Chapter 7 covers microbial physiology and genetics, emphasizing the vital life processes of microorganisms and their nutritional requirements, with classifications based on energy and carbon sources. It explains metabolism through catabolic and anabolic reactions, highlighting the role of enzymes and ATP in energy storage and transfer. The chapter further discusses bacterial genetics, including genetic engineering, mutations, and various methods by which bacteria acquire new genetic material, such as transformation and conjugation.

1. CHAPTER 7
MICROBIAL PHYSIOLOGY
AND GENETICS

2. MICROBIAL PHYSIOLOGY
INTRODUCTION
•Physiology is the study of the vital life
processes of organisms.
–Microbial physiology concerns the
vital life processes of
microorganisms.

3. MICROBIAL PHYSIOLOGY
MICROBIAL NUTRITIONAL REQUIREMENTS
•All living protoplasm contains six major chemical
elements: carbon, hydrogen, oxygen, nitrogen,
phosphorus, and sulfur.
– Combinations of these and other elements make up vital
macromolecules of life, including carbohydrates, lipids,
proteins, and nucleic acids.
•Materials that organisms are unable to synthesize,
but are required for building macromolecules and
sustaining life, are termed essential nutrients (e.g.,

4. MICROBIAL PHYSIOLOGY
CATEGORIZING MICROORGANISMS ACCORDING TO THEIR
ENERGY AND CARBON SOURCES
•Terms relating to an organism’s energy
source:
–Phototrophs use light as an energy source.
–Chemotrophs use either inorganic or
organic chemicals as an energy source.
•Chemolithotrophs use inorganic chemicals as
an energy source.
•Chemoorganotrophs use organic chemicals as

5. MICROBIAL PHYSIOLOGY
CATEGORIZING MICROORGANISMS ACCORDING TO THEIR ENERGY AND CARBON
SOURCE
•Terms relating to an organism’s carbon source:
– Autotrophs use carbon dioxide (CO2) as their sole source of
carbon.
– Heterotrophs use organic compounds other than CO2 as
carbon sources.
•Terms that combine both energy and carbon source:
– Photoautotrophs use light as an energy source and CO2 as a
carbon source.
– Photoheterotrophs use light as an energy source and organic
compounds other than CO2 as a carbon source.
– Chemoautotrophs use chemicals as an energy source and CO2
as a carbon source.

6. MICROBIAL PHYSIOLOGY
CATEGORIZING MICROORGANISMS ACCORDING TO THEIR
ENERGY AND CARBON SOURCES (CONT.)
•Ecology is the study of the interactions between
living organisms and the world around them,
including their nonliving environment.
•Interrelationships among the different nutritional
types are of prime importance in the functioning
of the ecosystem.
– Example: Phototrophs, such as algae and plants, are
the producers of food and oxygen for
chemoheterotrophs, such as animals.

7. METABOLIC ENZYMES
•Metabolism refers to all of the chemical reactions
that occur in a cell. The chemical reactions are
referred to as metabolic reactions.
– Metabolic reactions are enhanced and regulated by
enzymes known as metabolic enzymes.
•Biologic Catalysts
– Enzymes are biologic catalysts; they are proteins that
either cause a particular chemical reaction to occur or
accelerate it.
– An enzyme does not become altered during the

8. METABOLISM
• As previously stated, metabolism refers to all of the chemical reactions
within a cell. These reactions known as metabolic reactions.
• Metabolic reactions fall into two categories: catabolism and anabolism.
– Catabolism refers to all catabolic reactions in a cell.
– Anabolism refers to all anabolic reactions in a cell.
• Catabolic reactions involve the breaking down of larger molecules into
smaller ones.
– Whenever chemical bonds are broken, energy is released. Catabolic reactions
are a cell’s major source of energy.
• Anabolic reactions involve the assembly of smaller molecules into
larger molecules, requiring the formation of bonds. Once formed, the
bonds represent stored energy.

9. ANABOLIC AND CATABOLIC REACTIONS

10. METABOLISM (CONT.)
•Energy can be temporarily stored in high-
energy bonds in special molecules, usually
adenosine triphosphate (ATP).
– ATP molecules are the major energy-storing or
energy-carrying molecules in a cell.
•ATP molecules are found in all cells because
they are used to transfer energy from
energy-yielding molecules, such as glucose,
to energy-requiring reactions.

11. METABOLISM (CONT.)
•Energy is required not only for metabolic pathways
but also for growth, reproduction, sporulation,
and movement of the organism, as well as active
transport of substances across membranes.
•Some organisms (e.g., marine dinoflagellates) use
energy for bioluminescence.
•Cellular mechanisms that release small amounts of
energy as the cell needs it usually involve a
sequence of catabolic and anabolic reactions.

