Prokaryotic cells and Eukaryotic Cells Flashcards
1
Q
All living things, whether single-celled or multicellular, are composed of _______.
A
cells
Note:
Cells share the following common features:
- Basic shape – spherical, cubical, cylindrical
- Internal content – cytoplasm, surrounded by a membrane
- DNA chromosome(s), ribosomes, metabolic capacities
2
Q
What are the 2 Basic cell types?
A
Eukaryotic and Prokaryotic
3
Q
WHAT CELL IS THIS?
- Organisms: Animals, plants, fungi, and protists
- Contain membrane-bound organelles that compartmentalize the cytoplasm and perform specific functions.
- Contain double-membrane bound nucleus with DNA chromosomes
A
Eukaryotic cells
4
Q
WHAT CELL IS THIS?
- Organisms: Bacteria and Archaea
- No nucleus or other membrane-bound organelles
A
Prokaryotic cells
5
Q
FAMILIARIZE ONLY!
Fundamental Characteristics of Life in Cells:
A
- Reproduction & Heredity – Cells carry genetic material (DNA) stored in chromosomes and pass it to offspring through sexual or asexual reproduction.
- Growth & Development – Cells increase in size and go through stages of development to form fully functioning organisms.
- Metabolism – Cells break down nutrients, convert them into energy, and carry out biochemical reactions essential for life.
- Movement & Irritability – Cells respond to internal and external stimuli (e.g., bacteria moving toward food, plants bending toward sunlight).
- Support, Protection & Storage – Cells use walls (plants, fungi, bacteria), vacuoles (storage sacs), and granules/inclusions (reserve materials) for protection and nutrient storage.
- Nutrient & Waste Transport – Cells absorb essential nutrients and expel waste to maintain a stable environment.
6
Q
STUDY THE STRUCTURE OF A BACTERIAL CELL
A
- Fibriae
- Ribosomes
- Cell wall
- Cell membrane
- Capsule
- Cytoplasmic matrix
- Flagellum
- Inclusion body
- Pilus
- Chromosome (DNA)
- Actin Filaments
- Mesosome
- Slime layer
7
Q
- Cell _________ are structures that extend from the surface of a cell, allowing it to move, attach, or transfer DNA.
A
appendages
8
Q
What are the 2 Major groups of appendages?
A
- Motility structures – Help the cell move
Example: Flagella
- Attachment or channel structures – Help the cell attach to surfaces or exchange materials
Example: Fimbriae and pili
9
Q
- This is the Surface Coating. A protective outer layer made of sugars and proteins.
- Prevents dehydration, protects against the immune system, and helps bacteria stick to surfaces.
A
Glycocalyx
10
Q
- These are whip-like structures that help cells, especially bacteria, move in their environment.
A
Flagella
Note:
How Flagella Work:
✅ Rotates 360° like a propeller to push the cell forward.
✅ Enables motility (movement) to help bacteria swim toward nutrients or away from harmful substances (chemotaxis).
11
Q
What are the 3 Main Parts of Flagella?
A
- Filament
- Hook
- Basal body
12
Q
WHAT IS THIS?
- The long, thin, helical (spiral) structure made of flagellin protein that extends out from the cell.
A
Filament
13
Q
WHAT IS THIS?
- A curved sheath that connects the filament to the basal body and helps control movement.
A
Hook
14
Q
WHAT IS THIS?
- A stack of rings firmly attached to the cell wall; acts as a motor to rotate the flagellum.
A
Basal body
15
Q
Bacteria can have different flagellar arrangements, which affect how they move.
What are the 4 Main Types of Flagellar Arrangements?
A
- Monotrichous
- Lophotrichous
- Amphitrichous
- Peritrichous
REMEMBER THE ACRONYM M-LAP
16
Q
WHAT IS THIS?
- A single flagellum located at one end of the cell.
A
Monotrichous
Note:
- Moves in a straight or tumbling motion.
17
Q
WHAT IS THIS?
- A small bunch or tuft of flagella emerging from the same site.
A
Lophotrichous
Note:
- Moves more efficiently in one direction. (Madaming buntot)
18
Q
WHAT IS THIS?
