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Anatomy & Physiology: Cell Membrane, Transport, DNA, Protein Synthesis, and Cell Junctions

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Terms in this set (22)

  • What are the main structural components of a phospholipid molecule in the cell membrane?
    A phospholipid has a hydrophilic phosphate head and two hydrophobic fatty acid tails (one saturated and one unsaturated).
  • What is the structure of the cell membrane?
    The cell membrane is a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward.
  • What are the main components of the cell membrane besides phospholipids?
    The membrane contains 5% glycolipids and 20% cholesterol, which stabilize the membrane, plus various proteins.
  • List the primary functions of membrane proteins.
    Membrane proteins function in transport, cell recognition, receptors and ligands, anchoring cellular structures, enzymatic activity, and cell junction formation.
  • What is vesicular transport and what are its two main types?
    Vesicular transport moves large particles via ATP-dependent processes: endocytosis (into the cell) and exocytosis (out of the cell).
  • Describe endocytosis and its types.
    Endocytosis is the cell engulfing material by membrane invagination forming vesicles; types include phagocytosis (cell eating) and receptor-mediated endocytosis.
  • What happens during exocytosis?
    Exocytosis exports materials by vesicles fusing with the cell membrane, releasing contents outside and adding vesicle membrane to the cell membrane.
  • What creates the membrane potential (MP) in cells?
    MP arises from ion separation across the membrane, with positive charge outside and negative inside, mainly due to K+ ion movement through leakage channels.
  • How is the resting membrane potential established?
    It is established when the number of K+ ions leaking out equals those leaking in, balancing the charge difference across the membrane.
  • What is chromatin and how is it related to chromosomes?
    Chromatin is DNA and proteins in the nucleus; chromosomes are condensed chromatin structures containing genes.
  • What is DNA replication and why is it important?
    DNA replication copies DNA before cell division, ensuring each daughter cell receives a full set of genetic information.
  • What are the three stages of DNA replication?
    Initiation (strand separation by helicase), elongation (DNA polymerase builds new strands), and termination (completion of two identical DNA molecules).
  • What does 'semiconservative replication' mean?
    Each new DNA molecule contains one original strand and one newly synthesized strand, conserving half of the original DNA.
  • What is protein synthesis?
    Protein synthesis is the process of converting genetic information in DNA into proteins via transcription and translation.
  • What are the two main processes of protein synthesis?
    Transcription (DNA to mRNA in the nucleus) and translation (mRNA to protein at ribosomes in the cytoplasm).
  • What is the role of mRNA in protein synthesis?
    mRNA carries a copy of the genetic code from DNA out of the nucleus to ribosomes for protein assembly.
  • How does transcription occur?
    RNA polymerase synthesizes mRNA by adding nucleotides complementary to the DNA template strand.
  • How is the amino acid sequence determined during translation?
    mRNA codons (triplets) specify amino acids, which ribosomes link together to form the protein.
  • What are the three types of cell junctions in epithelial cells?
    Tight junctions, desmosomes, and gap junctions.
  • What is the function of tight junctions?
    Tight junctions seal adjacent epithelial cells, blocking extracellular space and controlling substance movement.
  • What role do desmosomes play in epithelial tissue?
    Desmosomes provide strong, flexible connections between cells and influence tissue shape and folding.
  • What is the function of gap junctions?
    Gap junctions form channels allowing fluid, ions, and small molecules to pass directly between adjacent cells for communication.