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refers to all of the chemical processes that occur inside living cells.
All biological processes require ?
are not used up or changed in any way during the reaction
What do Enzymes consist of
may be pure proteins or proteins plus cofactors such as metallic ions or coenzymes, organic group that contain groups derived from vitamins
Enzyme + Substrate =
The active site is the location on the enzyme where
the substrate fits
An enzyme works by
binding with its substrate, the molecule whose reaction is catalyzed
How are Enzymes are highly specific
There is an exact molecular fit between enzyme and substrate.
Some enzymes work with only one substrate, others work with a group of molecules
Catabolic (degradation) reaction catalyzed by
Anabolic (synthesis) reaction catalyzed by
Biological reactions require_______to proceed
molecule with stored energy
See Page 16 sunday week 1
ATP consists of
adenosine (adenine + ribose) and a triphosphate group
The bonds between the phosphate groups are
high energy bonds
An atom that gains an electron has been
reduced. Higher energy.
An atom that loses an electron has been
oxidized. Oxygen is a common electron acceptor.
Redox reactions always occur in pairs
–One atom loses the electron, the other gains the electron.
Energy is transferred from one atom to another via
Describe cellular respiration
the oxidation of food molecules to obtain energy
Cellular respiration has two stages what are they
- 1st: Glycolysis
- 2nd: Aerobic or anaerobic respiration
in the presence of oxygen
A large amount of ATP is made during
in the absence of oxygen
NAD+ is recycled during the
anaerobic process of fermentation.
see page 25 sunday week 1
In aerobic respiration, ATP forms as electrons are
- harvested, transferred along the electron transport chain
- and eventually donated to O2 gas.
–Oxygen is required & Glucose is completely broken-down during ?
Glycolysis – coupled reactions used to make
- –Occurs in cytoplasm
- –Doesn’t require O2
Oxidation – harvests electrons and uses their energy to power
- ATP production.
- –Only in mitochondria
- –More powerful
Electron transport chain (ETC) occures
•Occurs in the mitochondria of eukaryotes and cell membrane of bacteria
Different electron acceptors are used instead of oxygen (sulfur, or nitrate) in
A. Aerobic Metabolism
B. Anaerobic Metabolism
B. Anaerobic Metabolism
Start of Anaerobic respiration is
- GlycolisisThis means that glycolysis is part of aerobic and anaerobic respiration
Two steps in anaerobic respiration:
In the absence of oxygen, the end-product of glycolysis is
pyruvate, is used in fermentation.
Fermentation replenishes more
NAD+ and allows glycolysis to start again
During glycolysis, NAD+ gets used up
When this happens ________will stop.
Yeasts, single-celled fungi, produce
- Present in wine & beer.
- Alcoholic fermentation
The term microbial growth refers to the
growth of a population (or an increase in the number of cells), not to an increase in the size of the individual cell.
Cell division leads to
the growth of cells in the population
Microbial control of growth is important for
- –infection control
- –growth of industrial and biotech organisms
Factors Regulating Microbial Growth
- •Environmental conditions: temperature, pH, osmotic pressure
- •Generation time
Saprobe – lives on
organic matter of dead organisms
Parasite – lives on
organic matter of living host = pathogens
Environmental Factors Influencing Growth
- •Osmotic Pressure (tonicity)
- •Hydrostatic pressure
most common group of organisms
Top influencing factor in growth range
Optimum growth temperature is usually near the top of the growth range
Death above the maximum temp. comes from
Thermophiles used in
- Many industrial processes involve high heat
- –450C (113F) is a problem for most enzymes
- –First Extremophile found in 1972
- •Efficient enzymes to work in the cold
- –Enzymes to work on foods that need to be refrigerated
- –Perfumes - most don’t tolerate high temperatures
- –Cold-wash detergents
Strict or obligate anaerobes
oxygen kills the bacteria; ex. Clostridium tetani
Strict or obligate aerobes
lack of oxygen kills the bacteria; ex. Pserdomonas
•can shift their metabolism (anaerobic if oxygen is absent or aerobic if oxygen is present); ex. E.coli, Staphylococcus
the bacteria don’t use oxygen, but oxygen doesn’t harm them; ex. Lactobacillus
•like low oxygen concentrations and higher carbon dioxide concentrations; ex. Campylobacter
(acid-loving) – grow best at a pH of 1 to 5.4; Ex. Lactobacilllus (ferments milk)
exist from pH to 5.4 to 8.5; most bacteria that cause human disease are in this category.
