1. C. Metabolic Diversity in Bacteria
*Bacteria can be placed into 2 groups
based on how they obtain energy :
1. Heterotrophs – get energy by consuming organic molecules made by other organisms. *Most prokaryotes are heterotrophs.
2. Autotrophs – get energy by making their own food from inorganic molecules.

2. Types of Heterotrophs :
A. Chemoheterotrophs – organisms that must take in organic molecules for both energy & carbon.
B. Photoheterotrophs – organisms that are photosynthetic but need organic compounds as a carbon source.

3. Types of Autotrophs
A. Photoautotrophs – organisms that use energy from sunlight to convert CO2 & water to carbon compounds.
B. Chemoautotrophs – organisms that make organic molecules from CO2 using energy from chemical reactions.

4. Releasing Energy -Bacteria, like all organisms,
release energy through cellular
respiration, fermentation, or both.
Cellular respiration – process
that releases energy by breaking
down glucose & other food
molecules in the presence of
oxygen (O2).
Fermentation – process by which
cells release energy in the
absence of O2.

5. Obligate aerobes vs. anaerobes
-Organisms that require a constant
supply of oxygen in order to live
are called obligate aerobes, ex :
Mycobacterium tuberculosis .
-Organisms that must live in the
absence of oxygen are called
obligate anaerobes (oxygen would
kill them), ex : Clostridium botulinum.
-Organisms that can survive with or
without oxygen are called facultative
anaerobes, ex : E. coli.
-Anaerobes perform fermentation to
release energy & aerobes perform
cellular respiration to release energy.

6. D. Bacterial Growth & Reproduction
-Growth in bacteria is directly
related to availability of food &
production of waste products.
Some divide every 20 minutes.
Reproduction can occur by :
1. Binary fission – asexual reproduction in which an organism replicates it’s DNA & divides in half, producing 2 identical daughter cells.
2. Conjugation – sexual reproduction in which an organism exchanges genetic information.

7. Endospore Production -In poor environmental conditions, bacteria form
spores that remain
dormant for months, years,
etc. until conditions
become favorable again.
Endospore – type of spore
formed when a bacterium
produces a thick internal
wall that encloses its DNA
& a portion of its cytoplasm.