Micro ch 13,14,8,9 exam review

difrentiate among the terms colonization,infection,disease

• To colonization refers to the process of establishing control over a foreign territory,

• infection is the invasion and multiplication of pathogens in a host,

• disease is the disruption of normal bodily functions due to infection or other factors.

identify the sites where normal biota is found in humans

Normal biota is typically found in various sites in humans, including the skin, mouth, gastrointestinal tract, and respiratory tract. These sites harbor a diverse community of microorganisms that play important roles in health.

discuss how the human microbiome project has changed our understanding of normal biota

The Human Microbiome Project has revealed the vast diversity and complexity of microorganisms residing in and on the human body, highlighting their essential roles in health and disease, and changing perceptions of the relationship between humans and their microbiota.

explain some of the variables that influence whether a microbe will cause disease in a particular host

Factors include host immune response, microbial virulence, genetic predisposition, and environmental conditions.

differentiate between a microbes pathogenicity and its virulence

Pathogenicity refers to a microbe's ability to cause disease, while virulence measures the degree of damage a microbe can inflict on the host.

list the steps a microbe has to take to get to the point where it can cause disease

The steps include entering the host, colonizing, evading the immune system, and damaging host tissues.

list several portals of entry and exit

ways through which microbes enter or leave a host body, such as skin, respiratory tract, gastrointestinal tract, and urogenital tract.

define infectious dose,and explain its role in establishing infection

refers to the minimum number of microorganisms required to establish an infection in a host. It plays a crucial role in determining the likelihood of disease occurrence, as a higher infectious dose may increase the chances of infection.

describe three ways microbes cause tissue damage

Microbes can cause tissue damage through direct cell lysis, releasing exotoxins that disrupt cellular functions, or causing an inflammatory response that harms surrounding tissues.

compare and contrast major characteristics of exotoxins and endotoxins

Exotoxins are toxic proteins secreted by bacteria and can cause damage to host cells, while

Endotoxins are components of the bacterial cell wall released upon cell lysis and typically induce a stronger immune response.

Exotoxins are generally more potent and specific in their action,

Endotoxins have a broader impact related to inflammation and fever.

explain what an epigenetic change is and how it can influence virulence

refers to a modification in gene expression without altering the DNA sequence, often influenced by environmental factors. These changes can impact virulence by regulating the expression of genes involved in pathogenicity, allowing microbes to adapt to different hosts or conditions.

draw and label a curve representing the course of clinical infection

A graphical representation illustrating the stages of infection, including incubation, prodromal, illness, decline, and convalescence phases.

differentiate among the varoius types of reservoirs, providing examples of each

Reservoirs are environments or organisms that foster the survival and replication of pathogens. Examples include human hosts, animals (zoonotic reservoirs), and environmental sources such as soil or water.

list six different modes of horizontal transmission, providing an infectious disease spread by each

Horizontal transmission modes include

1. direct contact (e.g., HIV),

2. indirect contact (e.g., influenza),

3. droplet transmission (e.g., COVID-19),

4. vector-borne transmission (e.g., malaria),

5. airborne transmission (e.g., tuberculosis),

6. common vehicle transmission (e.g., salmonellosis).

list koch’s postulates , and explain alternative methods for identifying an etiologic agent

Koch's postulates are a set of principles used to establish a causal relationship between a microbe and a disease. They include: the microorganism must be found in abundance in all organisms suffering from the disease, it must be isolated from the host and grown in pure culture, it should cause disease when introduced to a healthy organism, and it must be re-isolated from the experimentally infected host. Alternative methods include molecular techniques and genetic sequencing.

identify the primary difference between the practice of medicine and epidemiology

medicine focuses on individual patient care and treatment, epidemiology studies health patterns, causes, and effects within populations.

describe the connection between public health nd epidemiology

Public health focuses on protecting and improving the health of populations,

epidemiology studies the distribution and determinants of health-related states to inform public health actions.

discuss the roles of two early epidemiologists of the modern era, florence nightingale and john snow

Florence Nightingale was a pioneer in nursing and public health, known for her work in applying statistics to healthcare improvements during the Crimean War,

John Snow is regarded as the father of modern epidemiology for his investigations of cholera outbreaks in London, particularly his identification of contaminated water as the source of the disease.

differentiate between incidence and prevalence

Incidence refers to the number of new cases of a disease in a specific time period,

prevalence indicates the total number of existing cases at a particular time.

define point-source, common-source, and propagated epidemics, providing an indication of time frame for all three

• Point-source epidemics occur when a group of people are exposed to a common source of infection over a short period, typically in one location.

