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Questions and Answers
What is the primary function of flagella in bacteria?
What is the primary function of flagella in bacteria?
- DNA transfer between cells
- Movement in liquid environments (correct)
- Protection from immune system
- Attachment to surfaces
What type of movement do bacteria perform when they swim in a zigzag pattern in search of nutrients?
What type of movement do bacteria perform when they swim in a zigzag pattern in search of nutrients?
- Random walk (correct)
- Linear motion
- Tumble movement
- Directional swimming
Which structure allows bacteria to stick to various surfaces, including epithelial tissue?
Which structure allows bacteria to stick to various surfaces, including epithelial tissue?
- Flagella
- Fimbria (correct)
- Glycolax
- Pili
What is the main role of pili in bacterial cells?
What is the main role of pili in bacterial cells?
What is a well-organized layer of uniform thickness around a bacterium called?
What is a well-organized layer of uniform thickness around a bacterium called?
Which type of glycolax layer is described as poorly defined?
Which type of glycolax layer is described as poorly defined?
What significant defense mechanism do pathogenic bacteria often rely on?
What significant defense mechanism do pathogenic bacteria often rely on?
What does the ability of a bacterium to be motile depend on?
What does the ability of a bacterium to be motile depend on?
What is a characteristic feature of prokaryotic cells?
What is a characteristic feature of prokaryotic cells?
What type of DNA structure is typically found in prokaryotic cells?
What type of DNA structure is typically found in prokaryotic cells?
Which of the following is true regarding eukaryotic cells compared to prokaryotic cells?
Which of the following is true regarding eukaryotic cells compared to prokaryotic cells?
How is the chromosome structure in eukaryotic cells typically characterized?
How is the chromosome structure in eukaryotic cells typically characterized?
Which of the following organisms are classified as eukaryotes?
Which of the following organisms are classified as eukaryotes?
Which component is absent in prokaryotic cells?
Which component is absent in prokaryotic cells?
What is the primary method of cell division in prokaryotic cells?
What is the primary method of cell division in prokaryotic cells?
What is the primary purpose of a microscope?
What is the primary purpose of a microscope?
What structure helps maintain the shape and provides protection in most bacteria?
What structure helps maintain the shape and provides protection in most bacteria?
Which type of microscope is commonly referred to as a biological microscope?
Which type of microscope is commonly referred to as a biological microscope?
What is the typical highest magnification of a compound microscope?
What is the typical highest magnification of a compound microscope?
What component of a compound microscope contains a power lens of either 10X or 15X?
What component of a compound microscope contains a power lens of either 10X or 15X?
What should be avoided when focusing a microscope?
What should be avoided when focusing a microscope?
How many objective lenses does a standard compound microscope typically have?
How many objective lenses does a standard compound microscope typically have?
Which of the following samples can be examined using a compound microscope?
Which of the following samples can be examined using a compound microscope?
What purpose does the diopter adjustment serve in a microscope?
What purpose does the diopter adjustment serve in a microscope?
What type of anaerobes can tolerate oxygen but cannot use it?
What type of anaerobes can tolerate oxygen but cannot use it?
Which classification of bacteria has flagella distributed evenly around the cell?
Which classification of bacteria has flagella distributed evenly around the cell?
Which type of bacteria is known for producing spores within the bacterial cell?
Which type of bacteria is known for producing spores within the bacterial cell?
What is the optimum pH for growth of Alkaliphiles?
What is the optimum pH for growth of Alkaliphiles?
Which of the following bacteria are classified as Acidophiles?
Which of the following bacteria are classified as Acidophiles?
Halophiles require which type of environment for optimal growth?
Halophiles require which type of environment for optimal growth?
Which of the following is an example of a monotrichous bacterium?
Which of the following is an example of a monotrichous bacterium?
What function does the glycolax perform aside from protection?
What function does the glycolax perform aside from protection?
What is the primary component of the bacterial cell wall?
What is the primary component of the bacterial cell wall?
What type of bacteria do not produce spores?
What type of bacteria do not produce spores?
How can bacteria be classified based on their cell wall structure?
How can bacteria be classified based on their cell wall structure?
What is a key characteristic of gram negative bacteria?
What is a key characteristic of gram negative bacteria?
What role do lipopolysaccharides (LPS) play in gram negative bacteria?
What role do lipopolysaccharides (LPS) play in gram negative bacteria?
What is the purpose of a differential stain in microbiology?
What is the purpose of a differential stain in microbiology?
What happens to bacteria without a proper cell wall structure in unfavorable conditions?
What happens to bacteria without a proper cell wall structure in unfavorable conditions?
What color do gram positive bacteria appear after gram staining?
What color do gram positive bacteria appear after gram staining?
What characteristic must agar have to be a suitable solidifying agent?
What characteristic must agar have to be a suitable solidifying agent?
Which of the following is a disadvantage of liquid media?
Which of the following is a disadvantage of liquid media?
Which component acts as a stimulant for bacterial growth in culture media?
Which component acts as a stimulant for bacterial growth in culture media?
What is the primary purpose of carbohydrates in media?
What is the primary purpose of carbohydrates in media?
