Introduction to Cell Biology Quiz

Introduction to Cell Biology

• Living things require cellular organization, reproduction, growth and development, energy transformation and utilization, homeostasis, response to environment, and adaptation.
• Living things evolve over time.
• Microscopes are essential for medicine; allow us to see cells and pathogens.
• Electron microscopes magnify 10,000,000x, Light microscopes magnify 1000x, and Dissecting microscopes magnify 100x.

Cell Structure and Organelles

• Lysosomes are cellular organelles that remove broken organelles and pathogens

  • They do this by degrading unwanted biomolecules.
  • Their acidic interior is maintained by an H+ pump.
  • Macrophages are a specific type of white blood cell that break down pathogens and toxins.

• Mitochondria are responsible for producing ATP.

  • They contain two membranes: an outer and an inner membrane.
  • The inner membrane has folds called cristae, which increase its surface area.
  • The space between the two membranes is called the intermembrane space, and the inside of the inner membrane is called the matrix.
  • The ATP is produced by oxidative phosphorylation.

• Endomembrane System is a structure with different shapes that are made of membranes including:

  • Plasma membrane, nuclear envelope, and the endoplasmic reticulum
  • The endomembrane system plays a role in making and modifying proteins and lipids.

Membrane Fluidity

• Proteins can move and rotate in the membrane

  • The flexibility of the membrane allows the cell to:
    • Divide
    • Deform
    • Fuse with vesicles

• The membrane fluidity is influenced by temperature and the fatty acid composition.

  • High temperatures increase the fluidity of the membrane.
  • Unsaturated fatty acids with cis double bonds reduce the membrane's rigidity.
  • Increased saturation and chain length increase rigidity and decrease fluidity.
  • Cholesterol can increase fluidity in low temperatures and decrease fluidity at high temperatures.

Membrane Structure

• The plasma membrane is a phospholipid bilayer.
  • The phospholipid bilayer is a spontaneous structure that is stable because the hydrophilic head and hydrophobic tail structure minimizes the exposure of hydrophobic tails to water, which is energetically unfavorable.
  • The structure of the phospholipid bilayer also allows for a closed compartment to form, which allows for organelle structure.
  • It has both hydrophilic and hydrophobic components.
  • Phosphatidylethanolamine and Phosphatidylserine are found on the inner side of the bilayer and contribute to the membrane potential.
  • Phosphatidylinositol is found exclusively on the inner side of the bilayer.

Membrane Proteins

• Integral Membrane Proteins
  • They have both hydrophilic and hydrophobic regions.
  • They are embedded in the phospholipid bilayer.
  • Their function may reside either inside or outside the membrane.
  • If their function is in the hydrophilic region, changes in membrane fluidity have little effect.
  • If their function is in the hydrophobic region, changes in membrane fluidity may have significant effects.
  • Some integral membrane proteins contain attached lipid groups for increased stability.
• Peripheral Membrane Proteins
  • They only associate with one leaflet of the membrane.
  • They are bound to the inner or outer surface of the membrane.
  • They are not embedded in the bilayer but are associated with it.
• Lipid-Anchored Proteins
  • They are bound to the inner or outer side of the membrane.
  • They are attached to the membrane lipid bilayer with modifications such as glycosylphosphatidylinositol (GPI) anchors.

Membrane Carbohydrates

• Glycoproteins
  • They are carbohydrate-linked proteins.
  • They can have N-glycosidic and O-glycosidic bonds with specific amino acids:
    • N-glycosidic bonds can be attached to the amide nitrogen of an asparagine side chain.
    • O-glycosidic bonds can be attached to the oxygen of a serine or threonine side chain.
  • They can serve as cell recognition markers and limit their movement in the membrane.
• Glycolipids
  • They are carbohydrate-linked lipids.
  • Their variable carbohydrate make-up can serve as binding sites for viruses, bacterial toxins, and cell recognition markers.
  • They can serve as specific recognition molecules for cell-cell interactions
  • The blood types A, B, and O are determined by the carbohydrate composition of the glycolipids.