Exam 3

Microbiology 200 with Ford at University of Kansas

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By: Lauren Cox
Created: 2011-04-12
Size: 140 flashcards
Views: 23

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DNA mutations

DNA mutations can change the information stored in DNA.

Types of DNA mutation

Base substitution
Deletion
insertion
inversion
translocation
duplication

base substitution

take one base and convert it to another. EX. Sickle Cell affect (change in one base)

deletion

removal of a base. Usually really BAD. End up changing all amino acids after removing the base.

Insertion

Add a base

Inversion

rotation in the sequence. EX. ACGTACG changed GCATGCA

Translocation

part of the chromosome is moved to the another.

duplication

duplicating a section of DNA. Important in bacterial evolution.

Consequences of Mutations

Silent mutations
Missense mutation
Nonsense mutation (Frame Shift)

Slient mutations

No change in protein. Most Mutations are silent! Can occur in a noncoding area. Can mutate a promoter and alter transcription levels.

Missense Mutation

change in amino acid (Sickle Cell anemia)

Nonsense mutation

change in frame. Change in stop codon making nonfunctional proteins eventually degrade the cell.

Mutation Related Diseases

Cancer
Genetic diseases

Cancer

misregulation of the cell cycle. Mutations can alter the function of the cell cycle. Tumor-suppressor genes can be mutated to become nonfunctional. HIGH RISK! Requires multiple mutations.

Genetic Diseases

Genes can be mutated. the DNA sequence for a gene gets errors, causing it to make a different protein. Can be inherited by family members. EX. Cystic fibrosis and Hemophilia.

Cause of Mutations

Radiation
Chemicals
Reactive Oxygen Species
DNA replication Errors (Not often)

Mutagen

a chemical that causes an increase in the mutation rate

Carcinogen

a chemical that can cause cancer. Most are Mutagens but not ALL

Ames Test

Uses bacteria to determine if a chemical compound is a mutagen. (EX. Salmonella with a mutant histidine synthesis gene. Salmonella requires histidine to grow. Some Salmonella revert back to normal. Adding a mutagen will increase the reversion chance.) Chemicals that cause reversions tend to cause cancer.

Recombinant DNA

Genes can be taken from one organism and added to another.

Restriction Enzyme

Can cut DNA. The cut pieces can be repaired with Ligase. Discovered in 1972 and partially banned in 1975.

Green Fluorescent Protein (GFP)

Come from Jelly fish. Added to organisms. Very useful for mapping where genes are expressed.

Transgenic bacteria products:

insulin
Human Growth Hormone
Erthropoietin (RBCs)
Factor 8- blood clotting factor

Causes of Food Spoilage:

Enzymatic reactions
Oxidation
Microbes

Food Spoilage in Dairy:

Sour taste- lactic acid and acetic acid production
Denaturation- proteolysis of casein and decreased pH
Bitter taste- protein degradation

Food Spoilage of Meat:

Rancid taste- oxidation of lipids
Smell- degradation of amino acids to make sulfides and amines.

Six Traditional Methods of Growth Control:

1. Apply heat
2. Consume Immediately
3. Desiccation (removal of water)
4. Raise Osmolarity ( increase solute concentration) Add salt of sugar
5. Fermentation
6. Increase Acidity

D- Value (On TEST)

Decimal reduction value of time required to kill 90% of cells.

Six Modern Methods of Growth Control:

1. Aspesis
2. Decrease temperature
3. Anitmicrobial chemicals
4. Radiation
5. Filter Sterilization
6. Antibiotics

Aspesis

avoid contamination

Dienococcus radiodurans

Resistant to desiccation, low temperatures, vaccum, low pH and radiation. Non pathogenic. Can survive 5,000 Gray. Killed 1/3 at 15,000 Gray radiation.

Bacteriocidal

Antibiotic that kills bacteria

Bacteriostatic

Antibiotic stops bacterial growth

Glycolysis

ten step process that breaks glucose down into 2 pyruvate molecules.

Fermentation

Anaerobes (dont require oxygen) will not use citric acid cycle of electron transport chain. Some can get ATP from Glycolysis alone!

Saccharomyces cerevisiae (On TEST)

Bakers or Brewers Yeast! Facultative anaerobe. Produces ethanol as a byproduct of fermentation. Acquires ATP from glycolysis alone.

