Chapter 3 Cellular level of Organism
Outline
1. Overview of cellular basis
 Basic unit of life
 First observed by Robert Hook in 1600s.
2. Plasma membrane structure (called phospholipid bilayer)
 Fluid mosaic model
 Bilayer of lipoprotein
 Hydrophilic and hydrophobic surfaces
 Phospholipids and glycolipids
 Integral proteins- and peripheral proteins-are attached to but can
separate from the membrane. Membrane proteins can act as
anchors, identifiers, enzymes, receptors, carriers and channels
 Glycocalyx—enriched in glycolipids and glycoproteins and its
function is lubrication, protection, anchoring.
3. Specializations of Plasma Membrane
Microvilli—hair like—increase membrane surface e.g. kidney tubule
Membrane junctions—Tight, gap, desmosomes-anchoring
4. Plasma membrane functions
Physical isolation: physical barrier separating the inside of the cell from the
surrounding extracellular fluid. Inside and outside conditions are very
different, these differences must be maintained to preserve homeostasis.
Regulation of exchange with the environment: Plasma membrane controls
entry and exit of ions, nutrients and wastes etc.
Sensitivity to the environment: Plasma membrane is the first that is
affected by changes in the concentration of extracellular fluid, pH,
concentration. It has receptors to receive chemical signals from other cells.
Structural support: Plasma membrane has special structures between
plasma membranes and extracellular materials to support and give tissue
stability.
Cytoplasm contains the fluid cytosol and the organelles. It differs from
extracellular fluid in composition.
etc.
Membrane transport ( plasma membrane is selectively permeable)
Simple diffusion-Net movement of substances from an area of higher
concentration to an area of lower concentration.
Carrier mediated transport - involves binding and transporting of specific
ions by integral proteins. Two ways of transport-- contratport and
countertransport channels.
Facilitated diffusion: by carrier protein--compounds are transported
across by binding to a receptor site within the channel of a carrier protein.
Osmosis— movement of water from higher concentration to lower
concentration through semipermeable membrane.
Tonicity-describes the effects of osmotic solution on cells--isotonic,
hypertonic and hypotonic solution
Active transport —ATP needed.
Vesicular transport—endocytosis, exocytosis, phagocytosis, pinocytosis
Receptor mediated endocytosis.
Transmembrane potential: The potential difference, measured in volts.
http://highered.mcgrawhill.com/sites/0072943696/student_view0/chapter8/animation__voltagegated_channels_and_the_action_potential__quiz_1_.html
5. The cytoplasm
 Cytosol
 Cytoplasmic organelles- Mitrochondria, Golgi apparatus,
Lysosomes, Endoplasmic reticulum, Ribosomes, Microvilli,
Peroxisomes, Proteasomes
6. Cytoskeleton
 Microfilaments
 Intermediate filaments
 Centrosome and centrioles
7. Cellular extentions
 Cilia and flagella
8. Nucleus
 Nuclear membrane
 Nucleoli
 Chromatin

9. Cell life cycle
 Mitosis –G1, S, G2 phases.
 Meiosis
 Apoptosis—genetically control cell death
10. Tumors and cancers—abnormal cell growth. Tumor or neoplasm can
be benign ( cell remainwithin the epithelium or a connective tissue) or
malignant-don’t remain confined to epithelium or a connective tissue
but spread into surrounding tissue (metastasis). Page 101 Martini.
Cell structure and function
https://www.youtube.com/watch?v=fKEaTt9heNM
https://www.youtube.com/watch?v=g4L_QO4WKtM
https://www.youtube.com/watch?v=Rp4XPgWNc_Q