Week 11 Exam 4 Flashcards
What is the goal of metabolism?
Microbial Growth
What is microbial growth?
What causes it?
Where is it observed?
Increase in population size of microbes
- because of binary fission
- observed in colonies or biofilms
What are the most common nutrients needed for growth?
What do cells NEED
- Carbon, Oxygen, Nitrogen, & Hydrogen
- Need: Carbon, Oxygen, hydrogen(electrons) source
Essential Nutrients
required substances for growth
Macroelements / Macronutrients
needed in large amounts
-C, O, H, N, S, P
Micronutrients / trace elements
required in small amounts
- K, Ca, Mg, Fe, Cu, Mn, Zn, Ca, Mo, Ni (most metals b/c of enzyme factors)
- often present in water or media components
Carbon source
- two types of organisms and the types of carbon sources they use
-all microorganisms need for growth
- carbon is 50% of dry weight of cells
two types:
-autotrophs: inorganic sources of carbon to make organic compounds (CO2) (plants)
-heterotrophs: catabolize reduced organic molecules from other organisms (proteins, carbs, amino acids, & fatty acids) (humans)
Energy source 2 types
- chemotrophs: acquire energy from redox reactions, inorganic or organic chemicals (aerobic, anaerobic, or fermentation) (humans)
- phototrophs: acquire energy from light via photosynthesis (plants)
Electron / hydrogen source two types
- organotrophs: heterotrophs acquire electrons from same organic matter that provided carbon source (humans)
- lithotrophs: (rock eaters) autotrophs acquire hydrogen atoms from inorganic molecules (N2, NO2-, H2S, Fe2+)
Obligate aerobes:
Obligate anaerobes:
Obligate aerobes: need oxygen to survive
Obligate anaerobes: die in presence oxygen
Why is oxygen toxic?
Reactive Oxygen Species: chemical reactions can produce toxic forms of oxygen that are highly reactive and damage cells
ROS 4 types:
- Singlet oxygen: produced by
- Superoxide Radical: caused by & removed by
- Peroxide Anion: produced by & removed by
- Hydroxyl Radical: produced by
- Singlet oxygen: produced during aerobic metabolism & light
- Superoxide Radical: caused by incomplete reduction of 02 in ETC, & it is removed by superoxide dismutase
- Peroxide Anion: produced by superoxide dismutase (product of antioidize enzyme) & removed by catalase or peroxidase
- Hydroxyl Radical: produced by toning radiation (sun, UV) & peroxide. Most toxic because of no antioxidant enzyme
How to get rid of ROS
- Singlet oxygen: boosted to a higher level energy source
- Superoxide Radical: superoxide dismutase
- Peroxide Anion: catalase or peroxide
- Hydroxyl Radical: nothing
Oxygen requirements / thioglycollate test
- aerobes: require oxygen
- anaerobes: de in the presence of oxygen
- facultative anaerobes: live w/ & w/o oxygen
- aerotolerant anaerobes: live w/ & w/o oxygen
- microaerophiles: live in low levels of oxygen
Nitrogen requirements
- makes up 14% of dry weight
- anabolism will stop w/o nitrogen
where is nitrogen from? - recycling amino acids / nucleotides or breaking down proteins
- use ammonia NH4+ o reiterate NNO3- from their environment
- Nitrogen fixing bacteria: reduce nitrogen gas N2 to ammonia NH3
generation time
time required for bacterial cell to grow and divide
- dependent on physical and chemical conditions
- growth is logarithmic or exponential
binary fission
-
Generation time equations:
- number of cells in a population
- for one cell:
- for more than one cell:
- number of generations:
- generation time:
- number of cells in a population
- for one cell: 2^n (n=number of generations)
- for more than one cell: original number of cells x 2^n
- number of generations: log(end cells) - log(beginning cells)/ .301
- generation time: 60 min x hours / number of generations
growth curve stages 4
- lag: cells adjust to environment, make enzymes to break present nutrients
- log: rapid and exponential growth, susceptible to antimicrobial drugs, nutrients in media are abundant
- stationary: nutrient level declines, waste products are made, growth slows, some are dying
- death: more cells are dying than reproducing
chemostat
continuous culture used to maintain microbial population in a particular growth phase (maintains nutrient level)
direct methods of measuring microbial growth
- microscopic counts:
- Coulter counts:
- flow cytometry:
- viable plate counts:
- microscopic counts:count specific volume by viewing cells under microscope
- Coulter counts: counts cells as they interrupt electrical current flowing to a detector
- flow cytometry: record changes in light transmission as cells pass through tube
- viable plate counts: series of dilutions plated on solid media to count CFU/mL, requires incubation
- membrane filtration
indirect methods of measuring microbial growth
- turbidity:
- dry weight:
- turbidity: measures the amount of light that passes through culture (measures cloudiness ) (more light = less turbid / bacteria)
- dry weight: organisms filtered from media, dried, & weighted (more weight= more bacteria)
enzymes two reactions
enzymes break or form bonds
- catabolic reactions: destabilize bonds before it will break
- anabolic reactions: collide with sufficient energy for bonds to form between them
catalysts/enzymes are essential to increase the likelihood of these reactions
enzyme activity & activation energy
Enzymes lower activation energy that is needed to carry out a reaction
-activation energy: amount of energy needed to trigger a chemical reaction
Activity of enzyme depends on ability of active site to bind to substrate shape
Shape is determined by proteins structure (Amino acid structure)
process of enzymatic activity
-
Factors influencing enzyme activity
- temperature:
- pH:
- substrate concentration:
- temperature: affects protein folding, could denature protein (after optimal temp. protein unfolding)
- pH: interfere with hydrogen bonding
- substrate concentration: increased substrate increases enzyme activity until it reaches saturation point
feedback inhibition
controls the activity of enzymes in a pathway
-end product inhibits earlier enzyme
-saves the cell energy
REVIEW MORE
Enzymatic reactions
- reduction/oxidation
- ATP production & energy storage
Oxidation & Reduction reactions
- metabolic reactions involve the making or breaking of chemical bonds and then transfer of electrons
- Oxidaton-reductoin (redox) reactions: electron transfer reactions
OIL RIG
Oxidation involves loss reduction involves gain
Redox reactions
- reduction can occur by
- oxidation can occur by
reduction can occur by -gain of a electron -gain a hydrogen atom oxidation can occur by -losing an electron -losing a hydrogen atom -gaining a oxygen atom
electron carriers
used to move electrons from one location in the cell to another
- Nicotinamide adenine dinucleotide (NAD+)
- Nicotinamide adenine dinucleotide phosphate (NADP+)
- Flavin adenine dinucleotide (FAD)
ATP production & energy storage
nutrients store energy in chemical bonds, as the nutrients are degraded, energy is released
-that energy can be stored in high-energy phosphate bonds: ATP
ATP generation and 3 ways
occurs through phosphorylation: inorganic phosphate added to substrate
- substrate-level phosphorylation: organic molecules receive a phosphate
- oxidative phosphorylation: electron movement is used to create ATP
- photophosphorylation: sunlight is used to make ATP