- Flagella at both ends of the cell.
A
Amphitrichous
Note:
- Can switch direction easily by reversing flagellar rotation. (Magkabilaan ang buntot)
19
Q
WHAT IS THIS?
- Flagella are spread all over the surface of the cell.
A
Peritrichous
Note:
- Moves in all directions with increased mobility.
20
Q
Flagella help bacteria move in response to external stimuli to find food or escape harmful environments.
What are the 2 Flagellar Responses or Stimuli?
A
- Chemotaxis
- Phototaxis
21
Q
WHAT IS THIS?
- Movement in response to chemical signals.
A
Chemotaxis
22
Q
Chemotaxis has two types. What are these?
A
- Positive chemotaxis
- Negative chemotaxis
23
Q
WHAT IS THIS?
- Moves toward nutrients or favorable chemicals.
A
Positive chemotaxis
24
Q
WHAT IS THIS?
- Moves away from harmful substances (toxins, antibiotics).
A
Negative chemotaxis
25
WHAT IS THIS?
* Movement in response to **light** (common in photosynthetic bacteria).
Phototaxis
26
Under how Flagella move, **signal** sets flagella into these **2 Motions**.
What are these?
**Clockwise** or **counterclockwise**
27
WHAT IS THIS?
* Counterclockwise rotation ➡ Produces a smooth, linear movement called ___?
run
28
WHAT IS THIS?
* Clockwise rotation ➡ Causes the cell to ______, changing its direction.
tumble
29
WHAT IS THIS?
* These are a special type of **internal flagella** that is enclosed in the space between the outer sheath and the cell wall peptidoglycan.
* Produce cellular by **contracting** and imparting **twisting** or **flexing** motion.
**Periplasmic Flagella**
Note:
* Instead of rotating like external flagella, they **contract and twist**, causing the entire cell to move in a **corkscrew-like motion**.
30
WHAT IS THIS?
* These are **fine, proteinaceous, hairlike bristles** emerging from the cell surface.
* Function in **adhesion** to other cells and surfaces.
Fimbriae
31
WHAT IS THIS?
* Pili (singular: pilus) are **rigid, tube-like** structures made of a protein called _______?
Pilin
32
Pili is found only in what cells?
Gram-negative cells
33
Pili connect two bacterial cells and allow the transfer of **genetic material** (plasmids) in a process called ________?
**Bacterial conjugation** or **conjugation**
34
WHAT IS THIS?
* The _______ is a **protective outer coating** found **outside the cell wall** of some bacteria. It is made up of **sugars and/or proteins** and plays an important role in bacterial survival.
Glycocalyx
35
What are the **2 Types of Glycocalyx**?
* Slime layer
* Capsule
36
WHAT IS THIS?
* **Loosely organized and attached**, helps bacteria stick to surfaces.
Slime layer
37
WHAT IS THIS?
* **Highly organized, tightly attached**, provides extra protection against the immune system.
Capsule
38
FAMILIARIZE ONLY
**Functions of the Glycocalyx – Explanation**
**Protection from Dehydration and Nutrient Loss**
* The glycocalyx acts as a **barrier** that retains **water** and **nutrients**, preventing the cell from drying out, especially in harsh environments.
**Inhibits Killing by White Blood Cells (Phagocytosis), Contributing to Pathogenicity**
* The **capsule** form of glycocalyx protects bacteria from being engulfed and destroyed by **white blood cells** (WBCs), a process called **phagocytosis**.
* This allows bacteria to **survive inside the human body**, leading to infections.
* Example: Streptococcus pneumoniae can avoid immune attacks due to its capsule, making it more likely to cause pneumonia.
**Attachment – Formation of Biofilms**
* The **slime layer** helps bacteria **stick to surfaces** like teeth, medical devices, and tissues.
* Bacteria living in **biofilms** are more resistant to **antibiotics** and **immune system attacks.**
* Example: Pseudomonas aeruginosa forms biofilms in hospital settings, making infections harder to treat.
39
WHAT IS THIS?
* This is an **External Covering** Outside the Cytoplasm.
