Exam 1 Flashcards
Microbes Timeline: 3.5 billion yr ago
Prokaryotes
Microbes timeline: 2.5 billion yrs ago
Eukaryotes
Microbes timeline: 1 billion years ago
Multi-celled organisms
Microbes timeline: 500 mil years ago
Development of brains
Microbes timeline: 475 yrs ago
Life moves to land
Microbes timeline: 230 yrs ago
Mammals
Microbes timeline: if you imagine Earth began as a single day
5 am: microbes
10pm: dinos
seconds before 12am: humans
Tree of life: 3 domains
Archaea, bacteria, eukaryota
Tree of life: Archaea
bacteria with internal membranes, found in extreme environments (out bodies too!)
Tree of life: bacteria
Single celled organisms, more forms of bacteria than any other organism on Earth
Tree of life: Eukaryota categories
Protista
Plantae
Fungi
Animalia
Tree of life: Eukaryota: Protista
mostly single-celled organisms that have a nucleus, usually live in water
Made up of: protozoa, unicellular algae, and slime molds
Protista examples
Algae, paramecium, amoeba
Protista are made up of
protozoa, unicellular algae, slime molds
Tree of life: Eukaryota: Plantae
Plants contain chlorophyll for photosynthesis and have cellulose for cell walls
Fixed in one place
Tree of life: Eukaryota: Fungi
Motionless organisms that absorb nutrients for survival
Ex. mushrooms, molds, and yeasts (the only that are not multicellular)
Tree of life: Eukaryota: animalia
Most complex organisms on earth
Divided into vertebrates and invertebrates
Include mammals, amphibians, reptiles, birds, and fish
Pathogen: 6 categories
Bacteria Viruses Fungi Protozoa ("first animal") Parasites Prion proteins
Increasing complexity: viruses 0.03-0.3µm, bacteria 0.1-10µm, fungi (4-10µm), parasites
Pathogens: Viruses
Non-cellular, size 20-300nm
no cytoplasm or organelles, no chromosomes (only RNA/DNA)
Covered in protein coat
depend on cells for metabolism/reproduction
Pathogens: Viruses: structure
Core of RNA/DNA enclosed in a capsid
Capsid surrounded by envelope
Surface proteins (spikes) on the outside
Viral shedding
Expulsions and release of virus progeny following successful reproduction during a host-cell infection
Bacteriophage viruses
Virus head “capsid” has high pressure and it pushes DNA into the cell
Bacteriophage can be dormant or lyse (burst) and kill host cell
Pathogen: Bacteria
Single celled microbes
No nucleus or membrane bound organelles
Genetic info is in a single loop of DNA
Extra genes in an extra loop of genetic material called plasmid (usually advantages like abx resistance )
Pathogens: Fungi
Usually saprophytes (consume dead organisms)
Fungal spore size 1-40µm in length
Ex. Candida albicans - alkalinizes local extracellular environment (picture of tongue)
Example of fungi pathogen
Candida albicans
Pathogen: Virus size
20-300nm
Pathogen: Fungi spore size
1-40µm
Pathogen: Prion proteins
Mad-cow disease starts when PrP in nervous system abnormally fold and cause normal PrPs to abnormally fold too, brain cells become clogged with abnormal PrPs
Usually due to mutation but can be passed along when animal/human eats infected nervous system tissue
Cannot be destroyed by cooking
Pathogens: Diseases caused by prions
Mad cow
Scrapie
Kuru
Creutzfeldt-Jakob disease
Pathogen: Prion: Creutzfeldt-Jakob disease
Caused by prion build up, brain slowly shrinks, tissue filled with holes looks like a sponge
Lose ability to think and move, memory loss
Always fatal, usually within a year of onset of illness
4 developments that have taken us from 2 generation society to a four
Vaccination
Hygienic medical practice
Chlorination
Antibiotics
Vaccines have been made for only ___ of the 400+ known pathogens that are harmful to man
34
What is chlorination?
Water chlorination is the process of adding Cl2 or hypochlorite to water
It kills bacteria and other microbes in tap water
Prevents spread of waterborne diseases such as cholera, dysentery, typhoid
What are some waterborne diseases chlorination helps prevent?
Cholera, dysentery, typhoid
What were Sir Alexander Fleming’s best known discoveries
enzyme lysozyme in 1923 and penicillin from the mold Penicillium notatum in 1923
Who were the 2 people Alexander Fleming shared the Nobel Prize in Physiology or Medicine in 1945 with?
Howard Florey and Ernst Boris Chain
What mold is penicillin made from?
Penicillium notatum
What are Koch’s postulates?
