Chapter 2 - Chemical Principles
Chapter 3 - Observing Microorganisms through a Microscope (read only
pp. 68-72)
Chapter 4 - Functional Anatomy
I. Biochemistry (Chapter 2)
A) You should have a basic knowledge of elements, atoms and the
formation of chemical bonds - covered in pp. 27-39 in text.
B) Major classes of biological macromolecules - Proteins,
Polysaccharides, Nucleic Acids.
1) All are polymers - made up of repeating
units of subunits called monomers.
a) Protein function - enzymes (biological catalysts)/metabolism,
transport of molecules, DNA & RNA synthesis,
structure of cell.
b) Polysaccharide function - energy source.
c) Nucleic Acid function - storage and expression of genetic material.
C) Proteins or polypeptides are polymers of amino acids.
1) Amino acid structure
2) 20 amino acids commonly found in all proteins.
3) Proteins held together by peptide bonds.
4) Once the primary amino acid chain is formed,
a protein can fold into a helix or a pleated sheet and then into a
3-D globular shape.
D) Polysaccharides are made up of sugar (monosaccharide)
subunits.
1) Polysaccharides (carbohydrates) are formed when
a glycosidic bond is formed between two sugar molecules.
E) Nucleic Acids - DNA and RNA
1) Flow of information in biological
systems.
2) DNA is a polymer of deoxyribonucleotides.
Sugar (deoxyribose - 5-carbon sugar), phosphate group (5ícarbon of
sugar), nitrogenous base (purine or pyrimidine ring)
Adenine, Guanine, Cytosine, Thymine (AGCT)
Purines (A, G), pyrimidines (C, T)
3í OH - direction
3) RNA is also a polymer of nucleotides,
except that the sugar is ribose, not deoxyribose. Also, base
uracil replaces thymine.
4) RNA and DNA held together by
phosphdiester bonds between two nucleotides.
F) One last important biological molecule, not classified
as a macromolecule because it is too small - Lipids.
1) not
polymers of smaller subunits
2) Phospholipids
- made up of fatty acids, glycerol, phosphate and are the main structural
component of cell membranes.
3) cell
membrane is a lipid bilayer.
The Prokaryotic Cell
Bacterial shapes and arrangements -
A) three basic shapes
1) coccus (cocci) - sphere-shaped
2) bacillus (bacilli) - rod-shaped or
cylindrical
3) spirillus (spirillum) - spiral-shaped
B) Bacterial cell arrangements
1) strepto - chains
streptococcus
- spherical cells in long chains
2) staphylo - clusters
3) diplo - groups of two
Bacterial structures by function
I) Cell Wall
A) The cell wall serves to enclose internal
contents and separate them from external environment, maintains integrity
of the cell.
1) Gram positive and Gram negative cell walls.
2) Gram positive cell wall is characterized by a thick peptidoglycan
layer.
a) Peptidoglycan made of 1) a glycan backbone made of two sugars,
N-acetylglucosamine (NAG)
and N-acetylmuramic acid (NAM) and 2) peptides which attach to the NAM
molecules to join them together.
- diaminopimelic acid is an unusual amino acid found only in bacterial
cell walls.
- The antibiotic Penicillin interferes with the synthesis of peptidoglycan.
- The Archaebacteria do not have peptidoglycan in their walls.
3) Gram negative cell wall - thinner layer of peptidoglycan plus
an outer membrane and a periplasm.
4) Staining procedures - learning in lab starting today.
a) Simple; differential; structural.
5) Mycolic acid is an unusual lipid found in the cell walls of bacteria
called the Acid-Fast bacteria -
mostly in the Genus Mycobacterium (M. leprae and M. tuberculosis)
a) Mycolic acid is a high MW fat which has the consistency of paraffin
wax, so cells with this molecule in their cell
walls are difficult to stain, but once the stain is difficult to decolorize/remove.
b) Acid-Fast refers to a special staining procedure which was developed
to stain these bacteria.
6) Some
bacteria lack a cell wall - Genus Mycoplasma.
B) The cell wall maintains the integrity
of the cell.
1) Bacterial
normally grow , in nature and lab, in aqueous environments that contain
low concentrations of
salts and other nutrients.
2)
Cytoplasm is a concentrated soup of organic salts, sugars, amino acids
and other molecules.
3)
The number of particles (solutes) tends to equalize on both sides of the
cell (osmosis).
And since there are more particles inside the cell, water tends to flow
into the cell.
This puts pressure on the membrane and without a cell wall, the cell would
burst.
4) Without a
cell wall, cells can be maintained if they are in a solution that contains
higher salt.
