Microbiology and Parasitology Lecture (L7-9) Flashcards
is the study of the vital life
processes of organisms
Physiology
concerns the vital life
processes of microorganisms.
Microbial physiology
- ideally suited- inexpensive to maintain, take up little space and
reproduce quickly (E. coli)
Bacteria
All living protoplasm contains six major
chemical elements:
carbon, hydrogen,
oxygen, nitrogen, phosphorus, and sulfur.
Other elements, usually required in lesser
amounts, include :
sodium, potassium,
chlorine, magnesium, calcium, iron, iodine,
and some trace elements.
All microbes have a need for three things:
carbon, energy, and electrons
(other nutrients).
refers to all the
biochemical reactions that
occur in a cell or organism.
Metabolism
a protein that either causes a particular chemical reaction to occur or
accelerates it.
Biologic catalyst
- Remain within the cell that
produced them - Digestive enzymes of
Phagocytes
Endoenzymes
- Leave the cell to catalyze rxns
outside the cell - Cellulase and pectinase, which
are secreted by saprophytic
fungi to digest cellulose and pectin.
Exoenzymes
-cannot, on their
own, catalyze a chemical reaction.
- must link up with a cofactor to catalyze a chemical reaction.
Apoenzymes
reactions that “break down”
molecules requiring the breaking of bonds. Major E source
Catabolic
reactions that build new
molecules requiring the formation of
bonds.
Anabolic
is a series of linked
biochemical reactions that occur in a stepwise
manner, leading from a starting material to an
end product
biochemical pathway
produced during glycolysis are converted into acetyl-CoA molecules which
then enter The CAC.
Pyruvic acid
the study of
heredity
Genetics
-the study of the mechanisms of heritable information in bacteria, their chromosomes, plasmids, transposons and
phages.
-The entire genetic content of a cell is its genome.
Bacterial Genetics
- Complete collection of genes
- The genetic material passed between generations.
Genotype
- All its physical traits, attributes
or characteristics - Manifestation of genotype
Phenotype
- Actively expressed all the time
- ribosomes are constantly
needed for protein synthesis
Constitutive Genes
- Expressed only when needed
- the glucose transporter proteins that muscle cells produce in response to insulin
Inducible Genes
beneficial, harmful, silent
A change in the characteristics of a cell caused by a change in the DNA molecule that is transmissible to the
offspring
Mutations
- Are of benefit to the organism
- lead to new versions of proteins that help
organisms adapt to changes in their environment. - lead to antibiotic-resistant strains of bacteria.
Beneficial mutation
-leads to the production of a nonfunctional enzyme.
-Lethal mutation
Harmful mutation
- They have no effect on the cell
Silent Mutations
- Involves bacteriophages and
the acquisition of new viral genes - Lysogenic conversion –>
lysogeny - prophage
- The bacterial cell containing
the prophage: lysogenic cell - imparts genes with special functions to bacterial cells
without such functions. - Corynebacterium diphtheriae
Lysogenic Conversion
- transfer of a DNA fragment from one
bacterium to another by a bacteriophage.
Transduction
is a form of genetic recombination in which a DNA fragment from a dead, degraded bacterium enters a competent recipient bacterium and is
exchanged for a piece of DNA of the recipient.
Transformation
- Cell-to-cell contact
- Sex pilus
- encoded by plasmids or transposons.
- a. General mechanism of transfer of conjugative
plasmids by conjugation in Gram-negative bacteria - This is the mechanism by which resistance
plasmids (R-plasmids), coding for multiple
antibiotic resistance and conjugation pilus
formation, are transferred from a donor
bacterium to a recipient. - F+ conjugation
- the donor bacterium carries a DNA sequence
called the fertility factor, or F-factor. - c. Hfr (high frequency recombinant) conjugation.
Conjugation
grow only in the presence of oxygen.
Obligate aerobes
require a low concentration of oxygen (2% to 10%) for growth, but higher
concentrations are inhibitory.
Microaerophiles