BioChem Lab Final Review

T/F: To prevent cross-contamination, a new pipette tip should be used for each different sample.

True

Why is it important to allow pipettes, sample fluids, and reagents to reach room temperature before pipetting?

Because temperature affects liquid volume and pipette accuracy

Which size micropipette would be most appropriate to accurately measure 15 μL?

P20 (2-20 μL range)

What is a potential consequence of letting the plunger snap back quickly after aspirating liquid?

Dispensing an incorrect sample volume due to turbulence or air bubbles

What is the primary difference between the traditional and reverse pipetting methods?

Reverse pipetting involves depressing the plunger past the second stop before aspirating, while traditional uses only the first stop.

What is the purpose of pre-wetting a pipette tip multiple times before dispensing the final volume?

To condition the tip and improve accuracy by equilibrating liquid inside the tip

Why is it critical never to lay down or invert a pipette with liquid inside the tip?

Because liquid may flow back into the piston causing damage and contamination 

Which pipette immersion depth is recommended for accurate aspiration using a 1000 μL micropipette?

2-4 mm

What is the main advantage of the reverse pipetting method compared to the traditional method?

It reduces the chance of air bubbles during aspiration for viscous or foaming liquids

What is the correct way to select a desired volume on an adjustable micropipette to ensure calibration precision?

Turn the volume selector higher than the desired volume, then slowly turn it down to the target volume

Why is it important to pre-wet the pipette tip several times before dispensing a sample?

To condition the tip and improve accuracy by reducing sample retention

In the traditional pipetting method, what is the function of pressing the plunger to the first stop before aspirating the sample?

It creates the vacuum space to aspirate the set volume of liquid

In the traditional pipetting method, to what position should you press the plunger before aspirating the sample?

To the first stop, which allows aspiration of the desired volume

Why is it important to store micropipettes in an upright position when not in use?

To prevent liquid from flowing back into the piston and causing damage or contamination

What is the purpose of pre-wetting a pipette tip multiple times before delivering the final sample volume?

To condition the tip and improve volume accuracy and precision

Which pipette size requires an immersion depth of 2-4 mm for proper aspirating?

200 μL and 1000 μL pipettes

What is the critical precaution regarding the plunger when ejecting or withdrawing fluid with a micropipette?

Never let the plunger snap back quickly to avoid damaging the piston

What is the relationship between molecule size and movement through the column for molecules below 60,000 daltons?

The smaller the molecule, the slower it moves through the column

Some individuals show signs of vitamin B₁₂ deficiency despite asequate intake due to a genetic disorder affecting:

Synthesis of the carrier protein

At what point is it acceptable for slight disturbances to the column bed to occur without affecting the separation?

When the protein mix has entered the column far enough that slight disturbances will not affect separation

T/F: The stationary phase in size exclusion chromatography typically consists of cross-linked porous polymers or silica beads

True

What is the significance of the heme group in hemoglobin?

It contains iron, which binds oxygen

What is the primary function of hemoglobin?

Transports O₂ to the body’s tissues

How do molecules larger than the exclusion limit of a size exclusion column behave?

They pass around the beads and elute faster

What action is taken after 5 drops of buffer have been collected into a tube?

Transfer the column to the next tube

T/F: Adding high concentrations of salt to the mobile phase in size exclusion chromatography helps minimize secondary interactions with the stationary phase

True

T/F: Size exclusion chromatography can be effectively used for desalting and buffer exchange of protein samples

True

What is the primary principle behind size exclusion chromatography?

Separates molecules based on their size

How does the body adapt to lower oxygen levels at high altitudes?

Increase red blood cell production

Why is it important to not jam the column tightly into the collection tubes?

To ensure proper drainage and separation of proteins

In size exclusion chromatography, what property of molecules determines their rate of travel through the column?

The size and shape of the molecules

What is attached to the beads in affinity chromatography to bind the protein of interest?

A biomolecule that bonds to the protein of interest

T/F: In size exclusion chromatography, molecules larger than the pores of the stationary phase are retained longer and thus elute later than smaller molecules

False

T/F: Size exclusion chromatography separates molecules based on their hydrodynamic volume rather than their molecular weight

True

Which of the following food sources are rich in vitamin B₁₂

Eggs, dairy products, and meats

T/F: Size exclusion chromatography offers high-resolution separation for molecules with nearly identical molecular weights

False

T/F: Size exclusion chromatography (SEC) columns typically operate at pressures above 1000 barr to achieve optimal separation

False

Why should the protein mix be loaded carefully just above the top of the column bed?

To minimize disturbances to the column bed

What is a characteristic of secondary immunodeficiency?

It is more common than primary immunodeficiency

What type of immunity is characterized by the production of antibodies that circulate in the bloodstream?

Humoral immunity

T/F: Indirect detection in immunological assays requires labeling every type of antibody used, making it time-consuming and costly

False

Which of the following is an example of an immunofluorescence assay (IFA)?

Identifying respiratory viruses

T/F: Secondary antibodies are produced by injecting antibodies from one animal into a different species of animal

True

What is a primary advantage of using recombinant DNA technology to produce therapeutic antibodies for patient treatment?

It allows for the creation of ‘humanized’ antibodies, reducing the risk of adverse immune reactions in patients

T/F: The substrate selection in manual ELISA protocols influences the type of optical detection method used

True

T/F: The primary function of macrophages is to produce antibodies

False

What is the purpose of indirect detection in antibody visualization?

