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GENERAL STRUCTURE OF A PROKARYOTE Flashcards

1
Q

GENERAL STRUCTURE OF A PROKARYOTE

A

Glycocalyx
Bacterial chromosome/ nucleiod
Pilus
Mesosome
Flagellum
Fimbriae
Inclusion/ granules
Cell wall
Cell membrane
Ribosomes

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2
Q

STRUCTURES EXTERNAL TO THE CELL WALL

A
  1. Glycocalyx
  2. Flagella
  3. Axial Filaments
  4. Fibriae and Pili
  5. Cell Wall
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3
Q

PROKARYOTIC CELLS are much more smaller than eukaryotic cells.
They have no____, they lack____
• They are encased by a____
• Many have a capsuled or a slime layer made of____
• Often have appendages or protrusions on their____

A

nucleus; organelles

cell wall

polysaccharide

surface

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4
Q

Filamentous protein attached to the cell surfaces that provide swimming movement

A

Flagella

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5
Q
  • specialized appendage attached to the cell by a basal body that holds a long rotating filament.

The movement pushes the cell forward and provides motility

A

Flagellum

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6
Q

Parts of flagella

A

filament
Hook
basal body

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7
Q

Flagellum

• Primarily a motility organelle that enables movement and chemotaxis

• Bacteria can have one flagellum or several, and they can be
(1)_____ - one or several flagella at one spot
(2)_____ - several flagella all over the bacterium

A

polar

peritrichous

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8
Q

1.______ - long, thin, helical structure composed of proteins
2._____ - curved sheath
3._____- stack of rings firmly anchored in cell wall

A

Filament

Hook

Basal body

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9
Q

Flagellum

• Rotates_____

_____distributed over entire cell

A

360 degrees

1-2 or many

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10
Q

Flagellar arrangements

A

(a) Monotrichous
(b) Amphitrichous
(c) Lophotrichous
(d) Peritrichous

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11
Q
  • no flagella
A

Atrichous

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12
Q

• - flagella dispersed over surface of cell, slowest / flagella surrounding the bacterial cell

A

Peritrichous

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13
Q

Family enterobacteriaceae if motile

A

• Salmonella typhi
• Escherichia coli
• Proteus spp. - highly motile organism

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14
Q
  • single flagellum at one end
A

Monotrichous

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15
Q
  • small bunches arising from one end of cell

Spirilla spp.

A

Lopotrichous

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16
Q
  • flagella at both ends of cell

Alcaligenes faecalis

A

Amphitrichous

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17
Q

have flagella which project in all directions.

______rotation of flagellar motors results in random re-orientation for the bacterium, but ______rotation produces approximate straight-line motion.

A

E. coli

Clockwise (CV)

counter-clockwise (CC)

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18
Q

is the directed motion of an organism toward environmental conditions it deems attractive and/or away from surroundings it finds repellent

A

Chemotaxis

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19
Q

• Movement of flagellated bacteria such as Escherichia coli can be characterized as a sequence of…

A

smooth swimming runs punctuated by intermittent tumbles

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20
Q

• last only a fraction of a second which is sufficient to effectivelv randomize the direction of the next run

A

Tumbles

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21
Q

• tend to be variable in length, extending from a fraction of a second to several minutes

A

Runs

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22
Q

The tendency to____ is enhanced when the bacterium perceives conditions to be worsening, or when an attractant concentrations decrease, or repellent concentrations increase.

____ is suppressed and cells keep running when they detect that conditions are improving.

A

tumble

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23
Q

enclosed between cell wall & cell membrane of spirochetes

Motility (corkscrew fashion )

A

Internal Flagella

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24
Q

Internal flagella

A

Axial Filaments
Periplasmic filaments

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25
Q

Appendages for Attachment

A

Fimbriae
Pili

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26
Q

fine hairlike bristles (oligomeric protein pilin) from the cell surface; “common pili or attachment pili”; 100-600 filaments per cell

For adhesion to other cells and surfaces

A

FIMBRIAE

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27
Q

Pilus/pili (special types)

Appendages for____ (sex pili, conjugative pili, F pilus) rigid tubular structure pilin (VirB2);

elongate and retract commonly seen in all_____

Function:_____

A

Mating

Gram negative bacteria

joins bacterial cells for DNA transfer (conjugation)

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28
Q

adhesion/adherence to cell surfaces, aggregation of microorganisms (biofilm formation), twitching motility

