Bacterial metabolism, exchange mechanisms, commensal, pathogenic, normal flora, and epidemiology Flashcards
What is microbial metabolism?
This is the collection of controlled biochemical reactions that take place within cells of an organism.
The ultimate goal / function of metabolism is to reproduce the organism.
What is catabolism?
What is anabolism?
Anabolism is the set of metabolic pathways that construct molecules from smaller units.
These reactions require energy.
What are oxidation and reduction reactions?
These are reactions that transfer electrons from molecule that donates electron to molecule that accepts the electron
These reactions are always coupled
Cells use electron carriers to carry electrons (Often, these are hydrogen atoms)
What are the three important electron carriers in redox reactions?
Nicotinamide adenine dinucleotide (NAD+) goes to NADH
Nicotinamide adenine dinucleotide phosphate (NADP) goes to NADPH
Flavin adenine dinucleotide (FAD) goes to FADH2
How is energy concentrated and stored?
Energy is concentrated and stored in the high-energy bonds of ATP.
What does phosphorylation mean?
Phosphorylation is the addition of organic phosphate being added to a substrate.
What are the three ways that cells phosphorylate ADP to ATP?
Substrate-level phosphorylation - Direct transfer of a phosphate
Oxidative phosphorylation - Uses energy released by the oxidation of nutrients
Photophosphorylation - Uses the energy of sunlight
How do anabolic pathways use the energy of ATP?
Anabolic pathways use the energy of ATP by breaking a phosphate bond.
What molecule is oxidized as a primary energy source for anabolic reactions?
Carbohydrates
Glucose is the most commonly used
What reactions are responsible for glucose catabolism?
Cellular respiration - Glycolysis, Krebs, ETC
Fermentation - Glycolysis, conversion of purvic acid into organic wastes
What does glycolysis involve?
Gycolysis involves the splitting a six-carbon glucose into two three-carbon sugar molecules.
Phosphate is transfered between two substrates four times (Substrate level phosphorylation)
What are the three stages of cellular respiration?
Synthesis of acetyl-CoA
Krebs Cycle
ETC
Pyruvic acid is oxidized to produce ATP via redx reactions
Where does the Krebs cycle occur in bacterial cells?
Cytoplasm
What does the Krebs cycle transfer most energy to?
NAD+
FAD
Where is the ETC caried out in bacterial cells?
Cytoplasmic membrane
This is the most significant source of ATP
Oxygen is the electron carrier; forms water
How is bacterial ETC different than in Eukaryotes?
ETC enzymes are embedded in the plasma membrane as opposed to the inner membrane of the mitochondria.
They also use different electron donors - Hydrogen, CO, ammonia, nitrite, sulfur, sulfide, and ferrous iron
Bacteria use different electron cariers - NADH dehydrogenase, quinone (oxidase), cytochrome (oxidase)
What is fermentation?
This is a metabolic process that takes place in the absence of oxygen
Anaerobic
This provides cells with an alternate source of NAD+
Organic molecules are the electron acceptor
Alcohol ferments sugars to ethanol and CO2
Lactic acid fermentation
Mixed acid fermentation
Butanediol fermentation (Pyruvate to acetoin to 2,3 butanediol)
What is vertical gene transfer?
This is when organisms replicate their genomes and provide copies to their descendents.
What is horizontal gene transfer?
This is when a donor contributes part of their genome to a recipient.
How many types of horizontal gene transfer are there?
Transformation
Transduction
Bacterial Conjugation
What is bacterial transformation?
Transformation is the genetic alteration of a bacterial cell resulting from the direct uptake, incorporation and expression of exogenous genetic material from its surroundings and taken up through the cell membrane(s).
NOTE: See Griffith’s Experiment:
Inject mouse with S strain - Mouse dies
Inject mouse with R strain - Mouse lives
Kill S strain by heating
Inject heat-killed S strain into mouse - Mouse lives
Mix heat-killed S strain with R strain
Inject mouse with this mix - Mouse dies. Living S-strain bacteria found in mouse
What is bacterial transduction?
Transduction is the process by which DNA is transferred from one bacterium to another by a virus. It also refers to the process whereby foreign DNA is introduced into another cell via a viral vector. Transduction does not require physical contact between the cell donating the DNA and the cell receiving the DNA
What is the Lysogenic cycle?
Lysogeny is characterized by integration of the bacteriophage nucleic acid into the host bacterium’s genome or formation of a circular replicon in the bacterium’s cytoplasm.
In this condition the bacterium continues to live and reproduce normally.The genetic material of the bacteriophage, called a prophage, can be transmitted to daughter cells at each subsequent cell division, and a later event can release it, causing proliferation of new phages via the lytic cycle.
Picture of Specialized Transduction
What is bacterial conjugation?
Conjugation refers to the transfer of DNA from one cell to another
Occurs in Gram - cells and requires a sex pilus (F pilus)
Involves transfer of genes on conjugation plasmid
Can happen in Gram + as well
What are the different types of plasmid that can be exchanged by conjugation?
Fertility (Genes for pili)
Resistance factors (Genes for antibiotic resistance)
Bacteriocin factors (Exotoxins that kill competing bacteria)
Virulence plasmids (Genes that cause pathogenicity)
