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Microbiology > Microbiology Chapter 4 > Flashcards

Microbiology Chapter 4 Flashcards

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1
Q

Glycocalyx (structure)

A

Both
In prokaryotes, it may take
the form of a capsule, a
slime layer, or the matrix
of a biofilm

It’s made of sticky carbohydrates and
covers the plasma membrane (in
eukaryotes—it covers the cell wall in
prokaryotes). Promotes adherence,
resistance to dessication, resistance to
phagocytosis (thereby increasing
virulence), and cell-cell recognition

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2
Q

Flagella (structure)

A

Both

Promotes taxis (e.g., chemotaxis,
phototaxis). In prokaryotic cells the
flagellum rotates clockwise or
counterclockwise, but a eukaryotic
flagellum undulates in a wavelike manner

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3
Q

Chemotaxis

A

movement of a motile cell or organism, or part of one, in a direction corresponding to a gradient of increasing or decreasing concentration of a particular substance.

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4
Q

Phototaxis

A

Phototaxis (phototactic response) is the cellular behavior in which cells swim toward or away from the light source (positive or negative phototaxis, respectively)

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5
Q

Cilia (structure)

A

Eukaryotes

Short projections (like eyelashes) on the
outside of a cell. For locomotion or feeding
(sweeps fluid across the surface of the cell
to bring food in)

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6
Q

Axial filaments
(endoflagella)
(structure)

A

Prokaryotes

Specific to spirochetes. They are internal
flagella that are twisted around the
organism and allow it to move in a
corkscrew motion

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7
Q

Fimbriae (structure)

A

Prokaryotes (common in
Gram - bacteria; also
found in Gram + bacteria
and archaea)

Can be just a few or hundreds. Promote cell
adherence. Ex: Neisseria gonorrhoeae.
Shorter and stiffer than pili

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8
Q

Gram + Bacteria

A

Bacteria that contain a thick cell wall.

Cell wall contains teichoic acid.

Appear blue or purple under a microscope.

Wall retains color.

Ex. Staphylococcus.

Do not have an outer membrane

Peptidoglycan is found within its cell wall.

Many types cause diseases that require specific antibiotics.

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9
Q

Gram Negative Bacteria

A

Bacteria that contain thin cell wall

The outer membrane of Gram-negative bacteria contains lipopolysaccharide.

Do not hold the dye well.

may appear red under the microscope because red-pink iodine is used alongside the Gram stain as a control.

far thinner layer of peptidoglycan

Have an outer membrane

bacteria are more challenging to treat

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10
Q

Pili

A

Prokaryotic

1 or 2 per cell. Involved in motility and the
transfer of plasmid DNA (“conjugation”).

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11
Q

Conjugation

A

the process by which one bacterium transfers genetic material to another through direct contact. During conjugation, one bacterium serves as the donor of the genetic material, and the other serves as the recipient. The donor bacterium carries a DNA sequence called the fertility factor, or F-factor.

Through sex pilus that connects the two cells

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12
Q

Cell Wall

A

Both
Most prokaryotes and
some eukaryotes (fungi,
plants, and algae)

Give shape to the cell and affect transport
of materials in/out of the cell.

Bacteria =peptidoglycan.

Fungi = chitin

Plants and algae = cellulose.

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13
Q

Peptidoglycan

A

BACTERIA

a substance forming the cell walls of many bacteria, consisting of glycosaminoglycan chains interlinked with short peptides.

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14
Q

Chitin

A

FUNGI

a fibrous substance consisting of polysaccharides and forming the major constituent in the exoskeleton of the cell walls of fungi.

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15
Q

Cellulose

A

PLANTS AND ALGAE

an insoluble substance which is the main constituent of plant cell walls and algae. It is a polysaccharide consisting of chains of glucose monomers.

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16
Q

Plasma membrane

A

Both

Cell-cell recognition,

transport of substances in/out of the cell. Phospholipid bilayer.

Eukaryotic membranes and those
of mycoplasmas are reinforced with special sterols.

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17
Q

Phospholipid Bilayer

A

Consists of two layers of phospholipids,

Hydrophobic, or water-hating, interior

Hydrophilic, or water-loving, exterior.

The hydrophilic (polar) head group

hydrophobic tails (fatty acid chains)

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18
Q

Transport proteins

A

Both

Integral membrane proteins (i.e., cross the
entire lipid bilayer) that can move (usually
large and/or polar) substances in/out of a
cell.

