BIOS 312 - EXAM #1 WITH COMPLETE SOLUTIONS
smallest subunit of a polypeptide - ANSWER amino acid
After a polypeptide has folded, _______ amino acids will be found in the interior -
ANSWER hydrophobic
After a polypeptide has folded, _______ amino acids will be found on the exterior -
ANSWER hydrophilic
SDS is a - ANSWER detergent
Define the term "cell lysis." - ANSWER break cells to avoid denaturing or
degrading of proteins/DNA
List two methods for releasing proteins from cells and explain - ANSWER break
cell apart by vibrations
using hypotonic buffer so the cell swells and bursts
What is the function of the NP-40 detergent in the extraction buffer - ANSWER
Helps disrupt the cell membrane in the tissue
Explain in your own words what "high-quality" and "high-yield" mean when
referring to protein extraction - ANSWER High yield = solubilized most protein
High quality = inhibiting proteases to stop denaturing of proteins
Describe two things you will do to ensure you have a "high-yield" extract -
ANSWER Mince and Vortex tissue
Describe two things you will do to ensure you have a "high-quality" extract. -
ANSWER Keeping on ice = inhibit proteases
Centrifuge = separate soluble proteins from tissue debris
"SDS-PAGE" (what does it stand for?) - ANSWER Sodium Dodecyl Sulfate
Polyacrylamide Gel Electrophoresis
An SDS-coated protein has a negative / positive charge. - ANSWER negative
The stacking gel in SDS-PAGE typically contains __% acrylamide. - ANSWER 4%
The resolving gel in SDS-PAGE typically contains ___% acrylamide. - ANSWER 8-
15%
, In SDS-PAGE, (smaller / larger) proteins reach the bottom of the gel first -
ANSWER smaller
Unpolymerized acrylamide monomer is toxic/non-toxic but polymerized
polyacrylamide is toxic/non-toxic. - ANSWER toxic
non-toxic
A protein band is 1 mm from the top of the gel. The loading (tracking) dye
travelled 10 mm from the top of the gel. Calculate the Relative mobility, Rf, for
this protein. - ANSWER Rf = (1mm)/(10mm) = 0.1
List 2 ingredients needed to make a polyacrylamide - ANSWER ammonium
persulfate and TEMED (tetramethylendiamine)
What is the function of bis-acrylamide in an SDS-PAGE gel? - ANSWER Creates
crosslinking "bridges" between linear acrylamide chains making a matrix
What is the function of ammonium persulfate in an SDS-PAGE gel? - ANSWER
Free radical generator
What is the function of TEMED in an SDS-PAGE gel? - ANSWER catalyst
When loading an SDS-PAGE gel, why is important to ensure there are no leaks
from the inner chamber? What will happen if the buffer level is too low? -
ANSWER Electrode assembly will leak when filled with buffer. Buffer must be
above the ledge created or gel will not run.
Why is it important to load samples quickly onto an SDS-PAGE gel? Explain what
would happen if you waited a long time between loading samples. - ANSWER
Protein will diffuse into gel immediately - can cause a smear.
Explain why it is important that you never touch an electrophoresis unit while it
is running. - ANSWER Very dangerous the voltage can kill you.
True or False: Tetrahymena is a common organism found in salt water. -
ANSWER False
True or False: Tetrahymena can be used as an alternative model organism to
research
structures and functions of human cells. - ANSWER True
True or False: Tetrahymena is a prokaryotic unicellular organism. - ANSWER
False
smallest subunit of a polypeptide - ANSWER amino acid
After a polypeptide has folded, _______ amino acids will be found in the interior -
ANSWER hydrophobic
After a polypeptide has folded, _______ amino acids will be found on the exterior -
ANSWER hydrophilic
SDS is a - ANSWER detergent
Define the term "cell lysis." - ANSWER break cells to avoid denaturing or
degrading of proteins/DNA
List two methods for releasing proteins from cells and explain - ANSWER break
cell apart by vibrations
using hypotonic buffer so the cell swells and bursts
What is the function of the NP-40 detergent in the extraction buffer - ANSWER
Helps disrupt the cell membrane in the tissue
Explain in your own words what "high-quality" and "high-yield" mean when
referring to protein extraction - ANSWER High yield = solubilized most protein
High quality = inhibiting proteases to stop denaturing of proteins
Describe two things you will do to ensure you have a "high-yield" extract -
ANSWER Mince and Vortex tissue
Describe two things you will do to ensure you have a "high-quality" extract. -
ANSWER Keeping on ice = inhibit proteases
Centrifuge = separate soluble proteins from tissue debris
"SDS-PAGE" (what does it stand for?) - ANSWER Sodium Dodecyl Sulfate
Polyacrylamide Gel Electrophoresis
An SDS-coated protein has a negative / positive charge. - ANSWER negative
The stacking gel in SDS-PAGE typically contains __% acrylamide. - ANSWER 4%
The resolving gel in SDS-PAGE typically contains ___% acrylamide. - ANSWER 8-
15%
, In SDS-PAGE, (smaller / larger) proteins reach the bottom of the gel first -
ANSWER smaller
Unpolymerized acrylamide monomer is toxic/non-toxic but polymerized
polyacrylamide is toxic/non-toxic. - ANSWER toxic
non-toxic
A protein band is 1 mm from the top of the gel. The loading (tracking) dye
travelled 10 mm from the top of the gel. Calculate the Relative mobility, Rf, for
this protein. - ANSWER Rf = (1mm)/(10mm) = 0.1
List 2 ingredients needed to make a polyacrylamide - ANSWER ammonium
persulfate and TEMED (tetramethylendiamine)
What is the function of bis-acrylamide in an SDS-PAGE gel? - ANSWER Creates
crosslinking "bridges" between linear acrylamide chains making a matrix
What is the function of ammonium persulfate in an SDS-PAGE gel? - ANSWER
Free radical generator
What is the function of TEMED in an SDS-PAGE gel? - ANSWER catalyst
When loading an SDS-PAGE gel, why is important to ensure there are no leaks
from the inner chamber? What will happen if the buffer level is too low? -
ANSWER Electrode assembly will leak when filled with buffer. Buffer must be
above the ledge created or gel will not run.
Why is it important to load samples quickly onto an SDS-PAGE gel? Explain what
would happen if you waited a long time between loading samples. - ANSWER
Protein will diffuse into gel immediately - can cause a smear.
Explain why it is important that you never touch an electrophoresis unit while it
is running. - ANSWER Very dangerous the voltage can kill you.
True or False: Tetrahymena is a common organism found in salt water. -
ANSWER False
True or False: Tetrahymena can be used as an alternative model organism to
research
structures and functions of human cells. - ANSWER True
True or False: Tetrahymena is a prokaryotic unicellular organism. - ANSWER
False