II) Membranes - important for regulating molecular traffic.
A) Cytoplasmic membrane (plasma membrane)
surrounds the cytoplasm of the cell.
B) 40% lipid, 60% protein.
C) Lipid - phospholipid bilayer.
D) Protein - integral proteins
peripheral proteins
E) Semipermeable
F) How do molecules get through the membrane?
1) Diffusion -
Passive -
Facilitated -
2) Active transport -
G) Exoenzymes -
III) Metabolism - sum total of all chemical reactions in the
cell; occurs in the cytoplasm.
Cytoplasm is the soup of
proteins inside the cell memb/wall.
A) Two important functions that occur
in the cytoplasm are:
Generation of energy
Protein synthesis
B) Energy - nutrient molecules are broken
down, and in the process, energy is created that the cell can use for
synthesis of cell components, DNA, proteins
C) Protein synthesis -
1) Protein factories of prokaryotic and eukaryotic cells are ribosomes.
Turn RNA into protein.
2) Structure -
D) Storage granules - aggregates of
large molecules stockpiles of useful molecules.
1) Several
types -
Glycogen - polymer of glucose molecules; energy, carbon
storage.
B-hydroxybutyric acid - energy, carbon storage
Volutin - Phosphate storage.
IV) Movement - Flagella (prokaryotic different from eukaryotic)
A) Three parts
1) filament
- composed of flagellin proteins twisted together in a helical conformation.
2) hook
- transition between filament and motor.
3) basal
body - anchor in cell wall and motor.
B) E. coli can move at a speed
of 20 body lengths per second (20 um/sec).
C) Arrangement of flagella - helpful
in identification of species.
1) single
- monotrichous
2) tuft
- lophotrichous
3) all
around - peritrichous
4) one
at each end - amphitrichous
D) Mechanism of movement - Read about in text.
1) Chemotaxis
- movement toward food or away from harmful substances.
E) No cilia in prokaryotes - only in
eukaryotes.
V) Cell attachment, transfer of genetic information - Pili
(fimbrae)
A) Pili are hairlike protein appendages
that extend from the cell surface.
1) Adhesins
are proteins on pili which help in the attachment process.
2) Attachment
is one of the first steps in cause of disease.
3)
Special pili involved in transfer of DNA from one cell to another
F or sex pili - more later
VI) Another special structure involved in cell attachment -
Capsule.
A) Capsule - slime layer (polysaccharides)
produced and deposited outside cell wall.
B) Cell envelope - Capsule, cell wall,
cytoplasmic membrane.
C) Slime components
D) Not all bacterial species make capsules;
can also depend on nutritional environment.
E) Bacti colonies are slimy
F) Capsules are visualized by stain
technique that involves negative staining (just learned in lab).
G) Capsule also involved in disease,
attachment - capsules provide a protective function to bacterial cells
VII) Special survival structure - Endospores (ěSporesî)
A) Present in some Gr+ bacilli
B) Develop inside the vegetative cell
(actively growing cell) when environment becomes unfavorable
- low carbon, low nitrogen.
C) Structure - coat, core
D) When conditions become favorable,
spore germinates and forms vegetative cell.
VIII) Storage of genetic information - DNA arranged in a nucleoid
(region).
A) Bacterial chromosome
1) one, sometimes a few, but all identical.
2) A single, long, double-stranded DNA molecule.
Stretched out - 1 mm (way bigger than cell)
3) Read about how DNA is organized so it fits inside the cell.
The Eukaryotic Cell
I) Eukaryotic plasma membrane and cell wall.
A) Cell wall (when present) contains cellulose
or chitin or glucan or mannan
B) Animal cells surrounded by glycocalyx.
C) Plasma membrane - phosholipid bilayer with proteins
1) Also carbohydrates
and sterols
2) Passive and active
transport
II) Eukaryotic cytoplasm - similar to prokaryote, but has a cytoskeleton.
A) Organelles - membrane bound structures
in the cytoplasm.
1) Nucleus - DNA, nuclear
envelope.
2) Endoplasmic Reticulum
- multifunctional.
3) Ribosomes - protein
synthesis, 80S.
4) Golgi Complex -
membrane formation, protein secretion.
5) Mitochondria -
ATP production, contain 70S ribosomes, DNA and multiply by fission.
6) Chloroplasts -
photosynthesis, contain 70S ribosomes, DNA and multiply by fission.
7) Lysosomes - digestive
enzymes
8) Vacuoles - storage
organelles
9) Centrioles - involved
in cell division.
10) Movement - flagella
and cilia.
III) Endosymbiont theory - evolution of eukaryotes.