**Cell envelope**
Note:
* It plays a crucial role in **maintaining cell shape** and **controlling substance exchange** with the environment.
40
The Cell Envelope is composed of **Two Basic Layers**. What are these?
**Cell wall** and **Cell membrane**
Note:
* Cell Wall: Provides structural support and determines the shape of the cell.
* Cell Membrane: Regulates the entry and exit of molecules, ensuring proper cell function.
**Maintains Cell Integrity**
* The cell envelope protects the bacteria from environmental stresses, such as changes in **osmotic pressure** (preventing the cell from bursting or collapsing).
41
What are the **Two Different Groups of Bacteria** Demonstrated by **Gram Stain**?
* Gram-positive bacteria
* Gram-negative bacteria
42
WHAT IS THIS?
* **Thick cell wall composed primarily of peptidoglycan and cell membrane.**
**Gram-positive bacteria**
Note:
* Thick peptidoglycan layer provides strength and protection.
43
WHAT IS THIS?
* **Outer cell membrane, thin peptidoglycan layer, and cell membrane.**
**Gram-negative bacteria**
Note:
* Outer membrane protects against antibiotics and immune defenses.
44
The cell wall gives bacteria their **distinct shape** (e.g., spherical, rod-shaped, spiral).
* **It prevents _______ when there are changes in osmotic pressure, ensuring survival in different environments.**
**lysis** (bursting)
45
WHAT IS THIS?
* __________ is the **primary component of cell wall**.
**Peptidoglycan**
Note:
* It is a unique macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments.
46
* **Gram-positive bacteria** have a **very thick** peptidoglycan layer with a thickness of ______, making their cell walls **strong and rigid.**
**20-80 nm**
Note:
* GPB - This thick layer retains the **crystal violet stain** during a Gram stain, making these bacteria appear **purple** under a microscope.
47
What are the **two important molecules** found only in Gram-positive bacteria?
* It function in cell wall maintenance and enlargement during cell division; move cations across the cell envelope; stimulate a specific immune response.
**Teichoic Acid** and **Lipoteichoic Acid**
48
WHAT IS THIS?
* Some Gram-positive bacteria have a **small space** between the **cell wall and membrane**. This is called as _____?
**Periplasmic space**
Note:
* This area **contains enzymes and other proteins** that help with metabolism and transport.
49
* Gram-negative bacteria have **two membranes**, with a **thin** peptidoglycan layer in between. What are the two membrane?
**Inner** and **outer membranes**
50
What is the difference between the **peptidoglycan of gram-positive** and **gram-negative bacteria**?
* Gram-positive Bacteria - **thick peptidoglycan**
This thick layer retains the crystal violet stain during a Gram stain, making these bacteria appear purple under a microscope.
__________________________
* Gram-negative Bacteria - **thin peptidoglycan**
Because of the thin peptidoglycan layer, Gram-negative bacteria do not retain crystal violet stain and appear pink after Gram staining.
51
The **outer membrane** of Gram-Negative Bacteria contains what?
**Lipopolysaccharides**
52
52
FAMILIARIZE ONLY!
* Lipopolysaccharides (LPS) is unique to Gram-negative bacteria and plays a critical role in bacterial survival and pathogenicity.
**Lipid A (Endotoxin):***
* Can be **toxic** when released into the body during infections, causing **fever, inflammation, and even septic shock.**
**Receptors and Immune Evasion:**
* Some parts of LPS **act as receptors** for specific molecules.
* LPS also **helps bacteria avoid the immune system** by blocking immune responses.
***Porin* Proteins in the Outer Membrane**
* These **control what enters and exits the cell**, helping bacteria survive in harsh environments.
* They can **regulate antibiotic entry**, making some Gram-negative bacteria more resistant to antibiotics.
53
* Study the (Diagram) of **Structures of Gram-Positive and Gram-Negative Bacterial Cell Walls**
* Study the (Table) about **Comparison of Gram-Positive and Gram-Negative Cell Walls**
PPT 3 - Slide 21 and 22
54
WHAT IS THIS?