A

Type IV Pili

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29
Q
  • Fine, hairlike bristles from the cell surface that help in adhesion to other cells and surfaces
A

Fimbriae

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30
Q
  • an elongate, hollow appendage used in transfers of DNA to other cells and in cell adhesion
A

Pilus

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31
Q

Bacterial Surface Coating – Cell envelope

A

Glycocalyx
Cell wall

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32
Q

external to the cell wall

polysaccharides (sugars/carbohydrates) and/or proteins

A

Glycocalyx

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33
Q

FUNCTIONS
▪ Attachment; receptors
▪ inhibits killing or phagocytosis by white blood cells or predatory protozoa

A

Glycocalyx

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34
Q

Glycocalyx

2 TYPES:

A

Capsule
Slime layer/ biofilm

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35
Q

Glycocalyx

highly organized
tightly attached

A

capsule

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36
Q

Glycocalyx

loosely organized and attached

A

slime layer / biofilm

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37
Q

is a complex, multilayered structure that serves to protect these organisms from their unpredictable and often hostile environment

A

bacterial cell envelope

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38
Q

• N-acetylglucosamine (NAG)
• N-acetylmuramic acid (NAM)
• Linked by polypeptides

provides strong, flexible support to the bacterial cell
Maintains cell integrity

A

PEPTIDOGLYCAN

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39
Q

– Peptidoglycan

A

Murein

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40
Q

Gram-positive Cell Wall -color

•thickness– several layers of peptidoglycan

A

purple

15-80 nm thick

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41
Q

• endotoxin

• may serve as receptor & block immune response

• With Braun lipoproteins & porins

(Omp C, Omp F, Omp A)

A

Lipopolysaccharides or LPS

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42
Q

Atypical Cell Walls

A

Mycobacterium, Nocardia

Mycoplasma

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43
Q

Gram-positive cell wall with mycolic acid

basis for acid-fast stain

A

Mycobacterium, Nocardia

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44
Q

no cell wall
pleomorphic
Membrane is stabilized by sterol-like molecules

A

Mycoplasma

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45
Q

Cell wall-less forms

A

spheroplasts, or protoplasts

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46
Q

> surrounded by a thin, peptidoglycan cell wall which itself is surrounded by an outer membrane containing lipopolysaccharide

A

Gram-Negative Bacteria

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47
Q

-> lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than in gram negatives.

Threading through the layers of peptidoglycan are the long anionic polymers called_____

A

Gram-Positive Bacteria

TEICHOIC ACIDS

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48
Q

• External covering outside the cytoplasm Composed of two basic layers:

A

(1) cell wall and
(2) cell membrane

49
Q

A vast polymer consisting of interlocking chains of identical peptidoglycan monomers

A

Peptidoglycan

50
Q

consists of two joint amino sugars and acetyl glucosamine or (NAG) and N-acetylmuramic acid or (NAM) with a pentapeptide coming off of the NAM.

A

peptidoglycan monomer

51
Q

Peptidoglycan is a rigid wall that gives the cell its structure and protects the plasma membrane, and it also prevents…

A

osmotic lysis

52
Q

macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments

provides strong, flexible support to keep bacteria from burstingor collapsing because of changes in osmotic pressure

A

Peptidoglycan

53
Q

The two major functions of the cell wall are:

A
  1. maintaining shape
  2. withstanding turgor pressure
54
Q

It is important to note that not all bacteria have a cell wall.

Most bacteria (about 90%) have a cell wall and have one of two types:

A
  1. Gram-positive cell wall
  2. Gram-negative cell wall
55
Q

The two different cell wall types can be identified in the laboratory by____
Developed in 1884, used ever since

A

differential stain, known as the Gram stain

56
Q

Consists of a homogenous sheath of peptidoglycan 20-80nm thick

A

Gram positive cell wall

57
Q

tightly bound acidic polysaccharides including, teichoic acid and lipoteichoic

acid cell membrane

Retain crystal violet and stain blue or purple.

A

Gram positive cell wall

58
Q

In a gram positive cell wall, it is:

Surrounds the cytoplasmic membrane

Decorated with teichoic acids, polysaccharides and proteins

Plays a major role in bacterial physiology since it maintains cell shape and integrity during growth and division

Acts as the interface between the bacterium and its environment

A

Peptidoglycan

59
Q

Which is more complex? Gram positive or negative cell wall?

