Module 2-week 5 Bacterial Nutrition And Metabolism Part A Flashcards
What are essential nutrients?
MacroNutrients and macroelements
- These are required in large quantities
- Play principle roles in cell structure and metabolism
- Availability of essential nutrients and elements impacts microbes ability to grow
List the bacterial macroelements
Carbon
Oxygen
Nitrogen
Hydrogen
Phosphorus
Sulfur
Microbes are classified based on their ___________ ________
Carbon source
What are heterotrophs?
Organisms that obtain carbon from organic matter
- Most common source-sugars I.e. glucose
- Most bacteria fall in this category
What are autotrophs?
Obtain carbon from inorganic C or CO2
-Ability to convert CO2 -> Organic compounds
Differentiate aerobic and anaerobic microbes
Microbes have variability to grow in the presence of gas O2(aerobic) or absence of O2 gas(anaerobic)
Describe the variable states of Oxygen
Oxygen is in variable states that can range from biologically usable to toxic to the cell
-Can originate from inorganic (NO2/O2) or organic (glucose) molecules
Give a general description of usage of oxygen
Used in proteins, carbohydrates, lipids and nucleic acids and important respiration
How is nitrogen usually supplied?
Usually supplied via inorganic molecule
NH3(ammonia), NO3(nitrate), NO2(nitrite) N2(gas)
What is nitrogen fixation?
Some soil microbes obtain N2 gas and convert it to other forms via nitrogen fixation
How do GI microbes obtain NO3 from our food and convert it to NH3?
Some GI microbes obtain NO3from our food and convert it to MH3
What molecules is nitrogen used in?
All amino acids/ proteins, DNA, RNA , ATP
What is hydrogen used in?
Used in REDOX reactions, buffer of pH, hydrogen bonding
What is the use of phosphorus(phosphates) ias an essential nutrients?
Used in nucleic acids, ATP, Buffer of pH
What is the use of Sulfur as an essential nutrient?
Used in some amino acids(cysteine, methionine), some vitamins, protein stability and shape
What are the sources of hydrogen?
Organic sources: glucose
Inorganic: H2O, H3PO4, H2S , CH4, H2
What are the sources of phosphorus(phosphates)?
Inorganic sources PO4 ^-3 from H3PO4
What are the sources of sulphur?
Inorganic: SO4^-2, FeS, H2S, elemental S
How are macronutrients acquired?
Can be acquired externally , synthesized by the cell or reassembled to create new large molecules, possibly from monomers
What are photo autotrophs?
Can use sunlight as energy source and CO2 as carbon source via the process of photosynthesis
CO2+ H2O ——> (CH2O)n + O2
E.g. plants, algae, Cyanobacteria
What are chemo-autotrophs?
Can use INORGANIC MOLECULES as energy source and CO2 as carbon source via the process of METHANOGENESIS
4H2 + CO2 —> CH4 + 2H2O
Give examples of methane gen’s
Methanosarcina, methanobacterium
What are photo-heterotrophs?
Use light as energy source and ORGANIC COMPOUNDS as carbon source via the modified process of photosynthesis
E.g. purple non-sulfur bacteria, heliobacteria
What are chemo-heterotrophs?
Organisms use ORGANIC COMPOUNDS as energy + carbon source via the process of RESPIRATION or FERMENTATION
E.g. most bacteria
[(CH2O)n] + O2 —> CO2 + H2O + ATP
What is catabolism?
The process of generating energy and substrates which are used in anabolism
What is anabolism ?
The use of energy and substrates for subsequent biosynthetic pathways
What is metabolism?
The net sum of energy transfer between catabolism and anabolism. If enough energy anabolic processes, cell can grow and replicate
How are relationships between microbes beneficial ?
Phototrophs produce oxygen which is needed by chemoheterotrophs
Chemotrophs produce Carbon dioxide and water which are needed by photoautotrophs
How is ATP used in metabolism?
Adenosine Tri-phosphate: energy is stored in high energy bonds between phosphate groups with catabolism.
How is ADP used in metabolism?
Energy is released with loss of a phosphate group and the energy is used in anabolism
What is the purpose of NAD/NADH?
Nicotinamide Adenine Dinucleotide/Hydrogen- serves as a co-enzyme Cartier molecule to shuttle electrons during metabolism
A diff usable electron carrier
What is energy currency?
biochemical energy is stored and transferred from catabolism to anabolism via ATP, NADH, NADPH
How are macronutrients used in catabolism?
