BIO 206 Exam 3

Environmental factors fundamentally affect the function of metabolic ________

enzymes

what type of environmental factors fundamentally affect the function of enzymes

-temperature

-pH

-gas requirement (oxygen)

-radiation

-barometric pressure

-ecological association

enzymes drive drive metabolic reactions= inactive=_____

death

microbial ecological hitches=

ability to control microbial growth

temperature

-define microorganisms growth curve

-most single cell organisms are poikilothermic

-3 cardinal temperatures

Poikilothermic

assume ambient T delta

3 cardinal temperature

-minimum temperature

-maximum temperature

-optimum temperature

minimum temperature

lowest temperature that permits a microbe's growth and metabolism

maximum temperature

highest temperature that permits a microbe's growth and metabolism

optimum temperature

promotes the fastest rate of growth and metabolism

is temperature rigidly fixed?

-no

-because of other environmental factors influence

four temperature adaptation groups

-psychrophilic

-psychrotolerant

-mesophiles

-thermophiles

-extreme thermophiles

Psychrophilic

-cold loving

10C to 25C

-optimum temperature 10-13 C

-ocean about 5C

-can grow in refrigerator

-not human pathogens

-lipids in cell membrane highly unsaturated= a lot of double bonds

psychotolerant

4 to 35 T

-optimum temperature 15-30

-grow slowly in cold

mesophiles

10 C to 45 C

-optimum temperature 20-40C

-human pathogens

-normal flora and environmental microbes

thermophiles

30 to 80C

-optimum temperature under 45C

-compost pile, hot water heater

extreme thermophiles

80C and greater

-we don't know optimum temperature

-hot springs, deep ocean vents

-archaea unique enzymes, increase C and G percentage

-lipids in cell membrane high saturated no double bonds

Psychrophiles

-organism that have an optimum temperature below 15

-grow at 0 degrees

-cannot grow about 25

psychotolerant

-grow slowly in cold but have an optimum temperature between 15 and 30C

pH

-measure of hydrogen activity of a solution

-degree of acidity or alkalinity

-0-14

-pH pure water= 7 neutral (blood)

-each species has a definite pH growth range

-optimum pH range for most 6-8 because acid/base can be damaging to proteins (enzymes), cell membrane parts (DNA)

effects of pH

-related to concentration of acid

-to the protection of bacteria cell wall

changes in pH can lead to

-denaturing enzymes and other proteins

-can interfere with pumping ions in cell membrane

-many bacteria produce large quantities of acids as they metabolize and grow= leads to high concentration of acid= toxic environment

-majority of microorganism at pH 6-8

acidophiles

-pH 0 to 5.5

-fungi grow at lower pH than bacteria

neutrophils

-pH 6 to 8

alkalophiles

-ph of 8.5 to 12

Natronomonas pharaonis

-found in soda lakes

-high salt and pH of 11

-grows at optimum 3.5 M NaCl and 8.5 pH

Heliobacteria pylorigm-spirochete

-found in stomach at about 2.5pH

-causes peptic ulcers

-not acid tolerant

-produces toxins= inflammation and damage

-aggravated by stress and environment

-protects itself by growing in protective mucus layers

-breaks down urea (NH4 base) which neutralizes the microenvironment

-treat with antibiotics

Gas Requirements

-most cells have developed (protective) enzymes that neutralize these chemicals

-catalase (H2O2), superoxide dismutase (OH)

-if a microbe is not capable of dealing with toxic oxygen= lacks protective enzymes

-forced to live in oxygen-free habitants anaerobe

oxygen

-highly reactive

-has single electron in outer orbit so steals electrons

-utilized transformed into several toxic products

-singlet (O2) superoxide ion (O2-)

categories of gas requirements

-aerobe

1. obligate aerobe

2. facultative anaerobe

3. microaerophilic

-anaerobe

1. obligate anaerobe

2. aerotolerant

aerobe

utilizes oxygen and can detoxify (38 ATP)