A

Negative cell wall

60
Q

• Consists of an outer membrane containing proteins, phospholipids and lipopolysaccharide (LPS)
• thin shell of peptidoglycan
• periplasmic space
• inner membrane

A

Gram negative cell wall

61
Q

• Lose crystal violet and stain red or pink from safranin counterstain

• Protective structure while providing some flexibility and sensitivity to lysis

A

Gram negative cell wall

62
Q

T or F

Gram negative cell wall also contains Peptidoglycan

A

True

Although only a couple of layers representing 5-10% of the total cell walls

63
Q

GRAM-NEGATIVE CELL WALL
• Most notable is the presence of a plasma membrane located outside of the peptidoglycan layers known as the________

A

outer membrane

64
Q

In gram negative cell wall

Makes up the bulk of the Gram-negative cell wall

Composed of a lipid bilayer, very similar in composition to eh cell membrane with polar heads, fatty acid tails and integral proteins.

A

Outer membrane

65
Q

Gram negative cell wall

It differs from the cell membrane by the presence of large molecules known as the ________ which are anchored into the outer membrane and project from the cell into the environment.

A

lipopolysaccharide (LPS)

66
Q

COMPONENTS OF THE LIPOPOLYSACCHARIDE
Three different components

A
  1. O-Antigen / O-Polysaccharide -
  2. Core polysaccharide
  3. Lipi A
67
Q

Lypopolysaccharides

    • outermost part of the structure
      2.
    • anchors the LPS into the outer membrane
A

O-Antigen / O-Polysaccharide

Core polysaccharide

Lipi A

68
Q

Chemical composition: Positive vs Negative

A

P:
Peptidoglycan
Teichoic acid
Lipoteichoic acid

N:
Lipopolysaccharide
Lipoprotein
Peptidoglycan

69
Q

Thickness: Positive vs Negative

A

P: Thicker (20-80 nm)

N: Thinner (8-11 nm)

70
Q

Outer membrane: Positive vs Negative

A

P: none

N: yes

71
Q

Positive vs Negative

Periplasmic space
Porin proteins
Permeability

A

P:
Narrow
No
More penetrable

N:
Extensive
Yes
Less penetrable

72
Q

Bacteria of the genus_______ which causes tuberculosis, and Hansen’s disease (leprosy)

  • These do not stain easily with the gram stain because these organisms are stained with______, hence the name Acid fast organisms

• They contain waxy lipids in their cell walls/ so called _____

A

Mycobacteria

Acid-fast stain

MYCOLIC ACID

73
Q

The genus_____ is also acid fast

74
Q

This stain is used to identify certain parasites like Cryptosporidium

75
Q

PLASMA (CYTOPLASMIC MEMBRANE)
• Also called as the

A

INNER MEMBRANE

76
Q

• Thin structure lying inside the cell wall and enclosing the cytoplasm of the cell

Provides protection for a cell
• Provides a fixed environment inside the cell

A

PLASMA (CYTOPLASMIC MEMBRANE)
• Also called as the INNER MEMBRANE

77
Q

• Composition of inner membrane

A

phospholipids and proteins

78
Q

Cytoplasmic membrane/ Inner membrane

FUNCTIONS

A
  1. Transport nutrients into the cell
  2. Transport toxic substances out of the cell
  3. Plasma membrane will have proteins on it which interacts with other cells
79
Q

Dense, gelatinous solution of sugars and amino acids and salt

Mostly of the composition of this is 70-80% of water

Serves as a solvent of materials used in all cell function

A

Inner membrane
Cytoplasmic membrane

80
Q

single, circular, double-stranded DNA molecule

A

NUCLEOID: CHROMOSOME

81
Q

contains all the genetic information required by a cell

A mass of genetic material/ DNA

the regulatory center

A

NUCLEOID: CHROMOSOME

82
Q

• The region regulates growth reproduction, and function of the prokaryotic cell.
• The previously mentioned proteins and enzymes are essential in these processes.