THREE Problems of Bakers/ Brewers Yeast:

1. Pyruvate waste product
2. NADH waste product
3. Limited NAD+

Ethanol Fermentation

-Carbon dioxide is removed to form Acetaldehyde
-Acetaldehyde is reduced to form ethanol (receives electrons).

Ethanol

-soluble in fats and waters
-Increase membrane fluidity, loose integrity
-no wine of beer over 12% ethanol
-Higher concentrations are made from distillation
-Depressant for some and a stimulant for others

Ethylene Glycol

antifreeze. EXTRA OH

Methanol

rubbing alcohol. ONE Carbon. Produced by wood fermentation. causes Blindness

Alcohol Flush Reaction

turn bright red because Acetaldehyde is not being broken down effectively. Jump to hangover state.

action potential

transmits an electrochemical signal from the cell-body to the axon.

synapse

space where the dendrite of one neuron meets the axon of another neuron.

Neurotransmitter of Ethanol

1. Serotonin- increase signaling
2. Dopamine- increase signaling
3. GABA- decrease
4. NMDA (formation of memories)- decrease
5. Glutanate (slowed speech)- decrease

Cause of Hangover

1. other fermentation products
2. Acetaldehyde
3. Disruption of REM and Non REM sleep
4. Accumulation of waste products
5. Dehydration
6. Withdraw

Spontaneous Generation

thought that microbes arose without cause through environmental conditions.

Antony Van Leeuwenhoek

Discovered the first bacteria

Louis Pasteur

Discovered that microbes did not arise spontaneously. ALL life arises from other life.

Joseph Lister

Tried Phenol on wounds

Types of Antimicrobials:

1. Disinfectants- sterilize objects (fomites) EX Phenol and Formaldehyde. High Concentrations!
2. Antiseptics- Sterilize living tissue. EX. iodine, alcohols, hydrogen peroxide. Low concentration!
3. Antivirals
4. Antifungals

Alexander Fleming

Discovered Penicillin in 1928.

Cell Wall Inhibitors:

1. B-lactam Antibiotics
2. Vancomycin
3. Bacitracin

B-lactam Antibiotics

-Half of all antimicrobial drugs.
-Penicillin and cephalosporins
-inhibit the formation of peptidoglycan cross links

Vancomycin

-Binds to the peptide links that hold sugar subunits of peptidoglycan together.
-Not effective against Gram Negative bacteria.
-Can ruin Kidneys
-Used to treat Staphylococcus aureus.

Bacitracin

-prevents peptidoglycan subunits from being transported across the inner membrane
-ONLY topical

Cell Membrane Disrupters

Gramicidin

-forms channels in membrane
-Ions leak in and out
-also works on eukaryotes
-lyse red blood cells
-ONLY topical

Protein Synthesis Inhibitors

1. Aminoglycosides
2. Tetracyclines
3. Macrolides

Aminoglycosides

-inlcude gentamicin and kanamycin
-Bind to the small subunit of the ribosome and prevent it from joining with the -large subunit.
-No exchange of info from mRNA to Protein.

Tetracyclines

-Bind to small subunit
-Prevent tRNA from binding
-Most are Bacteriostatic

Macrolides

-includes erythomycin
-binds to the large subunit of ribosome
-blocks polypeptide chain from leaving
-Can be both Bacteriocidal or Bacteriostatic

DNA Synthesis Inhibitors

1. Sulfa Drugs
2. Fluroquinolones
3. Metronidazole

Sulfa Drugs

-prevent the formation of nucleic acids by inhibiting the synthesis of folic acid.
-PABA- precursor to make folic acid which sulfa drugs prevent
-Competitive inhibitor.

Fluroquinolones

-include ciprofloxacin
-inhibits DNA gyrase from resealing nicks

Metronidazoles

-activated by flavodoxin
-damages DNA by causing nicks
- humans given the inactive form

RNA Synthesis Inhibitors:

1. Rifampin

Rifampin

-Binds to the B subunit of RNA polymerase
-Blocks the emergence of mRNA (blocks pores)
-prevents RNA from being created

General Causes of Antibiotic Resistance:

1. Overuse of Antibiotics
2. Misuse of Antibiotics
3. Human population density and interactions
4. Immune-suppressed individuals
5. Frequent Mutations
6. Bacterial populations densities
7. Short replication time
8. Horizontal Gene Transfer

5 Mechanisms fro Antibiotic Resistance

1. Restriction of Access
2. Enzymatic Inactivation
3. Target Modification
4. Failure to Activate
5. Alternate Pathway

porins (Restriction)

found in gram negative outer membranes. Some antibiotics are too large to diffuse the membrane

Reduced uptake (restriction)

Some antibiotics gain access to the cell through receptors on the inner membrane can be mutated to not bind to the drug. RARE mechanism

Antibiotic Efflux Pump (restriction)

Removes the drug from the cell as it diffuses in.

