Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Micro : Unit 1 > Chapter 3: Bacterial Cell Structure > Flashcards

Chapter 3: Bacterial Cell Structure Flashcards

1
Q

• Bacteria are referred to as → prokaryotes

A

• Lack a membrane-bound nucleus, membrane-bound
organelles, and internal membranous structures

The problem is some bacterial groups do have their genetic material enclosed in a → membrane
• Some also have membrane-bound → organelles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Most common shapes ___ and ___:

A

cocci ; rods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Cocci

A

spherical cells, single cells or clusters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Rod (bacilli)

A

cylindrical shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Less common cells shapes are

A

Spirilla, Spirochetes, Vibrio, and Pleomorphic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Spirilla

A

rigid, spiral-shaped cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Spirochetes

A

flexible, spiral-shaped cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Vibrio

A

resemble rods, comma
shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Pleomorphic

A

organisms that are
variable in shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Arrangement of cells is determined by what?

A

• Determined by plane of division
• Determined by whether or not there is cell →
separation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Diplococci

A

pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Streptococci

A

chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Staphylococci

A

grape-like clusters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Tetrads

A

4 cocci in a square

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Sarcinae

A

cubic configuration of 8 cocci

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Common features of a bacterial cell

A

• Cell envelope - 3 layers: cell membrane, cell wall, capsule
• Cytoplasm – internal fluid
• External structures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Bacterial Cell Envelope

A

• Cell envelope – plasma membrane and all of its external
surrounding layers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Bacterial plasma membrane

A

encloses the cytoplasm and
defines the cell’s → shape
• It is a selectively permeable barrier
• Only allows certain ions and molecules to enter or
exit and prevents others

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Fluid-mosaic model

A

states that membranes consists of
fluid lipids with floating proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Plasma Membrane Structure

A

• Lipids in the membrane are →
phospholipids
• Amphipathic – both polar and
nonpolar ends
• Hydrophilic – polar phosphate
ends interact with → water
• Hydrophobic – nonpolar fatty
acid ends are insoluble in water
and only associate with → one
another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Amphipathic

A

both polar and
nonpolar ends

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Hydrophilic

A

polar phosphate
ends interact with → water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Hydrophobic

A

nonpolar fatty
acid ends are insoluble in water
and only associate with → one
another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Peripheral proteins

A

connected
to the membrane and are easily
removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Integral proteins

A

transport
proteins that move materials into
and out of the cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Bacterial membranes lack

A

the sterol cholesterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Bacterial membranes contain hopanoids that are….

A

Similar to cholesterol and probably stabilizes the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Plasma membrane function as a barrier but also

A

have to
bring nutrients into the cell

Primary function is to obtain energy and nutrients
sources for the cell

Bacteria can only take in dissolved molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Bacteria mainly transport nutrients into the cell ____
their concentration gradient

A

against

• High levels in the cells (storage) and low levels in the
environment
• Bacteria commonly live in nutrient-poor habitats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Passive diffusion

A

movement of molecules from an area of high concentration to one with a low concentration
• Molecules move down the concentration gradient
• A large concentration gradient is required for adequate
nutrient uptake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

___
, ____
, and, ___ cross the membrane by passive diffusion

A

• O2
, CO2
, and, H2O

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Facilitated diffusion

A

substances move across the plasma
membrane with the help of a carrier or channel protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Facilitated diffusion

A

substances move across the plasma
membrane with the help of a carrier or channel protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Channel protein

A

pore, substances pass through

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Carrier protein

A

carry substances across the membrane

• Carrier proteins change their shape to facilitate the
movement of a substance across the membrane

• Go back to their original shape when transport is →
completed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Active transport

A

substance moves from an area of a low concentration to a high concentration with the help of → energy

• Movement against a concentration gradient

• Uses carrier proteins and some form of energy to drive the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Primary active transport

A

uses ATP
energy to move substances against a concentration gradient without
modifying the substance

Uses a uniporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

uniporter

A

moves a single
molecule across the membrane
• Ex. ABC Transporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Secondary active transport

A

moves
substances against a concentration
gradient with the use of ion gradient →potential energy

• Uses cotransporters, which move two
substances at the same time

• The ion that powers the transport and the substance being moved across the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Symporter (In secondary active transport)

A

ion and substance move in the same direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Antiporter (In secondary active transport)

A

ion and substance move in opposite directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Group translocation

A

molecule is chemically modified as
it is transported into the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Transporters of different types of sugars _____

A

phosphorylate
them (add a phosphate)

43
Q

Group translocation used by bacteria to _____

A

extract energy from organic energy
sources to generate ATP

44
Q

Cell wall

A

layer found outside of the plasma membrane

• Helps maintain cells shape and protects it from osmoticlysis (plasmoptysis)

