Microbial  Metabolism  &  Growth  

Basic  Organic  Chem  Review  

•  Four  Basic  Types  of  Macromolecules  •  A)  Proteins  (Made  up  of  Amino  Acids)  •  B)  Nucleic  Acids  (Made  up  of  NucleoEdes)  •  C)  Carbohydrates  (Mainly  Carbon,  Hydrogen,  and  Oxygen  in  a  1:2:1  raEo)  

•  D)  Lipids  (Mainly  Carbon  &  Hydrogen)  

A. Proteins

•  consist of long, complex chains of amino acids (20 kinds)

•  the most abundant organic components of microbes

•  function as structural materials as well as __________

•  destruction of the proteins in an organism usually results in death

Protein structure: amino acids

•  AMINO ACIDS are the building blocks of proteins

a  specific  amino  acid  

Protein structure: amino acids

NOTE:  All  amino  acids  look  alike  except  for  the  highlighted  porEons.    This  is  important  in  building    many  different  proteins.  

Peptide bonding of amino acids

•  Proteins are built by linking amino acids end to end. Each link is a ____________.

Protein structure: Primary

Protein structure: Secondary

Protein structure: 3 dimensional •  The 3 dimensional shape of a protein

dictates its function. •  If the 3 dimensional shape is altered, the

protein is destroyed.

Protein structure: Quaternary (Hemoglobin)

Protein _________

Altered  3-­‐D  shape  =  destroyed  protein  

B. Nucleic Acids •  Two types function in all living

things: •  _____ ( deoxyribonucleic acid )

acts as the genetic material of the chromosome

•  _____ ( ribonucleic acid ) functions in the construction of proteins

•  Both DNA and RNA are composed of repeating units called nucleotides

•  As with proteins, the nucleic acids cannot be altered without disrupting the organism or killing it.

C. Carbohydrates •  1. general formula = (CH2O)n •  2. sugars, starches, cellulose, etc •  3. have a vital function as energy

sources in cells •  4. also found in several cellular

structures such as cell walls and bacterial capsules

•  5. monosaccharides are the simplest carbohydrates, the building blocks e.g. ________, fructose C6H12O6

Carbohydrates •  6. disaccharides are double sugars (2

monosaccharides bonded together) – e.g. _______ (table sugar) is one glucose and

one fructose – C12H22O11: one H2O lost when bond forms

glucose   fructose  

NOTE:  2  monosaccharides  linked  together.  

DehydraEon  Synthesis  (PuVng  together)          Hydrolysis  (breaking  apart)  

O CH2OH CH2OH CH2OH CH2OH

H H H H

H H H

H

H

H

H

H

H H H

H

H

H H O O

H O

H OH

OH OH OH OH OH

OH OH OH HO HO HO OH O H2O

OH

Dehydration Synthesis

Hydrolysis

Macromolecules (How to Make Them)

C. Carbohydrates

•  7. complex sugars are called polysaccharides or complex carbohydrates (e.g. starch, cellulose )

•  long chains of sugars: sugar—sugar—sugar—sugar—sugar—sugar—sugar—

D. Lipids •  Broad group of organic compounds that

dissolve in oily solvents (e.g. acetone, or benzene) and alcohol but generally do not dissolve in water

•  Mostly composed of carbon and hydrogen

D. Lipids •  1. Best known lipids are fats

–  serve living organisms as important energy sources

–  consist of glycerol and up to three long-chain fatty acids

•  2. Modified fats called phospholipids are the major components of membranes

•  3. Other types of lipids include waxes and steroids

glycerine              faWy  acid  

Fatty Acids + Glycerol

Fats

Other  important  lipids  you  should  know!  

