What’s in a Cell?

From Ch. 4

Plant cell walls

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Figure 4.1 Arrangements of cocci.

.

Plane of division

Diplococci

Streptococci

Tetrad

Sarcinae

Staphylococci

Figure 4.2 Bacilli.

Single bacillus

Coccobacillus

Streptobacilli

Diplobacilli

Figure 4.3 A double-stranded helix formed by Bacillus subtilis.

Figure 4.4 Spiral bacteria.

Vibrio

Spirochete

Spirillum

Figure 4.5 Star-shaped and rectangular prokaryotes.

Star-shaped bacteria Rectangular bacteria

Figure 4.7 Arrangements of bacterial flagella.

Peritrichous Monotrichous and polar

Lophotrichous and polar Amphitrichous and polar

Figure 4.8 The structure of a prokaryotic flagellum.

Gram- negative

Cytoplasm Plasma membrane

Gram- positive

Cytoplasm

Figure 4.13a Bacterial cell walls.

Tetrapeptide side chain

Peptide cross-bridge

Carbohydrate “backbone”

Peptide bond

N-acetylmuramic acid (NAM) Side-chain amino acid Cross-bridge amino acid

NAM

N-acetylglucosamine (NAG)

Structure of peptidoglycan in gram-positive bacteria

.

Figure 4.13b Bacterial cell walls.

Protein

Plasma membrane

Cell wall Lipoteichoic acid

Peptidoglycan

Gram-positive cell wall Lipid A

Core polysaccharide O polysaccharide

Wall teichoic acid

Figure 4.13c Bacterial cell walls.

Gram-negative cell wall

Lipopolysaccharide

Outer membrane Peptidoglycan

Plasma membrane

Cell wall

Lipid A Porin protein

Phospholipid

Lipoprotein

Periplasm Protein

Lipid A

Core polysaccharide O polysaccharide

Parts of the LPS

Core polysaccharide

O polysaccharide

Figure 4.13 Bacterial cell walls.

Tetrapeptide side chain Peptide cross-bridge

Carbohydrate “backbone”

Protein

Plasma membrane

Cell wall

Wall teichoic acid

Lipoteichoic acid

Peptidoglycan

Gram-negative cell wall

Gram-positive cell wall

Lipopolysaccharide

Outer membrane Peptidoglycan

Plasma membrane

Cell wall

O polysaccharide Co r e p ol y s a c ch a r i d e

Lipid A

Porin protein

Phospholipid

Lipoprotein

Periplasm Protein

Lipid A Core polysaccharide O polysaccharide

Peptide bond

Pa rts of the L P S

N-acetylmuramic acid (NAM) Side-chain amino acid Cross-bridge amino acid

NAM

N-acetylglucosamine (NAG)

Structure of peptidoglycan in gram-positive bacteria

Figure 4.14 Plasma membrane.

Outside

Inside

Figure 4.16 The principle of simple diffusion.

Figure 4.18 The principle of osmosis.

At beginning of osmotic pressure experiment

At equilibrium

Isotonic solution. No net movement of water occurs.

Hypotonic solution. Water moves into the cell. If the cell wall is strong, it contains the swelling. If the cell wall is weak or damaged, the cell bursts (osmotic lysis).

Glass tube

Rubber stopper Rubber band

Sucrose molecule Cellophane sack

Water molecule

Water

Solute Plasma membrane

E. coli in pure water:

• What is likely to move into or out

of the cell?

• What can the cell do about it?

Figure 4.20 Magnetosomes.

Figure 4.21 Formation of endospores by sporulation.

Sporulation, the process of endospore formation

An endospore of Bacillus subtilis

Spore septum begins to isolate newly replicated DNA and a small portion of cytoplasm.

Spore coat forms. Endospore is freed from cell.

Two membranes

Cytoplasm

Endospore

Ancient endospores

Ancient endospores

Clostridium botulinum is a strict anaerobe; that is, it is

killed by the molecular oxygen (O2) present in air. People

can die of botulism from eating foods in which C.

botulinum is growing.

• How does this bacterium survive on plants picked for

human consumption?

• Why are home-canned foods most often the source of

botulism?

(Tortora, 11th ed., p. 110)

Figure 4.27 Mitochondria.

Matrix Cristae Inner

membrane Outer membrane

Figure 4.28 Chloroplasts.

Applications of Microbiology 4.1 Mixotricha, a protozoan that lives in the termite gut.

Applications of Microbiology 4.2 Arrangements of bacteria on the surfaces of two protozoans.

Protozoan flagella

Spirochetes

Bracket

Protozoan surface

Filament composed of overlapping flagella

Rod-shaped bacteria in grooves

Protozoan surface

Termite gut symbionts: https://www.youtube.com/watch?v=HOx7SDdIqyU

kennethnoll.uconn.edu

Termite gut symbionts

kennethnoll.uconn.edu

Termite gut symbionts