•(base loving) – exist from pH to 7.0 to 11.5; ex. Vibrio cholerae (causes cholera)
•Enzymes used to increase efficiency of animal feeds
–enzymes help animals extract nutrients from feed
–more efficient and less expensive
ARE KNOWN AS
–Alkaliphilic enzymes soften fabric and release some of the dyes, giving worn look & feel
- –Enzymes dissolve proteins or fats
- –Detergents do not inhibit alkaliphilic enzymes
salt lovers inhabit the oceans.
Acidophiles and Alkaliphiles sometimes excrete
protective substances and enzymes
Acidophiles often lack
used as food additives or as food-coloring agents
The extraction of carotene from carotene rich halobacteria and halophilic algae
bacteria that can exist in a dormant state in a dry environment
Spores of sport-forming bacteria
•Pressure exerted by standing water (ex. lakes, oceans, etc.)
Some bacteria have enzyme systems that can repair some mutations
Asexual two types
- Binary fission
- see pg 69
bacteria and some eukaryotes (including yeasts) may also replicate by budding, forming a bubble-like growth that enlarges and separates from the parent cell
Name A microbial lab culture typically passes through 4 distinct, sequential phases of growth that form the standard bacterial growth curve
- A. Lag Phase
- B. Log Phase
- C. Stationary Phase
- D. Death Phase
- •The number of cells doesn't increase.
- •However, considerable metabolic activity is occurring as the cells prepare to grow.
- •This phase may not occur, if the cells used to inoculate a new culture are in the log phase & provided conditions are the same.
- •Cell numbers increase exponentially
- •During each generation time, the number of cells in the population increases by a factor of two.
- •The number of microbes in an exponentially increasing population increases slowly at first, then extremely rapidly.
- •Organisms in a tube of culture medium can maintain log growth for only a limited time, as nutrients are used up, metabolic wastes accumulate, microobes suffer from oxygen depletion.
- •The number of cells doesn't increase, but changes in cells occur
- •Cell become smaller and synthesize components to help them survive longer periods without growing (some may even produce endospores)
- •The signal to enter this phase may have to do with overcrowding (accumulation of metabolic byproducts, depletion of nutrients, etc.).
- •In this phase, cells begin to die out.
- •Death occurs exponentially, but at a low rate.
- •Death occurs because cell have depleted intracellular ATP reserves.
- •Not all cells necessarily die during this phase!
Summary of Phase of Growth
–Adapt to nutrients
Summary of Phase of Growth
Summary of Phase of Growth
Death = Growth rate
Summary of Phase of Growth
- Nutrients consumed
- ph too low
Measures a property of the mass of cells and then ESTIMATE the number of microbes
A spectrophotometer can measure how
much light a solution of microbial cell transmits; the greater the mass of cells in the culture, the greater its turbidity (cloudiness) and the less light that will be transmitted.
- •The rate of utilization of a substrate, such as oxygen or glucose.
- •The rate of formation of metabolic products, such as gases or acids, that a culture produces.
•The rate of reduction of certain dyes.
Give more accurate measurements of numbers of microbes.
Direct Culture Counts
- •electronic counter
- • rapid & accurate only if bacterial cells are the only particles present in the solution.
- •[gives a total count - live & dead cells].
Bacterial colonies are viewed through the magnifying glass against a colony-counting grid; called a
- Quebec colony counter
- [gives a viable count]
Liquid medium is best when you want to
rapidly increase the concentration of the organism or when you want to grow motile cells
Culture plates are used when you want to test
- (1) antibiotic sensitivity
- (2) estimate culture concentrations from environmental samples
- (3) isolate individual colonies from environmental
Liquid medium is solidified by using
agar (agarose) and poured as a thin layer in the bottom of a culture dish (also sometimes called petri plate)
Discribe Differential Media
has an ingredient that causes an observable change in the medium when a particular biochemical reaction occurs (ex. a color or pH change).