- microorganisms must be found in abundance in all organisms suffering from the disease and none from healthy organisms
- Microorganisms must be isolated from a diseased organism and grown in pure culture
- Cultured microorganism should cause disease when introduced to a healthy organism
- Microorganism must be reisolated from inoculated diseased experimental host and identified as identical to the original specific causative agent
Endemic def
constant presence (regularly found among particular people or in a certain area)
Epidemic def
localized outbreak
Pandemic def
Widespread regional or global epidemic
What are the 5 characteristics of epidemics?
Infectivity Disease index Virulence Incidence Prevalence
Epidemics: Infectivity: def
The frequency with which an infection is transmitted when there is contact between the agent and a susceptible individual
Epidemics: Disease index: Def
The number of persons who develop the disease divided by total number infected (disease vs infected)
Epidemics: Virulence: Def
The number of fatal or severe cases per total number of cases
Epidemics: Incidence: Def
The number of new cases of a disease within a specified period, is described as a rate in which the number of cases is the numerator and the number of people in the population under surveillance is the denominator # cases / # of ppl in pop. under surveillance
Epidemics: Prevalence: Def
It can also be described as a rate to indicate the total number of case existing in the population at a risk at a point in time
What increases complexity?
Genes + proteins (+ microbes)
Our relationship with out microbes is not just one of ___ but ____
Not just one of TOLERANCE but ENCOURAGEMENT
You are 0.5% human: ___ human cells make the human body (___genes)
10 trillion human cells, 21,000 genes
You are 0.5% human: ___ plus or minus microbes on one person alone (____ genes)
100 trillion microbes, 4.4 million genes
You are 0.5% human: around ___ species of microbes are found in the intestines
1200
More than ____ species of microbes live in the stomach, where they graze on the slime lining its walls
100
Younger children who lose ___ from their stomach by taking antibiotics are molikely to develop asthma and allergies
Helicobacter pylori
Over your lifetime, you will play hose to bugs the equivalent weight of _____ african elephants
5
Most of the microbes living inside us die when they are exposed to ___ because ____
oxygen because they are adapted to an oxygen-free existence deep in our guts
Microbes on the subway: 1.6% is associated with the ___
eye
Microbes on the subway: almost ___ associated with BREATHING
10%
Microbes on the subway: ___ associated with MOUTH bacteria
6.5%
Microbes on the subway: ____ associated with GI tract
32.3%
Microbes on subway: ___ associated with SKIN bacterial
29%
Microbes on subway: ___ associated with urogenital tract
20%
Microbes on the subway: ____ of the genetic data found on the subway did not match to any known organism, showing how vast and unexplored the microbiome is
48%
Benefits of the normal flora: Many of these microbes do not hurt us but are essential for keeping us healthy and happy. Some functions are ___
produce vitamins we cannot make
Breakdown food for us
Strengthen immune system
Fight off disease-causing organisms
Microbiome at birth: For ___ years baby microbiomes grow while their immune systems develop, learning not to attack friendly bacteria
2-3 years
What is the name of the mummy that researchers found remains of his gut bacteria?
Oetzi the Iceman
Caecum is considered the _____ of the human body’s microbial community
Heart
The ___ is connected to the cecum
Appendix
___ is an intraperitoneal pouch that is considered to be the beginning of the large intestine
Cecum
Cecum is the epicenter of microbial life where trillions of microbes of at least ___ species make the most of the partially digested food that has passed through nutrient-extraction processes into the small intestine
4000 species
___ are left over for the microbes in the cecum to tack in round 2 digestion
Tough bits - plant fibers
The appendix helps protect out ____
beneficial gut bacteria when a serious infection strikes
Appendix is packed full of _____
specialized immune cells and molecules
The gut can be repopulated with its normal inhabitants, which have been lurking in the ___
Appendix (a safe house that human body has provided for its microbial inhabitants)
The appendix is a blind-ended tube connected to the caecum, from which it develops ____
embryologically
The appendix protects us from:
Recurrent GI infections Immune dysfunction blood cancer some autoimmune diseases Heart attacks
Biofilm def
Aggregates the bacteria embedded in a matrix produced by them interspersed by water channels
Example of biofilm
Dental plaque
What is quorum sensing
Microbes communicating with each other by chemical language via signals called auto inducers
Quorum sensing coordinates gene expression
Some studies suggested that C-section babies may have an elevated risk for developing immune and metabolic disorders like ____
T1DM, allergies, asthma, and obesity
What is vaginal microbial transfer?
When they introduce microbes from vaginal fluids (collected before surgery) to the baby after a C-section for 1-2 minutes
A mother’s vaginal fluids are loaded with one such essential bacterium ___ that helps digest human milk
lactobacillus
____ is considered to be a “newly discovered organ” since its existence was not generally recognized until the late 1990s and it is understood to potentially have overwhelming impact on human health
microbiome
Catabolic pathways: 2 types
Anaerobic respiration and aerobic respiration
What is anaerobic respiration (fermentation)?