Steroids  such  as  cholesterol  Phospholipids  

I. MICROBIAL PHYSIOLOGY •  _____________: the sum of all biochemical

processes taking place in a living cell. Two phases:

•  _____________: constructive metabolism; the synthesis reactions; small molecules bonded into larger molecules; energy is “used up”

•  _____________: destructive metabolism; decomposition reactions; large molecules split into smaller molecules; energy is released

A._________

•  the enzymes present in an organism determine the nature of its physiology

•  enzymes are biological catalysts (catalysts are agents that speed up chemical reactions)

•  Enzymes “are reusable protein molecules that brings about a chemical change while remaining unchanged itself”

________________= the amount of energy required to do the reaction

Without enzyme lactose

With enzyme

lactose glucose + galactose

activation energy without enzyme

net energy released

glucose + galactose

activation energy with enzyme

net energy released from splitting of lactose

Activation Energy = the amount of energy required to do the reaction

Enzymes __________ = what the enzymes works on

________ = what is made

Enzymes

Competitive Inhibitor Noncompetitive inhibitor

Active Site

Allosteric Site

Action of enzyme inhibitors

   Examples  of  inhibitors:    1.  CompeEEve=sulfa  drug  (sulfanilamide)    2.  NoncompeEEve=Certain  poisons,  such  as  cyanide  and  fluoride  (enzyme    

poison  in  bacteria)  

Factors influencing enzyme action:

•  a. Terms: •  optimum: the environmental state where the

enzyme works the fastest. •  maximum: The maximum environmental limit

where the enzyme works at all. •  minimum: The minimum environmental limit

where the enzyme works at all. •  e.g. temperature: every enzyme has its

optimum temperature (where it works fastest). Curve is unusual:

enzyme activity vs temperature

pH •  Measurement of acid/base balance

•  Logarithmic scale •  0-6.9 = acid •  7.1-14 = basic

(alkaline) •  7 = neutral

(like pure water)

enzyme activity vs pH •  every enzyme has its optimum pH (where

it works fastest). Bell curve

Naming of enzymes

•  names end with -ase •  name of substrate + ase

e.g. sucrose is digested by sucrase •  kind of reaction + ase

e.g. an enzyme that causes oxidation is called oxidase

Types of Enzymes based on location

•  endoenzymes: remain inside of the cell (work internally) – enzymes of cellular metabolism – vulnerable enzymes

•  exoenzymes: released to the exterior of the cell (work externally) – digestive enzymes and enzymes of virulence

Constitutive vs Induced Enzymes

•  ___________ enzymes: – always present – necessary for life of cell

•  __________ enzymes: – produced only when substrates are present – e.g. digestive enzymes – provide efficiency and adaptability

B. Energy and ATP •  Energy released from catabolism of foods is stored in a

compound called ATP (adenosine triphosphate) •  a molecule of ATP acts like a portable battery—it’s instant

energy for a cell to use •  ATP molecules are used everywhere in a cell to meet

energy needs. (When the supply is exhausted, the cell dies)

ADP + Phosphate + Energy = ATP

captures  heat   releases  heat  

ATP •  Although ATP molecules are used everywhere

in the cell to meet energy needs, they are not suitable for storing energy. The molecules are large and bulky, and surplus takes up too much space in a cell.

•  Therefore, cells synthesize or obtain small molecules such as glucose or lipids for energy storage. When needed, these energy storage molecules can be converted to ATP!

•  glucose is a principle source of energy for ATP production.

C. Pathways of Energy Production •  Most of a cell’s energy is produced from

carbohydrate catabolism •  Glucose is the most commonly used

carbohydrate:

•  C6H12O6 + 6 O2 + 38 ADP + 38 P 6 CO2 + 6 H2O + 38 ATP

•  To produce energy (ATP) from glucose, microbes use 2 general processes: – 1. respiration

•  in which glucose is completely broken down – 2. fermentation

•  in which glucose is partially broken down

•  Both processes usually start with the same first step (glycolysis), but follow different subsequent pathways