12. METABOLISM
CATABOLISM (CONT.)
•Catabolic reactions release energy (by breaking
bonds) and are a cell’s major source of energy.
–Some energy is lost as heat in catabolic
reactions.
•Catabolism of glucose by aerobic respiration
occurs in three phases (each is a biochemical
pathway):
–Glycolysis
–The Krebs cycle
–The electron transport chain
•The first phase (glycolysis) is actually anaerobic,

13. CATABOLISM
FERMENTATION OF GLUCOSE
•Fermentation reactions do not
involve oxygen.
•They take place in anaerobic
environments.
•There are many industrial
applications of fermentation

14. CATABOLISM
OXIDATION–REDUCTION (REDOX) REACTIONS
•Oxidation–reduction reactions are paired reactions in which
electrons are transferred from one compound to another.
•Oxidation occurs whenever an atom, ion, or molecule loses
one or more electrons in a reaction, in which case, the
molecule is said to be oxidized.
•The gain of one or more electrons by a molecule is called
reduction, and the molecule is said to be reduced.
•Within a cell, an oxidation reaction is always paired with a
reduction reaction, hence the term oxidation–reduction
reaction.

15. ANABOLISM
•Anabolic reactions require energy because
chemical bonds are being formed.
•The energy that is required comes from
catabolic reactions, which are occurring
simultaneously.

16. BACTERIAL GENETICS
•Genetics is the study of heredity.
•An organism’s genotype (or genome) is its
complete collection of genes.
•An organism’s phenotype refers to its physical
traits (e.g., hair and eye color in humans).
•An organism’s phenotype is the manifestation of
that organism’s genotype.
•Genes direct all functions of the cell.
•A particular segment of the chromosome

17. GENETIC ENGINEERING
•Genetic engineering or recombinant DNA technology
involves techniques to transfer eukaryotic genes
(particularly human genes) into easily cultured cells to
manufacture important gene products (mostly proteins).
•Plasmids are frequently used as vehicles for inserting
genes into cells.
•There are many industrial and medical benefits from
genetic engineering.
– Examples: synthesis of antibodies, antibiotics, drugs,
and vaccines, as well as synthesis of important

18. GENE THERAPY
•It involves the insertion of a normal gene into
cells to correct a specific genetic or acquired
disorder that is being caused by a detective gene.
•Viral delivery is currently the most common
method selected to target the DNA of specific
cells.
•Ex. Virus capable of infecting liver cells would be
used to insert a therapeutic gene/s into the DNA
of liver cells.

19. STRUCTURE AND FUNCTION OF GENETIC
MATERIAL
DNA & RNA
DNA=deoxyribonucleic acid
RNA=ribonucleic acid
Basic building blocks:
Nucleotides
Phosphate group
Pentose sugar
Nitrogenous base

20. STRUCTURE OF DNA
•Double stranded (double helix)
•Chains of nucleotides
•5’ to 3’ (strands are anti-parallel)
•Complimentary base pairing
•A-T
•G-C

21. DNA STRUCTURE
Phosphate-P
Sugar-blue
Bases-ATGC

22. DNA REPLICATION
•Bacteria have closed, circular DNA
•Genome: genetic material in an organism
•E. coli
• 4 million base pairs
• 1 mm long (over 1000 times larger that actual
bacterial cell)
• DNA takes up around 10% of cell volume

23. DNA REPLICATION-OCCURS AT THE
REPLICATION FORK
•5’ to 3 ‘
•DNA helicase-unzips + parental DNA strand that is
used as a template
•Leading stand (5’ to 3’-continuous)
*DNA polymerase-joins growing DNA strand after
nucleotides are aligned (complimentary)
•Lagging strand (5’ to 3’-not continuous)
*RNA polymerase (makes short RNA primer)
*DNA polymerase (extends RNA primer then
digests RNA primer and replaces it with DNA)
*DNA ligase (seals Okazaki fragments-the newly
formed DNA fragments)

24. REPLICATION FORK

25. PROTEIN SYNTHESIS
• DNA------- mRNA------ protein
transcription translation
Central Dogma
of Molecular Genetics

26. TRANSCRIPTION
•One strand of DNA used as a template to
make a complimentary strand of mRNA
•Promoter/RNA polymerase/termination
site/5’ to 3’
•Ways in which RNA & DNA differ:
•RNA is ss
•RNA sugar is ribose
•Base pairing-A-U