B-lactamase (Enzyme inactivation)

Cleave the beta lactam ring
Clavulanic acid- inactivated B-lactamase

Penicillin- Binding Protein Resistance (Target Modification)

Alters the shape of the protein so that penicillin can't fit into the binding site.

Vancomycin Resistance (Target Modification)

-Prevents the peptide interbridge from forming.
-Vancomycin resistant bacteria can alter the peptide bond.

Metronidazole Resistance (Failure to activate)

-Bacteria can mutate to not express flavodoxin
-mutate promoter region of gene itself

Sulfa drug resistance (Alternate pathway)

bacteria use another metabolic pathway to make folic acid

Transduction

involves use of a virus; SAME species

Types of Viral Infection

1. The Lytic Cylce
2. The Lysogenic Cylce

The Lytic Cylce

bacteriophages replicate inside a cell and cause it to lyse

The Lysogenic cycle

the viruses integrate their DNA into the host genome. Pull of genes form the host as the virus leaves transfering genes to another organism. EX: Diphtheria

Transformation

involves the up take of DNA/ PLASMIDS

Plasmids

small pieces of circular DNA
Have a size of 2kb to 50kb (killa base)

Common Plasmid Genes

1. Antibiotic Resistance
2. Metabolic Enzymes
3. Adhesion Factors
4. Toxins

Competence

Ability of bacteria to take up free DNA (Plasmids) from the environment.

Artificial Competence:

1. Calcium Chloride- make membrane more permeable
2. Electroporation- Short burst of electricity, puts holes in membrane

Non- Plasmid Transformation

Some bacteria can take up linear pieces of DNA and integrate them into their DNA.

Plasmid Transformation

Bacteria can take up plasmids

Conjugation

-Species, Genus, and Families trade genes
-Direct transfer of DNA between bacteria.
-Performed using sex pilus

F-factor

-transmitted plasmid is much larger
-fertility factor
-allows bacteria to make sex pilus

Transposons

-small pieces of DNA that can insert themselves into a chromosome
-can land inside genes and inactivate them
-carry antibiotic resistant genes

Types of Transposition

1. Nonreplicative Transpostion
2. Replicative Transpostion

Nonreplicative Transposition

The transposable element is moved. Transposon jumps from plasmid to chromosome

Replicative Transposition

The transposable element is duplicated. Tansposon jumps into chromosome while in the plasmid and can replicate themselves.

pathogen

any biological agent that can cause a disease. (prions, virus, bacteria)
MOST microbes are NOT pathogens

virulence

ability of a pathogen to cause a disease

Virulence factor

natural traits a pathogen can us to establish itself in a host. (Ex. Toxins)

Possible Reasons for Virulence:

1. bacteria have evolved to cause human disease (Primary pathogen)
2. Bacteria are attempting to create a non parasitic association, but fail.
3. Bacteria normally live in another niche, but have accidentally entered and caused an immune response.

Tuskegee Syphilis Experiment (ethical problem)

Black men with syphilis go untreated so that the government can track the progression of the disease.

Jewish Chronic Disease Hospital (ethical problem)

old people with dementia injected with cancer

Willowbrook State School (ethical problem)

Injected mentally disabled kids with hepatitis A without parents permission

50% Lethal Dose (LD 50)

amount of pathogenic bacteria required to cause a terminal infection in half of the animals
LOWER LD50 MORE virulent

50% Infectious Dose (ID 50)

Dose of bacteria required to infect half of the animals.
LOWER ID 50 MORE virulent

Germ Theory of Disease

Koch's postulates required to link a microorganism to a disease.

