MICROBIO 1.2

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Questions and Answers

What is a key advantage of prokaryotic cells being small?

They can divide sexually.

They have a faster rate of biochemical reactions. (correct)

They can store more nutrients.

They have more complex metabolic pathways.

Which of the following is NOT a characteristic of prokaryotes?

70S ribosomes

Binary fission reproduction

Presence of membrane-bound organelles (correct)

Circular DNA

What do the acronym RON stand for in the context of survival demands for free-living microbes?

Resistance, Occupancy, Nutrition (correct)

Resilience, Opportunity, Nutrition

Reproduction, Organization, Nutrients

Resistance, Opportunity, Nurturing

What method do prokaryotes use for reproduction?

Binary fission (C) Signup and view all the answers

Gram-positive bacteria are characterized by which structural feature?

Thick cell wall without an outer membrane (B) Signup and view all the answers

What is a disadvantage of being a free-living microbe?

Need to withstand environmental stresses (D) Signup and view all the answers

Which of the following statements about prokaryotic ribosomes is true?

They are 70S in size. (B) Signup and view all the answers

What is one reason why understanding pathogens is important for future physicians?

Pathogens can cause diseases that physicians will treat. (D) Signup and view all the answers

Which of the following best describes a prokaryotic organism?

They are typically unicellular and lack a nucleus. (B) Signup and view all the answers

Which type of pathogen is associated with antibiotic resistance and poses a threat in the U.S.?

Bacteria (B) Signup and view all the answers

What distinguishes gram-positive bacteria from gram-negative bacteria?

Gram-positive bacteria appear purple after a gram stain. (C) Signup and view all the answers

Which statement accurately describes a characteristic of fungi?

Fungi are eukaryotic organisms that often absorb nutrients from their environment. (A) Signup and view all the answers

How are viruses primarily classified?

By their type of genetic material and structure. (A) Signup and view all the answers

What characteristic is typically found in both prokaryotes and eukaryotes?

Ability to reproduce. (B) Signup and view all the answers

What is the primary role of peptidoglycan in bacterial cells?

Protects against osmotic pressure (B) Signup and view all the answers

What defines a parasite in the context of pathogens?

An organism that benefits at the expense of its host. (B) Signup and view all the answers

What function does Lipid A serve in Gram-negative bacteria?

Anchor LPS to the outer membrane (D) Signup and view all the answers

Which of the following best contrasts eukaryotes and prokaryotes?

Eukaryotes can have multiple cell types. (D) Signup and view all the answers

Which antibiotics are known to inhibit the synthesis of murein/peptidoglycan?

Penicillins, cephalosporins, and carbapenems (D) Signup and view all the answers

How do larger molecules such as B12 and iron typically enter Gram-negative bacteria?

Via specialized porin channels and passive diffusion (B) Signup and view all the answers

What is the periplasmic space in Gram-negative bacteria?

The compartment between the inner and outer membranes (C) Signup and view all the answers

In which type of bacteria does the presence of waxes in their cell walls typically classify them?

Acid-fast (D) Signup and view all the answers

What is the primary function of a bacterial capsule?

Prevents phagocytosis (A) Signup and view all the answers

What mechanism allows bacteria to move towards substances they are attracted to?

Bacterial chemotaxis (C) Signup and view all the answers

What is one of the mechanisms Gram-negative bacteria use to develop resistance to β-lactams?

Inactivating β-lactamases (A) Signup and view all the answers

Study Notes

Basic Characteristics of Pathogens

Pathogens cause disease and students will treat diseases.
The CDC reports over 2.8 million antibiotic-resistant infections annually in the US, resulting in over 35,000 deaths.
In 2017, there were at least 12,800 deaths related to Clostridioides difficile infections.
The 2019 Antibiotic Resistance Threat Report (CDC, 2019) identifies 21 bacteria and fungi as threats to the US, categorized as "urgent, serious, concerning, watch-list."
A recent PNAS publication highlights a group of H1N1 swine influenza viruses showing potential for human pandemic concern.

G4 Swine Flu Viruses

The CDC is taking action to deal with the G4 swine flu viruses in China, which pose a pandemic risk.
This recent publication in the Proceedings of the National Academy of Science (PNAS) describes H1N1 swine influenza viruses having the potential to infect humans.
These viruses are of major pandemic concern.

Mysterious Respiratory Illness in Dogs

Many US states are reporting unusual respiratory illnesses in dogs.
The illnesses were detected in October 2021.
There's no evidence of human-to-human spread.

Is It the Flu or COVID?

An at-home test can distinguish between the flu and COVID-19.

