88 Questions
Which type of signaling molecules can diffuse across the plasma membrane to bind to intracellular receptors?
Steroid hormones
What is the common mechanism of action for thyroid hormone, vitamin D3, and retinoic acid?
Binding to intracellular receptors
Which group of signaling molecules are synthesized from cholesterol?
Steroid hormones
Which hormones are produced by the gonads?
Estrogen and progesterone
Which hormones are produced by the adrenal gland?
Corticosteroids
What is the role of corticosteroids?
Stimulate glucose production
How are steroid hormones able to enter cells?
By diffusion across the plasma membrane
Which hormone plays important roles in development and regulation of metabolism?
Thyroid hormone
What is the role of vitamin D3?
Regulate Ca2+ metabolism
What is the role of retinoic acid and related compounds?
Play important roles in vertebrate development
Which family of proteins do the intracellular receptors for steroids, thyroid hormone, vitamin D3, and retinoic acid belong to?
Nuclear receptor superfamily
What are the distinct effects of ligand binding on different receptors within the nuclear receptor superfamily?
Some receptors are inactive in the absence of hormone
Which molecule is bound to the glucocorticoid receptor in the absence of hormone?
Hsp90 chaperones
What happens when glucocorticoid binds to its receptor?
Hsp90 is displaced and receptor dimers are formed
In the absence of hormone, what is the role of the thyroid hormone receptor?
It represses transcription of its target genes
What happens when hormone binds to the thyroid hormone receptor?
It interacts with coactivators instead of corepressors
What is the role of ligand binding on the function of nuclear receptors?
Regulates their function as activators or repressors of target genes
Which domain is NOT present in the intracellular receptors for steroids, thyroid hormone, vitamin D3, and retinoic acid?
Enzyme activity domain
What is the role of the nuclear receptor superfamily in gene expression regulation?
They activate or repress transcription of target genes
What is the role of ligand binding on the activity of the receptor as a transcriptional regulatory molecule?
It alters the activity of the receptor
Which molecules bind to intracellular receptors expressed by hormonally responsive target cells?
Steroids, thyroid hormone, vitamin D3, and retinoic acid
Which family of proteins do the intracellular receptors belong to?
Nuclear receptor superfamily
What are the three related domains found in the intracellular receptors?
Ligand binding, DNA binding, and transcriptional activation
How do steroid hormones and related molecules directly regulate gene expression?
By binding to intracellular receptors
What is the role of glucocorticoid binding in the glucocorticoid receptor?
It induces a conformational change in the receptor
What happens to the glucocorticoid receptor in the absence of hormone?
It is bound to Hsp90 chaperones
What is the role of the thyroid hormone binding in the thyroid hormone receptor?
It induces a conformational change in the receptor
What happens to the thyroid hormone receptor in the absence of hormone?
It is associated with a corepressor complex
How does hormone binding affect the activity of the receptor in other cases?
It alters the activity of the receptor as a transcriptional regulatory molecule
What is the outcome of hormone binding in other cases?
The receptor interacts with coactivators instead of corepressors
True or false: All signaling molecules act by binding to receptors expressed on the target cell surface.
False
True or false: Thyroid hormone is synthesized from cholesterol.
False
True or false: Retinoic acid and related compounds play important roles in vertebrate development.
True
True or false: Steroids, thyroid hormone, vitamin D3, and retinoic acid bind to extracellular receptors expressed by hormonally responsive target cells.
False
True or false: Ligand binding of the nuclear receptor superfamily proteins regulates the function of ligand binding, DNA binding, and transcriptional activation.
True
True or false: Hormone binding alters the activity of the receptor as a transcriptional regulatory molecule in all cases.
False
Which of the following is NOT a characteristic of neurotransmitters?
They can cross the target cell plasma membrane
Which signaling molecule is responsible for signaling the dilation of blood vessels that leads to penile erection?
Nitric oxide
What is the role of G proteins in neurotransmitter signaling?
They regulate ion channels
What is the molecular basis of nitric oxide (NO) action?
Activating guanylyl cyclase to stimulate synthesis of cyclic GMP
Which plant hormone was the first to be identified?
Auxin
What is the role of nitroglycerin in the treatment of heart disease?
It is converted to nitric oxide (NO) to dilate blood vessels and increase blood flow to the heart
What is one of the effects of auxins in plants?
Stem elongation
True or false: Nitric oxide (NO) is a major paracrine signaling molecule in the circulatory system.
True
True or false: Nitric oxide (NO) binds to a receptor that regulates transcription.
