[1ST] HISTOLEC

• Components of Cell Composition

  1. Protoplasm
  2. Cytoskeleton
  3. Inclusions
• Protoplasm


  living part of the cell
• Cytoskeleton


  movement, structure, and shapes
• Inclusions includes

  1. Hemosiderin - sidero/siderin = metal

  • Has iron; form of storage iron derived chiefly from the breakdown of erythrocytes 

  1. Glycogens stored form of glucose that is made up of many connected glucose molecules.

  • In neuron and cardiac muscle of older ages
  • Degradation of products of cell

  1. Lipofuscin wear and tear pigment
• Properties of a Cell

  1. Irritability - ability to respond to stimulus
  2. Contraction - changing shape (muscles)
  3. Conductivity - transmission of electrical impulses (nerve cell or neuron)
  4. Absorption - uptake of dissolved substance (lining of intestines)
  5. Secretion and Excretion - release of material (useful product or waste [like plants])
  6. Respiration - production of energy
  7. Growth and Reproduction
• goblet cells


  unicellular cell producing mucus
• Types of cells are classified based on its:

  1. nucleus
  2. function
  3. life span
• Types of Cells Based on Nucleus

  • Prokaryotes no nuclues
  • Eukaryotes true nucleus; has organelles
• Types of Cells Based on Function

  • Somatic cells mitosis; diploid
  • Sex cells meiosis; haploid
• Types of Cells Based on Life span

  1. Permanent cells neurons & myocardium cells
  2. Labile cells high-turn over

  • RBC (replaced every 20 days)
  • Skin cells
  • 3. Stable cells wear &tear; low-turn over
  • hepatocyte
• Cell Differentiation

  Embryonic cells undergoes a process and becomes specialized

  Occurs through gene expression
• Gene = instruction manual that codes for a specific protein

  1. Phenotype - observable characteristics
  2. Genotype
• Gene Expression

  • Process by which the information encoded in a gene is used to direct the assembly of a protein molecule
  • Cell Differentiation is when dramatic changes occurs in cell size, shape and energy requirement as does its ability to respond to signaling molecules
• Pluripotency

  • Ability of a single cell type to differentiate into multiple other types of cell. 
  • Observed in stem cells or progenitor cells is slowly lost as the cell differentiates and gains specialized functions
• Normal Cell

  • Development from a stem cell
  • As it becomes mature, it is more specialized and differentiated.
• Abnormal Cell

  • Tumor/Neoplasms
  • Can either be malignant or benign
• Cell Membrane

  • Limiting membrane that envelops eukaryotic cell
  • Plasma membrane
  • Permeability (semipermeable membrane with phospholipid bilayer) barrier allowing passage of materials in and out of the cell
• Membrane Phospholipids

  • made up of non polar long chain fatty acid (inner layer) linked to a charged polar head (outer layer) that bears a phosphate group
  • amphipathic nature
• Phospholipid


  head = phosphate, extracellular, polar

  tail = fatty acid, non-polar
• Membrane Lipids

  • Phosphoglycerates
  • Cholesterol - steroids; to stabilize the plasma membrane
  • Glycolipids
• Membrane Proteins

  1. Integral Proteins - multipass protein
  2. Peripheral proteins
• Proposed Models for Structure of the Cell Membrane

  1. Davson & Danielli - trilaminar structure; bilipid layer is sadwich between two layers of protein
  2. Fluid Mosaic Model - by S.J. Singer & Garth Nicholson; Globular proteins are compared to icebergs floating on a sea of lipids
• Fluid Mosaic Model

  • plasma membrane is a semi permeable layer
  • consists of phospholipid bilayer and membrane proteins that are free to move laterally within the plane of one leaflet
• Fluid Mosaic Model

  E-face = outer layer; violet

  Protoplasmic = inner layer; yellow
• Space


  purpose of phospholipids having a kink in their appearance thus preventing the close packing of the hydrophilic tails
• Fluidity and Flexibility of the Cell Membrane

  1. mosaic nature of the membrane
  2. phospholipid chemistry
  3. presence of cholesterol
• Phospholipid Chemistry

  • presence of unsaturated fatty acid on the tail region contains double bonds between adjacent carbon atoms, which creates the kink or bend of approximately 30 degrees in the string of the carbons
• purpose of the elbow room of phospholipids

  • helps maintain fluidity in the membrane at temperature
• Presence of cholesterol

  • stabilize and regulate the fluidity of the phospholipid bilayer
  • works as buffer
  • prevents lower temperatures from inhibiting fluidity
  • prevent higher temperatures from increasing fluidity too much
  • also serves as organizing clusters of transmembrane proteins into lipid rafts
• Carbohydrate Moieties

  • seen on the external surface
  • bound to either proteins (glycoproteins) or to lipids (glycolipids)
  • forms the "sugar coat" glycocalyx of the outer leaflet
• Glycocalyx

  • specialized sites
  • allows cell to recognize each other
  • important in determining between body cells ("self") and foreign cells or tissues ("non-self")
  • can also protect the cell membrane from the direct action of physical forces and stresses allowing the membrane to maintain its integrity
• formation of fuzzy coat

  • due to moieties
• Peripheral Proteins

  • found in cytoplasmic side of inner leaflet
• Intrinsic/Integral Proteins

  • slightly embedded in one of the leaflets with a lipid anchor
• Transmembrane Proteins

  • found in both sides of the phospholipid layer
  • span the lipid bilayer thus are functional on both sides
• Porins

  • allows the entry and exit
  • example: aquaporins - allows exit and entry of water
• Endocytosis

  • phagocytosis - cell eating
  • pinocytosis
  • receptor-mediated
• Phagocytosis

  • cell eating
  • vacuole/ vesicle
  • phagosome - vacuole containing the molecule
  • phagolysosome - fuses with lysosome
  • large particles
• pinocytosis

  • cell drinking
  • smaller particles
  • pinocytotic vesicle
• Receptor-mediated

  • need to recognize the molecules to activate endocytosis