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Lecture 3
Prokaryotic Cell Biology
Bio119
I. CYTOPLASM
A. The cytoplasm is thick!
B. It contains nucleoid, ribosomes, macromolecules like proteins
and RNA, small molecules like amino acids, some intracellular
inclusions
C. Nucleoid
1. DNA
a.
b.
c.
Table. Comparison of genome sizes of various organisms
Organisms
Mycoplasma genitalium
Borrelia burgdorferi
Helicobacter pylori
E. coli
Vibrio cholerae
Mycobacterium
tuberculosis
Methanococcus
jannaschii (archaea)
Saccharomyces
cerevisiae (eukaryote)
Human
Genome
Size (kbp)
Predicted
ORFs
580
910
1700
4600
4000
470
853
1600
4300
3890
Circular or
Linear, 1 or 2
molecules
C, 1
L, 1
C, 1
C, 1
C, 2
4400
3900
C, 1
1700
1682
C, 1 (plasmids)
12,000
6000
L, 16
3 million
30,000
L, 23
d. In an aggregate form called a nucleoid
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2. This structure may facilitate coupled:
D. Ribosomes—
1.
2. Two subunits
3.
E. Cytoplasmic Inclusion bodies
1. Two types
2. Some examples:
a. Energy or metabolite granules
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Lecture 3
Prokaryotic Cell Biology
Bio119
3. Magnetosomes
4. Gas, in Gas Vesicles
II. CYTOPLASMIC MEMBRANE
A. Also called inner membrane, plasma membrane
B. As in every other membrane, composed of Phospholipids
1.
2. Hydrophilic part:
3. Hydrophobic part:
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Prokaryotic Cell Biology
Bio119
4. Connection between the hydrophilic head and
hydrophobic tail is different in bacteria vs. archaea
5. The membranes of Archaea are unusual in other ways:
C. Organisms add more rigid molecules to the membrane to
give it strength
1. eukaryotes
2. most prokaryotes do not have sterols
D. Proteins of two types:
1. Peripheral
2. Integral
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Prokaryotic Cell Biology
Bio119
E. Functions of the cytoplasmic membrane
1. Mainly serves as a _____________________ barrier
2. An anchor for: ______________________
3.
III. CELL WALL
A. Needed to keep the prokaryotic cell from popping
B. In bacteria: can be divided into two types based on thickness
C. Cell wall Composition in Bacteria—Peptidoglycan:
1. Rigid layer
2. A polymer of two sugars: N-acetyl glucosamine and Nacetyl muramic acid in:
3. Multiple sugar chains are ___________________ by amino
acids
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Lecture 3
Prokaryotic Cell Biology
Bio119
4. Strength comes from the amino acid connection between
the 2 or more sugar chains
D. Archaeal Cell Walls are made of different molecules
1. Pseudopeptidoglycan
2. In other archaea they are protein or polysaccharide.
3. Archaea can also stain gram- and gram+, but this is not
based on the same underlying structures as in bacteria.
a) Gram – archaea do not have an outer membrane
They usually have surface layer of
protein/glycopprotein
b) Gram+ archaea have single thick layer for wall
F. Because the cell wall is necessary for prokaryote survival, if
you can compromise it, you can kill the bacteria
1. What happens if you remove the cell wall:
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Prokaryotic Cell Biology
Bio119
2. Because the wall is critical, it is the site of action of several
antibacterial chemicals and antibiotics
a. Lysozyme
Enzyme that cuts:_______________________
Made by: _____________________________
b. Antibiotics such as Penicillins and Cephalosporins
1) Bind to the ___________________ enzyme
2)
3) Penicillins:
4) This is called __________________________________.
5) Result is that sugar chain is not crosslinked, therefore
not as strong
6) w/o strong wall,
7) Death only occurs if the cells are ________________
Why?
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Prokaryotic Cell Biology
Bio119
8) Structure: -lactam ring
c. Resistance to penicillins can arise if the bacteria obtains:
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