exam 1 Flashcards
Contrast the diversity and population density of microbes compared to other organisms
Lowest: sharks Mammals Reptiles Birds Beetles Bacteria Highest: viruses Then: Lowest: Whooping cranes Humans Ants Bacteria Highest: Viruses Then: Largest: rigbee(dog) Cell phone Bee Flea Hair Human cell Bacteria Virus Atom
Recognize the role that microbes play in the biosphere
Play a vital role in anchoring the food web and bringing stability to the biosphere
Their absence would lead to disaster and collapse of the biosphere
Most species are benign therefore beneficial
Ex: yeast is important to food chain and tree burs help with nitrogen fixation
Can be good or bad
Cause influenza, zeka and norovirus
Important to ecosystem and food
Need microbes to survive
Review the impact that microorganisms have had on human health during the course of history
Black plague, also known as the bubonic plague. It was caused by the bacterium Yersinia Pestis, which killed a great number in Europe due to the occurrence of importing and exporting
Influenza caused many young healthy men to be infected
West Nile River Virus, which attacked the United States.
Zika which is the new buzz virus which came to the United States
Coronavirus and it being easily transmissable and deadly
Describe the function of components that make up the bacterial cell
Prokaryotes can be Gram Positive or Gram negative
Positive: They have a thick layer of peptidoglycan and only one plasma membrane, which help with substances going into and out of cells and has a purple color.
Negative: They have a thin layer of peptidoglycan, they have two plasma membranes. Top membrane which has LPS, which is an endotoxin and has a pinkish red color
Peptidoglycan are made up of NAM and NAG which are cross linking sugars.
Compare and contrast cell structure between bacteria and eukaryotes the bacterial cells based on their morphological features
Eukaroytes: Various organlles compartmentalization Dna in membrane Mitosis Dna with histones More than one chromosome Membrane bound organelles Large ribosome No cell wall Prokaryotes: Lack organization No compartments/organelles No dna in nucleus No mitosis No dna with histones One chromosome No membrane bound organelles Smaller ribosome Cell wall with peptidoglycan SAME: plasma membrane, ribosomes, nucleus, cytoplasm, DNA, chromosome
Diagram and label the cell wall and membrane(s) of both gram positive and gram
negative bacterial cells
gram positive= single cell wall, thick layer of peptidoglycan, teichoic does not touch membrane and leichoinic touches the membrane.
gram negative=double membrane with lps on outer membrane, single layer of peptidoglycan,
Describe how bacterial cells divide
Bacterial cells divide using binary fission (meiosis) – they divide autonomously
DNA replicates
Chromosome separate
Septum forms
Parent cell divides into two progeny (cytokenesis)
Logarithmic growth
Allow for dif cell arrangement via plane of segregation
Diagram and label a bacterial growth curve
- Replicate autonomously
- Lag phase upon initial entry into environement
- Log phase where this is exponential growth until environment becomes limiting
- Stationary phase
- Decline and cell death if conditions become unfavorable
Bacterial classificaiton
cocci=round bacilli=rod Shape and arrangement membrane/cell wall organizaiton G+ or g- Accessories Fimbriae-attach to surfaces Flagella-motility. Can be single, multiple, or peritrichous (all over surface) Capsule-has thick layer of polysaccharide adherence and evade immune system Sex pilus-allow for dna movement from receptor to recipient Growth conditions linked to metabolism Temp, ph, o2, nutrients
List various laboratory methods used to measure the growth of bacterial populations
Bacterial Culture which is plated on sample of media or the liquid broth and that is how they measure the oxygen levels
Aerobes: <3 Oxygen, they need it
Strict Anaerobes: Hate oxygen, can’t live with it
Facultative: Can and Can’t live, but prefer with
Microaerophiles: Only a little Oxygen (5%)
Areotolerant: Don’t care
Different Temperatures
Different pH
Internal Factors
Recall the basic concepts of glycolysis and respiration and how they provide energy for the cell
Glycolysis - the cell takes sugar and converts it into pyruvate - this yields 2ATP
Pyruvate can go two ways
Fermentation - gets rid of it (no oxygen)
Citric Acid Cycle - to make MORE energy
-pyruvate in high levels can be toxic
Classify bacteria based on the role of oxygen in their metabolism
Areboes: <3 Oxygen, they need it
Strict Anaerobes: Hate oxygen, can live with it
Facultative: Can and Can’t live, but prefer with
Microaerophiles: Only a little Oxygen (5%)
Areotolerant: Don’t care
Recognize the range and diversity of food sources available to bacterial populations
look at flashcard before
List various lab methods to characterize bacteria
- aspirated pus, swab, paper point
- clean sample
- smear (gram stain)
- culture (grow to purity in lab)
- agglutination test= pathogen must be in high enough concentration
- rapid identification still require isolation prior to characterization
Apply the concepts of the central dogma of molecular biology to bacterial cells
LIVING ORGANISMS ARE A COLLECTION OF GENES EVOLVING TO ENSURE SURVIVAL
- Replication → transcription → translation
- DNA → RNA → Proteins
- DNA starts replication with DNA synthesis, then continues onto RNA transcription with RNA polymerase, this then continues onto translation of the protein – which includes tRNA and ribosomes to make amino acids.
