Prokaryote Structure & Gram Stain

Question 1

Prokaryotes differ from eukaryotes in that they do not contain any organelles with _

Answer 1

Prokaryotes differ from eukaryotes in that they do not contain any organelles with membranes
* They lack a nucleus, ER, mitochondria, golgi, lysosomes, peroxisomes
* Bacteria also don’t have any introns

Question 2

Bacterial DNA is housed in the _ and has _ shape

Answer 2

Bacterial DNA is housed in the cytoplasm and has circular shape

Question 3

_ are elongated protein filament cylinders that are anchored inside the cell wall and plasma membrane (mostly of gram-negative bacteria)

Answer 3

Flagella are elongated protein filament cylinders that are anchored inside the cell wall and plasma membrane (mostly of gram-negative bacteria)

Question 4

Flagella at one or both ends is called _

Answer 4

Flagella at one or both ends is called polar flagella
* Ex: psudomonas aeruginosa

Question 5

Flagella that is all the way around is called _

Answer 5

Flagella that is all the way around is called peritrichous
* Ex: salmonella

Question 6

Flagella help propel bacterium but they also can help in a regulator response called _

Answer 6

Flagella help propel bacterium but they also can help in a regulator response called chemotaxis
* Chemotaxis is movement towards or away from certain chemicals in the environment

Question 7

_ appear as tiny hairs around a bacterium and they are more common in gram-negative species

Answer 7

Pili appear as tiny hairs around a bacterium and they are more common in gram-negative species

Question 8

Two special functions of pili are _ and _

Answer 8

Two special functions of pili are adhesion and resistance
* Adhesions on the tips of pili allow bacterium to attach to surfaces in the environment
* R-pili are involved in drug resistance transfer via bacterial conjugation

Question 9

The _ provides a barrier from the external environment, prevents osmolysis, and determines whether the bacteria will stain gram positive or negative

Answer 9

The cell envelope provides a barrier from the external environment, prevents osmolysis, and determines whether the bacteria will stain gram positive or negative

Question 10

The capsule is a component of both gram-positive and negative bacteria and it is composed of _ and _

Answer 10

The capsule is a component of both gram-positive and negative bacteria and it is composed of glycoproteins and glycolipids
* Its main function is to defend against host immune responses

Question 11

The outer (lipid) membrane is found in _ bacteria and is formed by a glycolipid layer which primarily contains _

Answer 11

The outer (lipid) membrane is found in gram-negative bacteria and is formed by a glycolipid layer which primarily contains lipopolysaccharide (LPS)

Question 12

LPS is a _ disaccharide that forms a barrier to hydrophobic molecules

Answer 12

LPS is a glucosamine disaccharide that forms a barrier to hydrophobic molecules
* Contributes to the outer membrane’s selective permeability

Question 13

The _ is a rigid structure made up of peptidoglycan; it forms a strong exoskeleton that helps to prevent lysis in hypotonic/isotonic solutions

Answer 13

The cell wall is a rigid structure made up of peptidoglycan; it forms a strong exoskeleton that helps to prevent lysis in hypotonic/isotonic solutions
* Both gram-positive and gram-negative have a cell wall
* If the peptidoglycan is damaged, the bacterium will lyse from the pressure of the internal cytoplasm

Question 14

The cytoplasmic lipid membrane is similar to the cell membrane of eukaryotic cells, however, it does not contain _ (with the exception of mycoplasma)

Answer 14

The cytoplasmic lipid membrane is similar to the cell membrane of eukaryotic cells, however, it does not contain sterols (with the exception of mycoplasma)
* Both gram-positive and gram-negative have this

Question 15

The outer membrane is only found in _ bacteria

Answer 15

The outer membrane is only found in gram-negative bacteria

Question 16

Because _ bacteria don’t have an outer membrane, their cell walls are much thicker

Answer 16

Because gram-positive bacteria don’t have an outer membrane, their cell walls are much thicker