•oxygen-binding agent added to the medium to prevent oxygen from exerting toxic effects on anaerobes
Actions of Microbial Control Agents
- •Alteration of membrane permeability
- •Damage to proteins and nucleic acids
Physical Control Methods
- •Osmotic pressure
The removal of water
- •Coagulates proteins by breaking hydrogenbonds
- •Boiling: 10 minutes kills most pathogens (hepatitis
- virus needs 30 minutes and spores need 20 hours!)
- •Autoclave: 15 psi for 15 minutes (121° C)
- •Used when taste of product would be damaged by longer heating: lowers numbers of pathogens (63°C for 30 minutes)
- •High-temperature short-term (HTST) pasteurization (72°C for 15 seconds)
Types of Ionizing radiation:
- gamma rays,
- X rays,
- high energy electron beams – most energetic
Describe UV Radiation
- •Thymine dimers in DNA
- •Germicidal lamps, vaccine disinfection
- •Not penetrating
- •Can damage eyes
- •Very little effect on microbes
- •Microwave ovens kill vegetative pathogens by heating
- •Solid foods heat unevenly
- •Disinfectants and antiseptics
- •Surface-active agents (surfactants)
- •Chemical food preservatives
- •Gas sterilization
- •Oxidizing agents
- •Kill/inhibit growth of microbes on surfaces
- •Phenols and phenolics: damage lipid membranes
- –Active in presence of organic matter
- –Persist for long periods after application
OH also called carbolic acid
- •protein denaturation and membrane damage
- – evaporate quickly– ethanol and isopropanol
- – [not effective if taken internally]
- silver nitrate (topical cream)
- mercuric chloride (paint)
- copper sulfate (algaecide)
- zinc (mouthwash, paints
- •Decrease surface tension
- •Soaps and detergents
- – Quaternary ammonium compounds : microbicidal
- •Formaldehyde (formalin) and glutaraldehyde
- –Disinfect instruments
- –Used to preserve tissues for pathology
- –Cross-link protein molecules
- •Hydrogen peroxide
- •Benzoyl peroxide
- •Peracetic acid
- – Interfere with metabolism (especially of
Types Bacterial Genetics
- •Genetic recombination
- •Genetic engineering
- •Microbial genomics
- •The genetic compliment of an organism
- •Types of genotypic changes
- •The genetic expression of an organism
- •Types of phenotypic expressions
The Bacterial Chromosome
•DNA is arranged as a single molecule with no histones present, and with no dominance or recessiveness in the genes.
are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes
- •Fragments of DNA in the cytoplasm
- •R Factors - confer drug resistance
- •Bacteriocins -proteins toxic to other bacteria and human cell
- •Many plasmids are found in Gram-Negative bacteria
- Spontaneous mutations = Example: Salmonella
- strains antibiotic resistance
- Induced mutations = Chemical
- or Physical agents enhance mutation rate
- –Mismatch repair “proofreads”
- –Damage repair
- »Excision repair
- »Dimer repair (UV light)
Transformation (Griffith's experiments)
DNA transformation involves the transfer of naked DNA into a recipient cell
Thetransfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells
Is the process by which DNA is transferred from one bacterium to another by a virus.
The lytic cycle is typically considered the
main method of viral replication, since it results in the destruction of the infected cell.
A key difference between the lytic and lysogenic phage cycles is that in the lytic phage, the viral DNA exists as a
separate molecule within the bacterial cell, and replicates separately from the host bacterial DNA
Genetic regulatory system found in bacteria and their viruses
- •Genetic engineering involves changing the genetic material in an organism to alter its traits or products
- •A recombinant DNA molecule contains DNA fragments spliced together from 2 or more organisms
Genetic Engineering Modern applications
- •Pharmaceutical production
- –Insulin, interferon, hormones, vaccines etc.
- •Genetically engineered plants
- •Animal gene alterations
- •Gene probes
- •DNA fingerprinting
- •The human genome initiative
Energy in the form of ATP is produced via
Growth of microbes depend on the
physical and chemical environment
We can utilize microbes for our benefit by altering their
•DNA to produce what we want