and excess cholesterol, from the body.
What is the difference between primary cells and immortalized cell lines in cell culture?
Primary cells are directly isolated from living organisms and maintain many of the characteristics of the tissue from which they were derived. However, they have a limited lifespan and can only divide a certain number of times.
Immortalized cell lines, on the other hand, are cells that have been genetically altered to bypass normal growth limitations and can proliferate indefinitely. They are often used in long-term studies, drug testing, and basic research.
How does the Ussing chamber measure ion or solute flux across epithelial cells?
The Ussing chamber is used to measure ion or solute transport across epithelial cell layers, such as those found in the gut or lungs. This technique applies an electric potential across the epithelial tissue to measure ion flux or solute movement. Unlike electrophysiology, which records electrical currents, the Ussing chamber is particularly useful for studying transporters that do not generate electrical signals.
What is the purpose of using calcium imaging in cellular research?
Calcium imaging involves tracking calcium ions in cells, often using fluorescent indicator dyes. Since calcium ions play a crucial role in various cellular processes, such as muscle contraction, signal transduction, and neurotransmission, calcium imaging allows researchers to monitor real-time cellular activities and responses to stimuli. It is particularly useful for studying dynamic processes in excitable cells, such as neurons and muscle cells.
