Cell 201 Final Exam
Comprehensive Questions
with Verified Answers
Graded A+
1. intercellular signalling mainly occurs through chemical signalling
-cells can release chemicals for dispersal at local or distant sites
-express chemical signals on the cell surface
chemical signals information across the plasma membrane by
binding of a ligand to specific receptors
1. ligand binds to receptor
2. conformational change on receptor
3. ligand does not go inside the cell
4. cascade of reactions inside the cell (multiple steps)
5. change in gene expression/direct cellular response Answer: Chemical
signalling + steps
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,2. Endocrine - signals through long distances in the circulatory
system (hor- mones)
Paracrine - local signals by diffusing through tissues (immune
signals) Juxtacrine - immediate dadjacent signalling through direct
contact
Autocrine - self-signalling to the cell that released a ligand (negative
feedback)-
Answer: Types of signals
3. interferon response is an example of a juxtacrine AND autocrine
signaling
ex. cell infected with virus with foreign rna, activation of PAMP
(pathogen associated molecular pattern) which is the IFN response,
IFN made in nucleus and secreted into extracellular space, IFN
attaches to receptors on cells right next to it and itself therefore
massive spike of interferon Answer: IFN
4. same type of specificity as enzyme-substrate
-receptor can typically only bind one type of ligand (LDL receptor can
only bind LDL, VLDL receptor can only bind VLDL)
1. saturability - finite receptors per cell, limited ligands can bind
2. specificity - highly specific
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, 3. reversible - at the end of the reaction the receptor and ligand are
unchanged-
Answer: receptor-ligand interactions
5. 1. amplification - a single molecule (ligand) can activate many
intracellular molecules, as goes on cascades becomes very
amplified
2. regulation - components of the signalling pathway may inhibit earlie
steps helps regulate certain pathways Answer: cascades advantages
6. not proteins - chemical structures that have a signalling
function small messengers that act as intracellular
carriers for the signal
synthesized or transported on demand in the target cell in response t
receptor activation Answer: second messengers
7. calcium - regulates the amount of calcium inside a cell or cell
compartment g-proteins - work through GTP-coupled proteins
kinases - add a phosphate to a protein Answer: types of receptors
8. -very tightly regulated since it is a strong inducer of other
signalling path- ways(will go out of control if not tightly
regulated)
-Ca2+ transported out of the cytosol by active transport
-a2+ ATPase is a P-type ATPase found in the plasma membrane and ER o
SR membrane
-Na+/Ca2+ exchange transporters are found in the plasma membrane
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Comprehensive Questions
with Verified Answers
Graded A+
1. intercellular signalling mainly occurs through chemical signalling
-cells can release chemicals for dispersal at local or distant sites
-express chemical signals on the cell surface
chemical signals information across the plasma membrane by
binding of a ligand to specific receptors
1. ligand binds to receptor
2. conformational change on receptor
3. ligand does not go inside the cell
4. cascade of reactions inside the cell (multiple steps)
5. change in gene expression/direct cellular response Answer: Chemical
signalling + steps
1/
18
,2. Endocrine - signals through long distances in the circulatory
system (hor- mones)
Paracrine - local signals by diffusing through tissues (immune
signals) Juxtacrine - immediate dadjacent signalling through direct
contact
Autocrine - self-signalling to the cell that released a ligand (negative
feedback)-
Answer: Types of signals
3. interferon response is an example of a juxtacrine AND autocrine
signaling
ex. cell infected with virus with foreign rna, activation of PAMP
(pathogen associated molecular pattern) which is the IFN response,
IFN made in nucleus and secreted into extracellular space, IFN
attaches to receptors on cells right next to it and itself therefore
massive spike of interferon Answer: IFN
4. same type of specificity as enzyme-substrate
-receptor can typically only bind one type of ligand (LDL receptor can
only bind LDL, VLDL receptor can only bind VLDL)
1. saturability - finite receptors per cell, limited ligands can bind
2. specificity - highly specific
2/
18
, 3. reversible - at the end of the reaction the receptor and ligand are
unchanged-
Answer: receptor-ligand interactions
5. 1. amplification - a single molecule (ligand) can activate many
intracellular molecules, as goes on cascades becomes very
amplified
2. regulation - components of the signalling pathway may inhibit earlie
steps helps regulate certain pathways Answer: cascades advantages
6. not proteins - chemical structures that have a signalling
function small messengers that act as intracellular
carriers for the signal
synthesized or transported on demand in the target cell in response t
receptor activation Answer: second messengers
7. calcium - regulates the amount of calcium inside a cell or cell
compartment g-proteins - work through GTP-coupled proteins
kinases - add a phosphate to a protein Answer: types of receptors
8. -very tightly regulated since it is a strong inducer of other
signalling path- ways(will go out of control if not tightly
regulated)
-Ca2+ transported out of the cytosol by active transport
-a2+ ATPase is a P-type ATPase found in the plasma membrane and ER o
SR membrane
-Na+/Ca2+ exchange transporters are found in the plasma membrane
3/
18