Contrast the structure of eukaryotic and prokaryotic genetic machinery including DNA structure and enzymes
Eukaryotic: DNA is organized and in the nucleus
-23 pairs of linear double stranded DNA chromosomes
-diploid
-3x10^9 bp
-25,000 proteins
Prokaryotic: The DNA is contained in nucleoid (non organized), circular chromosomes
-single,circular, double stranded DNA chromosome
-haploid
-5 million bp
-2000 proteins
-smaller scale than human cells
Phylogenetic Tree: Archaea, Eukaryotes, Bacteria
Describe the ability of bacteria to respond to their environment by regulating gene
expression
-Operon is how bacteria regulate the expression of their genes
-They have so many genes, but can turn on and off specific genes when they want - epigenetics
Operons
RNA Polymerase - the enzyme that takes DNA to make RNA
Binds to the DNA at binding site (promoter)
Repressor binds to the operator - this blocks transcription of RNA polymerase
CAP Binding site - when CAP binds, this promotes the likelihood of RNA binding
what sugar source does e coli prefer?
prefer glucose but not all environments have this
- must have another energy source (lactose)
- will only use if glucose is not around
operon function
- operon allows e coli to convert lactose to energy by having 3 separate genes
- advatangeous for all 3 genes to be controlled at the same time
operon defintion
region of genes in bacterial chromosome that are controlled through same regulatory network. they contain genes that are involved in the same biological process in bacterial cells
operon component functions
cap site=promotes rna polymerase binding by binding cap
promoter=allows rna polymerase to bind
operator=binds repressor and presents rna polymerase from binding
lac y,z,a=functional bit that are protein machinery needed to use lactose as energy source (ZYA order)
lacy
protein in cell membranes and transports lactose to cells
lac z
enzyme that breaks down lactose into smaller sugars to be used in glycolysis
lac a
enzyme with no known role yet
lac repressor with no lactose
lac repressor binds to operator and prevent rna polymerase from binding
lac repressor with lactose
- allolactose binds to repressor and makes repressor unbind to operator
- rna polymerase binds to promoter and transcribe rna
- rna used to make lac y,z, and a
cap with low glucose
when glucose low, camp is produced. camp attaches to cap and allows it to bind to DNA. cap helps rna polymerase bind to promoter
-high levels of transcription
cap with high glucose
with glucose high, no camp is made, cap cannot bind dna without camp
-transcription at low level
Distinguish between the processes of transformation, transduction, and conjugation
Transformation: gathering genes from the environment, just by being in it. Uptake of naked DNA - active process + requires machinery. Only a small amount of DNA.
Transduction: Mediated by bacteriophage (viruses)
Types of Life Cycles
Lytic phase - bacterial phage goes into the bacterial host cell and lysis the cell. Then releases viral progeny.
Lysogeny phase - alternative life cycle, viral genome becomes a part of the bacterial host’s chromosome.
Prophage is the process of the viral gene going into the host’s chromosome
Generalized - any fragment of bacterial chromosome transferred, just destroys cell, randomized chromosomes are in there
Specialized - becomes a part of the cell and uses cell nutrition to make more of itself
Conjugation: Sex pilus must be present to transfer genes through plasmids (mediated) A lot of DNA can be transfered. Plasmid mediated
Match cell structure and machinery with the corresponding mechanism of genetic transfer
all involve recombination (homologous or non-homologous) involves physical exchange of dna. new genotype
- horizontal transfer
- differences in type of methods of uptake of DNA
- unidirectional
- donor to recipient
- dna fragments
what does not require recombination
plasmids
- extra chromosomal genetic material
- replicon
- can be replicated independently of chromosome - small double stranded, circular DNA
- multiple copies inside a cell - encode toxinsm resistant to antibiotics, heavy metals - conjugative or non-mobile - in all strains of bacteria tested
Describe the impact gene exchange has on the diversity and adaptability of a bacterial population and how this relates to pathogenicity
Mutations can occur due to the survival of the fittest. Adaptability occurs in relation to the environment that the bacteria cells are surrounded in. Mutations can be neutral, advantageous or results in an inferior phenotype.
