Mixed Deck — All BACE Topics Flashcards

A biotechnician needs to confirm media has cooled enough after autoclaving before adding heat-sensitive supplements. Which tool is most appropriate?

Answer: A calibrated digital thermocouple or infrared thermometer

A calibrated digital thermocouple or infrared thermometer provides accurate, non-contact or low-contact temperature measurement suitable for monitoring media cooling safely.

What does 'GDP' (Good Documentation Practices) require when correcting an error in a paper record?

Answer: Draw a single line through the error, write the correction alongside, add initials, date, and reason for correction

GDP requires a single strikethrough that keeps the original entry readable, with the correction, signature/initials, date, and reason noted — never erasing or obscuring original entries.

Which macromolecule serves as the primary source of energy for most organisms?

Answer: Carbohydrates

Carbohydrates are the primary and most readily available source of energy for most organisms. They are broken down through cellular respiration to produce ATP, the main energy currency of the cell. Glucose, a simple carbohydrate, is a key molecule in this energy-generating pathway.

What is the primary purpose of a 'Site Master File' (SMF) in pharmaceutical cGMP?

Answer: It is a comprehensive document describing a facility's GMP operations submitted to regulatory authorities to facilitate drug product approval

A Site Master File provides regulatory authorities with a comprehensive description of a manufacturing facility's GMP systems, processes, and controls to support regulatory review.

What is a 'wet mount' preparation in light microscopy?

Answer: A specimen suspended in a drop of liquid between a slide and coverslip

A wet mount places a specimen in a drop of water or buffer covered by a coverslip, allowing observation of live or unstained specimens.

Why must you never use a mercury thermometer in a laboratory incubator or water bath?

Answer: If broken, mercury vapor and liquid mercury create serious health and environmental hazards that are difficult to remediate

Mercury is a potent neurotoxin; breakage releases mercury vapor and liquid mercury requiring specialized, costly cleanup and posing serious health risks to laboratory staff.

Hydrophobic interaction chromatography (HIC) typically uses which condition to bind proteins to the resin?

Answer: High salt concentration

HIC binding is promoted by high salt (kosmotropic salts like ammonium sulfate) which enhances hydrophobic interactions between the protein and the resin.

What is the correct order of operations when beginning work in a biological safety cabinet?

Answer: Turn on blower then wait 5 min for airflow to stabilize then wipe with 70% ethanol then begin work

The BSC blower must be running and airflow must stabilize before work begins; surfaces are then decontaminated with 70% ethanol before introducing materials.

When working with cell cultures in a Class II Biological Safety Cabinet (BSC), which of the following is a critical aseptic technique to prevent contamination?

Answer: Wiping the outside of all media bottles and flasks with 70% ethanol before placing them in the cabinet.

A fundamental principle of aseptic technique is to decontaminate the surface of all items before they enter the sterile field of the BSC. Wiping items with 70% ethanol kills microorganisms on the container surface, preventing their introduction into the cabinet and subsequent contamination of cultures.

A technician observes that a flask of cell culture medium, which was clear and pink the previous day, is now turbid (cloudy) and has turned a distinct yellow color. What is the most likely cause of this change?

Answer: Bacterial contamination.

Rapid turbidity (cloudiness) and a sharp drop in pH are classic signs of bacterial contamination. The bacteria grow quickly and produce acidic byproducts, causing the phenol red pH indicator in the medium to change from pink/red to yellow.

In a cGMP-compliant facility, which department is primarily responsible for the hands-on testing of raw materials, in-process samples, and finished products against established specifications?

Answer: Quality Control (QC)

Quality Control (QC) is the operational unit responsible for performing the physical and chemical tests on samples to ensure they meet predetermined specifications. Quality Assurance (QA) is responsible for the overall quality system and processes to prevent errors, but does not typically perform the routine lab testing.

When performing an autoclave validation, what biological indicator organism is typically used?

Answer: Geobacillus stearothermophilus spores

Geobacillus stearothermophilus spores are the standard biological indicator for steam autoclave validation because they are among the most heat-resistant organisms known.

What is a recombinant protein and how is it produced in biotechnology?

Answer: A protein encoded by a gene that has been introduced into a host organism's DNA using recombinant DNA technology allowing production of specific proteins at scale

Recombinant proteins are produced by cloning the gene of interest into an expression vector, transfecting or transforming a host cell (E. coli, CHO, yeast), and allowing the host to express and produce the protein.

What is the primary function of the ribosome in the cell?

Answer: Producing proteins

The ribosome is a crucial cellular organelle responsible for protein synthesis, a process also known as translation. It reads messenger RNA (mRNA) sequences and uses this genetic information to assemble amino acids into functional proteins. This function is fundamental for all cellular activities, as proteins perform a vast array of roles from structural support to enzymatic catalysis.

What type of electron microscopy is used to examine the internal ultrastructure of thin-sectioned specimens?

Answer: Transmission electron microscopy (TEM)

TEM passes electrons through thin specimens to create high-resolution images of internal cellular structures at the nanometer scale.

In thin layer chromatography (TLC), the Rf value is calculated as:

Answer: Distance traveled by spot / distance traveled by solvent

Rf (retention factor) = distance traveled by the analyte spot ÷ distance traveled by the solvent front, and ranges from 0 to 1.

What is the primary function of providing a 5% CO2 atmosphere in a standard mammalian cell culture incubator?

Answer: To work with the bicarbonate buffer system in the medium to maintain a stable pH.

The CO2 gas in the incubator dissolves in the cell culture medium and forms a bicarbonate buffer system. This system is crucial for maintaining a stable, physiological pH (typically around 7.2-7.4), which is essential for cell viability and growth.

During agarose gel electrophoresis, what is the primary reason that DNA fragments migrate towards the positive electrode?

Answer: The phosphate backbone of DNA carries a strong negative charge.

DNA has a net negative charge due to the phosphate groups in its sugar-phosphate backbone. When an electric current is applied to the gel, the negatively charged DNA molecules are repelled by the negative electrode (cathode) and attracted to the positive electrode (anode), causing them to migrate through the gel.

What does a Bradford assay (Coomassie Blue dye binding) measure, and what is its color shift?

Answer: Total protein concentration; Coomassie Blue shifts from reddish-brown to blue when it binds proteins under acidic conditions

The Bradford assay measures total protein by the color shift of Coomassie Brilliant Blue G-250 from its reddish-brown (free) form to its blue form upon binding to proteins — measured spectrophotometrically at 595 nm.

Under OSHA's Bloodborne Pathogen Standard (29 CFR 1910.1030), who must be offered the hepatitis B vaccine at no cost?

Answer: Employees with occupational exposure to blood or other potentially infectious materials (OPIM)

The standard requires employers to offer hepatitis B vaccination at no cost to employees with occupational exposure risk — those whose jobs involve potential contact with blood or OPIM.