• Protects the cell from → toxins

45
Q

Peptidoglycan

A

Rigid structure lying just outside the cell plasma
membrane

46
Q

Two types based on Gram stain

A

Gram-positive (monoderms)

Gram-negative (diderms)

47
Q

Gram-positive (monoderms)

A

stain purple; thick
peptidoglycan

48
Q

Gram-negative (diderms)

A

stain pink or red; thin
peptidoglycan and outer membrane

49
Q

Peptidoglycan
Structure

A

Meshlike polymer of identical
subunits forming long strands • Two alternating sugars • N-acetylglucosamine (NAG) • N- acetylmuramic acid (NAM) • Alternating → amino acids

50
Q

Peptidoglycan strands have a ___
shape

A

helical

51
Q

Peptidoglycan chains are _____ by peptides for _____

A

crosslinked; strength

• Called a peptide → interbridge
• Various structures occur

52
Q

Gram-positive bacteria

A

have thick cell walls made of
peptidoglycan and other polymers like → teichoic acids

53
Q

Teichoic acids

A

– polymers of glycerol or ribitol joined by
phospholipids (negatively charged)
• Covalently linked to → peptidoglycan

54
Q

Typical Gram-Positive Cell Walls
Consist Primarily of _____

A

Peptidoglycan

55
Q

Peptidoglycan

A

Create and maintain the structure of the cell envelope by
anchoring the cell wall to the plasma membrane
• Function to take-up → ions
• Help pathogenic species bind to host tissues

56
Q

Gram-negative

A

cell walls are more
complex then gram-positive
• Consist of a thin layer of
peptidoglycan surrounded by an
outer membrane
• Outer membrane composed of
lipids, lipoproteins, and →
lipopolysaccharide (LPS)
• No teichoic acids

57
Q

Gram-Negative Cell Walls

A

• The outer membrane of gram-negative bacteria lies outside of
the thin peptidoglycan layer
• Linked by lipoproteins
• Most abundant protein
linked to underlying
peptidoglycan and
embedded in the outer
membrane
• Outer membrane also contains
lipopolysaccharides (LPSs) – consist of both a
lipid and carbohydrates

58
Q

lipopolysaccharides (LPSs)

A

consist of both a
lipid and carbohydrates

59
Q

Functions of Gram-Negative Cell

A

• Contribute to the cells walls negative charge
• Stabilize the outer membrane and create a
permeability barrier
• Helps protect pathogenic bacteria from → host
defenses (O antigen)
• Acts as a toxin called endotoxin (lipid A) – causes
septic shock once it enters the bloodstream

60
Q

Hypotonic environments

A

• Solute concentration outside cell less than inside cell
• Water moves into cell and cell swells
• Cell wall protects from → lysis (plasmoptysis)

61
Q

Hypertonic environments

A

• Solute concentration outside cell is greater than inside
• Water leaves the cell
• Plasmolysis (plasma membrane shrinkage)occur

62
Q

Lysozymes

A

(antimicrobial in tears, saliva, and oil) breaks
bond between → NAG and NAM

63
Q

Penicillin inhibits

A

peptidoglycan synthesis
• If cells are treated, they lyse in a hypotonic solution

64
Q

Protoplasts

A

bacteria that have had the → cell wall
removed

65
Q

Bacteria that Lack Cell Walls

A

Mycoplasma
• Never produce a cell wall
• Plasma membrane more resistant to osmotic pressure

66
Q

Capsules

A

composed of polysaccharides, well organized,
and → not easily removed

Capsules help pathogenic bacteria resist phagocytosis by
host phagocytes
• Found outside of the cell wall
• When bacterial cells that lack capsules they are
phagocytized easily and do not cause disease
• When capsulated they can quickly cause disease

67
Q

Slime layer

A

Functions in attachment of bacteria to solid surfaces
and host tissue surfaces (biofilms)

• made of unorganized polysaccharides that
are → easily removed
• Produced by gliding bacteria to facilitate → movement
• Slime layers and capsules consist of glycocalyx – network
of polysaccharides coming off of the cell surface

68
Q

Protoplast

A

plasma membrane and everything contained
→ within

69
Q

Cytoplasm

A

the material contained within the plasma
membrane
(cytosol, ribosomes, and plasmids)

70
Q

cytosol

A

the liquid component

71
Q

Bacterial Cytoskeleton

A

Homologs of all 3 eukaryotic cytoskeletal elements have
been identified in bacteria

• Functions are similar as in eukaryotes
• Participate in → cell division
• Localize proteins
• Determine → cell shape

72
Q

Inclusions

A

formed by the clumping of substances
• Granules, crystals, or globules of organic or inorganic
material that are stored by the cell for → future use

73
Q

Storage inclusions are formed when a
nutrient has a….