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19
Q

Lysosomes

A

Lysosomes

Contain dozens of different digestive
enzymes; used to break down various
substances brought into the cell by
endocytosis (e.g., phagocytosis or
pinocytosis) so a cell can reuse their parts.

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20
Q

Phagocytosis

A

the ingestion of bacteria or other material by phagocytes and amoeboid protozoans.

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21
Q

Pinocytosis

A

the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane

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22
Q

Cytoskeleton

A

Both

Provides support and shape to a cell;
assists in transporting substances or
organelles throughout the cell. Can be
altered to allow cells to move

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23
Q

Nucleoid region
(structure)

A

Prokaryotes

Where the (usually) circular chromosome
is found. It is supercoiled around specific
proteins. Plasmids are not generally found
here.

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24
Q

Plasmids (Structure)

A

Prokaryotes

a genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan. Plasmids are much used in the laboratory manipulation of genes.

Small extrachromosomal genetic elements that aren’t vital to survival. They can be useful when they carry genes for antibiotic resistance or toxin production. Can be passed between cells via conjugation

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25
Q

Chromosome (structure)

A

Both

Holds the genetic information for the cell
(i.e., instructions for making proteins).

It is DNA in a complex with proteins (histones in eukaryotes).

Prokaryotes = usually circular;

eukaryotes = multiple linear molecules of DNA

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26
Q

Nucleus (organelle)

A

Eukaryotes

Contains the DNA (+ histones). Has a
double membrane called a nuclear
envelope. Where protein synthesis begins
(specifically, transcription).

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27
Q

Histones

A

any of a group of basic proteins found in chromatin.

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28
Q

Ribosomes (structure)

A

Both

Scaffolds upon which proteins are made.

In eukaryotes, can be free in the cytosol or
attached to another organelle (the rough
ER).

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29
Q

Rough endoplasmic
reticulum (organelle)

A

Eukaryotic

Extends from the nucleus. Processes and
transports proteins made by the attached
ribosomes to the Golgi complex. Also
makes lipids.

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30
Q

Smooth endoplasmic
reticulum (organelle)

A

Eukaryotic

Extends from the rough ER. Does not have
ribosomes on the surface. Synthesizes
lipids, including steroids.

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31
Q

Golgi complex
(apparatus)

A

Eukaryotic

Further processes proteins from the rough ER and sends them to their final
destination (plasma membrane, secretion
from the cell via the plasma membrane, or the lysosomes).

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32
Q

Inclusions or inclusion
bodies (structure)

A

Prokaryotes

Storages units for items the cells need.
Review the types in your book. Can be
useful clinically in identification

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33
Q

Chloroplasts (organelle)

A

Eukaryotes (algae and plants)

Photosynthesis (will be important for
chapter 27; see also Lynn Margulis in
chapter 4).

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34
Q

Mitochondria (organelle)

A

Eukaryotes

ATP (energy) production via cellular
respiration. May have originated as freeliving prokaryotes (endosymbiotic theory).

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35
Q

Endospores (structure)

A

Prokaryotes

Certain genera (Clostridium and Bacillus);
formed when the environment isn’t
conducive to survival (sporogenesis); not
for reproduction. Cell is revived through
germination.

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36
Q

Binary fission

A

Prokaryotes

Asexual reproduction. The DNA replicates
and the cell elongates to twice the original
length. A septum forms between the two
and the two cells are separate

37
Q

Mitosis/cytokinesis

A

Eukaryotes

Asexual reproduction of cells.

Mitosis = division of the cell nucleus.

Cytokinesis = division of the cytoplasm.

38
Q

Chemotaxis

A

Both

Movement of a cell in response to chemical stimuli (attractants or repellants).

39
Q

Passive transport
(simple vs. facilitated
diffusion, osmosis)

A

Both

Movement of substances down a
concentration gradient (from a
concentrated to a less concentrated area).

Does not require ATP.

Can occur through the lipid bilayer (simple diffusion and osmosis of water)

or through a transport protein (e.g., a channel; facilitated diffusion).

40
Q

Group translocation

A

Prokaryotes

A process in which an organic molecule
(e.g., glucose) is moved into a cell while
being chemically modified. This traps the
molecule in the cell so the cell can use it.

41
Q

Endocytosis (phagocytosis, pinocytosis, and receptor-mediated endocytosis)

A

Eukaryotes

Movement of substances into a cell.

