Week 6: Cell Culture and Cell Growth

Cell Division

The process by which a parent cell divides into two or more daughter cells.

Bacterial Cell Division

Involves DNA replication, cell elongation, cross wall formation, and separation into daughter cells.

Yeast Cell Division

Involves budding, nuclear division, and formation of a new yeast cell from a parent cell.

Mold Cell Division

Involves conidiophores, hyphae, and formation of conidia for reproduction.

Plant Cell Division

Involves interphase, preprophase, metaphase, anaphase, telophase, and cell plate formation.

Animal Cell Division

Involves prophase, metaphase, anaphase, telophase, and cytokinesis.

Mitotic Differences in Eukaryotic Organisms

Differences in centrosomes, nuclear envelope, cytokinesis, cell shape, mitosis duration, checkpoints, and regulation.

Cell Culture

The process of growing cells under controlled conditions outside their natural environment.

Suspension Cultures

Cells grow freely in the culture medium without requiring attachment.

Adherent Cultures

Cells require attachment to a surface to grow and proliferate.

Cell Passaging

The process of transferring cells to fresh growth medium to maintain healthy populations.

Cell Culture Media

Nutrient-rich gel or solution used to support cell growth, survival, and proliferation.

Solid Medium

Contains gelling agents like agar for colony formation or adherent cells.

Liquid Medium

Supports suspension cultures like bacteria, yeast, and some mammalian cells.

Undefined Medium

Contains complex ingredients like yeast extract or serum, making composition variable.

Defined Medium

A culture medium with an exact, known composition, used for controlled experiments and GMP applications.

Specialized Medium

Contains specific constituents for cell differentiation or produced under strict quality control.

Cell Culture Contaminants

Unwanted agents that compromise cell or microbial cultures.

Biological Contaminants

Bacteria, fungi, mycoplasma, viruses, or mixed cell lines.

Chemical Contaminants

Endotoxins, heavy metals, or other harmful chemicals.

Physical Contaminants

Dust, fibers, glass shards, or metal particles.

Antibiotics

Used to prevent microbial contamination and maintain plasmid-bearing cultures.

Aseptic Techniques

Procedures designed to maintain sterility and prevent contamination during culture work.

Microbial Cell Culture

Growing bacteria, yeast, or fungi in a controlled environment using nutrient-rich media.

Streak Plate Method

Used to isolate individual colonies of a microorganism from a culture.

Spread Plate Method

Used to distribute microorganisms evenly across an agar plate for quantification.

Bacterial Cells for Industrial Biotechnology

Examples include Escherichia coli for recombinant proteins and biofuels.

Fungal Cells for Industrial Biotechnology

Examples include Saccharomyces cerevisiae for ethanol and recombinant proteins.

Plant Suspension Culture

Growth of free-floating plant cells in a liquid nutrient medium.

Plant Cells for Industrial Biotechnology

Examples include Taxus chinensis for paclitaxel production.

Animal Cell Culture

Growth of mammalian cells under controlled conditions for research and therapy.

Animal Cells for Industrial Biotechnology

Examples include CHO cells for monoclonal antibodies.

Cell Preservation

Methods to maintain cell viability and consistency for industrial bioprocesses.

Cell Growth

Increase in cell population number through cell division.

Factors Affecting Cell Growth

Temperature, pH, osmolarity, and oxygen levels.

Effect of Temperature on Cell Growth

Influences enzyme activity, metabolism, and biomolecule stability.

Effects of pH

Influences protein structure, enzyme activity, DNA/RNA integrity, and membrane stability.

Effects of Osmolarity

Influences cell shape, volume, and physiological processes.

Effects of Oxygen

Varies by cell type, crucial for optimizing growth conditions

Oxygen Toxicity

Results from reactive oxygen species like superoxide and hydrogen peroxide.

Batch Growth

Cell culture in a closed system with no additional nutrients added during the process.

Growth Rate

Absolute increase in biomass or cell number over time.

Specific Growth Rate

Rate of biomass increase per unit of biomass concentration.

Continuous Exponential Growth

Assumes cell division and biomass accumulation occur continuously.

Discrete Exponential Growth

Models cell division at specific intervals, not continuously.

Monod Model

Describes microbial growth kinetics in relation to substrate concentration.

Ks Values

Half-saturation constant for various organisms and substrates.

Multi-Substrate Monod Kinetics

Describes growth when multiple substrates are present.

Alternative Models for Complex Systems

Includes Contois, Cybernetic, Pitt's Equation, and Andrews models.

Zero-Growth Bioprocesses

Systems where cell populations are maintained without net biomass increase.

Yield

Efficiency of converting substrates into biomass or desired products.

Biomass Yield

Grams of biomass produced per gram of substrate consumed.

Product Yield

Grams of product formed per gram of substrate consumed.

Inoculum

Population of cells introduced into a culture medium to initiate growth or fermentation.

Monitoring Cell Growth

Essential for biological, medical, and industrial applications.

Direct Methods for Monitoring Cell Growth

Includes hemocytometer, automated cell counters, plate counting, and flow cytometry.

Indirect Methods for Monitoring Cell Growth

Includes spectrophotometry, metabolic activity, and dry weight.

Microscope Counting

Manual cell counting using a hemocytometer.

Plate Counting

Estimating viable bacteria or fungi by counting colonies on agar plates.

UV-Vis Spectrometry

Estimating cell density by measuring optical density at specific wavelengths.

Cell Immobilization

Trapping or attaching cells to a solid support or within a matrix.

Types of Cell Immobilization

Adsorption, ionic binding, covalent binding, cross-linking, and encapsulation.

Advantages of Cell Immobilization

Process simplification, reusability, protection, and continuous processing.

Disadvantages of Cell Immobilization

Mass transfer limitations, activity loss, cost, and stability issues

Ludeking-Piret Equation

Obligate Aerobes

Require oxygen for survival

Obligate Anaerobes

Cannot survive in the presence of oxygen

Facultative Anaerobes

Can grow with or without oxygen but prefer oxygenated environments

Microaerophiles

Require oxygen but at lower concentrations than atmospheric levels

Aerotolerant Anaerobes

Do not use oxygen but can tolerate its presence