• Common-source epidemics result from exposure to a single source over an extended time,

• Propagated epidemics stem from person-to-person transmission, gradually spreading over time.

provide examples of practical applicatiosn of modern genetic technologies

Modern genetic technologies can be applied in areas such as gene therapy: for treating genetic disorders, CRISPR: for gene editing, and Next-Generation Sequencing: for personalized medicine.

explain the role of restriction endonucleases in the process of recombinant DNA technologies

Restriction endonucleases, also known as restriction enzymes, cut DNA at specific sequences, allowing for the manipulation and insertion of genes in recombinant DNA technologies. This facilitates the cloning and analysis of specific DNA segments.

list the steps in the in the polymerase chain reaction and discuss one disadvantage to this technique

The polymerase chain reaction (PCR) involves the steps of denaturation, annealing, and extension to amplify DNA. One disadvantage of this technique is its susceptibility to contamination, which can lead to false results.

describe how recombinant DNA is created, and discuss its role in gene cloning

Recombinant DNA is created by combining DNA from different sources using techniques such as restriction enzyme digestion and ligation. It plays a crucial role in gene cloning by allowing for the insertion of specific genes into vectors for propagation and study.

describe how gel electrophoresis is used to analyze DNA

Gel electrophoresis is a technique that separates DNA fragments based on their size by applying an electric field to a gel matrix. DNA molecules move through the gel, allowing for the visualization and analysis of genetic material.

outline the general steps in DNA profiling

involves collecting biological samples, extracting DNA, amplifying specific regions using PCR, and analyzing the DNA through techniques such as gel electrophoresis or capillary electrophoresis to compare genetic markers.

outline in general terms the process of DNA sequencing.

DNA sequencing involves determining the exact order of nucleotides in a DNA molecule, typically through methods like Sanger sequencing or next-generation sequencing. This process includes sample preparation, amplification, sequencing reaction, and data analysis to interpret the resulting sequence.

discuss the significance of single nucleotide polymorphisms in DNA analysis

Single nucleotide polymorphisms (SNPs) are variations at a single base pair in DNA that can influence traits, diseases, and responses to drugs. Their significance lies in their ability to serve as genetic markers for association studies and in personalized medicine.

describe the uses of microarray technology

is used to analyze gene expression patterns, study genetic variation, and diagnose diseases. It allows for the simultaneous screening of thousands of genes or genetic markers.

compose your own definition of personalized medicine

is a medical model that tailors treatment and healthcare strategies to individual characteristics, especially genetic makeup. It aims to optimize the efficacy of therapies and minimize adverse effects.

provide several example of recombinant products that have contributed to human health

Recombinant products such as insulin, monoclonal antibodies, and growth hormones that are produced using recombinant DNA technology to treat various medical conditions.

list examples of recombinant bacteria and plants, and a purpose for each

Recombinant bacteria such as Escherichia coli are used to produce insulin, while genetically modified plants like Bt corn are engineered for pest resistance.

differentiate between somatic and germline gene therapy

Somatic gene therapy targets non-reproductive cells to treat diseases, while germline gene therapy involves altering genes in reproductive cells, affecting future generations.

describe miRNA and ways in which their discovery can impact human diseases

MicroRNAs (miRNAs) are small non-coding RNA molecules that regulate gene expression by binding to complementary sequences on target mRNAs, leading to their degradation or translational repression. Their discovery offers insights into various diseases, including cancer and genetic disorders, by providing potential therapeutic targets and biomarkers.

explain how the CRiSPR-Cas9 system can be used to cure genetic diseases

The CRISPR-Cas9 system is a revolutionary genome-editing technology that allows scientists to precisely alter DNA sequences and modify gene function. By utilizing a guide RNA to target specific DNA sites, it can effectively cut the DNA, enabling the addition, deletion, or replacement of genetic material, which holds great promise for curing genetic diseases.

explain why nucleic acid amplification techniques are useful for infectious disease diagnosis

Nucleic acid amplification techniques allow for the rapid detection and quantification of pathogens by amplifying specific DNA or RNA sequences, enabling diagnosis even at low levels of infection.