Describe key features that allow bacteria to be pathogenic and cause disease
They are sticky, can invade, transmit, and toxic.
Differentiate between opportunistic and exogenous bacterial pathogens
When normal flora is exposed to pathogens, it becomes an opportunistic pathogen.
-exogenous bacterial pathogen comes from outside source and can cause disease in healthy ppl with normal immune diseases
Illustrate the routes of infection (the 3I’s)
- Ingestion (eat it) by ingesting contaminated food or water. by not following proper protocol like hand washing, wearing gloves, or flushing lines.
- inhalation (breathing it in) by breathing in infected particles from someones cough
- inoculation (needle, mosquito) by fomite and touch infected surace and then touch face. accidental self injury with contaminated needle or sharps
Recall the principles of diagnosis of infection and identification of pathogens
Exotoxin, endotoxin, mobility, characteristics, antibiotic resistance, ability to survive and mutate in different environments.
List Koch’s Postulates
- bacteria must be present in every case of disease
- bacteria must be isolated from host with the disease and grown in pure culture
- specific disease must be reproduced when a pure culture of bacteria is inoculated into a healthy susceptible host
- bacteria must be recovered from experimentally infected host
Explain the mechanism by which betalactam antibiotics work
Betalactam: Competitively binds transpeptidase that generates cross-links in the cell wall.
Failure in cell wall causes cell death, usually by osmotic shock.
Aerobic Gram positives and some anaerobic gram negatives
Classify antibiotics into distinct groups based on their mechanism of action
Binds transpeptidase that generates cross-links in the cell wall (B-lactams)
Pen V and Pen G
Most narrow
Amoxicillin and Ampicillin
Broader range than Pen V and G
Isoxazolyl Penicillins
Broader than Amoxicillin and Ampicillin
Clavulanic Acid
No inherent antimicrobial activity
B-lactam core that does not bind transpeptidases.
Cephalosporins
Large class of B-lactam derivatives.
Carbapenems
Late generation of B-lactams
Considered drug of last resort
Interfere with folic acid biosynthesis
Sulphonamides
Inhibit DNA gyrase or topoisomerase IV (replication)
Quinolones
Inhibits protein synthesis
Tetracyclines and Clycyclcylines
Doxycycline
Tigecycline
Lincosamides: binds to specific subunit of ribosome where it inhibits aminoacyl translocation (stop synthesis of proteins)
Clindamycin
Macrolides: binds to specific subunit of ribosome where it inhibits aminoacyl translocation (stop synthesis of proteins)
Erythromycin
Azithromycin
Inhibits cell wall synthesis (sugar and protein)
Vancomycin
Drug of last resort
Prodrug (inactive precursors)
Metronidazoles: Converted by anaerobes into a toxin compound that binds DNA
For anearobic bacteria and is not active
Theu have enzyme that activates
Describe how microorganisms can gain antibiotic resistance
Natural resistance
Bacterium is inherently resistant
Mutation
Gene for target enzyme, transport pathway or prodrug activator
altered by random mutation
Acquired resistance( problem speeds up )
Horizontal gene transfer
Generally within species
Can be between species
Digest it
Produce an enzyme capable of digesting the drug
ex. Penicillinase (b-lactamase) seen in Staphs ( break down beta lactam)
Alter it’s target
Modification of target enzyme (
Supposed to shut down
MRSA has modified transpeptidase that does not bind b-lactam antibiotics (not effective )
Avoid it
Reduce uptake into the cell
Chloramphenicol
Secrete it
Tetracycline is transported out of the cell by an efflux
pump
Predict how the increased prevalence of antibiotic resistance can impact public health and treatment of bacterial infections
Can impact public health by bacterium not being sensitive to any antibiotics therefore humans becoming more ill because there will be no antibiotics to kill bacteria.
