Cell Biology
? Tool for studying microbiology:
Microscopes and Microscopy
Microscope,
(a) Bright-field
(b) Phase contrast
(c) Dark-field
(d) Fluorescence
Staining,Dyes can be used to stain cells
and increase their contrast-Gram Staining
The Prokaryotic Cells
Consisting of cell wall,cytoplasmic membrane,ribosomes,
inclusions,chromosome,flagella
Morphology of Prokaryotes
Coccus or Cocci
Rod
Spirillum or Spirilla
Spirochete
Budding and appendaged
Filamentous
The Eukaryotic Cells
Chloroplast
Cytoplasmic Membrane,Structure
Cytoplasmic Membrane,Structure
? Lipid bilayers,flexible structures,
embedded with proteins.
Structure of the cytoplasmic membrane
Prokaryotes
Membrane Stabilizers:
hydrogen bonds
hydrophobic interactions
Mg2+,Ca2+,hopanoids
Membrane Strengthening Agents,
Sterols and Hopanoids
(a) General structure of a sterol;
(b) The structure of cholesterol;
(c) The structure of the hopanoid
diploptene.
Enkaryotes membrane stabilizer:
Sterol
Archaeal Membranes
Chemical
linkages in lipids:
(a) ester linkage
(b) ether linkage
(c) isoprene
Functions of the Cytoplasmic Membrane
The cytoplasmic membrane is selectively permeable
and contains specific carrier proteins that participate
in the transport process
Selectively Permeability,nonpolar and fat-soluble such as
fatty acids,alcohols and benzene (permeable) ; charged
molecules such as organic acids,amino acids and inorganic
salts (impermeable,must be specifically transported)
Carrier Proteins,or Membrane Transport Proteins:
Uniporters,Symporters and Antiporters
Three Types of Carrier Proteins
Ionophores （离子载体）
Structure of the
peptide ionophore
(and antibiotic)
tyrocidin.
Note the
predominance of
nonpolar and
aromatic amino
acids,The ion is
carried in the
center of the
molecule.
The action of membrane transport proteins
1,Facilitated diffusion
(carrier-mediated diffusion) (not energy required)
2,Group translocation (energy required)
3,Active transport (energy required)
Facilitated
diffusion
? Characteristics:
Conformational change
Not energy required
Group translocation
PEP,磷酸烯醇丙酮酸
The phosphotransferase system
Active
Transport
Proton pumps linked
to transport are key
constituents of all pro-
karyotic membranes
and are also present in
the inner membranes
of mitochondria and
chloroplasts
Ion Gradients
in Eukaryotes
The Cell Wall of Bacteria,Structure and Function
To give shape and rigidity to the cells (peptidoglycan or murein)
Peptidoglycan cell
wall structure:
Glycan Tetrapeptide
Manner in which the peptide and glycan units are connected
in the formation of the peptidoglycan sheet
M,N-acetylmuramic acid
G,N-acetylglucosamine
Overall Structure of the Gram-positive Cell Wall
a) Teichoic acid,磷壁酸
Outer Wall Layer of Gram-negative Bacteria
Outer membrane layer of many Gram-negative bacteria is frequently toxic to animals
Osmosis,lysis and protoplastic formation
Mycoplasmas are essentially free-living protoplasts
On Line Resource for This Textbook
Http://www.prenhall.com/~brock
My e-mail,chengq@mail.tsinghua.edu.cn
? Tool for studying microbiology:
Microscopes and Microscopy
Microscope,
(a) Bright-field
(b) Phase contrast
(c) Dark-field
(d) Fluorescence
Staining,Dyes can be used to stain cells
and increase their contrast-Gram Staining
The Prokaryotic Cells
Consisting of cell wall,cytoplasmic membrane,ribosomes,
inclusions,chromosome,flagella
Morphology of Prokaryotes
Coccus or Cocci
Rod
Spirillum or Spirilla
Spirochete
Budding and appendaged
Filamentous
The Eukaryotic Cells
Chloroplast
Cytoplasmic Membrane,Structure
Cytoplasmic Membrane,Structure
? Lipid bilayers,flexible structures,
embedded with proteins.
Structure of the cytoplasmic membrane
Prokaryotes
Membrane Stabilizers:
hydrogen bonds
hydrophobic interactions
Mg2+,Ca2+,hopanoids
Membrane Strengthening Agents,
Sterols and Hopanoids
(a) General structure of a sterol;
(b) The structure of cholesterol;
(c) The structure of the hopanoid
diploptene.
Enkaryotes membrane stabilizer:
Sterol
Archaeal Membranes
Chemical
linkages in lipids:
(a) ester linkage
(b) ether linkage
(c) isoprene
Functions of the Cytoplasmic Membrane
The cytoplasmic membrane is selectively permeable
and contains specific carrier proteins that participate
in the transport process
Selectively Permeability,nonpolar and fat-soluble such as
fatty acids,alcohols and benzene (permeable) ; charged
molecules such as organic acids,amino acids and inorganic
salts (impermeable,must be specifically transported)
Carrier Proteins,or Membrane Transport Proteins:
Uniporters,Symporters and Antiporters
Three Types of Carrier Proteins
Ionophores （离子载体）
Structure of the
peptide ionophore
(and antibiotic)
tyrocidin.
Note the
predominance of
nonpolar and
aromatic amino
acids,The ion is
carried in the
center of the
molecule.
The action of membrane transport proteins
1,Facilitated diffusion
(carrier-mediated diffusion) (not energy required)
2,Group translocation (energy required)
3,Active transport (energy required)
Facilitated
diffusion
? Characteristics:
Conformational change
Not energy required
Group translocation
PEP,磷酸烯醇丙酮酸
The phosphotransferase system
Active
Transport
Proton pumps linked
to transport are key
constituents of all pro-
karyotic membranes
and are also present in
the inner membranes
of mitochondria and
chloroplasts
Ion Gradients
in Eukaryotes
The Cell Wall of Bacteria,Structure and Function
To give shape and rigidity to the cells (peptidoglycan or murein)
Peptidoglycan cell
wall structure:
Glycan Tetrapeptide
Manner in which the peptide and glycan units are connected
in the formation of the peptidoglycan sheet
M,N-acetylmuramic acid
G,N-acetylglucosamine
Overall Structure of the Gram-positive Cell Wall
a) Teichoic acid,磷壁酸
Outer Wall Layer of Gram-negative Bacteria
Outer membrane layer of many Gram-negative bacteria is frequently toxic to animals
Osmosis,lysis and protoplastic formation
Mycoplasmas are essentially free-living protoplasts
On Line Resource for This Textbook
Http://www.prenhall.com/~brock
My e-mail,chengq@mail.tsinghua.edu.cn