Phagocytosis = cell eating (large particles),

pinocytosis = cell drinking (extracellular
fluid),

receptor mediated endocytosis (cells
internalize specific substances by latching
onto them via cell-surface receptors).

All items are delivered to lysosomes for
digestion.

42
Q

Sporulation (sporogenesis) vs.
germination

A

Prokaryotes (endospore-forming species only)

Sporogenesis = creation of an endospore

germination = conversion of endospore to living, growing (i.e., vegetative) cell

43
Q

R-Factor

A

Genes for resistance to various drugs

44
Q

Bacteria Cell Shapes

A
  1. Spherical (cocci)
  2. Rod-Shaped (Bacilli)
  3. Spherical-vibrio and spirochetes
45
Q

Arrangements of Cocci

A

Can exist

  1. Singly,
  2. Pairs (as diplococci ),
  3. Groups of four (as tetrads ),
  4. Chains (as streptococci ),
  5. Clusters (as stapylococci ),
  6. Cubes consisting of eight cells (as sarcinae).

Cocci may be oval, elongated, or flattened on one side.

46
Q

Arrangements of Bacilli

A
  1. Single Bacillus
  2. Diplobacilli: Two bacilli arranged side by side with each other.
  3. Streptobacilli: Bacilli arranged in chains.
  4. Coccobacillus: Oval and similar to coccus (circular shaped bacterium).
47
Q

How long are MOST bacteria?

A

2.0 to 8.0 µm

48
Q

Acid-fast cell walls contain high concentrations of:

A

Mycolic Acid

49
Q

Acid-fast cell walls

A

Acid-fast microorganisms are characterized by wax-like, nearly impermeable cell walls; they contain mycolic acid and large amounts of fatty acids, waxes, and complex lipids. This type of cell wall is resistant to most compounds, therefore acid-fast microorganisms require a special staining technique

50
Q

Monotrichous

A

having a single flagellum at one pole. used of bacteria.

51
Q

Amphitrichous

A

Having a single flagellum on each of two opposite ends. (Only one flagellum operates at a time, allowing the bacterium to reverse course rapidly by switching which flagellum is active.)

52
Q

Lophotrichous

A

Having multiple flagella located at the same point, so that they can act in concert to drive the bacterium in a single direction

53
Q

Peritrichous

A

having or being flagella which are uniformly distributed over the body.

54
Q

Spirochete

A

a flexible spirally twisted bacterium, especially one that causes syphilis.

Moves by axial filiments

55
Q

Capsule

A

a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell.

It is a well-organized layer, not easily washed off, and it can be the cause of various diseases.

Protects pathogenic bacteria from phagocytosis

56
Q

Proteins that distinguish among serovars (a distinct variation within a species of bacteria or virus or among immune cells of different individuals) of Gram-negative bacteria are found in which structures?

A

Flagella

57
Q

Which of the following is NOT a way materials can move across prokaryotic plasma membranes?

A

Endocytosis (Modern prokaryotes lack endocytosis or phagocytosis)

58
Q

Prokaryotic ribosomes are composed of two subunits of what sizes?

A

30S + 50S

59
Q

The nucleus in a eukaryotic cell is surrounded by

A

a nuclear envelope

60
Q

In chloroplasts, chlorophyll is contained in flattened sacs called:

A

Thlakoid

61
Q

Which organelle contains enzymes that can oxidize various organic substances?

A

Peroxisomes

62
Q

Which organelle synthesizes phospholipids, fats, and steroids?

A

Smooth ER

63
Q

Which contain 70S ribosomes?

A

prokaryotes, mitochondria, and chloroplasts

64
Q

True or false? The LPS layer in a Gram-negative bacterium is located inside of the plasma membrane.

A

True

65
Q

Lipopolysaccharides (LPS)

A

Lipopolysaccharides (LPS) are important outer membrane components of gram-negative bacteria.

66
Q

What do streptobacilli and streptococci have in common?

A

They both appear as chains of cells under a microscope.

67
Q

In Gram staining, a bacterium that has a thin layer of peptidoglycan and an outer membrane will stain pink. Why is this?

A

The alcohol wash dissolves the outer membrane and pierces holes in the peptidoglycan, allowing the initial dye to wash out, so that the bacterium can stain pink.

68
Q

_________, an endotoxin known to induce fever, clotting abnormalities, and low blood pressure in humans, is found in _________ bacteria.

