IBSS 1520 exam 2 questions with
complete solutions73
Is cholesterol hydrophobic or hydrophilic? - ANSWERS-it contains both hydrophilic and
hydrophobic regions, but for the most part, it is hydrophobic
How does the structure of bile differ from that of cholesterol? what is the effect od this? -
ANSWERS-they have similar structures, but bile has more hydrophilic groups. This allows it to
act like a detergent and emulsify fats
Where in the body is bile formed? - ANSWERS-in the gall bladder
What two things do intestinal cells secrete when they recognize lipids? - ANSWERS-
cholecystokinin (CCK) and secretin
What is a benefit of the mixed micelle structure in the absorption of lipids in the intestine? -
ANSWERS-this structure helps the lipids penetrate the water layer on top of the brush border
cells that they must absorb through
Which type of lipoprotein is the apolipoprotein ApoB-100 involved in? - ANSWERS-LDLs
What is contained in the endosomes that form via LDL receptor mediated endocytosis? -
ANSWERS-LDL bound to LDLR receptors
What is hypercholesterolemia? What causes it? - ANSWERS-chronic high levels of LDL in the
body, which is usually caused by mutations in either LDLR or ApoB-100, which inhibits delivery
of cholesterol to tissues and causes it to instead accumulate in the blood
,What is the clinical significance of LDL? - ANSWERS-it can cause conditions like atherosclerosis if
in high levels
What occurs in atherosclerosis? What can result? - ANSWERS-it involves accumulation of
cholesterol in arteries which can cause heart attack or stroke if the blood flow to the brain is
blocked through the carotid
What is the function of LDLR and clathrin in the delivery of cholesterol to tissues? - ANSWERS-
The inner core of lipoproteins contain
A. free fatty acids and cholesterol
B. phospholipids
C. triacylglycerol and cholesterol esters
D. apolipoproteins - ANSWERS-C
What, in general, occurs in a signal transduction pathway? - ANSWERS-an extracellular stimulus
binds a receptor of a cell and initiates an intracellular cascade that results in some modification
of the cell's activity or function
What does GPCR stand for? - ANSWERS-G-protein coupled receptors
What are the six components of a signal transduction pathway? - ANSWERS--extracellular
stimulus
-extracellular receptor domain
-intracellular receptor domain
-G protein
-effector proteins
-second messengers
,What is the end result of a signal transduction pathway? - ANSWERS-there is a transcriptional
response in the nucleus, or modified enzyme activity
What is the extracellular stimulus in a signal transduction pathway? - ANSWERS-a ligand
What is the extracellular receptor domain of a signal transduction pathway? - ANSWERS-it is a
region of a cell receptor that interacts with a given ligand
What is the structure of G protein-coupled receptors? - ANSWERS-they are single polypeptide
transmembrane proteins
What are the three domains of GPCRs? - ANSWERS-ligand binding domain
transmembrane domain
intracellular domain
What is another name for the ligand binding domain of a GPCR? - ANSWERS-extracellular
domain
How many transmembrane domains are there in GPCRs - ANSWERS-7, because it traverses the
membrane 7 times
What is the function of the ligand binding domain of GPCRs? - ANSWERS-they bind to a ligand in
the extracellular space
What is the structure of the transmembrane domain of a GPCR? - ANSWERS-it traverses the
membrane 7 times
, What is the function of the intracellular domain of a GPCR? - ANSWERS-it undergoes a structural
change once a ligand binds and interacts with the G protein complex
What is the structure of G protein associated with GPCRs? - ANSWERS-they are trimeric, with
three subunits, alpha, beta, and gamma
What are the five steps of GPCR activation/deactivation? - ANSWERS--ligand binds to the GPCR
and causes a conformational change
-the receptor binds the G protein complex and activates GEF activity
-G alpha binds ATP and dissociates from the trimeric complex
-G alpha binds and activates adenylyl cyclase
-G alpha hydrolyzes its GTP and binds back to the trimeric complex
How are GPCRs deactivated? - ANSWERS-GAP activates the weak GTPAse activity of G alpha,
causing it to hydrolyze its GTP, become inactive, and rejoin the trimeric complex
What are G proteins? - ANSWERS-a family of GTP binding proteins that activate when bound to
GTP. They have a trimeric structure with alpha, Beta, and gamma subunits
Which subunit of G protein binds GTP? - ANSWERS-G alpha
Which molecule activates G protein? Which deactivates it? - ANSWERS-GEF activates it and GAP
deactivates it
How is adenylyl cyclase activated in a signal transduction pathway? - ANSWERS-When G alphas
are activated within the pathway, they activate andylyl cyclase