-has protective enzymes

obligate aerobic bacteria

-can't grow without oxygen

-must have oxygen

facultative anaerobe

-utilize oxygen but can also grow in absence

-prefer oxygen

Microaerophilic

-requires only a small amount of oxygen

-best at 5% oxygen

-ATM has 20% oxygen

anaerobe

-doesn't utilize oxygen

-lacks protective enzyme

obligate anaerobe

-lacks the enzymes to detoxify oxygen so cannot survive oxygen environment

aerotolerant

-grows in presence of oxygen but doesn't use usually lacks enzymes

-have other mechanisms of protection (metal)

osmotic pressure

-availability of water in environment varies on amount of water and concertation of solute

-microbes exist under hypotonic (isotonic) conditions

halophiles

-increase in salt concentration

Osmotolerant

-don't require increase concentration solutes but can tolerate it

Water activity (aw)

-measurement of water that is available by use by an organisms

-decreases by adding solute

-increases in concentration of solute

-increase osmotic pressure and aw decrease (inversely)

-enzymes require an aqueous solution

(decrease in aw and decrease in enzyme function and decrease in metabolism= death)

-most organisms require aw .9-1.00 for metabolic activity and growth

Staphylococcus aureus

-growth at 0.85 aw

-grows on skin (salty)

-MRSA

fungi

0.70aw

radiation

-UV light causes mutations (T-T dimers) can kill

-some organisms have enzymes system that can repair certain kinds of DNA damage

-ionizing radiation can be used to sterilize items

-endospores can survive large doses of ionizing radiation

Bacillus stearothermophilus

-purple sugar broth in ampule and spores on a piece of filler paper

-autoclave and then crush ampule to release broth to coat filter paper with spores

-if it turns yellow, sperms germinated and grew so spores not killed, sterilization did not take place

pressure

-many organisms spend their lives on land or on surface of water and are always subjected to 1 atm

hydrostatic pressure

-pressure exerted by a water column as a result of the weight of the column with each 10m water depth= 1 atm

-pressure of greater than 200 generally inactivates enzymes and disrupts cell membrane/transport

-can reach 1000 atm (2-3C) in deep ocen

barophiles

-will rupture in normal pressure

-enzymes depend on pressure to maintain 3D shape

-destroy shape=destroy enzyme=death

prokaryote growth

-105C used to be the highest temperature but we now know it to be 350C

-microbes grow for 2 hours

-sea water boils at 460C

Symbiosis

A relationship in which two different organisms live in close association with each other

-at least one member is dependent

mutualism

A relationship between two species in which both species benefit

Commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

Paratism

one organism lives on or in another and harms it

Lichens

-mutualism

-association between fungus and photosynthetic microbe (algae or cyanobacteria)

-form unique structure

-given genus and species name based on fungi

-fungus gets organic carbon from photosynthetic organism and in return

1. protect it from excess light

2. supplies water and nutrition

3. while providing a support structure

-lichens resist to T delta extreme and desiccation but sensitive to pollution

human gut microbe

-mutualism using host metabolic byproducts and actively producing vitamin (k)

-commensalism using host metabolic byproduct but host not harmed or benefited

-parasitic antibiotics wipe out much of normal flora (sporeformers germinate and produce toxins)

BSL 1

no special precautions

-not known to cause disease

BSL 2

-lab coat, gloves, eye protection

-associated with human disease especially in immunocompromised

BSL 3

-biosafety cabinets to prevent airborne transmission

-causes diseases

-treatable and/or have vaccines

BSL 4

sealed, negative pressure; "hot zone"

-exhaust air is filtered twice through HEPA filters

-deadly organisms for which we have no treatment or vaccine

-Ebola (90% death rate)

the study of microbial growth occurs at which two levels

-growth at the cellular level with increase in cell size

-growth in cell population

how do bacteria divisions occur

through binary fission

binary fission

-parent cell enlarges

-duplicates its chromosome

-forms a central transverse septum

-divides the cell into 2 daughter cells (new/identical)

how long does DNA replication in E.Coli take? how long to reproduce?

