Cell biology and physiology MCQs

• Which protein is required for formation of a tight junction where three cells meet together?

  Tricellulin
• What type of cell death is anokis?

  Cell death due to loss of cell-matrix attachment
• What type of signalling can induce the activation of integrins?

  Outside-in signalling
• What are integrins?

  Molecules that act as cellular messengers
• Which cellular structure connects the cytoplasm of adjacent plant cells and enables cell to cell communication?

  Plasmodesmata
• When does actin treadmilling occur?

  In the presence of intermediate concentrations of actin
• Which amino acid motif is present in fibronectin and acts as a binding site for integrins?

  RGD
• What is the role of the centrosome?


  Nucleation site for microtubules
• What is the role of glycosaminoglycans, within the extracellular matrix?

  To resist compressive forces
• What is the role of the slime layer in bacterial cells?

  Its the first protective layer from environmental dangers
• Which animal tissue typically has the greatest proportion of extracellular matrix?

  Connective tissue
• A cell releases a signal for a hormone to reach a receptor in a different tissue system. What is this type of cell communication called?

  Endocrine
• Where is the signal sequence of a protein found?

  Mostly at the N-terminus, but can vary depending on the protein
• Do cilia move in a wave-like motion?

  No, they move in a beat-like motion
• When a cell releases a signal molecule into the environment and the target sites are located on the same cell, this type of signalling is known as?

  Autocrine signalling
• What occurs during the M/G1 checkpoint during the cell cycle?

  There is an equal distribution of chromosomes between new daughter cells
• How to cilia and flagella attach to the cell?

  Via the basal body
• When a cell releases a signal molecule into the environment and a number of cells in the immediate vicinity respond, this type of signalling is known as?

  Paracrine signalling
• Which type of signal sequence would a cytoplasmic protein have?

  No signal sequence
• What are the 5 steps allowing muscle contraction?

  1. Action potential reaches the axon terminal of a motor neuron

  2. Acetylcholine is released by the motor neuron

  3. Voltage-gated Ca2+ channels (DHP receptors) in the T-tubules undergo a conformational change

  4. Ca2+ efflux from the sarcoplasmic reticulum into the cytoplasm

  5. Ca2+ binds to troponin
• When are semi-lunar valves open and closed?

  OPEN:

  Ventricular Systole:

  • Pressure: Ventricles > Aorta
  • Open to allow passage of blood

  CLOSED:

  Ventricular diastole

  • Pressure: Ventricles < Aorta
  • Close to prevent backflow
• If cells were unable to produce major histocompatibility proteins, what would the consequence be?

  Antigens would not be presented to T cells and their receptors
• What cellular behaviour does a WST-1 assay measure?

  Cell proliferation
• What is cell proliferation?

  Process by which cells divide and reproduce
• What type of bone is more prone to osteoporosis?

  Compact
• Where is glucagon produced?

  Alpha cells of pancreas
• Where is insulin produced?

  Beta cells of pancreas
• Which components are needed for the transport of cargo (eg vesicles) in neuronal axons to the cell periphery?

  Microtubules, kinesin-type motor protein and ATP
• Collagens are trimeric molecules, and the subunit chains are stably held together by...

  Formation of a distinct left-handed triple helix
• Which component is found exclusively linked with hemidesmosomes in epithelial cells, but is not associated with desmosomes?

  Keratin filaments linked to hemidesmosomes
• How to fibroblast cells migrate?

  They can only migrate on a two-dimensional layer of ECM matrix
• Does the presence of CO2 stimulate the binding of oxygen to haemoglobin?

  No
• What is the function of desmosomes?

  - Bind epithelial cells to one another

  - Link intermediate filaments in adjacent cells

  - Provide tensile strength to epithelial tissues
• What are desmosomes composed of?

  They are made from the transmembrane protein cadherin
• Order of events at a chemical synapse:

  1. Action potential arrives and depolarises presynaptic membrane
  2. Depolarisation causes calcium channels to open
  3. Influx of calcium ions causes vesicles w neurotransmitters to fuse w presynaptic membrane and release contents to synaptic cleft
  4. neurotransmitters bind to receptors on post synaptic membrane
  5. neurotransmitters are broken down by enzymes
• • NPY: Made in the hypothalamus, Stimulates food intake and promotes energy storage
  • NTS: Made in the CNS, Controls gastrointestinal motility (digestion)
  • Ghrelin: Made in the stomach, Stimulates appetite and food intake
• Stereocilia are non-motile cells made of actin filaments. They are found in the hair cells of the inner ear
• Leptin is a hormone that suppresses appetite
• connexins, proteins that create gap junctions between cardiac muscle cells. These gap junctions allow electrical impulses to quickly spread between cells
• electrical syncytium is the synchronisation of myocardial (heart muscle) cells in response to an electrical impulse.