What is a unique property of gelatin compared to agar?
What is a unique property of gelatin compared to agar?
Which mineral is specifically mentioned as essential for enzymatic activities of bacterial growth?
Which mineral is specifically mentioned as essential for enzymatic activities of bacterial growth?
How does solid media differ from liquid media?
How does solid media differ from liquid media?
Which of the following statements about agar is false?
Which of the following statements about agar is false?
Flashcards
What is a microscope?
What is a microscope?
A microscope is a tool used to see tiny objects invisible to the naked eye, like cells or bacteria.
What is a compound microscope?
What is a compound microscope?
A compound microscope is used in laboratories, schools, and medical settings to view very small samples like cells and bacteria. It uses multiple lenses to magnify objects.
What does 'microscopic' mean?
What does 'microscopic' mean?
Microscopic means something is too small to be seen with the naked eye, requiring a microscope to be visible.
What are the main parts of a compound microscope?
What are the main parts of a compound microscope?
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What is the eyepiece?
What is the eyepiece?
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What are objective lenses?
What are objective lenses?
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What does the term 'magnification' mean?
What does the term 'magnification' mean?
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What is a diopter adjustment?
What is a diopter adjustment?
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Prokaryotic Cell
Prokaryotic Cell
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Eukaryotic Cell
Eukaryotic Cell
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Nucleoid
Nucleoid
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Peptidoglycan
Peptidoglycan
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Capsule
Capsule
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Cytoskeleton
Cytoskeleton
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Chromosome
Chromosome
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Microtubules and Microfilaments
Microtubules and Microfilaments
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What are flagella?
What are flagella?
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How do flagella help bacteria?
How do flagella help bacteria?
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What is a random walk?
What is a random walk?
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What are fimbria?
What are fimbria?
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What is the function of pili?
What is the function of pili?
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What is the glycolax layer?
What is the glycolax layer?
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What is the difference between a slime layer and a capsule?
What is the difference between a slime layer and a capsule?
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How does a capsule help pathogenic bacteria?
How does a capsule help pathogenic bacteria?
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What is a glycocalyx?
What is a glycocalyx?
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What is a biofilm?
What is a biofilm?
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What are the health risks of biofilms?
What are the health risks of biofilms?
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What is the function of the bacterial cell wall?
What is the function of the bacterial cell wall?
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Why is the bacterial cell wall important for survival?
Why is the bacterial cell wall important for survival?
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What is peptidoglycan?
What is peptidoglycan?
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What are Gram-positive bacteria?
What are Gram-positive bacteria?
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What are Gram-negative bacteria?
What are Gram-negative bacteria?
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Aerotolerant Anaerobe
Aerotolerant Anaerobe
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Microaerophile
Microaerophile
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Atrichous
Atrichous
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Monotrichous
Monotrichous
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Lophotrichous
Lophotrichous
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Amphitrichous
Amphitrichous
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Peritrichous
Peritrichous
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Spore-forming Bacteria
Spore-forming Bacteria
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Culture Media
Culture Media
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Tryptophan
Tryptophan
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Meat Extract (Lab Lemco)
Meat Extract (Lab Lemco)
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Yeast Extract
Yeast Extract
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Mineral Salts
Mineral Salts
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Carbohydrates in Culture Media
Carbohydrates in Culture Media
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Liquid Media (Broth)
Liquid Media (Broth)
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Solid Media
Solid Media
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Study Notes
Microscopy
- A microscope is a laboratory instrument used to examine objects too small to see with the naked eye
- Microscopy is the science of investigating small objects and structures using a microscope
- Microscopic means being invisible to the naked eye unless aided by a microscope
Types of Microscopes
- Compound Microscope
- Stereo Microscope
- Inverted Microscope
- Metallurgical Microscope
- Polarizing Microscope
Compound Microscopes
- Also referred to as a biological microscope
- Used in laboratories, schools, wastewater treatment plants, veterinary offices, and histology/pathology
- Samples viewed under a compound microscope must be prepared on a microscope slide using a cover slip to flatten the sample
- Can view blood cells, cheek cells, parasites, bacteria, algae, tissue, and thin sections of organs
- Common magnifications are 40x, 100x, 400x, and sometimes 1000x
- Microscopes advertising magnification above 1000x offer empty magnification with low resolution and should not be purchased
Microscope Parts
- Eyepiece: The lens the viewer looks through to see the specimen. Usually contains a 10x or 15x power lens.
- Diopter Adjustment: Useful for correcting vision differences between the two eyes.
- Body Tube (Head): Connects the eyepiece to the objective lenses.
- Arm: Connects the body tube to the base of the microscope.
- Coarse Adjustment: Brings the specimen into general focus.
- Fine Adjustment: Fine tunes focus and increases detail of the specimen.
- Nosepiece: A rotating turret that houses the objective lenses
- Objective Lenses: The lenses closest to the specimen. Standard microscopes have 3-5 objective lenses ranging from 4x to 100x power.
- Specimen/Slide: The specimen is the object being examined and is placed on a glass slide.
- Stage: The flat platform where the slide is placed.
- Stage Clips: Metal clips that hold the slide in place.
