Biochemistry Lab Midterm Practical

lactase

catalyzes hydrolysis of lactose —> breaks it into D-glucose and D-galactose

lactate dehydrogenase (LDH)

converts NADH to NAD+ during anaerobic respiration

lactose

disaccharide milk sugar

What does the R² describe?

the proportion of variance between dependent and independent variables

What was added to the cuvette to measure the enzyme activity of LDH?

pyruvate, NADH, and LDH

spectrophotometer

measures amount of light the sample absorbs

How is protein measured on food labels?

grams/serving

What standard did we use to measure the total protein content in milk?

bovine serum albumin (BSA)

Why do we adjust the bin size on a histogram?

to characterize the distribution of the data

The coomassie dye used in the protein assay:

• does NOT bind proteins directly

• only binds to BSA (which is why it’s a standard)

• has increased absorbance when it is bound to a protein

Which muscle type has more LDH?

white muscle —> burst activity

What is a t-test used for?

to evaluate the means of one or two populations

How does pH influence enzyme function?

• can change the primary sequence of amino acids on the enzyme

• can change the peptide bond structure of the enzyme

• can alter the enzyme’s R-group composition

describe the chemical reaction performed in lab 3 with LDH as the enzyme

pyruvate is REDUCED to lactate, NADH + H is OXIDIZED into NAD+ (anaerobically)

What is ONPG?

synthetic alternative substrate for lactose that has a yellow coloration

describe the chemical reaction performed in lab 4 with lactase as the enzyme

ONPG (lactose) is hydrolyzed by lactase to form glucose and galactose