Exam 1

Question 1

Which of these mathematical parameters associated with a protein standard curve are sufficient to determine the concentration of an “unknown” sample from its absorbance in the Bradford assay

Answer 1

Slope and y-intercept

Question 2

Unknowns and standards have to be assayed at the same time for a comparison between the two to be valid T/F

Answer 2

True (bc environmental factors, temp, could be diff at diff times)

Question 3

A standard curve is usually considered valid only if its correlation coefficient (R-squared) is

Answer 3

greater than 0.90

Question 4

The reducing agent beta mercaptoethanol

Answer 4

Breaks disulfide bonds in proteins which ensures that all proteins will have a uniform linear shape

Question 5

The dye Coomassie Blue G-250 forms colored complexes with

Answer 5

proteins

Question 6

1 x 10^6 uL

Answer 6

1L

Question 7

1000 mL

Answer 7

1L

Question 8

1kda

Answer 8

1000 Da

Question 9

An SDS-coated protein has a positive/negative charge

Answer 9

negative

Question 10

Unpolymerized acrylamide monomer is toxic but polymerized acrylamide is ______

Answer 10

nontoxic

Question 11

What is the function of bisacrylamide in an SDS-PAGE gel?

Answer 11

Crosslinker “bridges” between the linear acrylamide chains

Question 12

Why is it important that there are no leaks from the inner chamber when loading an SDS PAGE gel? What will happen if the buffer is too low?

Answer 12

incomplete circuit

Question 13

If the cilia of a Tetrahymena cell are damaged or their function is inhibited, the rate of food vacuole formation will increase/decrease/remain the same

Answer 13

decrease

Question 14

True or False. The cilia found on Tetrahymena cells have the same fundamental structure as cilia found on human cells

Answer 14

True

Question 15

Why is phase contrast microscopy useful for viewing Tetrahymena cells?

Answer 15

It does not require use of toxic chemical stains and uses changes in refractive index to play on light so cells are visible with more detail.

Question 16

Tetrahymena food vacuoles fuse with an organelle called a _______ where the food particles are digested.

Answer 16

lysosome

Question 17

True or False. Eukaryotic cells must be stained with chemical dye before they can be seen by phase contrast.

Answer 17

false

Question 18

Describe 2 potential health concerns about e-cig use:

Answer 18

Metal nanoparticles in the vape get in lungs and cause damage in lungs
Cancerous ingredients in vapor that can cause cancer with sustained use

Question 19

The use of e-cigs doubled between 2011 and 2012- True/False

Answer 19

True

Question 20

Explain why metal particles are found in e-cig vapor

Answer 20

Metal coil in vape heats up to vaporize nicotine, nanoparticles of metal get released as well- so small that can get in lungs

Question 21

Are propylene glycol safe ingredients in e-cig liquid?

Answer 21

No- supposed to be eaten, not inhaled. The effects are still unknown

Question 22

How long have e-cigs been available in the US?

Answer 22

Made by Chinese pharmacist in 2003, been around since 2010

Question 23

Purpose of homogenizing and chopping up tissue-

Answer 23

increases surface area and breakdown cells

Question 24

Purpose of detergent in homogenization buffer

Answer 24

SDS is a detergent that binds to proteins, causing them to lose their normal 3-D shapes

Question 25

Purpose of 2 high speed centrifugation step

Answer 25

separates pellet with unwanted debris

Question 26

High yield

Answer 26

protein is extracted efficiently from the tissue

Question 27

High quality

Answer 27

protein is not degraded or contaminated

Question 28

how to get high yield

Answer 28

chop and homogenize tissue well to maximize surface area, and vortex thoroughly to ensure that most cells are lysed.

Question 29

how to get high quality

Answer 29

keep the samples on ice to inhibit proteases in the tissue, and avoid introducing external proteases

Question 30

In coomassie dye in bradford assay: More blue color =

Answer 30

more protein present

Question 30

In coomassie dye in bradford assay: More blue color =

Answer 30

more protein present

Question 30

SDS adds ______ charge to the proteins

Answer 30

negative

Question 31

Proteases =

Answer 31

enzymes that split protein molecules into fragments

Question 32

Larger proteins will move through the gel _________. Smaller proteins will move ______

Answer 32

slowly, quickly

Question 33

The ______-charged proteins move down the gel toward a _________charged electrode

Answer 33

negatively, positively

Question 34

(buffering compound that adjusts pH to 6.8)

Answer 34

Tris

Question 35

(reducing agent that breaks disulfide bonds)

Answer 35

Beta mercaptoethanol

Question 36

Protein mobility

Answer 36

Rf = band distance (mm) / dye front distance (mm)

Question 37

Destaining removes the excess Coomassie dye from the background polyacrylamide of the gel, allowing bands where Coomassie is bound to protein to be seen. T/F

Answer 37

T

Question 38

The single greatest advantage of phase-contrast microscopy

Answer 38

does not require the use of toxic chemical stains, making it the best method for observing living cells and tissues

Question 39

Core of cilia is composed of

Answer 39

microtubules

Question 40

microtubules are connected by the motor protein

Answer 40

dynein

Question 41

dynein movement causes microtubules to slide past one another T/F

Answer 41

T

Question 42

cytoproct

Answer 42

The vacuole then re-fuses with the cell membrane and its remaining contents are expelled by this

Question 43

In the Bradford assay, how does the light absorbance of Coomassie Blue change when the dye binds to protein?

Answer 43

The absorbance increases

Question 44

What was the purpose of the protein standard curve in your Bradford assay?

Answer 44

The standard curve provided a reference for determining the concentration of protein in the “unknown” samples, by establishing the relationship between protein concentration and absorbance

Question 45

Name two factors that must be controlled to ensure that you obtain a high-quality extract when extracting protein from tissue.

Answer 45

Temperature (keep the sample cold to slow protease activity) Proteases (avoid introducing materials that might include them) Contamination (centrifuge to remove undesired materials)

Question 46

Which piece of lab equipment would allow you to separate water soluble components of a suspension from insoluble components? Vortex Microcentrifuge Micropipette Spectrophotometer

Answer 46

microcentrifuge

Question 47

allows you to mix suspensions or solutions

Answer 47

vortex

Question 48

measures small volumes of liquid

Answer 48

micropipette

Question 49

measures light absorbance

Answer 49

spectrophotometer

Question 50

Before SDS-PAGE, protein samples must be heated in a solution containing SDS and a reducing agent. Explain the reason for this.

Answer 50

The procedure denatures proteins, breaks covalent disulfide bonds, and gives polypeptides a uniform ratio of negative charge to mass.

Question 51

Which one of these microscope parts is the first to produce a magnified image of the specimen? Ocular Condenser Objective Rheostat

Answer 51

objective

Question 52

further magnify the image produced by the objective.

Answer 52

Oculars

Question 53

focuses light on the specimen

Answer 53

The condenser

Question 54

controls lamp brightness.

Answer 54

rheostat