Glycolysis •  the first stage in the breakdown of glucose

glucose  

2  pyruvic  acid  

(energy  source  )  

series  of  controlled    reacEons  releasing  a    liWle  ATP  

Overview of Respiration & Fermentation

glycolysis  

respiraEon   fermentaEon  pathways  pathways  

Aerobic=  CO2  +  H2O  +  38  ATP                                          an  organic  end-­‐product  

                       (like  alcohol  or  lacEc  acid)                                                                                                                    with  low  ATP  yield  

Classification of organisms by oxygen use (study table 6.1)

•  1. obligate aerobes: (= strictly aerobic): must have oxygen to grow (go dormant without oxygen)

•  2. microaerophiles: grow best at low oxygen levels (less than atmospheric)

•  3. facultative anaerobes: use oxygen if it’s present, but can also grow anaerobically (capable of growing at any oxygen level, but greater growth with oxygen present)

•  4. aerotolerant anaerobes: never use oxygen, but not inhibited by it

•  5. obligate anaerobes: grow only in absence of oxygen (inhibited by oxygen)

Good  Essay  QuesEon!  (This  or  the  picture  or  BOTH)  

Growth at different oxygen levels

E. Growth at different temperatures

•  Each species has different temperature requirements •  minimum growth temperature: lowest temperature at which

growth will occur (very slow growth at this temp) –  below the minimum, most microorganisms go dormant,

but do not die •  optimum growth temperature: temp at which most rapid

growth occurs •  maximum growth temperature: highest temp at which growth

occurs –  above this temp, enzymes are denatured and death

might occur •  NOTE: Growth parallels rate of enzyme activity.

Growth speed vs temperature

Gro

wth

Sp

eed

F. Classification by temperature requirements

•  _____________ (= cryophiles): cold-loving organisms; have optimum growth temp below 25° C

•  _____________ (meso = middle): have optimum of 25-40°C

•  ____________: heat-loving organisms; have optimum > 40°C

•  ______________: growth range = 70-105oC; optimum > 90oC

mesophiles  

hyperthermophiles  

Good  Essay  QuesEon  Also!  

Growth versus temperature

Does size of pan (with same

volume) matter?

G. pH and microbial growth

•  every organism has its minimum, optimum, and maximum growth pH

•  microorganisms often change the pH of their environment – usually create acidity – sometimes create alkalinity

Gro

wth

spe

ed

Thus, the requirements for bacterial

growth include: •  Physical aspects

– Temperature – pH – Osmotic pressure

•  Chemical aspects – Carbon, nitrogen, sulfur, phosphorus, trace

elements, oxygen, and organic growth factors

H. Bacterial fission (cell division)

•  less complex than mitosis (division of eucaryotic cells) – only one chromosome

•  Binary fission (see figure 6.12)

Remember... •  When we talk about microbial growth, we

are really referring to the number of cells, not the size of the cells.

•  Microbes that are “growing” are increasing in number, accumulating into clumps of hundreds, colonies ( can be seen with naked eye ) of hundreds of thousands, or populations of billions.

How do we measure microbial growth?

•  Plate counts and serial dilutions –  We’ll do as part of the microbiology of water and milk lab –  See figure 6.16

•  Filtration –  We’ll do as part of the microbiology of water lab –  See figure 6.18

•  Direct Microscopic Count –  See figure 6.20

•  Turbidity –  Using the spectrophotometer –  See figure 6.21

•  Dry weight

I. Population dynamics •  potential populations:

–  huge –  doubling time of 20-30 minutes for many

microorganisms –  from 1 cell to over a million in 10 hours (with 30

minute generation) – See figure 6.13 & 6.14

•  populations are self-limiting –  depletion of food supply –  accumulation of toxic metabolic wastes

•  population growth curve

lag  phase:  slow  growth  

logarithmic  (log)  phase:  rapid  growth  

maximum  staEonary  phase  (aging  populaEon)  

death  phase:  rapid  decline  

survivor  phase  

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