Cell communication Flashcards
(20 cards)
What is the function of tight junctions?
a) Hold cells together
b) Prevent diffusion of water and small molecules
c) Connect the cytoplasm of adjacent cells
d) Bind cells to the extracellular matrix
b) Prevent diffusion of water and small molecules
Which of the following is NOT a type of anchoring junction?
a) Adherens junction
b) Desmosome
c) Gap junction
d) Hemidesmosome
c) Gap junction
What type of filament is associated with desmosomes in epithelial cells?
a) Actin
b) Keratin
c) Desmin
d) Collagen
b) Keratin
Which second messenger is involved in the release of calcium from intracellular stores?
a) cAMP
b) cGMP
c) IP3
d) DAG
c) IP3
What is the role of transcription factors in gene expression?
a) They transport mRNA from the nucleus to the cytoplasm.
b) They synthesize RNA nucleotides.
c) They help turn specific genes “on” or “off”.
d) They degrade proteins that are no longer needed.
c) They help turn specific genes “on” or “off”.
Which type of cell junction is most likely to be found in tissues that require a strong mechanical connection, such as skin and heart muscle?
a) Tight junctions
b) Gap junctions
c) Adherens junctions
d) Desmosomes
d) Desmosomes
Which of the following statements about cadherins is FALSE?
a) They are calcium-dependent adhesion molecules.
b) They play a critical role in cell sorting during development.
c) They interact with the cytoskeleton through cytoplasmic adapter proteins called integrins.
d) They mediate cell-cell adhesion but do not interact with the extracellular matrix.
c) They interact with the cytoskeleton through cytoplasmic adapter proteins called integrins.
Which second messenger is directly activated by nitric oxide (NO)?
a) cAMP
b) cGMP
c) IP3
d) DAG
b) cGMP
Which of the following is NOT a function of calcium ions in cell signalling?
a) Activation of protein kinase C b) Muscle contraction
c) Synthesis of cAMP
d) Release of neurotransmitters
c) Synthesis of cAMP
What is the difference between general transcription factors and specific transcription factors?
a) General transcription factors are required for the transcription of all genes, while specific transcription factors regulate the expression of particular genes.
b) General transcription factors bind to DNA, while specific transcription factors bind to RNA.
c) General transcription factors are found in the cytoplasm, while specific transcription factors are found in the nucleus.
d) General transcription factors activate gene expression, while specific transcription factors repress gene expression.
a) General transcription factors are required for the transcription of all genes, while specific transcription factors regulate the expression of particular genes.
A researcher is examining a tissue sample under a microscope. They observe that the cells are tightly connected, forming a barrier that prevents the movement of molecules between them. Which type of cell junction is most likely responsible for this observation?
a) Anchoring junctions
b) Gap junctions
c) Tight junctions
d) Signal-relaying junctions
c) Tight junctions
Case Study: A patient presents with muscle weakness and fatigue. A biopsy of their muscle tissue reveals abnormalities in the structure of intercalated discs.
What is the most likely consequence of abnormal intercalated disc structure in cardiac muscle?
a) Increased cell-cell adhesion b) Reduced intracellular calcium signalling
c) Impaired transmission of electrical signals
d) Enhanced contractile force generation
c) Impaired transmission of electrical signals
A research team is investigating the effects of a new drug on the blood-brain barrier. The drug is designed to temporarily disrupt tight junctions between endothelial cells.
What is the primary function of tight junctions in the blood-brain barrier?
a) To facilitate the transport of nutrients into the brain
b) To prevent the entry of pathogens and toxins into the brain
c) To anchor neurons to the surrounding extracellular matrix
d) To allow for communication between neurons and glial cells
b) To prevent the entry of pathogens and toxins into the brain
A scientist is studying a group of cells that exhibit coordinated movement during embryonic development. They hypothesise that cadherins play a crucial role in this process.
What is the primary function of cadherins in cell-cell interactions?
a) To mediate cell adhesion in a calcium-dependent manner
b) To form channels for direct cytoplasmic communication between cells
c) To bind cells to the extracellular matrix
d) To transmit signals across the cell membrane
a) To mediate cell adhesion in a calcium-dependent manner
A pharmaceutical company is developing a new drug to treat chronic inflammation. The drug targets a specific transcription factor known to regulate the expression of pro-inflammatory genes.
What is the most likely mechanism of action of this drug?
a) It activates the transcription factor, enhancing the expression of pro-inflammatory genes
b) It inhibits the transcription factor, suppressing the expression of pro-inflammatory genes
c) It promotes the degradation of pro-inflammatory proteins
d) It blocks the release of pro-inflammatory cytokines from cells
b) It inhibits the transcription factor, suppressing the expression of pro-inflammatory genes
Which of the following is NOT a characteristic of tight junctions?
a. They are abundant in epithelial layers.
b. They can regulate or block the movement of water.
c. They are formed by adhesion proteins of the cadherin family.
d. They prevent the diffusion of electrolytes and plasma proteins.
c. They are formed by adhesion proteins of the cadherin family.
Which type of cell junction is responsible for the coordinated contraction of cardiac muscle cells?
a. Tight junctions
b. Gap junctions
c. Desmosomes
d. Hemidesmosomes
b. Gap junctions
Which of the following second messengers is NOT water-soluble?
a. cAMP
b. cGMP
c. IP3
d. DAG
d. DAG
Which of the following statements about transcription factors is INCORRECT?
a. They can bind to DNA.
b. Activators enhance gene transcription, while repressors suppress it.
c. Specific transcription factors are commonly involved in all RNA transcription.
d. Transcription factor binding sites can be enhancers, silencers, or promoters.
c. Specific transcription factors are commonly involved in all RNA transcription.
Which signaling pathway involves the activation of protein kinase G (PKG)?
a. cAMP pathway
b. cGMP pathway
c. DAG/IP3 pathway
d. Calcium ion pathway
b. cGMP pathway
