Untitled Quiz

In vivo modeling offers a controlled environment for studying biological processes.
Scientists can manipulate factors like pH, temperature, humidity, osmotic pressure, carbon dioxide, and osmolarity to mimic physiological conditions.
It's crucial to control nutrient concentrations and hormone levels to ensure proper cell function.

### Economy, Scale, and Mechanization

In vivo modeling uses lower volumes and concentrations of reagents, making it cost-effective for screening numerous variables.
The use of 96-well trays in high-throughput screening further reduces costs.
Quantitation is simplified by the standardized format.
Ethical concerns surrounding animal experimentation are eliminated.
Automation and microtitration using small liquid volumes streamline the process.

### Homogeneity of Sample/Cell Line

Cell lines derived from tissues are initially heterogeneous but can be made homogenous through subculturing and multiple passages.
This homogeneity is achieved through selective pressure of culture conditions, use of selective media, and cloning.
Replicates reduce the statistical analysis needed for variance.
Preservation of cell lines in liquid nitrogen or ultralow freezers at -78 to -80°C ensures long-term storage.

### Importance of Cell and Tissue Culture

This technique plays a critical role in understanding the biology of cells from multicellular organisms.
It provides an in vitro model for studying tissues in a controlled environment.
Researchers can easily manipulate and analyze cells and tissues in culture.

The development of monoclonal antibody technology was made possible through cell culture.
Provides valuable insights into antibody mechanisms of action.
Allows researchers to study gene expression, cell interactions, and intracellular control mechanisms.
Crucial for understanding cell differentiation and development.

### Limitations of Cell Culture

Expertise is required for proper technique and maintenance.
Cell culture is often limited by quantity, as it can be challenging to grow large numbers of cells.
Dedifferentiation and selection of cells during culture can influence results.
The origin of cells and their potential for changes in their original characteristics during culture must be considered.
Increased DNA polymerase and DNA synthesis, often observed in culture, can introduce artifacts.

### Log Phase

Characterized by exponential cell growth.
This phase terminates after cell confluence is reached, typically within one to two population doublings.
The length of the log phase is influenced by seeding density, cell growth rate, and the density that inhibits proliferation.
Cells are randomly distributed in the cell cycle during the log phase,necessitating cell synchronization for specific experiments.

### Plateau Phase

### Confluency

Refers to the percentage of surface area covered by cells.
50% confluent means half of the surface is covered, allowing for further cell growth.
100% confluence indicates that the surface is completely covered by cells, with no space for further growth as a monolayer.

### Kinetics of Cell Culture

Understanding the kinetics of cell culture is crucial for optimizing growth and experimentation.
Factors like growth rate, cell doubling time, and cell cycle are important variables.
Cell cultures involve a variety of different phases, such as lag phase, log phase, and stationary phase.

### Buffering of Culture Media

Open cultures are susceptible to pH changes due to carbon dioxide evolution, which can cause pH to rise and bicarbonate to decrease.
High cell concentration in transformed cell lines can lead to overproduction of CO2 and lactic acid, resulting in a decrease in pH.
Bicarbonate can be incorporated into the media or added exogenously to prevent loss of CO2 and bicarbonate from the medium.

The pH of biological fluids must be near neutral (pH 7.0) for optimal cell survival.
Cell survival is generally observed at pH 6.6 to 7.8.
Optimal cell growth usually falls between pH 7.2 and 7.4.
Cell death can occur within 24 hours if pH falls below 6.8 or rises above 7.8.

### Characterization

Cytology provides information about the structure and function of cells
Immunostaining uses antibodies to detect specific proteins in samples.
Immunohistochemistry, using fluorescent dyes and enzymes, is used for cell labeling.
Flow cytometry analyzes cell populations by detecting their physical and chemical characteristics.

### Advantages of Tissue Culture

### Blood

Easily accessible and collected.
Simple to handle and culture.
Has a shorter growth curve compared to other cell types.
Can be cultured as whole blood (microculture) or as separated lymphocytes (macroculture).

### Primary Cell Culture

Cells are directly isolated and cultured from a subject.
Cells proliferate under appropriate conditions until confluent, at which point they can be harvested or subcultured (passaged).
Subculturing involves transferring cells to a new vessel and providing fresh medium.
Primary cell cultures have a limited growth potential and finite lifespan.

### Primary Cell Culture (continued)

Maintenance and growth of cells directly removed from the tissue or original source.
Tissue is mechanically disaggregated or enzymatically digested (e.g., using collagenase, trypsin, DNase) to produce smaller pieces or single cells.

### Types of Cell Culture Technique

Microculture: Uses whole blood.
Macroculture: Involves separating lymphocytes from whole blood using density gradient centrifugation.

### Macroculture Technique

### Cells/ml = Average Cell Count x 11 * 10,000 / 10⁶

This formula is used to calculate cell density per milliliter.
The hemocytometer is a specialized counting chamber used for determining cell number.

### Cell Viability

Cell viability refers to the percentage of live cells in a culture.
It's calculated by subtracting the number of dead cells from the total cell count and dividing by the total cell count.