Biology 160
A Tour of the Cell
Ch. 4
All (?) organisms are made of cells.
Basic unit capable of performing all functions necessary for life.
single
multicellular
inbetween??
Limits of size of cells:
lower limits:
upper limits:
exceptions to upper limits
Two different Structural Types of Cells:
Prokaryotes- structurally simple
Eukaryotes- more complex, have internal membrane bound organelles
Plasma Membrane: found in all cells, main function: selective permeability
Fluid Mosaic Model:
Phospholipid bilayer- main structural component
Protein: many functions
Transporters across the membrane
Enzymes
Signal receptors
+/- Sterols; animal cells have cholesterol
important in maintaing the correct fluidity
+/- Short polymers of sugars, always facing the outside
identify types of cells, tissues
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Components of the Prokaryote Cell:
Plasma (Cell) membrane
nucleoid- region with the chromosome composed of DNA + protein
Function: genetic information
ribosomes- made of RNA and protein
Function: protein manufacturing
cell wall (most) peptides and polysaccharides
Function: shape, rigidity
+/- capsule- proteins and sugars
Function: attachment
+/- flagella- protein
Function: movement
+/- pili- protein
Function: attachment, “sex”
Components of the Eukaryote Cell:
plasma membrane
nucleus-membrane encircled region with chromosomes
ribosome- found in two locations; cytosol + rough endoplasmic reticulum
Endomembrane system- connected membranes via physical contact or by vesicles
synthesis, storage and export of materials
nuclear membrane- double membrane with pores
rough endoplasmic reticulum- manufacture of membranes and proteins
smooth endoplasmic reticulum- manufactures lipids, metabolism of carbohydrates,
detoxify some drugs, calcium storage
golgi apparatus- manufactures various macromolecules finishes, sorts and ships
products
lyosomes- filled with digestive enzymes;(animals only)
fuse with vesicles and digest the food/organelles/ bacteria
vacuoles- plants--storage of pigments, toxins, digestive enzymes, take up space
animals-- water collectors
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Other Membrane Enclosed Organelles (not the ER System):
mitochondria- cellular respiration - extract chemical energy from foods
plastids- (plants only)- variety
Chloroplasts- photosynthesis- make sugars
Amyloplasts- store starch
peroxisomes- breaks down various substances, detoxify various drugs
The Cytoskeleton:
support
changes in shape
movement, inside the cell and the whole cell
signal transmission
Three types of Cytoskeleton: all made of different proteins
microtubules
microfilaments
intermediate filaments
Motor or Molecular Proteins: work with the Cytoskeleton, ATP powered
Cell Surfaces
cell walls:
rigid structure,
found in plants, most fungi (bacteria)
plants-cellulose, other polysaccharides
fungi- chitin (polysaccharide)
extracellular matrix: not rigid, but surrounds and attached to the plasma membrane
found in animals and animal-like, single-celled organisms
complex structure---glycoproteins including collagen, others, etc…
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