Question 17

The thick gram-positive cell walls contain anionic polymers, _ and _ to provide reinforcement and structural integrity to the cell walls

Answer 17

The thick gram-positive cell walls contain anionic polymers, teichoic acids and lipoteichoic acids to provide reinforcement and structural integrity to the cell walls

Question 18

In prokaryotes, the _ is simply all of the space within the cytoplasmic lipid membrane

Answer 18

In prokaryotes, the cytoplasm is simply all of the space within the cytoplasmic lipid membrane

Question 19

The only structure found in prokaryote’s cytoplasm is _ ; and it is the area that contains the circular bacterial chromosome

Answer 19

The only structure found in prokaryote’s cytoplasm is nucleoid ; and it is the area that contains the circular bacterial chromosome

Question 20

“Competent” bacteria have the ability to absorb naked DNA from the environment and integrate it into the bacterial chromosome via _

Answer 20

“Competent” bacteria have the ability to absorb naked DNA from the environment and integrate it into the bacterial chromosome via homologous recombination

Question 21

Bacteria that must have oxygen to grow are called _

Answer 21

Bacteria that must have oxygen to grow are called obligate aerobes

Question 22

Bacteria that cannot grow in the presence of oxygen are _

Answer 22

Bacteria that cannot grow in the presence of oxygen are obligate anaerobes

Question 23

Bacteria that can grow with or without oxygen are called _

Answer 23

Bacteria that can grow with or without oxygen are called facultative anaerobes
* They can switch between states

Question 24

Obligate anaerobes lack _ and _ which protect bacteria from oxygen free radicals

Answer 24

Obligate anaerobes lack superoxide dismutase and catalase which protect bacteria from oxygen free radicals
* Some antibiotics take advantage of this

Question 25

Bacteria that only grow when specific nutrients are present (such as iron, CO2) are called _

Answer 25

Bacteria that only grow when specific nutrients are present (such as iron, CO2) are called **fastidious bacteria**

Question 26

Pathogenic bacteria that require free iron for survival are capable of excreting _ compounds to bind iron and steal it from the blood and tissue proteins

Answer 26

Pathogenic bacteria that require free iron for survival are capable of excreting **chelating** compounds to bind iron and steal it from the blood and tissue proteins * Chelating compounds are known as *siderophores*

Question 27

Bacteria that cause human infections only replicate through _

Answer 27

Bacteria that cause human infections only replicate through **binary fission** * The chromosome of a single bacterium is replicated --> division of the cytoplasm into two equal daughter cells

Question 28

Some bacteria can transform into _ when they are in adverse conditions without nutrients; they become dormant, withstand harsh conditions, and become reactivated when the environment is more favorable

Answer 28

Some bacteria can transform into **spores** when they are in adverse conditions without nutrients; they become dormant, withstand harsh conditions, and become reactivated when the environment is more favorable --> called **sporulation** * *Example: bacillus, clostridium*

Question 29

Infants cannot have honey because they have immature digestive systems that can't clear out the spores of _ that can contaminate honey

Answer 29

Infants cannot have honey because they have immature digestive systems that can't clear out the spores of ***clostridium botulinum*** that can contaminate honey * Spores can germinate and grow toxin-forming bacteria * This is called infant botulism * The first sign is usually constipation, then respiratory distress, lack of facial expression, drooling, muscle weakness can follow

Question 30

In _ phase, bacteria mature and adapt to the growth environment; reproduction is slow

Answer 30

In **lag phase**, bacteria mature and adapt to the growth environment; reproduction is slow

Question 31

_ is the period of rapid bacterial growth; the new cells created is proportional to the number of bacteria --> this phase continues until bacteria run out of resources

Answer 31

**Exponential growth phase** is the period of rapid bacterial growth; the new cells created is proportional to the number of bacteria --> this phase continues until bacteria run out of resources

