Chapter 3 Microbiology
Cellular Structure and Function p. 56-89
All living things can:
1)Grow- increase in size
2)Reproduce- increase in number
3)Respond- to environment
4)Metabolize- take in nutrients and use for energy
*How are Viruses different?
-unable to do 1, 2, 4 outside of a host cell, but respond
to env.
Schwann & Schleiden- all living things composed of cells
(living)
Review pg 60 – dif in cells
Prokaryotes- External Structures
1. Glycocalyces- gelatinous, sticky, surrounds outside of
cell
-protect from drying
-capsule or slime layer
-enable to survive and cause disease
Ex: pneumonia
2. Flagella- whiplike, used for movement
-composed of filament, hook, basal body
Arrangement:
a. Monotrichous-single
b. Lophotrichous- tuft at one end
c. Amphitrichous- both ends
d. Peritrichous- covering
Endoflagella- spirochetes, spiral
tightly
around cell to form axial filament instead of into
environment, corkscrew rotation
Taxis- move w/ series of runs and tumbles in
response to stimulus
Ex: Chemotaxis & Phototaxis
3. Fimbriae- sticky, bristlelike, adhere to one
another and to substances in envir.
-function in Biofilms-slimy masses of bact.
-99% of bacteria in nature exist as
4. Pili- short hairs
-move across a substrate or towards another
bact
- Used for conjugation (transfer of plasmid
from one bacteria to another)
Bacterial Cell Walls
- Composed of a complex polysaccharide called
Peptidoglycan
- Chains of sugars are connected by crossbridges
of amino acids
- Two types of cell walls: gram negative and gram
positive
Gram Positive
- Thick layer of peptidoglycan that also contains teichoic
acids (negative charge)
- Lipoteichoic acids anchor cell wall to cell membrane
- Create exotoxins
- Gram stain results in purple color
- Ex. Mycobacterium species
Gram Negative
- Thin layer of peptidoglycan but contains an outer
membrane that covers layer (ex. E. coli)
- Outer membrane contains lipopolysaccharides (LPS)
- Hard to treat infections due to outer membrane
- Lipid portion of LPS (Lipid A) released when outer
membrane disintegrates, creates endotoxin
- Killing lots of Gram – bacteria releases lots of lipid A
- Porin proteins allow transport of molecules through
outer membrane and into periplasmic space
- Gram stain pink
Cytoplasmic Membranes (cell membrane)
Structure
-double-layered structure- phospholipids bilayer
-hydrophilic phosphate heads (+water)
-hydrophobic lipid tails (-water)
-integral proteins
*Fluid Mosaic Model
*not in Archae- why
they don’t melt
Function
 separates contents of cell from outside
 controls passage of substances
 energy production & harvests light energy
 Selectively Permeable-allows some substances in
and not others
 concentration gradient- conc of a chemical on both
sides of memb
 electrical gradient- charged chemicals
Passive Processes- no energy to
move
1.Diffusion-net movement of a chemical down its conc. gradient
-higher conc to lower conc
2.Facilitated Diffusion- proteins act as channels/carriers for certain
molecules to flow
3.Osmosis- diffusion of water from higher conc of water to lower
conc. of water
Isotonic- same conc of solutes and water
Hypertonic- solution w/ higher conc of solutes, less water
Hypotonic- solution w/ lower conc of solutes, more water
Active Processes-require energy
to move
1. Active transport- uses proteins but requires ATP
uniport- 1 molecule
symport- 2 molecules in same directions
antiport- 2 molecules, in opposite directions
2. Group translocation- only in some prokaryotes
-substance is chemically changed
Cytoplasm of Prokaryotes- pg 75
-semiliquid, gelatinous material inside a cell
1. Cytosol- liquid portion
-contains DNA in nucleoid
-site of chemical reactions-produce amino acids
2. Inclusions- reserve deposits of lipids, starch, or compounds
store when nutrients are in abundance until needed
Nonmembranous
3. Ribosomes- site of protein synthesis
-composed of protein and rRNA
-70S vs 80S
4. Cytoskeleton- internal network of fibers, basic shape
Eukaryotes
External Structures
1. Glycocalyces- protection, adhesion, cell
to cell recognition
-absent in cells w/ cell walls
(plants, fungi, algae)
2. Flagella- are within the cell membrane
-"9+2" arrangement
-9 pairs of microtubules around 2 in
the center
-basal body "9+0" but no hook
-undulate rhythmically, push & pull, no
runs and tumbles
3. Cilia- hairlike, only on Eukaryotes
-same arrangement (9+2)
-beat rhythmically for movement
Cell Walls- provides protection, shape & support
Plants-composed of cellulose
Algae- agar, algin, carrageenan
Fungi-chitin
*All have cytoplasmic membranes (fluid mosaic)
also contain steroid lipids- controls movement in and out
Processes
same as prokaryotes, but also:
Active-uses ATP
1. Endocytosis- bringing in
-membrane distends (pseudopodia-false feet) to
surround food
Phagocytosis- solid
Pinocytosis- liquid
2. Exocytosis- exports substances
Organelles
Nonmembranous
1. ribosomes- protein synthesis (80S)
2. Cytoskeleton-anchor and movement of
organelles, shape
3. Centrioles in Centrosome- animal and some
fungal
-role in mitosis, cell division (cytokinesis)
Organelles
Membranous
1. Nucleus- spherical to ovoid, largest organelle in cell
-contains DNA- "control center of cell"
-nucleoplasm-liquid matrix, contains nucleoli- RNA synthesis
and chromatin(mass of DNA)
-surrounded by nuclear envelope w/ nuclear pores
2. Endoplasmic Reticulum (ER)
-smooth (no ribosomes) lipid synthesis, transport
-rough (ribosomes)- protein production
3. Golgi Body- shipping department, receives, processes, packages
in secretory vesicles (sacs)
4. Sacs Vacuole- (plants and algal) storage
Vesicle- storage, digestion, transport
Lysosomes- (animal) breakdown of nutrients, eat
old/damaged cells
Peroxisomes- neutralization of toxins
5. Mitochondria- "powerhouse of cell"
produce ATP
2 membranes- inner folds into cristae
6. Chloroplasts- photosynthesis, light harvesters
Endosymbiotic Theory- pg 87
Lynn Margulis
-to explain presence of circular DNA, 70S ribosomes, and
2 bi-lipid membranes in mitochondria and chloroplasts
-Eukaryotes formed from the phagocytosis of small
aerobic prokaryotes by larger anaerobic prokaryotes
-became internal parasites
-not universally accepted
Cell Biology Video
 http://www.youtube.com/watch?v=zufaN_aetZI