* It is a **differential staining technique** used to classify bacteria based on their **cell wall structure**. It helps in **identifying bacteria** and choosing the right **antibiotic treatment.**
Gram stain
55
WHAT IS THIS?
* Retain crystal violet and stain purple.
Gram-positive
56
WHAT IS THIS?
* Lose crystal violet and stain red from safranin counterstain.
Gram-negative
57
FAMILIARIZE ONLY!
**What are the importance of Gram Stain?**
* Important basis of bacterial classification and identification
* Practical aid in diagnosing infection and guiding drug treatment
58
WHAT IS THIS?
* It refer to **bacteria that do not fit** into the usual **Gram-positive or Gram-negative** cell wall categories. These bacteria have **unique structures** that give them special characteristics, such as resistance to antibiotics or the ability to change shape.
Nontypical cell walls
59
WHAT IS THIS?
* These bacteria have a **Gram-positive-like** cell wall but contain a **waxy lipid called mycolic acid (cord factor).**
**Mycobacterium & Nocardia**
Note:
**The mycolic acid makes them:**
* Pathogenicity and high degree of resistance to certain chemicals and dyes.
* Basis for **acid-fast stain** used for diagnosis of infections caused by these microorganisms.
60
WHAT IS THIS?
* These bacteria **completely lack a cell wall.**
* Instead, their cell membrane is **stabilized by sterols**, which help them survive without a rigid wall.
* They are **pleomorphic**, meaning they can change shape since they do not have a fixed structure.
Mycoplasma
61
WHAT IS THIS?
* The **cell membrane**, also called the **plasma membrane**, is a **thin, flexible barrier** surrounding the cell. It is primarily made up of **phospholipids and proteins** and follows what model?
This model means that the components move freely like a liquid.
**Fluid mosaic model**
Note:
Functions of the Cell Membrane:
* **Energy Production & Metabolism** → Some reactions for energy production occur at the membrane.
* **Nutrient Transport** → Controls what enters and exits the cell (selectively permeable).
* **Waste Removal** → Allows the discharge of waste products.
62
WHAT IS THIS?
* It is the **inner substance** of a bacterial cell. It is a **gel-like solution** that contains **sugars, amino acids, salts, and other essential molecules** needed for cell survival.
CYTOPLASM
63
The cytoplasm contains how many percent of **water**?
**70-80%**
Note:
**Why is the High Water Content (70-80%) Important?**
* **Acts as a Solvent** → Dissolves nutrients and molecules so they can be transported and used in chemical reactions.
* **Supports Cellular Reactions** → Many metabolic processes occur in a liquid environment.
Maintains Cell Shape &
* **Pressure** → Helps prevent dehydration and contributes to cell stability.
64
UNDER NUCLEOID
* **Single, circular, double-stranded DNA molecule that contains all the genetic information required by a cell**.
Chromosome
65
UNDER NUCLEOID
* Free small circular, double stranded DNA
* Not essential to bacterial growth and metabolism
* Used in genetic engineering - readily manipulated and transferred from cell to cell
Plasmids
66
Ribosomes are made of 60% (a)________ and 40% (b)________.
(There are two answers)
* (a) ribosomal RNA
* (b) protein
67
Ribosomes consist of **two subunits**. What are these?
* Large subunit (50S)
* Small subunit (30S)
NOTE:
* Ribosome (**70S**)
68
WHAT IS THIS?
* This is the **site of protein synthesis**
* Found in **all cells**
**Ribosomes**
Note:
* Prokaryotic differ from eukaryotic ribosomes in size and number of proteins.
69
WHAT IS THIS?
Under Bacterial Internal Structures,
* These are **intracellular storage bodies** that bacteria use to store nutrients.
* Their **size, number, and content** vary depending on the bacterial species and environmental conditions.
* When nutrients in the environment become **scarce or unavailable**, bacteria can use these stored materials for survival.
**Inclusions and granules**
Examples: [additional info only]
* **Glycogen granules** (store energy)
* **Polyphosphate granules** (store phosphorus for ATP production)
* **Sulfur granules** (found in sulfur bacteria)
70
WHAT IS THIS?
