Bacterial Growth Flashcards
Physical growth requirements for bacteria
- temperature
- ph
- osmotic pressure
(Environment)
Chemical growth requirements for bacteria
(Consuming)
- carbon
Nitrogen, sulfur, phosphorus
- oxygen (sometimes)
- trace elements (iron, copper)
- osmotic growth factors = can’t be made by organisms
Optimal growth on growth curve
Temperature at which a microbe grows best
Maximum/ minimum growth on bacteria growth curve
Range of possible growth
High temperatures doe what to proteins and the plasma membrane
Proteins - denature
Membrane - more permeable
Low temperatures causes the plasma membrane and proteins to
Proteins - lose flexibility = can’t move
Membrane - loses permeability
What are the 4 groups of bacteria?
Psychorophiles, psychrotrophs, measophiles, Thermophiles
What group of Bactria have enzymes that are more flexible at lower temperatures?
Physcorophiles
What a group of bacteria’s enzymes do not unfold easily (more stable)?
Thermophiles
Saturated vs. unsaturated
- the # of hydrogens
Saturated - 4 hydrogens (lower permeability)
Unsaturated - 2 hydrogens (more permeable)
Psychrophiles have more _________ fatty acids in membrane
Unsaturated double bonds)
Thermophiles have more ________ fatty acids in membrane
Saturated
Acidic environments
Less then 7 ph
Basic environments
- high ph (greater then 7)
What bacteria have a more permeable membrane, acidophilus or alkaliphiles?
Alkaliphiles - it helps keep h+ in the cell
What is the consequence of extreme ph rates over the optimum?
It causes proteins/ enzymes to denature (unfold)
Alkaphiles membranes
Less permeable to protons to keep protons in the cell
Acidophiles membrane
Less permeable to protons to keep protons (H+) out of the cell
What are hemophiles?
Bacteria that require higher salt concentration to live
Plasmolysis
Cells cytoplasm shrinks inhibiting growth
Why does bacteria need oxygen as a chemical growth requirement?
Needed for aerobic respiration (bring air in)
Why does a bacteria Ned phosphorus as a chemical growth requirement?
Needed in ATP synthesis ( from phosphate ions)
How can oxygen be toxic to bacteria?
Superoxide anion - it’s unstable and creates radicals
- o2 picks up extra e-
What enzymes are used to breakdown oxygen?
Sod (superoxide dimutase)
CAT - catalase
Why can’t SOD just break down o2?
It breaks down oxygen into hydrogen peroxide - oxygen allow will contain toxic anion = superoxide
Facultative means
Can tolerate but does not prefer whatever condition
Obligate
“Requires’ whatever condition
Aerobe means
Using oxygen to live
Anaerobe means
Unable to use oxygen to live
What does it mean for a microb to grow?
Grow by increasing in number not size
What is the main protein used in binary fission?
Ftsz protein
What is the main function of Ftsz protein?
Works for cell division/ forms ring, which directs septum in middle to split cell in two
Steps of binary fission
- DNA replication
- Elongation
- cell elongates and dna moves toward each end - Separation
- Ftsz protein creates ring to facilitate cell dividing - Division
- septum dives two cells - Pinch off
- cells pinch apart w/ Ftsz in each cell
How do you calculate exponential growth
Total # of cells = 2^n (number of generations) X # of initial cells
Exponential growth is often shown on ________ scale
Logarithmic
Bacterial growth curve contains 4 phases, what are they?
- Lag phase
- Log phase
- Stationary phase
- Death phase
Lag phase
Preparing for binary fission by making enzymes
Log phase
Cells begin dividing
- # of cells dividing > # cells dying
Stationary phase
The number of cells dividing = number of cells dying
Death phase
Number of cells dividing < number of cells dying
- not sufficient nutrients present
Plate count
Counting the number of colony forming units on a solid media
What four ways can you see bacterial growth?
Plate count
Filtration counting
Turbidity
Microscopic cell count
CFU (colony forming unit)
Filtration counting
Good for dilute samples like water
Turbidity
Allows light to shine through - increased cloudiness = more cells
What is a con of using Turbidity to count bacteria growth
You can’t tell which cells are alive and what are dead
What type of bacteria have endospores?
Gram positive (G+)
Why are endospores formed?
- like a bunker to hid away
Formed when conditions are not good for dividing (not ideal living conditions)
Endospores are very durable
TRUE or FALSE
TRUE: they can last thousands of years
What is sporulation
Endospores formation
Explain the process of sporulation
- Chromosome copied and surrounded by structure
- Water is removed from endospore and metabolism of endospore stops
- Cells holding endospore lyse (break open) releasing endospore
Germination
Process of starting to grow from a spore into a endospore
What is free energy
Ability to do work
How does the stability of a molecule relate to its ability to do work?
The more stable a molecule is the less ability to do work
Unstable = more work
Anabolic reaction
Endergonic (puts energy in to system)
- formation of molecule (Delta G positive)
Catabolic Reaction
Exergonic (energy being released)
- the breaking down of molecules (Delta G is negative)
What is ATP and its role
ATP is the main molecule that provides energy to do work
Oxidation
Loss of electron
Reduction
Gain of electron
Do electrons carry energy? Which electrons carry the most energy?
Yes they carry energy
- carry most if further away from nucleus
Is NAD+ being reduced or oxidized when it turns into NADH?
Reduced
What kind of molecule is NADH?what does it do?
Electron Carrier - it donates/ accepts electrons from and to various places in cellular respiration
What are ways in which organism,s can convert high energy in electrons in food into ATP?
Via redox reaction in cellular respiration
What are the steps of cellular (aerobic) respiration and where does it occur?
- Glycolysis
- Intermediate step
- Citric acid cycle (kreb cycle)
- all occur in the cytoplasm!!!
Glycolysis input
Glucose molecule
- 2 ATP
Glycolysis output
2 pyruvate
- 4 ATP (net gain of 2 ATP)
- NADH (2x)
How is atp made in glycolysis?
Substrate level phosphorylation
- transfer of a phosphate from a substrate in the bacteria to ADP using an enzyme
Electron carriers
NADH now carry 2 electrons
How much ATP is made during cellular respiration
Glycolysis - 2
Intermediate step - 0
Citric acid cycle - 2
