• Animal Plant Fungi Protist Eubacteria Archea

Heterotroph/Autotroph/Both

Mulitcellular/Unicellular

Cell Wall?If so, what material?

Prokaryote/ Eukaryote

I.What is a bacterium? A. Unicellular prokaryote.

Slide 3

Fig. 22.3, p. 356

bacterial flagellum

pilus

capsule

cell wall

plasma membrane

cytoplasm

DNA

ribosomesin cytoplasm

I.What is a bacterium?

B. Anatomy

1. Cell Wall – often made of peptidoglycan

2. DNA – usually in single, circular strand

3. Plasmids – extra DNA, codes for nonvital traits

4. Ribosomes – assemble amino acids

5. Flagellum – movement

6. Plasma Membrane – under cell wall

7. Pilus – use for attachement

I.What is a bacterium?

Slide 4

in-text, p. 356

coccus bacillus

spirillum

C. Bacterial Shapes

I.What is a bacterium?

D. Bacterial Classification

1. Gram Positive/Negative

Gram Positive

display

peptidoglycan

in cell wall.

I.What is a bacterium?

D. Bacterial Classification 2. Metabolism: a. Photoautotroph: Use light as energy source. b. Chemoautotroph: Autotrophs that use inorganic compounds as energy source. c. Heterotroph

II. Bacterial Growth and Reproduction

A. Asexual: Prokaryotic Fission

Circular DNA (lacking histones) replicates, then is divided between two new cells.

Fig. 22.7, p. 358

a  Bacterium (cutaway view) before DNA replication. The bacterial chromosome is attached to the plasma membrane.

b  DNA replication starts. It proceeds in two directions away from the same site in the bacterial chromosome.

c  The new copy of DNA is attached at a membrane site near the attachment site of the parent DNA molecule.

d  New membrane grows between the two attachment sites. As it increases, it moves the two DNA molecules apart.

e  At the cell midsection, deposits of new membrane and new wall material extend down into the cytoplasm.

f  The ongoing, organized deposition of membrane and wall material at the cell midsection divides the cell in two.

II. Bacterial Growth and Reproduction

B. Sexual Recombination: Bacterial Conjugation

A plasmid (extrachromosomal DNA) can be transferred from one bacterium to another through the extension of a sex pilus.

Fig. 22.8, p. 359

a  A conjugation tube has already formed between a donor and a recipient cell. An enzyme has nicked the donor’s plasmid.

b  DNA replication starts on the nicked plasmid. The displaced DNA strand moves through the tube and enters the recipient cell.

c  In the recipient cell, replication starts on the transferred DNA.

d  The cells separate from each other; the plasmids circularize.

nicked plasmid conjugation tube

II. Bacterial Growth and Reproduction

C. Transduction: DNA transferred through

virus

When a virus infects a bacterium, it may

transfer bacterial DNA when it infects

other bacteria.

III. Bacterial Diversity

Prokaryotes are too diverse to fit into one kingdom, ‘Monera’

A. Archea: Extremophiles, Live in extreme environments.

1. Methanogens: Swamps, animals guts; anaerobic.

2. Halophiles: Salt-loving

3. Thermophiles: Heat-loving

III. Viruses

A. Noncellular Infectious Agent

B. Contain either DNA or RNA (never both)

C. Have outer protein coat (capsid)

D. May have tail or other attachment adaptation

E. Smaller than bacterium

III. Viral Infection

A. There are four stages to a viral infection:• Attachment – the virus must be of the correct shape to ‘fool’ a

host cell into importing the genetic material (remember, large and charged items can’t pass through a cell membrane, so the virus can’t just pass through with no resistance).

• Penetration – the entire virus, or just the genetic material, is injected into the host cell.

• Assembly – the viral DNA is read and transcribed by the host cell. In some cases, restriction enzymes cut the host DNA and the viral genes are inserted directly into the host genome (this is how the first restriction enzymes were discovered).

• Release – once the viral genetic material has been translated, the new viruses are released from the cell and are set to infect other cells.

Fig. 22.18a, p. 366

e Lysis of host cell is induced; infections particles escape.

a Virus particles bind to wall of suitable host cell. Viral genetic material enters cell cytoplasm.

c Viral protein molecules are assembled into coats; DNA is packaged inside.

d Tail fibers and other parts are added to coats.

LYTIC PATHWAY

IV. Viral Infection

B. Lytic Virus: Cause host cell to lyse, or burst.

C. Lysogenic Virus: Displays latent period, during which virus DNA is inserted into host DNA and ‘quietly’ replicates.

D. Retrovirus: Insert RNA, then use ‘reverse transcriptase’ to copy back into DNA.