MICR 2420 Lecture Notes - Lecture 3: Microorganism, Nitrogen Fixation, Biofilm
27 Jun 2018
School
Department
Course
Professor
Chapter 3: Cell Structure and Function
Characteristics of Bacteria
Thick complex outer envelope
Compact genome
Tightly coordinated functions
Cell wall
15-30nm in thickness, 10%-25% of dry weight
-Protecting cell from osmotic lysis
Fortress like structure composed of sugar chains linked covalently by peptides
find more resources at oneclass.com
find more resources at oneclass.com
Peptido-glycan Polymer (amino acids + sugars)
Unique to bacteria
Sugars; NAG & NAM
-N-acetylglucosamine
-N-acetymuramic acid
Functions of Cell Wall
Maintaining the cell's characteristic shape- the rigid wall compensates for the flexibility
of the phospholipid membrane and keeps the cell from assuming a spherical shape
Countering the effects of osmotic pressure
Providing attachment sites for bacteriophages
Providing a rigid platform for surface appendages- flagella, fimbriae, and pili, all
emanate from the wall and extend beyond it
Cell Membrane/ plasma membrane
Cytoplasm is contained by cell membrane
Bilayer Phospholipid
Water can penetrate
Flexible
Cell membrane prevents cytoplasmic leaking out and maintains gradients of ions &
find more resources at oneclass.com
find more resources at oneclass.com
nutrients
In Gram negative bacteria, inner membrane is called cell membrane
Not strong, ruptures easily
oOsmotic Pressure created by cytoplasm
Cytoplasm
Composed largely of water, gel like network composed of proteins, nucleic acid, lipids
and small amount of sugar and salts
Ribosomes: numerous, 15-20nm in diameter, distributed throughout cytoplasm
-no organelles (mitochondria, golgi, etc)
-chromosome is organized within the cytoplasm called nucleoid
Plasmids: extra chromosomal genetic elements
Inclusions: sources of stored energy, example: volutin
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Fortress like structure composed of sugar chains linked covalently by peptides. Maintaining the cell"s characteristic shape- the rigid wall compensates for the flexibility of the phospholipid membrane and keeps the cell from assuming a spherical shape. Providing a rigid platform for surface appendages- flagella, fimbriae, and pili, all emanate from the wall and extend beyond it. Cell membrane prevents cytoplasmic leaking out and maintains gradients of ions & nutrients. In gram negative bacteria, inner membrane is called cell membrane. Not strong, ruptures easily: osmotic pressure created by cytoplasm. Composed largely of water, gel like network composed of proteins, nucleic acid, lipids and small amount of sugar and salts. Ribosomes: numerous, 15-20nm in diameter, distributed throughout cytoplasm. Chromosome is organized within the cytoplasm called nucleoid. Essential ions potassium, magnesium, phosphates, chloride ions. Small organic molecules lipids & sugars. Macromolecules proteins, nucleic acids (dna & rna) Other macromolecules peptidoglycan in cell wall (1% of cell mass)