Koch's Postulates:

1. Microorganism must be found in all cases of the disease
2. It mush be isolated and grown in culture
3. It must reproduce the disease when introduced to a host
4. It must be reisolated from the host with the disease

Postulate Problems:

1. Some strains of microbes are pathogenic while others are not. (Ex. E. coli)
2. Some microbes can be very difficult to culture (EX. Syphilis)
3. Genetics can make a person more or less susceptible to the disease
4. Age can also make someone more or less susceptilble
5. An animal model may not exist (ex. Cholera)

Ulcer Causes:

1. Non steroidal Anti-inflammatories
2. Helicobacter pylori

Helicobacter pylori

penetrates the mucus and adheres to the epithelial cells and produce urase in the stomach.

Salmonella

- motile with peritrichous flagella
-moves with run and tumble motility
-infects small intestine
-causes gastroenteritis
-Gram negative facultative anaerobe
-survive water at cold temps

Salmonella typhi

-incubation for a month
-rash on abdomen
-Bacteria travel from liver and spleen
-Delirium and convulsions

Mary Mallon

-Typhoid Mary
- Asymptomatic/ chronic carrier- no symptoms

Five F's of food poisoning:

1. fluids
2. food
3. fingers
4. flies
5. fecal material

Reservoir

natural host or habitat of a pathogen (Ex. person infected, animal, part of the environment)

Source

organism or object responsible for transmitting the disease. (Ex. contaminated food)

Reservoir types:

1. Carrier: spread- infection without showing symptoms
2. Biological vector- plays a direct role in pathogen's life (mosquitoes and ticks)
3. mechanical vector- transports the pathogen (house fly)

Toxins

Chemical products produced by an organism, which have a poisonous effect on other organisms . FIRST virulence factor discovered!

Toxinoses

diseases caused my toxins

Toxemias

the toxin is spread by the flow of blood. (EX tetanus and Diphtheria)

Intoxication

caused by ingestion. EX. Botulism

Exotoxins

-disrupt cellular process
-include Botulism, Diphtheria, tetanus
-inactivated by heat

Endotoxins

non protein toxins
gram negative bacteria

Lipopolysaccharid

gram negative bacteria causes massive inflammatory response. Septic shock

Lipoteichoic acid

component of cell wall causes inflammatory response

Pore-forming exotoxin (membrane disrupting)

forms pores in membrane with protiens composed of alpha helices and beta sheets

Phospholipase Exotoxin (membran disrupting)

Also called hemolysins or ctyolysins, can cleave the phosphate from the lipid disrupts the cell membrane. (EX. Gangreen)

A-B toxins

-A (active)- has enzyme activity
-B (binding)- binds to a receptor and moves A into the cell
-A-B subunits separated by proteolysis
-A chain can only get into a certain type of tissue because of B chain

Flora

organism that lives in a particular region. Not involved in pathogenic processes. Colonize particular regions so pathogens can't grow.

Opportunistic infection

normally non pathogenic microbe can cause a disease

nosocomial infections

acquired in the hospital

Skin Flora

-arid, acidic, aerobic
-Staphylococcus epidermidis- forms biofilms on implants and catheters
-Propioribactrium acnes- Anaerobic lives in pore and hair follicles

Nasopharynx Flora

Staphylococcus aureus- 1/3 of people

Oral Flora

Streptococcus mutans- tooth decay; ferments sucrose to lactic acid and creates dextran which allows a biofilm to form.

Urinary Tract Infection Causes:

1. More frequent in women
2. Travel upward along urinary tract
3. E. coli MOST common cause
4. Spermicides

Escherichia coli

-urine washed bacteria away
- Type 1 Pili- allows E. coli to bind to the mucosa of the urethra.

Staphylococcus aureus

-Gram positive Facultative anaerobe
-Golden Cluster Seed
-Infects cuts, glands, and hair follicles
-may require surgery

Staphylococcus aureus infections:

1. toxic shock syndrome
2. Furuncles
3. Meningitis
4. Endocarditis

Staphylokinase Toxin

-Dissolves blood clots
-Assists in colonizing new tissues and migrating out of abscesses

fomite

-object (non living) that can carry a pathogen
-Staphylococcus aureus can live on fomites

MRSA

-Mec A gene- penicillin binding protein with a modified target, resistant to B lactams.
-Frequently resistant to other antibiotics as well

About this deck

By: Lauren Cox
Created: 2011-04-12
Size: 140 flashcards
Views: 23

About StudyBlue

“I have used this website for three exams, and I see a huge difference in my test results.”
Naj