Name two examples of techniques that employ hybridization

to detect specific nucleic acid sequences, such as southern blotting and in situ hybridization

Explain how whole-genome sequencing can be used for diagnosis

Whole-genome sequencing enables the identification of genetic variants linked to diseases, facilitating accurate diagnosis and personalized treatment.

describe the benefits of “lab on a chip” technologies for global public health

'Lab on a chip' technologies offer rapid diagnostics, reduced costs, and improved accessibility to healthcare, enhancing disease prevention and management.

identify an advantage presented by mass spectrometry and also by imaging techniques as diagnostic tools

Both techniques provide rapid and accurate analysis of molecular composition and structure

list the essential nutrients of a bacterial cell

essential nutrients needed for growth and reproduction, including carbon,nitrogen, phosphorus, sulfur, and trace elements

differentiate between macronutrients and micronutrients

Macronutrients are needed in large amounts for energy and growth (carbohydrates, proteins, and fats), while micronutrients are required in smaller quantities for essential processes (vitamins and minerals).

list and define four different terms that describe an organism’s sources of carbon and energy

• Autotrophs: Organisms that produce their own food from inorganic sources.

• Heterotrophs: Organisms that consume organic matter for carbon and energy.

• Phototrophs: Organisms that derive energy from light.

• Chemotrophs: Organisms that obtain energy from chemical compounds.

define saprobe and parasite, and explain why these terms can be an oversimplification

Saprobe: An organism that feeds on dead organic material.

Parasite: An organism that lives on or in a host and benefits at the host's expense.

compare and contrast the process of diffusion and osmosis

Diffusion: Movement of molecules from high to low concentration.

Osmosis: Movement of water through a membrane from low to high solute concentration.

identify the effects of isotonic ,hypotonic , and hypertonic conditions on a cell

• Isotonic: Cell retains shape; equal concentration of solutes inside and outside.

• Hypotonic: Cell swells; lower solute concentration outside causes water to enter.

• Hypertonic: Cell shrinks; higher solute concentration outside causes water to exit.

name two types of passive transport and three types of active transport

Two types of passive transport are diffusion and osmosis, while three types of active transport include endocytosis, exocytosis, and sodium-potassium pump.

list and define five terms used to express that temperature-relayed growth capabilities of microbes

• Psychrophiles: Microbes that thrive at low temperatures (below 15°C).

• Psychrotrophs: Microbes that can grow at low temperatures but prefer moderate temperatures (20-30°C).

• Mesophiles: Microbes that grow best at moderate temperatures (20-45°C).

• Thermophiles: Microbes that thrive at high temperatures (45-80°C).

• Hyperthermophiles: Microbes that grow optimally at very high temperatures (above 80°C).

Summarize three ways in which microorganisms function in the presence of oxygen

Microorganisms function in the presence of oxygen through:

1. aerobic respiration (using oxygen to produce energy)

2. fermentation (anaerobic process to generate energy without oxygen)

3. obligate anaerobiosis (growing only in the absence of oxygen)

identify three other physical factors that microbes must contend with in the environment

Microbes must contend with temperature, pH, and osmotic pressure in their environment.

list and describe the five major types of microbial association

The five major types of microbial associations include:

1. mutualism (both benefit)

2. commensalism (one benefits, the other unaffected)

3. parasitism (one benefits at the expense of another)

4. symbiosis (close interaction)

5. biofilms (communities of microorganisms).

discuss characteristics of biofilms that differentiate them from free-living bacteria and their infections

Biofilms are structured communities of microorganisms attached to surfaces, differing from free-living bacteria, and often involved in infections.

Summarize the steps of binary fission, and name another method of reproduction used by other bacterial infections

1. Parent cells enlarges

2. Chromosomes are duplicated

3. Cell envelope pulls together in the center of the cell to form a spetum

4. Cell divides into two daughter cells

Term: Other Method of Reproduction

Definition: Bacteria can also reproduce through processes such as conjugation, transformation, or transduction.

define doubling time , and describe how it leads to exponential growth

The time required for a complete fission cycle from parent cell to two new daughter cells. The cells reach the maximum rate of cell division during exponential growth

compare and contrast the four phases of growth in a bacterial growth curve

1. Lag Phase: newly inoculated cells require a period of adjustment, enlargment, and synthesis

2. Exponential Growth Phase (log phase): The growth curve increases dramtically as long as cells have adequate nutrients and the environment is favorable

3. Stationary Growth Phase: cell enters survival mode and stop growing or grow slowly

4. Death Phase: limiting factors intensify and cells begin to die at an exponential rate

identify one culture-based and one non-culture-based method used for analyzing bacterial growth

• -Culture-based - Length of Generation Time: measure of growth rate; environmental bacteria measured in months.