complete solutions73
Is cholesterol hydrophobic or hydrophilic? - ANSWERS-it contains both hydrophilic and
hydrophobic regions, but for the most part, it is hydrophobic
How does the structure of bile differ from that of cholesterol? what is the effect od this? -
ANSWERS-they have similar structures, but bile has more hydrophilic groups. This allows it to
act like a detergent and emulsify fats
Where in the body is bile formed? - ANSWERS-in the gall bladder
What two things do intestinal cells secrete when they recognize lipids? - ANSWERS-
cholecystokinin (CCK) and secretin
What is a benefit of the mixed micelle structure in the absorption of lipids in the intestine? -
ANSWERS-this structure helps the lipids penetrate the water layer on top of the brush border
cells that they must absorb through
Which type of lipoprotein is the apolipoprotein ApoB-100 involved in? - ANSWERS-LDLs
What is contained in the endosomes that form via LDL receptor mediated endocytosis? -
ANSWERS-LDL bound to LDLR receptors
What is hypercholesterolemia? What causes it? - ANSWERS-chronic high levels of LDL in the
body, which is usually caused by mutations in either LDLR or ApoB-100, which inhibits delivery
of cholesterol to tissues and causes it to instead accumulate in the blood
,What is the clinical significance of LDL? - ANSWERS-it can cause conditions like atherosclerosis if
in high levels
What occurs in atherosclerosis? What can result? - ANSWERS-it involves accumulation of
cholesterol in arteries which can cause heart attack or stroke if the blood flow to the brain is
blocked through the carotid
What is the function of LDLR and clathrin in the delivery of cholesterol to tissues? - ANSWERS-
The inner core of lipoproteins contain
A. free fatty acids and cholesterol
B. phospholipids
C. triacylglycerol and cholesterol esters
D. apolipoproteins - ANSWERS-C
What, in general, occurs in a signal transduction pathway? - ANSWERS-an extracellular stimulus
binds a receptor of a cell and initiates an intracellular cascade that results in some modification
of the cell's activity or function
What does GPCR stand for? - ANSWERS-G-protein coupled receptors
What are the six components of a signal transduction pathway? - ANSWERS--extracellular
stimulus
-extracellular receptor domain
-intracellular receptor domain
-G protein
-effector proteins
-second messengers
,What is the end result of a signal transduction pathway? - ANSWERS-there is a transcriptional
response in the nucleus, or modified enzyme activity
What is the extracellular stimulus in a signal transduction pathway? - ANSWERS-a ligand
What is the extracellular receptor domain of a signal transduction pathway? - ANSWERS-it is a
region of a cell receptor that interacts with a given ligand
What is the structure of G protein-coupled receptors? - ANSWERS-they are single polypeptide
transmembrane proteins
What are the three domains of GPCRs? - ANSWERS-ligand binding domain
transmembrane domain
intracellular domain
What is another name for the ligand binding domain of a GPCR? - ANSWERS-extracellular
domain
How many transmembrane domains are there in GPCRs - ANSWERS-7, because it traverses the
membrane 7 times
What is the function of the ligand binding domain of GPCRs? - ANSWERS-they bind to a ligand in
the extracellular space
What is the structure of the transmembrane domain of a GPCR? - ANSWERS-it traverses the
membrane 7 times
, What is the function of the intracellular domain of a GPCR? - ANSWERS-it undergoes a structural
change once a ligand binds and interacts with the G protein complex
What is the structure of G protein associated with GPCRs? - ANSWERS-they are trimeric, with
three subunits, alpha, beta, and gamma
What are the five steps of GPCR activation/deactivation? - ANSWERS--ligand binds to the GPCR
and causes a conformational change
-the receptor binds the G protein complex and activates GEF activity
-G alpha binds ATP and dissociates from the trimeric complex
-G alpha binds and activates adenylyl cyclase
-G alpha hydrolyzes its GTP and binds back to the trimeric complex
How are GPCRs deactivated? - ANSWERS-GAP activates the weak GTPAse activity of G alpha,
causing it to hydrolyze its GTP, become inactive, and rejoin the trimeric complex
What are G proteins? - ANSWERS-a family of GTP binding proteins that activate when bound to
GTP. They have a trimeric structure with alpha, Beta, and gamma subunits
Which subunit of G protein binds GTP? - ANSWERS-G alpha
Which molecule activates G protein? Which deactivates it? - ANSWERS-GEF activates it and GAP
deactivates it
How is adenylyl cyclase activated in a signal transduction pathway? - ANSWERS-When G alphas
are activated within the pathway, they activate andylyl cyclase