Under Bacterial Internal Structures
* Many bacteria possess an **internal network of protein polymers** that is closely associated with the cell wall.
Cytoskeleton
71
WHAT IS THIS?
Under Bacterial Internal Structures,
* These are **dormant**, **highly resistant structures** formed by certain **Gram-positive bacteria** (e.g., Clostridium, Bacillus, Sporosarcina).
**Endospores**
Note:
* They serve as a **survival mechanism**, not for reproduction.
72
What are the **2-Phase Life Cycle** of Endospores?
**Sporulation** and **Germination**
Note:
* **Vegetative cell** – Actively growing and metabolizing under favorable conditions.
* **Endospore** – Formed under *harsh conditions* (e.g., extreme heat, dehydration, radiation, chemicals).
73
WHAT IS THIS?
* This is the process of converting a vegetative cell into an endospore (**Endospore Formation**).
* This is triggered by **adverse conditions** (lack of nutrients).
* Endospores can withstand extreme temperatures, drying, radiation, and chemicals, making them the **hardiest life forms on Earth**.
Sporulation
74
WHAT IS THIS?
* It is the process of converting an endospore back into a vegetative cell (**Return to Vegetative Growth**).
* When conditions improve, the endospore **absorbs water and "awakens"** to return to an **active vegetative state.**
Germination
75
FAMILIARIZE ONLY!
**"Sporulation Cycle"**
The **sporulation cycle** describes how certain **Gram-positive bacteria** (e.g., Bacillus and Clostridium) form endospores in response to **harsh conditions**. This process ensures bacterial survival rather than reproduction.
**(1) Vegetative cell**
* The bacterium is actively growing and metabolizing under favorable conditions.
**(2) Chromosome is duplicated and separated**
* The bacterial DNA is copied to ensure that the future spore has genetic material.
**(3) Cell is septated into a sporangium and forespore**
The cell membrane pinches in, creating two compartments:
* *Sporangium* (the larger part that will nourish the developing spore).
* *Forespore* (the smaller compartment that will become the endospore).
**(4) Sporangium engulfs forespore for further development**
* The forespore is fully enclosed within the sporangium, allowing further development.
**(5) Sporangium begins to actively synthesize spore layers around forespore**
* The forespore is protected by multiple layers, increasing its resistance.
**(6) Cortex and outer coat layers are deposited**
* The cortex (peptidoglycan layer) and protective protein coat form around the forespore, making it highly resistant.
**(7) Mature endospore**
* The spore fully develops inside the cell, becoming highly resistant to extreme conditions.
**(8) Free spore is released with the loss of the sporangium**
* The sporangium dies, releasing the endospore into the environment.
**(9) Germination spore swells and releases vegetative cell**
* When conditions become favorable again, the spore absorbs water and reactivates into a vegetative cell, restarting the cycle.
76
FAMILIARIZE ONLY!
This provides information about **endospores**, which are highly resistant, dormant structures formed by some bacteria to survive extreme conditions.
KEY points include:
* **Dehydrated and metabolically inactive**: Endospores have minimal water content, making them resistant to damage.
* **Thick coat**: Provides protection from environmental stress.
* **Extreme longevity**: Some endospores can remain viable for *250 million years*.
* **Resistant to cleaning and boiling**: They survive harsh treatments that kill most bacteria.
* **Destroyed by pressurized steam at 120°C for 20-30 minutes**: This is the principle behind autoclaving in sterilization.
77
Bacteria come in various **shapes, arrangements, and sizes**, which help in their classification and identification.
What are the **three basic shapes** of Bacteria?
* **Coccus** — spherical
* **Bacillus** — rod
→ *Coccobacillus* — very short and plump
→ *Vibrio* — gently curved
* **Spirillum** — helical, comma, twisted rod
→ *Spirochete* — spring-like
78
WHAT IS THIS?
* This refers to the ability of **bacteria** to **vary in shape and size** within the **same species**. This variation often occurs in response to **environmental conditions**, genetic factors, or lack of a rigid cell wall.
**PLEOMORPHISM**
Note:
* Bacteria **do not have a fixed shape**; they can appear as coccus, bacillus, etc.