-40 minutes

-20 minutes

*synthesis begins before previous round of DNA synthesis is done

when a bacteria cell divides what does each cell receive?

-complete chromosome

-additional portion of genome whos synesis was initated part way through fission cycle

during binary fission what happens?

-cell must partition the DNA and cytoplasmic components by synthesizing a septum or crosswall

-septum initiated by invaginations of the cell envelope layers (CM and CW)

what's the signal for septum initiation?

it's unknown

how many proteins are in E.coli for septation

at least 12 proteins

generation time

-time required for a complete fission cycle

-exponential growth

what happens with each new fusion cycle?

-increase the population by a factor of 2 (double)

what's the average generation time for bacteria given what conditions?

-20 to 60 minutes

-given optimum conditions

what happens when you leave food at room temperature

-few bacteria can grow to large numbers in a short time

mycobacterium leprae

-leprosy

-generation time is a few days due to waxy cell wall

equation for population growth

Nf=(Ni)^2n

why do bacteria not maintain their potential growth rate in most systems?

they are influenced by environmental factors

if environmental factors aren't optimum what happens to growth rate?

-there's a decrease in nutrients

-increase in acids

-decrease in growth rate

does a population tend to drastically change over time or hold a rather constant curve?

rather constant growth curve

closed system

nutrients and space are finite and the growth period over a few hours to about one day produces a curve consisting of a log, phase, lag phase, stationary phase, or death phase

lag phase

-preparing for population growth so no increase in population

-cells may be old and depleted of enzymes, ribosomes, and/or nutrients which are needed to metabolize and grow

-medium may be different from previous one (different sugar, different metabolic pathway, different enzymes)

-most of the time bacteria are getting ready to divide so cells are making necessary components and getting larger

log phase

-exponential growth

-bacteria are growing and dividing at max/optimum rate

-population uniform

-actively growing cells are more vulnerable to conditions that disturb binary fission and/or cell membrane

-organisms divide at most rapid time

conditions that disturb binary fission and cell metabolism

drugs, antibiotics, chemicals, environmental factors, immune

when using bacteria for research, industry or medicine in what phase do researchers/ scientists use?

log phase

cells will continue to grow at an exponential rate if they have what conditions

-nutrients present

-environmental factors are good

stationary phase

-eventual growth ceases and the cure becomes horizontal (about 10^9 bacteria/ml)

-total number of viable microorganisms remains constant

why do the total number of viable microorganisms remain constant in the stationary phase

-balance between cell division and death

-population simply cease to divide through remaining metabolically active (decrease rate)

what causes the stationary phase

-decrease in nutrients

-decrease in space and pH

-increase in acids and increase in accumulation of waste

death phase

-exponential decay

-detrimental environmental changes decrease in number of viable cells characteristic of death phase

-limiting factors intensify

-loss of nutrients and pH is now toxic

when are microorganisms more infectious? (i.e in what phase)

-in log phase

-because they are at their best

-shorter generation time so more easily a pathogen can reach increase numbers quickly

Metabolism

all chemical reactions and physical workings in an organism

anabolism

-building

-two small subunits to one large one

-energy used

endergonic

requires energy

Catabolism

-breaking down

-one large molecule to two smaller ones

-energy produced

Exergonic

releases energy

Enzymes

-Catalysts for chemical reactions in living things

-increase rate by decreasing activation energy

-physically promote a reaction (serve as a site to act on which the substrate can be positioned for)

-not changed in the reaction

Simple enzyme structure

consist of protein alone

conjugated enzymes structure

-proteins and non proteins

-made up of cofactors

Two types of cofactors

metal ions and coenzymes

coenzymes

organic cofactors

metal ions

inorganic cofactors

what's the difference between cofactor and coenzyme?

-nothing used interchangeable

metal ion enzyme substrate interactions

-temporary union and substrate

-once complex has formed, appropriate reaction occur on substrate, often with aid of a cofactor, products are formed and released

-better fit between enzyme and substrate