the scientific study of cells
cyto = , logy =
cell, study of
proto = , plasm =
squam = , ous =
scale, characterised by
cub = , oidal =
cube; like, resembling
Cell theory is
All organisms are composed of cells and cell products
The cell is the simplest structural and functional unit of life
An organism’s structure and all of its functions are due to the activities of its cells
Cells come from pre-existing cells
Because of a common ancestry, the cells of all species have many fundamental similarities both chemically and metabolically
List and describe 9 cell shapes and give examples
Squamous = thin and flat with bulge at nucleus (alveoli of lungs, epidermis)
Cuboidal = squarish-looking (liver cells, kidney tubules)
Columnar = more taller than wide (intestines)
Polygonal = irregular angular shapes with 4,5 or more sides (epidermis)
Stellate = starlike shape (cell bodies of nerve cells)
Spheroidal = round to oval (egg cells, white blood cells)
Discoid = disc shaped (red blood cells)
Fusiform = spindle shaped; elongated with thick middle and tapered at both ends (smooth muscle cells)
Fibrous = long, slender and threadlike (skeletal muscle cells)
poly = , gon =
stell = , ate =
star, characterised by
fusi = , form =
What is the human cell size usually?
most cells are from 10 - 15 µm (micrometer or 10-6) in diameter
egg cells (very large)100 µm diameter
nerve cell (very long) up to 1 metre long
Explain ratios of diameter, surface area and volume in cells
If diameter (D) increased by a factor of 2 then surface area increases by a factor of 4 (=D2) and volume increases by a factor of 8 (=D3)
What are the limitations on cell size?
cell growth increases volume more than surface area.
If cell grows too big the ability to absorb nutrients is reduced.
If cell grows too big the ability to remove waste is reduced.
There is too much cytoplasm needing nourishment and not enough membrane surface for nutrient and waste exchange
State and identify the three major components of a cell
What is TEM and explain what it does?
Transmission Electron Microscope uses a beam of electrons in place of light and enabled scientists to see a cell's ultrastructure. Invented mid 20th century.
What is LM?
What is SEM and what can it do?
It is a scanning electron microscope and it produces dramatic three dimensional images at high magnification and resolution but can only view surface features.
What is the plasma cell membrane made of?
proteins and lipids
Structure of representative cell see diagram
Describe the general structure of the plasma membrane
The outermost component of a cell that functions as a semi-permeable barrier between substances inside (intracellular) and outside (extracellular) the cell
Structurally it consists predominantly of a phospholipid bilayer with embedded membrane proteins
The plasma membrane is 45-50% lipids, 45-50% proteins and 4-8% carbohydrates
To clarify: intracellular face of membrane faces cytoplasm and extracellular side faces outward.
a class of lipids that are a major component of all cell membranes as they can form lipid bilayers and are also amphiphile.
is a term describing a chemical compound possessing both hydrophilic (water-loving, polar) and lipophilic (fat-loving) properties, according to wikipedia.
In textbook: describes this as both hydrophilic and hydrophobic.