False
True or false: Nitric oxide (NO) stimulates synthesis of cyclic GMP inside the cell by activating guanylyl cyclase.
True
True or false: Neurotransmitters are able to cross the target cell plasma membrane.
False
True or false: Plant hormones regulate plant growth and development.
True
True or false: Auxins induce plant cell elongation by strengthening the cell wall.
False
True or false: The first plant hormone to be identified was auxin.
True
Which of the following is NOT true about G proteins?
G proteins are activated by hydrolysis of GTP
How many different α subunits are encoded by the human genome?
21
What is the role of RGS proteins in G protein signaling?
RGS proteins stimulate hydrolysis of GTP
Which of the following is NOT a type of signaling molecule in animals?
Steroids
Which of the following is NOT an example of a peptide hormone?
Epidermal growth factor
Who discovered nerve growth factor (NGF) and serendipitously discovered epidermal growth factor (EGF)?
Both Rita Levi-Montalcini and Stanley Cohen
Which group of polypeptide growth factors is responsible for regulating the development and differentiation of blood cells and controlling the activities of lymphocytes during the immune response?
Cytokines
Which type of signaling molecules act by binding to cell surface receptors and are unable to cross the plasma membrane of their target cells?
Peptide hormones
What is the basis for a variety of diseases, including many kinds of cancer?
Abnormal expression of the EGF receptor
Which family of cell surface receptors transmits signals to intracellular targets via the intermediary action of guanine nucleotide-binding proteins called G proteins?
G protein-coupled receptors
True or false: Peptide hormones include insulin and the hormones produced by the pituitary gland?
True
True or false: Neuropeptides are naturally occurring compounds that bind to the same receptors on brain cells as morphine does?
True
True or false: Epidermal growth factor (EGF) stimulates cell proliferation?
True
True or false: The activity of the α subunit is terminated by hydrolysis of the bound GDP, which is stimulated by RGS proteins?
False
True or false: The human genome encodes 21 different β subunits of the G protein?
False
True or false: Different G proteins always associate with the same receptors?
False
True or false: PDGF stimulates the proliferation and movement of fibroblasts in the vicinity of the clot, contributing to regrowth of damaged tissue.
True
True or false: Polypeptide growth factors that remain associated with the plasma membrane function as signaling molecules during direct cell-cell interactions.
True
True or false: G protein-coupled receptors are characterized by seven membrane-spanning α helices.
True
True or false: G proteins consist of three subunits designated α, β, and γ.
True
Which enzyme is responsible for the formation of cAMP from ATP?
Adenylyl cyclase
What is the role of cAMP-dependent protein kinase in animal cells?
It phosphorylates serine residues on target proteins
Which protein kinase is phosphorylated and activated by protein kinase A in the regulation of glycogen breakdown?
Phosphorylase kinase
Which enzyme catalyzes the synthesis of many molecules of cAMP?
Adenylyl cyclase
What is the regulatory sequence called that is found in specific target genes activated by cAMP?
cAMP response element
Which enzyme dephosphorylates the serine residues of proteins phosphorylated by protein kinase A?
Protein phosphatase 1
In the sensory neurons of the nose, how does cAMP directly regulate ion channels?
By directly opening Na+ channels
Which family of proteins is responsible for phosphorylating the STAT proteins?
JAK family kinases
What is the role of the STAT proteins in gene expression?
They stimulate transcription of target genes
Which group of proteins are responsible for signaling downstream of cytokine receptors and receptor tyrosine kinases?
Src family kinases
Which molecules are responsible for the attachment of cells to the extracellular matrix?
Integrins
Which family of cell surface receptors are directly linked to intracellular enzymes?
Tyrosine kinases
What was the first tyrosine kinase discovered during studies of?
Rous sarcoma virus
What is the common structural organization of receptor tyrosine kinases?
Extracellular ligand-binding domain, single transmembrane α helix, and cytosolic C-terminal domain with tyrosine kinase activity
Which of the following is NOT a characteristic of receptor tyrosine kinases?
They are associated with nonreceptor tyrosine kinases
What is the role of SH2 domains in receptor tyrosine kinase signaling?
They bind to phosphotyrosine-containing peptides
How do cytokine receptors differ from receptor tyrosine kinases?
Cytokine receptors lack ligand-binding domains
What are the key targets of the JAK kinases associated with cytokine receptors?
STAT proteins
Test your knowledge on intracellular receptors and their role in cellular signaling with this quiz. Explore the different types of receptors and learn about the signaling molecules they respond to. Challenge yourself with questions on receptor localization and their impact on cellular functions.
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