A

Nucleoid: chromosome

83
Q

small circular, DOUBLE-STRANDED DNA.
different than chromosomal DNA
• all genetic material found in an organism’s chromosomes

84
Q

free or integrated into the chromosome

duplicated and passed onto offspring

not essential to bacterial growth & metabolism

85
Q

may encode antibiotic resistance, tolerance to toxic metals, enzymes & toxins
used in genetic engineering-readily manipulated & transferred from cell to cell

86
Q

replicates independently of chromosomal DNA

87
Q

FUNCTIONS
may contain genes that enhance the survival of an organism either by killing other organisms or by defending the host cell by producing toxins

some plasmids facilitate the process of replication in bacteria

since plasmids are so small, they usually only contain a few genes with a specific function as opposed to a large amount of non-coding DNA

88
Q

Functions of plasmid

A

may contain genes that enhance the survival of an organism either by killing other organisms or by defending the host cell by producing toxins

some facilitate the process of replication in bacteria

since they are so small, they usually only contain a few genes with a specific function as opposed to a large amount of non-coding DNA

89
Q

• Site of protein synthesis

90
Q

• microscopic factories found in all cells including bacteria
• they translate the genetic code from the molecular language of nucleic acid to that of amino acids in which amino acids are the building blocks of proteins

91
Q

• are the molecules that perform all the functions of cells and living organisms

92
Q

•intracellular storage bodies/reserve deposits

A

Inclusions and granules

93
Q

• important component of metabolism in many organisms spanning the bacterial eukaryotes and archaeal domains
• the parts of the cell that store the cell’s energy reserves as well as other important metabolites

A

Inclusions and granules

94
Q

• resting, dormant cells

produced by some Gram (+) genera -Clostridium, Bacillus & Sporosarcina

A

ENDOSPORES

95
Q

ENDOSPORE

• have a 2-phase life cycle

A

vegetative cell
endospore

96
Q

Endospore

TWO PROCESSES
- formation of endospores
- return to vegetative growth

A

Sporulation

Germination

97
Q

• withstand extremes in heat, drying, freezing radiation & chemicals

Ensure the survival of bacteria in adverse environmental conditions such as: Nutrient deficiency; carbon deficiency; overpopulation

98
Q

Endospore

Spores that form within the cells mainly in bacteria

formed within bacterial vegetative cells or mother cells known as______

99
Q

Basis for acid- fast stain

A

Mycolic acid

100
Q

Gram positive cell wall with mycolic acid

A

Mycobacterium, Norcardia

101
Q

• Serves as the site for electron transport processes & systems (ETS), enzyme ATP synthetase

A

Cytoplasmic Membrane or Plasma Membrane

102
Q

• Highly sensitive to changes in the environment (permeability barrier)

A

Cytoplasmic Membrane or Plasma Membrane

103
Q

• Composed of 40% phospholipid, 60% protein; arranged in fluid mosaic model

A

Cytoplasmic Membrane or Plasma Membrane

104
Q

An aqueous, dense gelatinous solution of:

Macromolecules: proteins (enzymes), mRNA, tRNA

Small molecules of energy sources, precursors of macromolecules, metabolites or vitamins

Various inorganic ions and cofactors

105
Q

Cytoplasm is ______% water; solvent for materials used in cell functions

106
Q

Primary components of cytoplasm

A

nucleoid, ribosomes, inclusions

107
Q

single, circular DNA molecule, free in the cytoplasm, coiled/supercoiled & anchored by proteins

A

Bacterial Chromosome (Nucleoid)

108
Q

= the total DNA content (contains all the genetic information)

A

Cell genome

109
Q

Self-replicating, small circles of extrachromosomal DNA

duplicated & passed on to offspring

110
Q

Encodes for antibiotic resistance, toxic metal tolerance, enzymes & toxins

readily manipulated & transferred (genetic engineering )

111
Q

Distinct granular appearance in the cytoplasm

Composed of proteins and RNA; site of protein synthesis

112
Q

Are distinct granules; intracellular storage bodies

A

Inclusions

113
Q

Dormant, resting cells (cryptobiotic)

Intracellular but to be released as free endospores

A

Endospores

114
Q

Highly resistant to environmental stresses: high temperature, irradiation strong acids, disinfectants, etc.

Bacillus, Clostridium species

115
Q

Endospores

resistance linked to high levels of

A

calcium & some acids (Calcium dipicolinic acid)

116
Q

Endospore

Longevity:

Control: pressurized steam at ____for 20-30 minutes

A

25 - 250 million years

120 C

117
Q

Gram-positive or Gram-negative
Acid fast or non-acid fast
Cocci, bacilli, spiral or spirochete
In singles, pairs, clusters, chains, palisades

118
Q

Encapsulated or non-encapsulated

Smooth, mucoid or rough colonies

119
Q

Endospore-forming or non-sporulating
Centrally, terminally, subterminally located

A

Endospores

Bacte LEC (51 decks)

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