• -Non-culture based - Turbidity: (fast way to count cells through measurement) nutrient solid becomes turbid, or cloudy, as microbes grow; the greater the turbidity, the larger the population -- turbidimeter.

What are the four steps needed to do a differential stain procedure

Primary Stain: Apply the first stain to color all cells or structures.

Mordant: Add a mordant to fix the primary stain, enhancing its binding to the target.

Decolorization: Use a decolorizing agent to remove the primary stain from certain cells or structures, leaving others stained.

Counterstain: Apply a contrasting stain to color the decolorized cells or structures, enabling differentiation.

Steps for the gram stain

Primary Stain: Crystal violet stains all cells purple.

Mordant: Gram's iodine forms a complex with crystal violet, fixing it in Gram-positive cells.

Decolorization: Alcohol or acetone removes the stain from Gram-negative cells.

Counterstain: Safranin stains Gram-negative cells pink, while Gram-positive cells remain purple

Steps for Endospore Stain

Primary Stain: Malachite green stains endospores.

Heat Application: Heat is used to drive the stain into the endospores.

Decolorization: Water removes the stain from vegetative cells but not endospores.

Counterstain: Safranin stains vegetative cells pink, while endospores remain green

What is a selective and a differential media?

Selective Media:

Purpose: It inhibits the growth of certain types of microorganisms while allowing others to grow.

Example: MacConkey Agar selectively supports the growth of Gram-negative bacteria while inhibiting Gram-positive bacteria due to bile salts and crystal violet.

Differential Media:

Purpose: It differentiates between microorganisms based on specific biochemical characteristics, using indicators to show distinct visual changes.

Example: Blood Agar differentiates bacteria based on their hemolytic activity, with patterns like alpha, beta, or gamma hemolysis.

What are the 5 steps of pathogenesis

Portal of entry into the host: The pathogen enters the host through a specific portal of entry, such as the respiratory tract, gastrointestinal tract, or skin (e.g., through wounds).

Attachment or adherence: The pathogen adheres to host tissues using specialized structures like pili, fimbriae, or adhesins, which allow it to establish a foothold.

Survival against host defenses: To continue multiplying, the pathogen must evade or overcome the host's immune defenses. Mechanisms include producing capsules to avoid phagocytosis or secreting enzymes to neutralize immune responses.

Damage to host tissues: The pathogen directly harms the host by producing toxins, enzymes, or inducing harmful immune responses (e.g., inflammation or autoimmune reactions).

Portal of exit from the host: The pathogen leaves the host through a portal of exit (e.g., respiratory secretions, feces, blood), enabling transmission to other potential hosts.

What are at minimum of four ways a resident microbe could switch from non- pathogenic to pathogenic.

Immune System Suppression: If the host's immune system is weakened (e.g., due to illness, medication, or stress), resident microbes may exploit the opportunity to grow unchecked and cause infections.

Introduction to a New Site: When microbes are introduced to a part of the body where they are not normally found (e.g., E. coli from the gut entering the urinary tract), they can cause disease.

Acquisition of Virulence Factors: Horizontal gene transfer (e.g., via plasmids or bacteriophages) can provide microbes with new genes that encode toxins, enzymes, or other factors that enhance their pathogenicity.

Changes in the Microbial Environment: Alterations in the host's microbiome (e.g., due to antibiotic use) can disrupt the balance of microbial populations, allowing certain microbes to overgrow and become pathogenic.

How does pathogenicity differ from virulence?

Pathogenicity refers to the ability of a microorganism to cause disease. It's a broad term describing whether an organism can infect a host and cause harm.

Virulence: degree or severity of harm caused by a microorganism. It's a measure of the microorganism's "strength" or "intensity" in causing disease, often determined by its virulence factors like toxins, enzymes, and adhesion mechanisms.

• How would changing the portal of entry affect the pathogenicity of a microorganism?

Changing the Portal of Entry: The portal of entry is crucial to a microorganism's pathogenicity because it determines whether the microbe can access suitable tissues or environments to thrive.

• Are all pathogens always pathogenic? Explain why!