A

Lipid A,

Gram Negative

69
Q

A Gram-positive bacterium that has been exposed to human saliva (which contains lysozyme) would be called a/an:

A

Protoplast

Protoplasts can be generated by stripping the cell wall from plant, bacterial, or fungal cells by mechanical, chemical or enzymatic means.

70
Q

Would penicillin be as effective against the cell wall of an alga as it would be against the cell wall of a bacterium? Why or why not?

A

yes because both cell walls are made up of peptidoglycan

The antibiotic penicillin blocks the bacterial processes that build the cell wall. Due to the lack of cell wall, the organism dies easily. Human cells don’t have a cell-wall. So penicillin cannot have such an effect on human cells.

71
Q

Prokaryotic Reproduction

A

Reproduction in prokaryotes is asexual and usually takes place by binary fission. The DNA of a prokaryote exists as as a single, circular chromosome. Prokaryotes do not undergo mitosis; rather the chromosome is replicated and the two resulting copies separate from one another, due to the growth of the cell.

72
Q

What will happen if a bacterial cell is placed in a hypertonic solution containing 10% NaCl?

A

Will Plasmolyze

a solution containing 10% salt is hypertonic. When a cell is placed in a hypertonic environment, there is a net movement of water to the outside of the cell (from the higher water environment inside the cell). The cell shrinks in response

73
Q

Plasmolysis

A

Plasmolysis is the shrinking of protoplasm away from the cell wall of a plant or bacterium. The protoplasmic shrinking is often due to water loss via exosmosis, thereby resulting in gaps between the cell wall and the plasma membrane

74
Q

In a phospholipid bilayer, water interacts with the _______________ heads of the phospholipid molecules.

A

Polar

75
Q

All fungal cells contain __________ in their cell walls.

A

Chitin

76
Q

Flagella

A

Relatively long filamentous appendages consisting of a filament, hook, and basal body.

-Prokayotic flagella rotate to push cell.

-Motile bacteria exhibit taxis; positive taxis is movement toward an attractant, and negative taxis is movement away from a repellent.

-Flagellar (H) protein is an antigen.

77
Q

Axial Filament

A

Spiral cells that move by means of an axial filament (endoflagellum) are called spirochete.

-Axial filaments are similar to flagella, except that they wrap around the cell.

78
Q

Fimbrae

A

Help cells adhere to surfaces.

79
Q

Pili

A

Are involved in twitching motility and DNA transfer.

80
Q

Gram positive bacteria Cell Wall

A
  1. Gram positive bacteria- have many layers of peptidoglycan forming a thick, rigid structure.
    -The crystal violet iodine complex combines with peptidoglycan.
81
Q

Gram negative bacteria Cell Wall

A

Gram negative bacteria- have a thin layer of peptidoglycan.
-The decolorizer removes the lipid outer membrane of this G-NEG. bacteria and washes out the crystal violet.

82
Q

Acid-fast bacteria Cell Wall

A

Acid-fast bacteria- Identify all bacteria of the genus Mycobacerium and pathogenic species of Nocardia. AFB contain high concentration of a hydrophobic waxy lipid in their cell wall that prevent the uptake of dyes, including those used in the Gram stain.

83
Q

Archaea Cell Wall

A

Semi rigid cell wall that protects them from the environment. The cell wall of archaea is composed of S-layers and lack peptidoglycan molecules with exception of methanobacteria who have pseudpeptidoglycan in their cell wall.

84
Q

Mycoplasms

A

A bacteria that lack a cell wall around their cell membranes. With out cell wall they are unaffected by many common antibiotics like penicillin.

85
Q

Differentiate protoplast, spheroplast, and L form.

A

Protoplast is a wall-less cell

  • Spheroplast is a wall-less gram-negative cell
  • Protoplasts and spheroplasts are susceptible to osmotic lysis
  • L forms are wall-less cells that swell into irregular shapes
86
Q

How do protoplasts differ from L forms? Under what
circumstances do L forms arise?

A

Protoplasts are cells that have lost their cell wall due to hydrolysis brought about by lysozymes. L forms are cells that intentionally lose their cell walls spontaneously or in response to a particular condition such as the activity of antibiotics or lysozymes.

87
Q

Describe the structure, chemistry, and
functions of the prokaryotic plasma
membrane

A
88
Q

Hypertonic Solution

A

a medium having a higher concentration of solutes than inside the cell has (hyper means above or more)

88
Q

Hypotonic Solution

A

outside the cell is a medium whose concentration of solutes is lower than that inside the cell. (hypo meaning under or less)

Microbiology (4 decks)

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