79
WHAT IS THIS?
* The way bacteria **arrange** themselves after **cell division** depends on **how they divide** and **whether they stay attached**.
Bacterial Arrangements
80
List the **Arrangements of Cocci (Spherical Bacteria)**
Note: There are *6*
✔ **Single** – One individual bacterial cell.
✔ **Diplococci** – Two cocci in **pairs**.
✔ **Tetrads** – Groups of **four** cells.
✔ **Irregular Clusters** – Random, **grape-like** clusters (e.g., Staphylococcus).
✔ **Chains** – Cocci arranged in **long chains** (e.g., Streptococcus).
✔ **Cubical Packets (Sarcina)** – **Eight or more** cocci arranged in a **cube**.
81
List the **Arrangements of Bacilli (Rod-Shaped Bacteria)**
Note: There are *4*.
✔ **Single** – One independent **bacillus** cell.
✔ **Diplobacilli** – Two **bacilli** joined end-to-end.
✔ **Chains** – Bacilli arranged in **long chains** (e.g., Streptobacillus).
✔ **Palisades** – Bacilli **stacked** side by side like a **fence** (e.g., Corynebacterium).
82
Scientists classify **prokaryotes** (bacteria and archaea) based on different characteristics to help identify and understand them.
List the **Classification Systems for Prokaryotes**.
Note: There are *5*
* Microscopic morphology
* Macroscopic morphology
* Bacterial physiology
* Serological analysis
* Genetic and molecular analysis
83
Under Classification Systems for Prokaryotes
* **Individual cell appearance**.
A. Microscopic Morphology
B. Macroscopic Morphology
C. Bacterial physiology
D. Serological analysis
E. Genetic and molecular analysis
**A. Microscopic Morphology**
Note:
✔ Focuses on the appearance of individual cells under a microscope.
✔ Includes shape, size, and arrangement (e.g., cocci, bacilli, spirilla).
✔ Also considers the presence of structures like flagella, pili, and endospores.
84
Under Classification Systems for Prokaryotes
* **Colony appearance**.
A. Microscopic Morphology
B. Macroscopic Morphology
C. Bacterial physiology
D. Serological analysis
E. Genetic and molecular analysis
**B. Macroscopic Morphology**
Note:
✔ Looks at the appearance of bacterial colonies on a petri dish.
85
Under Classification Systems for Prokaryotes
* **Presence of products that are the result of bacterial metabolism and physiological activities**.
A. Microscopic Morphology
B. Macroscopic Morphology
C. Bacterial physiology
D. Serological analysis
E. Genetic and molecular analysis
**C. Bacterial physiology**
Note:
✔ Studies how bacteria function, including:
* What nutrients they use.
* What waste products they produce.
* Their metabolic activities (e.g., fermentation, respiration).
86
Under Classification Systems for Prokaryotes
* **Basically antibody binding properties (antibody is a large molecule produced by the body to attack foreign agents)**.
A. Microscopic Morphology
B. Macroscopic Morphology
C. Bacterial physiology
D. Serological analysis
E. Genetic and molecular analysis
**D. Serological analysis**
Note:
✔ Involves antibodies (proteins the immune system uses to recognize bacteria).
✔ Some bacteria have unique surface molecules that trigger specific antibody reactions.
✔ Used in medical diagnosis (e.g., blood tests for bacterial infections).
87
Under Classification Systems for Prokaryotes
* **Identification based on the presence of genetic materials or molecules**.
A. Microscopic Morphology
B. Macroscopic Morphology
C. Bacterial physiology
D. Serological analysis
E. Genetic and molecular analysis
**E. Genetic and molecular analysis**
Note:
✔ Identifies bacteria based on DNA, RNA, or proteins.
✔ Uses techniques like PCR (Polymerase Chain Reaction) and gene sequencing.
✔ More accurate than morphological or physiological methods.
88
WHAT IS THIS?
* It is the **most widely used reference** for classifying and identifying bacteria.
* A **five-volume** guide covering all known **prokaryotes**
Bergey's Manual of Determinative Bacteriology
89
WHAT IS THIS?