Carbs, fats and proteins (Energy yielding products)
Catabolism which is exergonic and produces Chemical energy, ATP, NADH/NADPH
carbs, fats and proteins are converted to energy poor products( CO2, H2O, NH3)
How molecules used for anabolism?
Precursor molecules ( amino acids, sugars, fatty acids, nitrogenous bases)
Anabolism is endergonic and uses ATP, NADH/NADPH to synthesize complex molecules( proteins, lipids, nucleic acids and polysaccharides)
Where does glycolysis occur?
In the cytoplasm of both eukaryotes and prokaryotes and is independent of oxygen
What is the net output of glycolysis?
2 ATP, 2 NADH and 2 pyruvate( pyruvjc acid)
What is the first step of Glucose catabolism?
Glycolysis- During the first step of glucose catabolism, Glucose-6-Carbon gets broken down to 2x molecules of Pyruvate 3-carbon
What 2 different pathways can microbes break down glucose(both forms of glycolysis)?
The Embden-Meyerhoff-Parnas(EMP)-both eukaryotes and prokaryotes
Entner-Duodoroff(ED)
What are the net end products of EMP?
2 ATP
2 NADH
2 pyruvate
What are the net end products of enter-duodoroff-ED?
1 ATP
1 NADPH
1 NADH
2 Pyruvate
When do bacteria usually perform fermentation?
- Occurs in absence in oxygen
- Less efficient than aerobic or anaerobic respiration(2 ATP)
When do bacteria perform aerobic respiration?
- Occurs in presence of oxygen
- Oxygen is a preferred terminal electron acceptor
- Lots of ATP produced(38 ATP)
When do bacteria undergo anaerobic respiration?
- Occurs in absence of oxygen
- Use of an alternative electron acceptor
- Less efficient than aerobic (5-30 ATP)
How does oxygen presence effect efficient of glucose metabolism?
In the presence of Oxygen, glucose metabolism is much more energy efficient than fermentation due to the Kreb’s cycle and ETC
What is the net total output of aerobic respiration?
6CO2 + 6H2O + 36/38 ATP
What is the function of Oxygen in aerobic respiration?
Oxygen acts as a Terminal electron acceptor in the ETC of the electrons from NADH and FADH, which generates ATP energy
What happens to pyruvate, NADH and FADH2 in aerobic respiration?
- Pyruvate is completely oxidized via intermediate step and Kreb’s cycle
- NADH and FADH2 are reduced via glycolysis and Kreb’s cycle and are then associate with the Electron Transport
Summarize the steps in aerobic respiration
- Glycolysis
- Pyruvate metabolism
- Kreb’s cycle
- Chemiosmosis and electron transport chain
Where does the Kreb’s cycle/TCA cycle/ Citruc acid cycle occur ?
Occurs in cytoplasm in prokaryotes
Occurs in mitochondria in eukaryotes
What is the net output of the Kreb’s cycle?
6CO2+ 2ATP+ 2FADH2 + 8NADH
What are the goals of the Kreb’s cycle?
- main goal is the oxidation of pyruvic acid.
- Efficient transfer of electrons from carbon molecules to reduce coenzyme electron carriers NADH and FADH
- Important for production of amino acid intermediates
What are the goals of the Electron Transport Chain?
- Goal is oxidation of NADH and FADH via transfer of electrons to the Electron Transfer Chain
- The process is coupled with ATP synthase to generate ATP
- Important for production ATP and recycling co-enzymes
Where is the electron transport chain?
In the cell membrane in prokaryotes
In the mitochondria in eukaryotes
What type of phosphorylation occurs in the electron transport chain?
Produces 32 ATP (ETC) via oxidative phosphorylation
Summarize the events of the ETC
- NADH donates electrons and is oxidized back to NAD+
- Oxygen accepts electrons and is reduced to H2O( Nitrate can serve as electron acceptor for anaerobic respiration)
- Energy from the electron shuttling is captured in ATP
What are some applications of anaerobic respiration?
Relevant in nitrogen cycling and diagnostics
E.x. Nitrite in urine indicates infection
What are the goals of anaerobic respiration?
Goal is oxidation of NADH in pathways that serve as electron shuttle mechanism and occurs in cell membrane in prokaryotes
Anaerobic respiration can recycle the co-enzymes needed for glycolysis
Describe Anaerobic respiration
In the absence of oxygen as terminal electron acceptor, bacteria can use an alternative inorganic electron acceptor ex. NO3
Why does fermentation have a very low yield of energy?
Has a very low yield of energy (2 ATP) per glucose as it comes from glycolysis ONLY and occurs in the absence of oxygen
What are the applications of fermentation?
