ASU Cell BIO 353 Exam 3 SA Questions And Answers
With Verified Solutions
How do mitochondria get their lipids? Give a detailed answer. ANS a. Lipids synthesized in ER
b. transported to mitochondria
c. switch of lipid takes place between ER and mitochondria & between mitochondrial membranes
d. Membrane-tethering & lipid transfer proteins in mitochondria provides FIRST insight into
mechanisms and transport processes
e. Mitochondria DO NOT participate in vesicle trafficking, obtain lipids from ER through
mitochondrial-associated ER membranes
List the chaperones in the order that they are used in the long path of getting a protein into the
mitochondrial matrix. (Note you should start in the cytoplasm.) ANS a. cytoHSP70- in
cytoplasm, chaperone that coats mRNA
b. mitoHSP70- in between inner&outer mitochondrial membranes
c. mitoHSP60- mitochondrial matrix, enables whole protein to come in w/ COOH end, uses ATP for
chaperone
Describe evolution of endomembrane system -include why it is important. Contrast this with the
evolution of the endosymbiotic origin of mitochondria and chloroplasts. ANS a. endomembrane
system is involved in a comprehensive communication system between cells.
b. Components of endomembrane system are central to eukaryotic cell life
c. Endosymbiosis.
Analyze the signal sequence, and related characteristics that suggest that mitochondria and
chloroplasts did not originate as part of the evolution of the endomembrane system ANS a.
Components of endomembrane system are central to eukaryotic cell life
b. Endosymbiosis- improved fitness of the cell
c. Mitochondria can make their own protein from circular DNA, now most has been outsourced to
nucleus with genes transcribed in cytoplasm
d. Signal sequence recruits HSP70 and coats growing protein
, Explain how cells take in water and general food at the periphery of the cells. ANS a. Food-
phagocytosis - plasma membrane is pushed out around food, creating two lamellipodia and fuse
together to form vesicle around food
b. Water- pinocytosis - invagination forms around water, taken into cytoplasm through membrane
channels to avoid damaging cell if vesicle explodes- membrane "Straw" used to "sip" water
Explain how general food and food taken in by receptor mediated endocytosis merge with elements
of the endomembrane system to digest and absorb those nutrients (including cholesterol). ANS a.
When a ligand binds to a receptor, receptor undergoes a conformational change.
b. Exposes binding site for adaptor protein AP-2
c. Capping occurs when same type of receptors bind to their ligands all over surface of cell come
together over small area; looks like baseball cap without the brim.
d. Adapter protein recruits triskelon to form clathrin coat
e. Receptor and ligand move using molecular motors
f. Amino acid subunits pumped into cytoplasm & indigestible components removed by exocytosis
Explain how membrane flow participates with membranes that are part of the endomembrane system,
but also part of the plasma membrane. ANS a. Vesicular transport moves newly synthesized
lipids, transmembrane proteins, and luminal proteins within the endomembrane system.
b. Forms spherical vesicle
c. Vesicle is transported on microtubule pathway from ER to cis-face GA then move to cell periphery,
transfer to actin filament, and move to PM
Distinguish between communication between cells and communication within cells ANS a. 1.
Autocrine communication- cell talks to self- endomembrane system synthesizes ligands that bund to
receptors
b. 2. Paracrine communication- ligand siffuses from site of exocytosis through isosmotic fluid
c. Endocrine communication- exocytosed ligands enter circulatory system & carry to distant parts of
organism, where ligand contacts receptors in other cells to cause change in cell behavior
d. Juxtacrine communication- 2 or more cells are in physical contact & tug/push on neighboring cells
e. For cell to receive signal receiving cell must have receptor or cell wont detect ligand
f. Target cell= cell with receptor for specific ligand
With Verified Solutions
How do mitochondria get their lipids? Give a detailed answer. ANS a. Lipids synthesized in ER
b. transported to mitochondria
c. switch of lipid takes place between ER and mitochondria & between mitochondrial membranes
d. Membrane-tethering & lipid transfer proteins in mitochondria provides FIRST insight into
mechanisms and transport processes
e. Mitochondria DO NOT participate in vesicle trafficking, obtain lipids from ER through
mitochondrial-associated ER membranes
List the chaperones in the order that they are used in the long path of getting a protein into the
mitochondrial matrix. (Note you should start in the cytoplasm.) ANS a. cytoHSP70- in
cytoplasm, chaperone that coats mRNA
b. mitoHSP70- in between inner&outer mitochondrial membranes
c. mitoHSP60- mitochondrial matrix, enables whole protein to come in w/ COOH end, uses ATP for
chaperone
Describe evolution of endomembrane system -include why it is important. Contrast this with the
evolution of the endosymbiotic origin of mitochondria and chloroplasts. ANS a. endomembrane
system is involved in a comprehensive communication system between cells.
b. Components of endomembrane system are central to eukaryotic cell life
c. Endosymbiosis.
Analyze the signal sequence, and related characteristics that suggest that mitochondria and
chloroplasts did not originate as part of the evolution of the endomembrane system ANS a.
Components of endomembrane system are central to eukaryotic cell life
b. Endosymbiosis- improved fitness of the cell
c. Mitochondria can make their own protein from circular DNA, now most has been outsourced to
nucleus with genes transcribed in cytoplasm
d. Signal sequence recruits HSP70 and coats growing protein
, Explain how cells take in water and general food at the periphery of the cells. ANS a. Food-
phagocytosis - plasma membrane is pushed out around food, creating two lamellipodia and fuse
together to form vesicle around food
b. Water- pinocytosis - invagination forms around water, taken into cytoplasm through membrane
channels to avoid damaging cell if vesicle explodes- membrane "Straw" used to "sip" water
Explain how general food and food taken in by receptor mediated endocytosis merge with elements
of the endomembrane system to digest and absorb those nutrients (including cholesterol). ANS a.
When a ligand binds to a receptor, receptor undergoes a conformational change.
b. Exposes binding site for adaptor protein AP-2
c. Capping occurs when same type of receptors bind to their ligands all over surface of cell come
together over small area; looks like baseball cap without the brim.
d. Adapter protein recruits triskelon to form clathrin coat
e. Receptor and ligand move using molecular motors
f. Amino acid subunits pumped into cytoplasm & indigestible components removed by exocytosis
Explain how membrane flow participates with membranes that are part of the endomembrane system,
but also part of the plasma membrane. ANS a. Vesicular transport moves newly synthesized
lipids, transmembrane proteins, and luminal proteins within the endomembrane system.
b. Forms spherical vesicle
c. Vesicle is transported on microtubule pathway from ER to cis-face GA then move to cell periphery,
transfer to actin filament, and move to PM
Distinguish between communication between cells and communication within cells ANS a. 1.
Autocrine communication- cell talks to self- endomembrane system synthesizes ligands that bund to
receptors
b. 2. Paracrine communication- ligand siffuses from site of exocytosis through isosmotic fluid
c. Endocrine communication- exocytosed ligands enter circulatory system & carry to distant parts of
organism, where ligand contacts receptors in other cells to cause change in cell behavior
d. Juxtacrine communication- 2 or more cells are in physical contact & tug/push on neighboring cells
e. For cell to receive signal receiving cell must have receptor or cell wont detect ligand
f. Target cell= cell with receptor for specific ligand
