dna and rna quantification

260

Absorbance at _______ nm is used to measure nucleic acid concentration

280

Absorbance at _______ nm is used to detect protein contamination

230

Absorbance at _______ nm is used to detect chemical contaminants like salts and extraction reagents.

Template

Downstream reactions need a defined amount of _______

inhibit

Too little template gives weak or failed results, while too much can _______ or give non-specific products.

enzymes

: Leftover extraction chemicals and proteins can inhibit _______ even when the nucleic acid amount looks fine.

re-extracted

Quantity and purity together decide whether a sample can go straight into a test, needs cleanup, or must be _______.

integrity

Absorbance tells us quantity and purity, not _______.

pure

Degraded RNA can still look _______.

UV

Nitrogenous bases absorb _______ strongly near 260 nm.

tyrosine

Aromatic amino acids, mainly tryptophan and _______, absorb near 280 nm.

guanidine

Contaminants such as salts, phenol, carbohydrates, and _______ absorb near 230 nm

ε

The Beer-Lambert law equation is A = _______ · c · l.

extinction

the Beer-Lambert law, symbol 'ε' stands for the _______ coefficient.

Cm

In the Beer-Lambert law, symbol 'l' represents the path length of light in _______

1

A standard cuvette has a path length of _______ cm

quartz

Cuvettes used for UV spectrophotometry must be UV-transparent, such as _______ or UV-grade cuvettes.

1

Microvolume pedestals have a path length of about _______ mm or less

1

: The reliable absorbance range for A260 on a cuvette reader is roughly 0.1 to _______

50

An A260 value of 1.0 corresponds to approximately _______ µg/mL of double-stranded DNA

40

An A260 value of 1.0 corresponds to approximately _______ µg/mL of RNA.

33

An A260 value of 1.0 corresponds to approximately _______ µg/mL of single-stranded DNA or oligos

hypochromic

: In a double helix, stacked bases absorb less light, a phenomenon known as the _______ effect

ng/µL

The unit 1 µg/mL is equal to 1 _______.

dilution

Concentration is calculated as A260 × conversion factor × _______ factor

sample

Dilution factor is calculated as final volume divided by _______ volume

1.8

The target A260/A280 ratio for pure DNA is approximately _______

2.0

The target A260/A280 ratio for pure RNA is approximately _______

2.2

The target A260/A230 ratio for both pure DNA and pure RNA is 2.0 to ______

phenol

A low A260/A280 ratio indicates contamination by protein or _______.

guanidine

A low A260/A230 ratio indicates contamination by salts, carbohydrates, phenol, or _______

A260/A280

Protein contamination lowers the _______ ratio.

both

Phenol contamination lowers _______ ratios.

A260/A230

EDTA and buffer salts lower the _______ ratio.

yield

Contamination by the other nucleic acid overestimates the sample _______. (

lower

Acidic solutions can _______ the A260/A280 ratio.

raise

Basic solutions can _______ the A260/A280 ratio.

purity

Fluorescent dye assays are more selective and sensitive, but do not report _______.

shear

Hard vortexing can _______ long DNA molecules.

guanidine

Do not add bleach to _______ waste because it produces toxic gas.

nuclease-free

RNases are found on skin and surfaces, so work with gloves and _______ water

Mg²⁺

In PCR, EDTA chelates the _______ ions required by polymerase.