A

good supply, and another →
does not

• End products of metabolic reactions are
commonly stored and used later used by
the microbe when it is in a harsh
environmental condition

74
Q

Microcompartments enclose one or more

A

enzymes

75
Q

Carboxysomes

A

present in
cyanobacteria (photosynthetic bacteria)
• Contain enzymes of photosynthesis
reactions
• Microcompartment prevents CO2
from escaping so it can be
converted into → sugars

76
Q

Gas vacuoles

A

allow aquatic,
photosynthetic bacteria to be→
buoyant
• Made up of clumped→ gas vesicles

77
Q

Microbes can adjust their depth to
reach proper

A

light, oxygen
concentrations, and nutrient levels
• Descend by collapsing vesicles and
ascend by forming → new ones

78
Q

Magnetosomes

A

formed by magnetotactic
bacteria that orient along → magnetic fields
• Intracellular chains of magnetite or greigites
particles (iron ores) enclosed within
invaginations of the plasma membrane
• Act as tiny magnets to swim to nutrient-rich
sediments or locate fresh or marine water
habitats

79
Q

Ribosomes

A

site of → proteins synthesis
• Found in the cytoplasm or attached to the plasma
membrane

80
Q

• Bacterial ribosomal RNA =

A

70S
• 16S small subunit
• 23S and 5S in large subunit

81
Q

Nucleoid

A

contains the cell’s chromosomes and several
proteins
• Most bacterial have a single circular chromosome of
DNA, some have a linear chromosome, and some have
more than one chromosome

82
Q

Binary fission

A

asexual reproduction in bacteria

Single circular chromosome → replicates

Plasma membrane and cell wall separate
the cell into → two identical cells

83
Q

Plasmids

A

extrachromosomal DNA

• Found in bacteria, archaea, some fungi
• Usually small, closed circular DNA molecules
• Exist and replicate independently of chromosome

84
Q

Episomes

A

may integrate into chromosome
• Inherited during → cell division

85
Q

Fimbriae or pili

A

fine, hair-like
structures that are thin and short

86
Q

Fimbria

A

function to attach cells
to solid surfaces like host tissue or
rocks in streams

87
Q

Sex pili

A

involved in motility and
gene transfer
• Conjugation

88
Q

Flagella

A

used by many motile bacteria
• Threadlike appendage that extends outward from the
plasma membrane and cell wall
• Main function is → motility

89
Q

Flagellar Movement

A

Flagellum rotates like a propeller
• Very rapid rotation up to 1100
revolutions/sec
• In general, counterclockwise (CCW)
rotation causes forward motion (run)
• In general, clockwise rotation (CW)
disrupts run causing cell to stop and
tumble

90
Q

Swarming

A

• Occurs on moist surfaces as a type of
group behavior by bacteria
• Most swarmers have peritrichous
(uniform) flagella
• Production of molecules that aid
movement is typical

91
Q

Spirochete Motility

A

• Multiple flagella form axial fibril
which winds around the cell
• Flagella remain in periplasmic space
inside outer sheath
• Corkscrew shape exhibits flexing and
spinning movements

92
Q

Twitching

A

• Pili at ends of cell
• Short, intermittent, jerky motions
• Cells are in contact with each other and the surface

93
Q

Gliding

A

• Smooth movements (slime layer)

94
Q

Chemotaxis

A

the movement toward or away from
chemical attractants or repellants
• Move in response to temperature, light, oxygen,
osmotic pressure, and gravity

95
Q

Phototaxis

A

movement of a motile
organism in response to light,
either toward the source of light or
away from it
• Common with → cyanobacteria

96
Q

Endospores

A

dormant cells formed within mother cells
• Resistant to environmental stresses like heat, ultraviolet
radiation, gamma radiation, chemical disinfectants, and
desiccation

97
Q

Clostridium botulinum

A

Example of endospore.

causes botulism toxin, food-borne disease
• Food must be prepared and stored properly

98
Q

Bacillus anthracis

A

Example of endospore.

causes anthrax if inhaled , spores
germinate in the lungs

99
Q

Endospore forming bacterial are commonly found in

A

soil

100
Q

Sporulation

A

process of making endospores.

growth ceases due to a → lack of
nutrients
• Produces a dormant cells that can survive until
nutrients are available and vegetative growth will
restart

101
Q

Formation of Vegetative Cell

A

• Activation

• Germination

• Outgrowth

102
Q

Activation

A

• Prepares endospores
for germination
• Often results from
treatments like →
heating

103
Q

Germination

A

• Environmental
nutrients are detected
• Spore swelling and
rupture or absorption
of spore coat
• Increased metabolic
activity

104
Q

Outgrowth

A

• Emergence of
vegetative cell

Micro : Unit 1 (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions