BACTERIAL BIOCHEMISTRY METABOLISM Flashcards
Study of the vital life processes of microorganisms
- Nutritional needs
- Metabolic pathways
- Reproduction, growth and death
MICROBIAL PHYSIOLOGY
*All living protoplasm contains 6 major chemical elements:
C, H, O, N, P, S
*Combinations of all these elements make up the
macromolecules: carbohydrates, proteins, lipids and
nucleic acids
*To build necessary cellular materials, every organism
requires a source/s of energy, carbon and other nutritional
requirements
Nutritional Requirements
ENERGY SOURCE
light
PHOTOTROPHS
ENERGY SOURCE
chemicals
CHEMOTROPHS
inorganic materials
Chemolitotrophs
organic materials
Chemoorganotrophs
CO2 as their sole source of carbon
Examples: plants, algae and cyanobacteria
AUTOTROPHS
CARBON SOURCE
AUTOTROPHS
HETEROTROPHS
organic compounds
other than CO2
Examples: humans, animals, fungi, bacteria and
protozoa
HETEROTROPHS
use light as energy source and CO2 as carbon source
Plants, algae, cyanobacteria, purple and green sulfur bacteria
PHOTOAUTOTROPHS
use light as energy source and organic compounds aside from CO2 as carbon
source
Purple nonsulfur and green nonsulfur bacteria
PHOTOHETEROTROPHS
Use electrons from reduced inorganic compounds as a source of energy and
they use CO2 as their main source of carbon
Thiobacillus thiooxidans, Nitrosomonas, Nitrobacter, Hydrogenomonas
CHEMOAUTOTROPHS
use chemicals as energy source and organic compounds other than CO2 as carbon
source (all clinically impt bacteria are of this group)
Animals, protozoa, fungi and most bacteria
CHEMOHETEROTOTROPHS
Biochemical reactions or cellular processes for survival and
replication. Involves:
* Break down of organic compounds
* Synthesis of new bacterial parts
BACTERIAL METABOLISM
Energy is generated from these metabolic breakdowns and all
these biochemical reactions are controlled by specific
enzymes
BACTERIAL METABOLISM
Anaerobic process carried by both obligate and facultative
anaerobes; electron acceptor is an organic compound
Fermentation
When fermentation occurs, a mixture of end products is
accumulated like: lactate, butyrate, ethanol, acetoin
Fermentation
In dx micro: fermentation could indicate any type of
utilization (fermentative or oxidative) of a CHO (sugar)
with the resulting production of an acid pH
Fermentation
These pathways break down GLUCOSE to form
PYRUVIC ACID; precursor metabolites are also produced
by these 3 central pathways:
1.Embden-Meyerhof-Parnas (EMP)Pathway
2.Entner-Doudoroff Pathway
3.Pentose Phosphate Shunt
Biochemical Pathways
Fermentation pathways of microbes in the human host:
- Alcoholic fermentation
- Homolactic fermentation
- Heterolactic fermentati0n
- Propionic acid fermentation
- Mixed acid fermentation
- Butanediol fermentation
- Butyric acid fermentation
Anaerobic Utilization of Pyruvic
Acid (Fermentation)
cycle is the most important
pathway for the complete oxidation of a substrate under
aerobic conditions
Krebs/TCA/Citric acid
Krebs/TCA/Citric acid cycle is the most important
pathway for the complete oxidation of a substrate under
aerobic conditions
Aerobic Utlization of Pyruvic acid
Oxidation
In this cycle, pyruvate is oxidized, carbon skeletons are
created, and the e- are passed through the electron
transport chain (ETC) and used to generate energy in the
form of ATP
Aerobic Utlization of Pyruvic acid
Oxidation
This cycle results in the productionn of acid and CO2
Aerobic Utlization of Pyruvic acid
Oxidation
Process of bacterial heredity and variation
BACTERIAL GENETICS
3 major aspects of microbial genetics:
1.Structure and organization of genetic material
2.Replication and expression of genetic information
3.Mechanisms by w/c genetic information is changed
and exchanged among bacteria
where hereditary information is encoded; DNA
and RNA; made up of a 5-carbon sugar, nitrogen-containing “base”
and a phosphate group
Nucleic acids
sugar, PO4 and bases of nucleic acids; DNA and RNA
are nucleotide polymers (chains/strands)
Nucleotide
order of bases along a DNA or RNA strand
Base Sequence
exists as double-stranded molecules; carry genetic code
DNA
exists as a single-stranded molecule; plays a key role in gene
expression
RNA
DNA sequence that encodes for a specific product (RNA or protein)
Gene
all genes taken together within an organism
Genome
- when a genome is organized into a single discrete unit;
- gene carrier;
- Haploid - only one chromosome is present in a bacterial nucleoid
- a single circle containing about 4000 kbp (kilobase pairs) of DNA
CHROMOSOME
only one chromosome is present in a bacterial nucleoid
Haploid
extra-chromosomal genetic elements; miniature
chromosomes; replicates independently from the chromosome
Plasmids
Bacterial genes are carried on
Bacterial chromosome Plasmids
Transposable elements
pieces of DNA that move from one
genetic element to another; they do not exist as separate entities since
they must be incorporated into a plasmid or chromosome; “jumping
genes” ; two types:
Transposable elements
contains genes that encode information
required for movement among plasmids and chromosomes
Insertion sequence
contains genes for movement as well as genes that
encode for other features like drug resistance
Transposon
during bacterial cell division, the genome must be replicated so
that each daughter cell receives the same complement of functional
DNA from the parent cell
Replication of Genetic Information
is the processing of information encoded in
genetic elements (chromosome, plasmid, transposon) that results in
the production of biochemical products
Expression of Genetic Information
copying of the DNA molecule by mRNA
Synthesis of mRNA, tRNA and rRNA
RNA polymerase – enzyme central to the transcription process
Transcription (synthesis of RNA)
-mRNA codons are read, amino acids are brought to the mRNA strand and
polypeptides (proteins) are produced at the ribosomes
-Initiation, elongation and termination
-Translation ends with the production of a protein
Translation (synthesis of protein)
Genetic change in bacteria is accomplished by 3 basic mechanisms:
1 Mutation
2 Genetic recombination
3 Gene exchange
Change in the original nucleotide sequence of a gene/s (genotype)
This change may involve a single DNA base w/in a gene, an entire gene, or several
genes
Usually results in insertion of a different amino acid into a protein resulting to an
altered phenotype
Mutation
DNA segment/s are physically
exchanged/transferred from a donor cell to the
recipient cell;
DNA segment/s are physically
exchanged/transferred from a donor cell to the
recipient cell;
is a characteristic w/ members of the genera: Haemophilus Streptococcus Neisseria
Competence
Recipient cell directly takes up naked DNA released from the donor cell altering its genotype
Transformation
DNA of donor cell that
contains bacteriophages is
transferred to the recipient
cell; phage mediated
Transduction
when bacterial DNA is randomly
incorporated w/ viral DNA;
caused by virulent phages; only
host DNA is transferred
Generalized transduction
When bacterial DNA is incorporated along w/ adjacent viral DNA; caused by temperate phages; viral and host genes are transferred
Specialized transduction
In conjugation, DNA is
transferred directly by
cell-to-cell contact through
the donor’s sex pilus.
Conjugation
Plasmids are most frequently
transferred by conjugation.
This is mediated by a
fertility or F
factor/self-transmissibl
e plasmid.
contain genes
conferring drug
resistance
R factors
fertility and resistance
plasmids
F and R plasmids
Transposition is the process by which “jumping genes” excise from one genomic location and insert into another.
Transposition
) can insert
themselves into a donor
chromosome w/o having
DNA homology.
Transposons and insertion
sequences (IS)
