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Flashcards in Midterm 1 Deck (36)
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1
Q

How do we express the amount of small molecules?

A

Concentration such as

  • millimoles per liter
  • or mg of protein per mL of soln
2
Q

What did we do in experiment 1?

A

measure protein content in food and compare our results to manufacturers label

3
Q

How is protein usually expressed?

A

mg protein/mL of solution

4
Q

What techniqure did we use in experiment 1?

A

Bradford Protein Assay

5
Q

What is the correlation used in the bradford protein assay?

A

Higher absorbance at a particular wavelength = greater amount of protein present

6
Q

What is the first step in protein assay?

A

generate standard curve which shows how absorbance of the dye changes as the concentration of a protein standard of known concentration changes

-standard curve used as reference

7
Q

What protein standard did we use in experiment 1?

A

Bovine Serum Albumin, BSA

8
Q

What dye did we use in experiment 1?

A

Coomassie G-250

-binds primarily to basic and aromatic amino acids, especially arginine

9
Q

When bound to protein, at what wavelength does coomassie G-250 absorbs strongly at?

A

595 nm

10
Q

What is one of the principal methods of separating proteins?

A

Sodium-dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE)

11
Q

How does SDS PAGE separates proteins?

A

based only on differences in their molecular weight

12
Q

What ration does SDS bind proteins?

A

SDS is a negatively charged molecule that binds to proteins in a ratio of approximately 1 SDS molecule for every 2 amino acids

13
Q

In native electrophoresis, how does mobility differ?

A

differ due to differences among proteins in size, shape and charge

14
Q

How does SDS only measure differences in molecular size?

A

Since SDS binds at a constant ratio to all proteins and denatures the protein as well

-no longer differences among proteins in charge and shape

15
Q

What was the point of experiment 2?

A

electrophoretically determine the molecular weight of serum albumin

-comparing the electrophoretic mobility of your unknown protein(s) to that of the markers, you can estimate the molecular weight of your unknown protein(s).

16
Q

What is the structure of SDS?

A
17
Q

What does chromatography involve?

A

flow of a buffer solution, called the mobile phase, through a column of beads called the stationary phase

  • Molecules move through the column at different rates, which leads to their separation
  • The samples are eluted (washed) from the column
  • samples are collected in series as the eluent leaves the column
  • The collected samples are called fractions.
18
Q

How does affinity chromatography separate proteins?

A

separates proteins based on differences in their ability to bind specifically to functional groups located on the stationary phase beads.

19
Q

What did we use affinity chromatography for in experiment 3?

A

isolate albumin from horse blood serum

20
Q

How did we use affinity chromatography to isolate albumin from horse blood serum in experiment 3?

A

The stationary phase of the column contains functional groups that bind to albumin

  • causing it to be retained on the column while other proteins are eluted
  • The bound albumin can then be eluted and collected as a fraction using elution buffer that disrupts the weak interactions that cause the specific binding
21
Q

Would you expect a higher LDH activity in white muscle that is used for burst-type exercise (like sprinting) or red muscle that is used for endurance exercise (like jogging)?

A

White muscle

22
Q

What are the parts of the pipette

A

(1) Control button.
1st stop is measuring stroke. The desired volume is aspirated or dispensed. 2nd stop is for blow-out of any liquid remaining in tip after it is emptied

(2) Setting ring.
Turn to the appropriate volume.
(3) Tip ejector button.

Depress to eject tip.

(4) Calibration opening.
Do not touch!!

(5) Tip ejector sleeve.

23
Q

What is the lowest volume a 1000 microliter pipette, P1000, can be calibrated for?

A

100 microliters

24
Q

What must be included in a graph?

A

no negative unless needed

no line to connect data

legend

title

equation

units

25
Q

What must be included in a data table?

A

units the same as in graph

Title

26
Q

What is the purpose of homogenization?

A

break up solid tissue into smaller pieces which release cytoplasmic proteins

27
Q

Ditheothreiotol, DTT, is used in sample buffer for SDS-PAGE gels to break what kind of bonds?

A

Disulfide bonds from methionine

28
Q

What is the purpose of using SDS in SDS-PAGE?

A

PUTS UNIFORM NEGATIVE CHARGE ON PROTEINS

29
Q

How do you calculate dilution factor?

A

DF = VF / VI

30
Q

How many microliters is 2.00 mL?

A

200 MICROLITERS

31
Q

If you conducted column chromatography to purify enzyme of itnerest would the activity increase or decrease?

A

increase

32
Q
A
33
Q

Lactase breaks down lactose into what?

A

galactose and glucose

34
Q

ONPG is a analog of what sugar?

A

lactose

35
Q

In enzyme kinetics, Km represents what?

A

dissociation constant for ES complex

half of maximal velocity for reaction

36
Q
A