27. TRANSCRIPTION

28. TYPES OF RNA
•Three types:
•mRNA: messenger RNA
•Contains 3 bases ( codon)
•rRNA: ribosomal RNA
•Comprises the 70 S ribosome
•tRNA: transfer RNA
•Transfers amino acids to ribosomes for protein
synthesis
•Contains the anticodon (3 base sequence that is
complimentary to codon on mRNA)

29. GENETIC CODE
•DNA: triplet code
•mRNA: codon (complimentary to triplet
code of DNA)
•tRNA: anticodon (complimentary to codon)

30. GENETIC CODE
•Codons: code for the production of a specific
amino acid
•20 amino acids
•3 base code
•Degenerative: more than 1 codon codes for
an amino acid
•Universal: in all living organisms

31. GENETIC CODE

32. TRANSLATION
•Three parts:
•Initiation-start codon (AUG)
•Elongation-ribosome moves along mRNA
•Termination: stop codon
reached/polypeptide released and new
protein forms
•rRNA=subunits that form the 70 S
ribosomes (protein synthesis occurs here)
•tRNA=transfers amino acids to ribosomes

37. BACTERIAL GENETICS
MUTATIONS
•A change in a DNA molecule (genetic
alteration) that is transmissible to
offspring is called a mutation.
–There are three categories of mutations:
•Beneficial mutations
•Harmful mutations (some are lethal mutations)
•Silent mutations
•Mutation rate (the rate at which mutations
occur) can be increased by exposing cells
to physical or chemical agents called
mutagens.
•The organism containing the mutation is

38. NORMAL DNA/MISSENSE MUTATION

39. NONSENSE MUTATION/FRAMESHIFT
MUTATION

40. BACTERIAL GENETICS
WAYS IN WHICH BACTERIA ACQUIRE
NEW GENETIC INFORMATION
•Ways in which bacteria acquire new
genetic information (i.e., acquire new
genes):
–Lysogenic conversion
–Transduction
–Transformation
–Conjugation
•An extrachromosomal DNA molecule is
called a plasmid. An organism that
acquires a plasmid acquires new genes.

41. GENETIC TRANSFER IN BACTERIA
•Genetic transfer-results in genetic variation
•Genetic variation-needed for evolution
•Three ways:
•Transformation: genes transferred from one
bacterium to another as “naked” DNA
•Conjugation: plasmids transferred 1 bacteria to
another via a pilus
•Transduction: DNA transferred from 1 bacteria
to another by a virus

42. BACTERIAL GENETICS
WAYS IN WHICH BACTERIA ACQUIRE NEW GENETIC
INFORMATION (CONT.)
•Lysogenic conversion
– Temperate phages (or lysogenic phages) inject
their DNA into a bacterial cell.
– The phage DNA integrates into the bacterial
chromosome but does not cause the lytic cycle to
occur. This is known as lysogeny.
– The bacterial cell exhibits new properties,
directed by the viral genes. This is referred to as

43. BACTERIAL GENETICS
WAYS IN WHICH BACTERIA ACQUIRE NEW GENETIC INFORMATION,
CONT.
•Transduction (“to carry across”):
– This involves bacteriophages.
– In transduction, bacterial genetic material is
“carried across” from one bacterial cell to another
by a bacterial virus; thus, in transduction, bacteria
acquire new bacterial genes.
– Note how this differs from lysogenic conversion,
wherein bacteria acquire new genetic information
in the form of viral genes.
– Only small amounts of genetic material are

44. TRANSDUCTION BY A BACTERIOPHAGE

45. BACTERIAL GENETICS
WAYS IN WHICH BACTERIA ACQUIRE NEW GENETIC
INFORMATION (CONT.)
•Transformation
–A bacterial cell becomes genetically
transformed following the uptake of DNA
fragments (“naked DNA”) from its
environment.
–The ability to absorb naked DNA into the
cell is called competence and bacteria
capable of absorbing naked DNA are said to

46. TRANSFORMATION

47. BACTERIAL GENETICS
WAYS IN WHICH BACTERIA ACQUIRE NEW GENETIC
INFORMATION (CONT.)
•Conjugation
–This involves a specialized type of pilus called
a sex pilus.
–A bacterial cell with a sex pilus (called the
donor cell) attaches by means of the sex pilus
to another bacterial cell (called the recipient
cell).
–Some genetic material (usually a plasmid) is
transferred from the donor cell to the recipient
cell through a conjugative pore.
–A plasmid that contains multiple genes for
antibiotic resistance is known as a resistance
factor or R-factor. A bacterial cell that receives

48. CONJUGATION IN E. COLI

49. CONJUGATION CONTINUED…