Class Objectives

Compare and contrast prokaryotes and eukaryotes (including cell walls).
Understand the advantages and disadvantages of being a prokaryote and identify adaptive strategies.
Identify fundamental differences among bacterial types (gram-positive, gram-negative, acid-fast).
Define fungi, distinguishing them from viruses and bacteria, and explain their organizational structure.
Define parasites and their basic organizational structure.
Understand how viruses are categorized.

Prokaryotes vs. Eukaryotes

Prokaryotes have free-floating DNA, while eukaryotes have DNA bound to protein.
Prokaryotic DNA is circular, and eukaryotic DNA is linear.
Prokaryotes typically lack a nucleus and membrane-bound organelles.
Prokaryotic ribosomes are 70S, and eukaryotic ribosomes are 80S.
Prokaryotes reproduce through binary fission, whereas eukaryotes reproduce through mitosis or meiosis.
Prokaryotic cells are generally smaller (1-5 μm) than eukaryotic cells (10-100μm).
Prokaryotes are haploid, while eukaryotes can be diploid or higher.

Pros of Being Prokaryotic

Coupled transcription and translation, leading to faster processes.
Simpler and faster binary fission compared to mitosis.
Reduced space requirements.
High metabolic rates, allowing microbes to double in size every 20 minutes due to high surface area to volume ratio.

Bacteria in the Large Intestine

The human large intestine contains trillions of bacteria, contrasting with only 7.6 billion people on Earth.

Cons of Being Free-Living

The three main challenges for microbes are resistance (to damaging agents), occupancy (finding a suitable environment), and nutrition (intermittent availability).

Goal: Adapt and Survive (Efficiently)

The intrinsic nature of microbes is to adapt and survive efficiently.

Mechanisms of Survival

The bacterial cell wall protects the cytoplasmic membrane.
Bacteria protect their cytoplasmic membrane through techniques like being gram-positive, gram-negative, or acid-fast.

Gram-Positive vs. Gram-Negative Bacteria

Gram-positive bacteria retain the crystal violet-iodine complex after alcohol decolorization.
Gram-negative bacteria do not retain the crystal violet-iodine complex.
Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thin layer.

Peptidoglycan

Peptidoglycan, also known as murein, protects against osmotic pressure.
Bacterial shapes (cocci, bacilli, spirilla) are determined by peptidoglycan structure.
Certain antibiotics impede peptidoglycan synthesis.

Lipopolysaccharide (LPS)

LPS anchors itself to the outer membrane.
It is responsible for eliciting fever in the host.
It contains hydrophilic side chains that prevent hydrophobic compounds from entering the cell.

Periplasmic Space

The periplasmic space is located between two membranes, containing enzymes and proteins that aid in transport and nutrition.

Acid-Fast Bacteria

Acid-fast bacteria have waxy cell walls that prevent standard Gram staining.
Special stains are required for identification.

Occupancy

Microbes must find hospitable environments.
Development of mechanisms to evade common environmental behaviors.
Employing biofilms for attachment and protection are examples of adapting to an environment.

Movement

Capsule for protection against phagocytosis.
Flagella for motility, chemotaxis toward favorable environments.
Pili for attachment.

Nutrition

Bacteria require readily available nutrients in their environments.
The bacterial growth cycle demonstrates that nutrients ebb and flow in the environment.

Cytoplasmic Membrane and Transport

The cytoplasmic membrane contains permeases to facilitate entry of most metabolites.
Facilitated diffusion-molecules move along the concentration gradient.
Active transport-molecules move against the concentration gradient, requiring energy.
Group translocation-molecules are chemically modified during transport.

Viral Classification

Viruses are classified based on morphology and replication.

What are Fungi?

Fungi are usually multicellular eukaryotic organisms.
They are heterotrophs (cannot make their own food).
Fungi play crucial roles in nutrient cycling.
They reproduce both sexually and asexually.

Basics of Fungi

Fungi are eukaryotic, with a nucleus, mitochondria, Golgi, and endoplasmic reticulum.
Fungal cells have rigid walls composed of chitin and glucans.
The cell membrane contains ergosterol.
Multiple forms (unicellular, multicellular, or dimorphic) exist.
Reproduction is dependent on environmental factors (temperature, pH, CO2).
Fungi produce spores, use budding, or both.

Parasites

Parasites live on or in a host and obtain nutrients from the host.
Two main groups: protozoa and helminths.
Protozoa include amoebas, flagellates, ciliates, and apicomplexans.
Helminths include nematodes, trematodes, and cestodes.

What About Viruses?

Viruses are neither prokaryotic nor eukaryotic
Viruses cannot reproduce by themselves

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Description

This quiz covers the basic characteristics of pathogens, including antibiotic resistance and specific diseases caused by bacteria and viruses. It highlights significant stats from CDC reports and recent findings on H1N1 swine flu viruses and their potential risks. Prepare to test your knowledge on these critical health issues.