Bacterial Growth Flashcards by Hailey Lopez

Physical growth requirements for bacteria

temperature
ph
osmotic pressure
(Environment)

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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

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Optimal growth on growth curve

Temperature at which a microbe grows best

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Maximum/ minimum growth on bacteria growth curve

Range of possible growth

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High temperatures doe what to proteins and the plasma membrane

Proteins - denature

Membrane - more permeable

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Low temperatures causes the plasma membrane and proteins to

Proteins - lose flexibility = can’t move
Membrane - loses permeability

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What are the 4 groups of bacteria?

Psychorophiles, psychrotrophs, measophiles, Thermophiles

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What group of Bactria have enzymes that are more flexible at lower temperatures?

Physcorophiles

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What a group of bacteria’s enzymes do not unfold easily (more stable)?

Thermophiles

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Saturated vs. unsaturated

the # of hydrogens

Saturated - 4 hydrogens (lower permeability)

Unsaturated - 2 hydrogens (more permeable)

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Psychrophiles have more _________ fatty acids in membrane

Unsaturated double bonds)

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Thermophiles have more ________ fatty acids in membrane

Saturated

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Acidic environments

Less then 7 ph

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Basic environments

high ph (greater then 7)

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What bacteria have a more permeable membrane, acidophilus or alkaliphiles?

Alkaliphiles - it helps keep h+ in the cell

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What is the consequence of extreme ph rates over the optimum?

It causes proteins/ enzymes to denature (unfold)

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Alkaphiles membranes

Less permeable to protons to keep protons in the cell

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Acidophiles membrane

Less permeable to protons to keep protons (H+) out of the cell

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What are hemophiles?

Bacteria that require higher salt concentration to live

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Plasmolysis

Cells cytoplasm shrinks inhibiting growth

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Why does bacteria need oxygen as a chemical growth requirement?

Needed for aerobic respiration (bring air in)

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Why does a bacteria Ned phosphorus as a chemical growth requirement?

Needed in ATP synthesis ( from phosphate ions)

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How can oxygen be toxic to bacteria?

Superoxide anion - it’s unstable and creates radicals

o2 picks up extra e-

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What enzymes are used to breakdown oxygen?

Sod (superoxide dimutase)

CAT - catalase

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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

1. DNA replication 2. Elongation - cell elongates and dna moves toward each end 3. Separation - Ftsz protein creates ring to facilitate cell dividing 4. Division - septum dives two cells 5. 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?

1. Lag phase 2. Log phase 3. Stationary phase 4. 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

1. Chromosome copied and surrounded by structure 2. Water is removed from endospore and metabolism of endospore stops 3. 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?

1. Glycolysis 2. Intermediate step 3. 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