Question 32

When the bacteria runs out of nutrients, accumulates toxic waste, or runs out of space, it enters the _ phase

Answer 32

When the bacteria runs out of nutrients, accumulates toxic waste, or runs out of space, it enters the **stationary** phase

Question 33

During the _ stage, the number of new bacteria appearing and dying is roughly the same

Answer 33

During the **stationary** stage, the number of new bacteria appearing and dying is roughly the same

Question 34

The _ phase is when the bacterial population diminishes and eventually dies

Answer 34

The **death phase** is when the bacterial population diminishes and eventually dies

Question 35

Bacterial infections in humans are measured in [unit]

Answer 35

Bacterial infections in humans are measured in **colony forming units (CFUs)** ## Footnote acute infection

Question 36

When stained, _ bacteria will appear purple/blue

Answer 36

When stained, **gram-positive** bacteria will appear purple/blue * Their thick peptidoglycan cell walls retain the crystal violet die-iodine complex after the decolorizing step * Ex: Staphylococcus

Question 37

When stained, _ bacteria will appear pink

Answer 37

When stained, **gram-negative** bacteria will appear pink * They only retain the safranin stain so they appear pink * Ex: E.coli

Question 38

Atypical bacteria are gram nonreactive and don't retain any dye from the staining process; instead we must use _ staining

Answer 38

Atypical bacteria are gram nonreactive and don't retain any dye from the staining process; instead we must use **acid-fast** staining * Ex: *Chlamydiaceae, Legionella, Mycobacteria, Nocardia*

Question 39

Acid-fast bacteria have large amounts of _ in their cell walls

Answer 39

Acid-fast bacteria have large amounts of **mycolic acid** in their cell walls * Carbol fuchsin dye is used --> it dyes all cells, but once the cells are washed with acid alcohol, only acid-fast bacteria will be bright red

Question 40

The most common method for endospore staining is _

Answer 40

The most common method for endospore staining is **Schaeffer-Fulton method** * Bacteria is stained with malachite green (binds spores) then counterstained with safranin * Spores will be green and bacteria pink * Ex: *Clostridium, bacillus* (including B anthracis)

Question 41

How do we visualize capsules?

Answer 41

Capsules do not bind to most dyes; we can stain the background with **India ink or nigrosine** --> then the bacteria can be counterstained

Question 42

How does LPS activate systemic immune reactions?

Answer 42

LPS interacts with immune cell receptors --> leads to release of cytokines and inflammatory factors --> blood vessel dilation, increased permeability

Question 43

_ are a more elongated coccobacillus, rod-shaped, like a hot dog

Answer 43

**Bacillus** are a more elongated coccobacillus, rod-shaped, like a hot dog

Question 44

_ are spherical bacteria

Answer 44

**Coccus** are spherical bacteria

Question 45

_ are an intermediate between cocci and bacilli that look like short rods/ ovals

Answer 45

**Coccobacillus** are an intermediate between cocci and bacilli that look like short rods/ ovals

Question 46

_ are curved/ comma shaped

Answer 46

**Vibrio** are curved/ comma shaped

Question 47

_ are wavy shaped bacteria

Answer 47

**Spirillum** are wavy shaped bacteria

Question 48

_ are a twisted shape like the threads on a screw

Answer 48

**Spirochete** are a twisted shape like the threads on a screw

Question 49

_ are bacteria that form pairs

Answer 49

**Diploids** are bacteria that form pairs * ex: *Neisseria*

Question 50

_ are bacteria that form short, single-file lines

Answer 50

**Chains** are bacteria that form short, single-file lines * *Streptococcus*

Question 51

_ are bacteria that bunch together like grapes

Answer 51

**Clusters** are bacteria that bunch together like grapes * ex: *Staphylococcus*

Question 52

_ are bacteria that form long thread-like filaments

Answer 52

**Hyphae** are bacteria that form long thread-like filaments * ex: *Nocardia*