Fermentation by-products from Pyruvate are important for:
-Industry
Cheese, pickles, yogurt, alcohol, chocolate,souring milk
Industrial agents
- human health
Maintaining homeostasis
-Diagnostics
Lab tests
What happens to pyruvate in the absence of oxygen?
Pyruvate is concerted to lactic acid/lactate
This produces the oxidation of NADH —> NAD+
What are some bacteria which undergo fermentation?
Streptococcus and lactobacillus sp.
What are some uses of fermentation to produce industrial reagents ?
Butyric acid (Butanol) fermentation by Clostridium sp.
Pyruvate —> variety of products
Includes:
Acetone+ CO2
Isopropanol + CO2
Butyrate
Butanol
Used for production of commercial organic solvents
How does fermentation contribute to human health?
- Consumption of fermented products is beneficial to a variety of health conditions and promotes diversity of the GI microbiota
- Normal flora maintain low pH to inhibit growth of pathogens
How is fermentation used in diagnostics ?
Methyl Red test
- tests availability to ferment glucose to variety of fermentation acids
- Addition of methyl red pH indicator results in color change due to acidity of broth from acid production
- # 1 yellow is negative (Enterobacter)
- # 2 red is positive E. coli
What are the meanings of yellow and red in the methyl red test?
- # 1 yellow is negative (Enterobacter)
- #2 red is positive( E. coli)
Energy metabolism is another term for…
Catabolism
Biosynthetic metabolism is another term for…
Anabolism
What do we need for biosynthesis?
-convert organic molecules and ATP into the “building blocks”(precursor monomers for macronutrients), which are required for cell growth and replication
What are sugars used to produce in biosynthesis?
Polysaccharides
What are amino acids used to produce in biosynthesis?
Complex proteins
What are nucleic acids used to produce in biosynthesis?
DNA, RNA
What are lipids used to produce in biosynthesis?
Lipid belayer of membrane
How are sugars converted to complex sugars?
Intermediate products of glycolysis are converted to complex sugars at the expense of ATP
Glucose 6-phosphate —> ADPG —> glycogen(in bacteria) (ATP required)
Glucose 6-phosphate —> UDPG —> glycogen (in animals)(UTP required)
Fructose 6-phosphate —> UDPNAc —> peptidoglycan (in bacteria)(UTP required)
What is the biosynthesis process of amino acids
Intermediates of lentos pathway, Kreb’s cycle and ED are converted to amino acids for protein synthesis
This is done via a inaction or transamination
Briefly describe the biosynthesis of nucleic acids
Intermediate products of glycolysis, pentose pathway, Kreb’s cycle and ED are converted to nucleic acids for DNA synthesis
Briefly describe the biosynthesis of lipids
Intermediate product of Glycolysis and Kreb’s cycle are converted to simple lipids for complex lipid synthesis
What are the 4 processes involved in binary fission?
- Requires anabolic process for building blocks
- DNA replication
- Increase in cell size (cell elongation)
- Cell division by cleaving of cell membrane and wall
Describe the bacterial growth rate
Growth is exponential and measured in log10(best for graphing)
One bacterial cell of E. coli with a population-doubling time of 20 minutes
- will give rise to 10 million cells within 8 hours
- 10,000,000- 10^7
Describe the kinetics of bacterial reproduction
- Binary fission results in doubling of viable cell number
- Cell count is predicted as Log2 over time
What is Generation/ doubling time(g)?
Time required for a complete fission replication cycle which varies between organisms, depending on conditions
What are each of the axis in a logarithmic plot ?
Logarithmic plots are preferred with X-axis scale of generations over time (could be minutes hours or days )
Y-axis scale of Log10
When are the most accurate cell numbers recorded in bacterial growth?
Most accurate cell numbers recorded during early growth
What are the conditions under which a growth curve is made?
In a closed system: nutrients and space are finite no removal of waste products
What are the phases of a growth curve?
- Stationary phase
- Exponential (log) phase
- Stationary phase
- Death phase
Explain the lag phase of bacterial growth
- Newly inoculated cells, adjust to new environment
- Cells not multiplying at maximum rate
- Population is sparse or dilute
What is the exponential (log) phase of bacterial growth dynamics?
- Growth occurs at an exponential rate
- Cells reach maximum rate of cell division
- Continues as long as nutrients and environment are favorable
What is the stationary phase of bacterial growth dynamics?
- Population reaches maximum numbers
- Rate of cell inhibition or death= rate of multiplication
What is the death phase of bacterial growth phase?
- Decline in growth rate
- Caused by depletion of nutrients, O2Excretion of toxic waste products
Increased density of cells (limited space)