* This is the study of how organisms have evolved over time.
* **Classification is based on genetic information**.
Phylogenetic
90
What are the **2 Domains of Prokaryotes**?
**Archaea** and **Bacteria**
Note:
✔ Archaea – ancient, often live in extreme environments (hot springs, salty water).
✔ Bacteria – more common, found in soil, water, and living organisms.
91
**Five Major Subgroups of Bacteria** (Based on Bergey's Manual)
* Phylum **P**roteobacteria (Gram-Negative Bacteria)
* Phylum **F**irmicutes (Gram-Positive Bacteria)
* Phylum **A**ctinobacteria (High G+C Gram-Positive Bacteria)
* Phylum **B**acteroidetes (Gram-Negative Anaerobes)
* Phylum **C**yanobacteria (Photosynthetic Bacteria)
REMEMBER THE ACRONYM ***PF-ABC***
92
WHAT IS THIS?
* This is used to identify **bacterial disease agents** based on **phenotypic (observable) characteristics**. This method is **quick and practical** for medical diagnosis.
Diagnostic scheme
93
WHAT IS THIS?
* This is a **collection of bacterial cells** which share a overall similar pattern of traits in contrast to other bacteria whose pattern differs significantly.
Species
94
WHAT IS THIS?
* This is a **culture** derived from a single parent that **differs in structure** or metabolism from other cultures of that species (biovars, morphovars).
Strain or Variety
95
WHAT IS THIS?
* A **subspecies that can show differences** in antigenic makeup (serotype or serovar), susceptibility to bacterial viruses (phage type) and in pathogenicity (pathotype).
**Type**
Note:
A type is a subspecies that shows differences in:
* **Antigenic makeup (serotype/serovar)** → Identified by immune response (antibodies).
* **Susceptibility to bacterial viruses (phage type)** → Classified based on resistance or sensitivity to bacteriophages.
* **Pathogenicity**→ Differences in disease-causing ability.
96
WHAT IS THIS?
* These bacteria do **not** cause disease and often play beneficial roles in the environment.
Free-living Nonpathogenic Bacteria
97
WHAT IS THIS?
* These bacteria use **light energy** to produce nutrients from **inorganic compounds** (like CO₂ and water). Unlike plants, they do **not** always release oxygen as a byproduct.
**Photosynthetic Bacteria**
Examples:
* **Cyanobacteria (Blue-Green Algae)** → Produces oxygen as a byproduct.
* **Green and Purple Sulfur Bacteria** → Do not produce oxygen; use sulfur compounds instead of water as an electron donor.
* **Gliding and Fruiting Bacteria** → Motile bacteria that move by gliding over surfaces without flagella.
Form fruiting bodies under starvation conditions, producing spores for survival.
These carry out more photosynthesis than all plants combined.
98
WHAT IS THIS?
Some bacteria have unique adaptations that make them medically important, especially as pathogens.
* **Bacteria that require a host cell to survive and multiply.**
Obligate intracellular parasites
99
WHAT IS THIS?
* Very tiny, gram-negative bacteria
* Most are pathogens
* Obligate intracellular pathogens
* Cannot survive or multiply outside of a host cell
**Rickettsias**
* Example: Rickettsia rickettisii
* Causes: Rocky Mountain Spotted Fever (RMSF).
* Transmission: Bite from an infected tick (Dermacentor species).
100
WHAT IS THIS?
* Tiny
* Obligate intracellular parasites
* Not transmitted by arthropods
**Chlamydias**
This is a common sexually transmitted infection (STI) caused by the bacterium Chlamydia trachomatis. It can affect both men and women.
101
WHAT IS THIS?
* A severe **eye infection** and one of the most common **sexually transmitted** diseases.
**Chlamydia trachomatis**
Note: This can lead to *blindness*.
102
WHAT IS THIS?
* Causes **lung infections** like pneumonia and bronchitis.
* Spread through **respiratory droplets** (coughing, sneezing).
* Symptoms: Cough, sore throat, fever, fatigue.
Chlamydia pneumoniae or *C. pneumoniae*
