Lecture 3 Prokaryotic Cell Biology

Lecture 3Prokaryotic Cell BiologyBio119

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

d. In an aggregate form called a nucleoid

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

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:

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

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 N-acetyl muramic acid in:

3. Multiple sugar chains are ______by amino acids

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:

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?

8) Structure: -lactam ring

c. Resistance to penicillins can arise if the bacteria obtains:

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