Partial breakdown of organics that occurs w/o O2
Yields 2 ATP
What is aerobic respiration?
Complete breakdown of organics with O2
Yields 36 or 38 ATP
_____ yields only 2 ATP while ___ yields 36 or 38 ATP
Anaerobic yields 2 ATP
Aerobic yields 36 or 38 ATP
Compare fermentation and aerobic respiration
Both use glycolysis (glu to pyruvate)
Have different e-acceptors (pyruvate/acetaldehye vs O2)
Aerobic respiration produces 36 or 38 ATP/glucose but fermentation produces 2 ATP/glucose
Obligate aerobes def
Require an ample oxygen source to perform respiration
Microaerophilic/microaerobic
Requires small amounts of oxygen
Capnophilic def
Microbes that require low oxygen but high CO2 conc
Facultative anaerobes def
Organisms that perform anaerobic glycolysis in the absence of oxygen but can perform aerobic respiration in the presence of oxygen
Obligate anerobes def
Die in presence of oxygen because they lack chemistry to produce organic compounds via reduction of oxygen
Bacteria use 3 main mechanisms to adapt to changing environments
- gene transfer
- Regulation of gene expression
- mutation
Bacteria adaptation: Gene transfer consists of these 3 things
- transformation
- transduction
- conjugation
Gene transfer: Transformation def
The recipient cell directly takes up naked DNA released from the donor cell altering its genotype (it can occur in the medium and natural transformation can also occur)
Gene transfer: Transduction
Process by which DNA is transferred from one bacterium to another by a virus
Gene transfer: Conjugation
Cell to cell contact and transfers genetic material (male/female cells)
Plasmids are most frequently transferred by conjugation
Sex pilus is responsible for the attachment of donor and recipient cell (male has sex pilus)
Gene transfer: conjugation: Which cell has the sex pilus?
Male cell
What are operons?
A group of genes that are transcribed at the same time
Usually control an important biochemical process
Only found in PROKARYOTES
includes a series of structural genes along a segment of DNA and two other portions of DNA (promoter and operator)
Operons are only found in ___
Prokaryotes
In prokaryotes, genes are turned on and off using ___
operons
Operons: what happens when the operator area is ON
RNA polymerase attaches at the promoter and transcription occurs
Operons: What happens when operator is “off”?
Operator area is blocked by repressor protein and transcription cannot occur
What is the lac operon?
Operon processing the sugar lactose
One of the mis the gene for the en
Enzyme beta-galactosidase (lactase)
Lactase breaks down lactose into glucose and galactose
What happens when the lac operon is on?
Lactose inhibits the repressor, allowing RNA polymerase to bind with the promotor and synthesize lactase
Lactase will digest all of the lactose until there is none to bind to the repressor and then the repressor will bind to the operator
Explain process of gram staining
Crystal violet is applied to the specimen, then iodine (kills cell and fixes the stain)
Slide washed with alcohol
Gram positive - retains crystal violet iodine stain (purple)
Gam negative - safranin dye (pink)
Structural differences between gram-neg and gram-pos bacteria
Gram-pos: peptidogylcan and membrane
Gram-neg: outer membrane, peptidoglycan (much thinner than the gram-positive one), membrane
4 Phases off population bacterial growth in closed culture
Lag phase Log phase (optimal growth) Stationary phase (bacterial pop levels out and population growth nears 0 again, fermentation/pharmaceuticals use chemostat to keep bacteria in stationary phase) Death phase (waste and dead cells begin to accumulate, population declines, spore formers can persist beyond this stage and can regenerate a population if conditions become favorable again)
The chemostat is used in fermentation and pharmaceutical industries to keep bacterial growth in the ___ phase
stationery
Infection vs infectious disease
Infection is the INVASION, MULTIPLICATION of disease causing agents and the REACTION of host tissues to these organisms and toxins they produce
Infectious disease (aka transmissible disease or communicable disease) is illness resulting from an infection
Bacteria that causes dental caries
Streptococcus mutans
T/F: Streptococcus mutans is an example of obligate anaerobes
FALSE - it is a facultative anaerobe
T/F: Streptococcus mutans is gram-NEGATIVE
FALSE - it is gram-positive coccus
Dental caries (tooth decay) is caused by specific types of bacteria that produce acid in the presence of fermentable carbohydrates such as ____
sucrose, fructose, and glucose
Complications of dental caries
S. Mutans colonize in the heart, often in heart valves and cause inflammation (endocarditis) and can be lethal
Endocarditis is most often caused by invasion of S. mutans
Endocarditis can be caused by which two bacteria
Staphylococcus aureus and streptococcus mutans