No, not all pathogens are always pathogenic. While pathogens are defined as microorganisms that have the ability to cause disease, several factors can determine whether they actually do so:

1. Host Immune System Strength: A healthy immune system can often suppress or eliminate pathogens before they can establish an infection. For example, Staphylococcus aureus might colonize the skin without causing harm, but in an immunocompromised host, it can lead to severe infections.

What are the stages of infection and when can a human be a carrier and transmit the causative agent?

What are the different types of epidemics (a.e. 3 kinds of common source, propagated)

1. Incubation Period:

   • The time between exposure to the pathogen and the onset of symptoms.

   • The pathogen multiplies silently, and the host shows no signs of illness.

   • Humans can sometimes be carriers during this stage, transmitting the pathogen unknowingly (e.g., asymptomatic carriers of Typhoid fever).

2. Prodromal Stage:

   • Early, mild symptoms appear (e.g., fatigue, low fever).

   • The pathogen is actively multiplying, and individuals may transmit the causative agent, albeit less effectively than in later stages.

3. Acute Stage:

   • The peak of infection, where symptoms are most severe, and the pathogen is at its highest concentration.

   • Transmission risk is highest during this stage, as pathogens are expelled actively (e.g., coughing, sneezing).

4. Convalescent Stage:

   • Symptoms begin to subside, and the immune system works to eliminate the pathogen.

   • Transmission may still occur, especially if the pathogen persists in the body (e.g., carriers of Staphylococcus aureus during wound healing).

5. Resolution or Chronic Carrier State:

   • The host either fully recovers or becomes a chronic carrier.

   • Chronic carriers harbor the pathogen long-term and may intermittently transmit it (e.g., Hepatitis B carriers).

What are the steps of recombinant DNA technology (cloning)

1. Isolation of DNA

2. Cutting DNA with Restriction Enzymes

3. Insertion into a Vector

4. Ligation

5. Transformation

6. Selection and Screening

7. Expression or Replication

How does recombinant DNA technology make protein products for pharmaceutical uses?

Recombinant DNA (rDNA) technology allows scientists to genetically engineer organisms to produce therapeutic proteins used in medicine. This process involves inserting a gene of interest into a host organism (like bacteria, yeast, or mammalian cells), which then acts as a "factory" to produce the desired protein.

• Can you think of any examples of when a genetically engineered drug (for example human growth hormone or insulin) might not work for a patient?

Examples:

Insulin: If left in extreme heat or frozen, it can aggregate or degrade, losing potency.

Monoclonal Antibodies (e.g., Adalimumab): If shaken too much, proteins can unfold and become ineffective.

What are hybridization technique examples and what does hybridization mean?

Hybridization in the context of molecular biology refers to the process of forming a double-stranded nucleic acid (DNA or RNA) molecule by pairing complementary base sequences.

exs:

• Southern Blotting

• Northern Blotting

• Fluorescence In Situ Hybridization (FISH)

• Microarray Technology

• Colony or Plaque Hybridization

Why can hybridization be used in both genomic and transcriptomic studies, but not in proteomic studies?

• Which type of study (genomic, proteomic, transcriptomic) will give you the most accurate picture of gene expression and phenotype?

because Proteomic Studies: Proteomics focuses on proteins, not nucleic acids. Since hybridization relies on the specific pairing of nucleic acids, it cannot directly study proteins. Instead, proteomics uses other approaches like mass spectrometry or antibody-based methods (e.g., ELISA).

Transcriptomic studies offer the most direct insight into gene expression, as they analyze RNA transcripts produced from active genes. RNA levels correlate closely with actual gene activity, reflecting dynamic changes in expression.

• Which of these do humans use and how can you tell (be specific about example chemicals they use and make*)

• Which of these do plants use and how can you tell (be specific about example chemicals they use and make*)

List as many different environmental factors that can effect microbial growth rate

Why do microbes in nature (a.e. in your body, on surfaces) grow slower than

microbes in media in the lab?

• What is the purpose of adding NaCl to the base recipe for all media? What would

happen to the cells in the culture if this factor was adjusted or forgotten?

• What is the purpose of the incubator in culturing? What would happen to the culture

if this factor was adjusted or forgotten?

What are the limitations to using various measurement methods to obtain cell numbers (viable count, turbidometry, flow cytometer, PCR, coulter counter, direct microscopy cytometer)? Which will OVER-ESTIMATE the number of cells? Which might UNDER-ESTIMATE?

• What are the 4 stages of standard growth curve – during which can the calculations be used?

• Can the calculations be used in conjunction with PCR? Why or why not?