- Stage Height Adjustment: Moves the stage left/right or up/down.
- Aperture: The hole in the middle of the stage that allows light from the illuminator to reach the specimen.
- On/off switch: Controls the illuminator. Older microscopes used mirrors, most now use a low-voltage bulb.
- Illumination: The light source for the microscope
- Condenser: Gathers and focuses light from the illuminator onto the specimen.
- Iris Diaphragm: Adjusts the amount of light that reaches the specimen.
- Base: Supports the microscope and houses the illuminator.
Cells
- All living things are made of cells
- Cells are the smallest units that can be alive
- Life on Earth is classified into five kingdoms
- Each kingdom has its own kind of cell
- There is a key division between prokaryotic and eukaryotic cells
Prokaryotes
- Lacking well-defined nuclei and membrane-bound organelles.
- Chromosomes composed of a single closed DNA circle
- Typical prokaryotic cells range from 0.1 to 5.0 micrometers in diameter.
- Common bacteria are prokaryotic and are found everywhere on Earth.
- The majority of prokaryotic DNA is found in a central region called the nucleoid.
- Most are surrounded by a rigid cell wall made of peptidoglycan (a polymer). This helps cell shape and prevents dehydration.
- Many bacteria also have a capsule (carbohydrate layer) that helps with adhesion to surfaces.
Eukaryotes
- Contain complex cells or single cells with complex structures.
- Genetic material organized into chromosomes in the nucleus
- Usually much larger than prokaryotes (10-100 μm).
- Contain organelles (other structures with membranes)
- Eukaryotic DNA is put in bundles called chromosomes. These are separated by a microtubular spindle during cell division.
- Most eukaryotes reproduce sexually.
- The number of chromosomes is usually typical for each species.
Prokaryotic vs. Eukaryotic Cells (Table)
| Feature | Prokaryotic Cell | Eukaryotic Cell |
|---|---|---|
| Nuclear Membrane | Absent | Present |
| Chromosome | Single, circular | Multiple |
| DNA | Circular | Linear |
| Nucleolus | Absent | Present |
| Cell Division | Mitosis (fission) | Mitosis or meiosis |
| Ribosomes | 70s | 80s |
| Chloroplasts | Absent | Present |
| Mitochondria | Absent | Present |
| Cell Organelles | Absent | Present |
| Cell Wall | Usually present, contains peptidoglycan | Usually present, varies |
| Flagella | Simple arrangement | Complex arrangement |
| Average Size | 0.2-2um | 10-100um |
| Plasma Membrane | No carbohydrates, lacks sterols | Sterols and carbohydrates present |
| Number of Cells | Generally unicellular | Generally multicellular |
Bacteria Cell Shapes
- Cocci (round)
- Bacilli (rod-shaped)
- Coccobacillus (oval-shaped)
- Vibrio (comma-shaped)
- Spirillum/Spirochete (corkscrew/spiral-shaped)
External Features of Bacteria
- Flagella: Long filamentous appendages that function as a propeller for movement in liquid environments
- Fimbriae: Smaller appendages that allow bacteria to attach to surfaces.
- Pili: Long appendages that function similarly to fimbriae, often used for bacterial conjugation (sharing DNA)
- Glycocalyx: Carbohydrate and protein matrix that forms when cells are in harsh environments or need to adhere to a surface.
Cell Wall Structure
- Bacteria have a cell wall structure that protects their cellular membrane from damage in unfavorable conditions.
- The cell wall helps the bacteria withstand/resist the hypotonic environment.
- Bacteria are often surrounded by peptidoglycan.
Gram Stain
- Shows the difference between gram-positive and gram-negative bacteria.
- Bacteria with thick peptidoglycan layers in their walls stain purple.
- Bacteria with thin layers will clear of stain after a rinse and stain pink with Saffranin.
Bacterial Internal Structures
- Mesosomes: Convoluted invaginations in the cytoplasmic membrane. Play a role in cell division and secretion
- Nucleoid: The region containing the DNA contained within the cytoplasm of the cell (no membraneous envelope)
- Ribosomes: Located throughout the cytoplasm. The site of protein synthesis. Important for conveying genomic code.
- Cytoplasmic inclusions: Sources of reserved food for the cell (e.g., glycogen, volutin)
Bacterial Taxonomy and Classification
- Taxonomy is the science or study of classifying living organisms.
- It groups living organisms into categories (e.g. kingdom, phylum, etc.).
- The original taxonomy system used in biology is called binomial nomenclature and is credited to Carolus Linnaeus. It is an accepted system for communication about organisms around the world.
- The system involves two parts and includes the genus name in the first, capitalised part and a specific epithet (a descriptor) in a second, non-capitalised part.
Mechanisms of Drug Resistance in Bacteria
- Spontaneous mutations in DNA.
- Transfer of DNA (e.g. through plasmids) from one bacterium to another (resistance properties often encoded on these).
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Description
Test your knowledge on bacterial structures and their functions in this quiz. Topics include flagella, pili, and the differences between prokaryotic and eukaryotic cells. Gauge your understanding of how bacteria navigate and adhere to surfaces.