To visualize all antibodies produced in one type of animal

What is the primary purpose of using indirect detection in immunological assays?

To amplify the signal and reduce costs by using a universal labeled secondary antibody

Macrophages serve what two primary functions in the immune response?

1. They process antigens to present them on their cell surfaces

2. They remove foreign cells and molecules from the blood

What is the role of T cells in the immune response?

To bind and destroy infected cells

T/F: Immunodeficiency can be caused by external factors such as infections or drug treatments

True

Humoral immunity involves the production of _____ by _____. In contrast, cell mediated immunity involves _____ that directly attack and destroy infected cells

1. antibodies

2. B cells

3. T cells

What is the role of macrophages in the immune response?

To present antigens to the T cells

T/F: Humoral immunity involves the production of T lymphocytes that bind and destroy infected cells

False

When evaluating scientific literature, why is it important to understand the limitations of the Bradford Assay in biophotonic research?

Its sensitivity and potential for interference from various chemicals can affect the accuracy of protein measurements, which in turn influences experimental conclusions

How does the Bradford Assay facilitate the study of protein interactions in a biological sample using optical biosensors?

By measuring changes in light absorbance due to protein-dye binding

Which type of spectroscopy is utilized in the Bradford Assay?

Absorbance spectroscopy

T/F: Bradford Assay sensitivity can be enhanced by increasing the temperature during the staining process to accelerate dye-protein interactions

False

How does the principle of absorbance linearity in the Bradford Assay relate to the principles of spectroscopic quantification in optical imaging modalities?

Both rely of Beer-Lambert law to correlate absorbance with concentration

T/F: The Bradford Assay exclusively uses laser light for protein detection

False

Why is the Bradford Assay preferred over some other protein quantification methods?

It is faster and requires fewer steps

When evaluating recent biophotonics research, why is it important to understand the photophysical properties of dyes used in the Bradford Assay?

Because dye properties affect light absorption and assay accuracy

Which optical property of protein-dye complexes is primarily measured in the Bradford Assay?

Absorbance at 595 nm

Which of the following best explains why the Bradford Assay is useful in analyzing biological  samples in biophotonics research?

It provides a rapid, sensitive method to quantify total protein concentration, which is essential for standardizing samples before optical analysis

T/F: The Bradford Assay can be utilized to quantify proteins in samples that also contain high concentrations of detergents without interference

False

In light-based protein assays like the Bradford Assay, how does solvent polarity potentially affect the assay’s colorimetric response?

It causes a shift in the absorption peak due to changes in dye-protein interactions

How does the Bradford Assay exemplify the application of light and optics principles in biological assays?

By utilizing absorption of visible light to quantify biomolecules

T/F: The Bradford Assay requires a standard curve generate with a known protein to accurately determine unknown protein concentrations

True

Which step is critical to ensure reproducibility in Bradford Assay measurements when reviewing scientific literature?

Use of consistent incubation times and reagent volumes

T/F: The Bradford Assay can be combined with optical biosensors to enable label-free detection of protein concentrations in complex biological samples

False

In relation to optics, what role does light wavelength play in the Bradford Assay?

Specific wavelength absorption at 595 nm is used to detect the protein-dye complex

What is one major advantage of the Bradford Assay compared to other protein quantification methods in terms of optical measurement?

Rapid measurement with a single absorbance reading

T/F: The Bradford Assay can be used directly as a diagnostic imaging technique in medicine

False

T/F: The Bradford Assay can be utilized to quantify proteins in samples that also contain high concentrations of detergents without interference

False

T/F: The absorbance peak shift observed in the Bradford Assay is a direct consequence of laser-induced fluorescence

False

T/F: The Bradford Assay can directly measure protein localization within a cell when combined with fluorescence microscopy

False

T/F: The actin & myosin standard is used as a reference to identify major muscle proteins and as a positive control for gel analysis

True

Adaptations are phenotypic characteristics, such as variations in _____, _____, and _____, that make an organism more suited to its environment

1. anatomy

2. physiology

3. behavior

T/F: Sodium dodecyl sulfate (SDS) is a positively charged detergent used in electrophoresis

False

T/F: The proteome is a constant entity that does not change across different cells or environmental conditions

False

Darwins theory of evolution is based on the concept of _____ and common descent

natural selection

T/F: Proteomics is solely focused on cataloging all proteins expressed in cells

False

Mounting research suggests that RNA editing systems are far more _____ than previously thought and may have significant evolutionary importance

widespread

Antibodies can provide positive _____ of the proteins

identification

Sarcomeres are composed of thin filaments of actin aligned with thick filaments of _____ in a parallel and partly overlapping manner

myosin

T/F: Adding a reducing agent to the Laemmli sample buffer reduces background bands

True

T/F: The central dogma of molecular biology states that information flows form RNA to DNA to protein

False

In SDS-PAGE, proteins migrate in a gel as if they have equivalent _____ charge densities

negative

T/F: Phosphorylation can regulate the activity of proteins by causing conformational changes within them

True

T/F: The tape at the bottom of the precast gel and the comb must both remain in place during electrophoresis

False

In higher eukaryotes, pre-messenger RNA (pre-mRNA) contains non-coding regions called _____ that are removed during splicing, and coding regions called exons that are joined together to form the mature mRNA

Introns