Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Microbiology > Chapter 2: Cell structure and function > Flashcards

Chapter 2: Cell structure and function Flashcards

1
Q

Cell envelope

A

It is a series of layered structures surrounding cytoplasm and governing interactions with the environment.
It includes:
Cytoplasmic membrane
Cell Wall
Outer membrane
S-layers (capsules and slime layers)

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

Cytoplasmic membrane

A

Also called plasma membrane
Surrounds cytoplasm
its main function is selective permeabilty so nutrients enter and wastes leave and membrane proetins facillitate these reactions and functions in energy metabolism

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

Plasm membrane structure

A

8-10nm wide
It is a phospholipid bilayer containing embedded proteins
It contains both hydrophobic fatty acid tails and hydrophilic glycerol and phosphate and other functional groups
The fatty acids associate inwards to form hyrdrophobic environment and the hydrophilic head groups remain exposed to external environment and cytoplasm

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

membrane proteins

A

Embedded proteins: Integral membrane proteins
Transmembrane proteins: extend completely across membrane
Peripheral membrane proteins; Loosely attached

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

Domains

A

Bacteria
Archae
Eukarya

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

Archael cytoplasmic membranes

A

-Ether linkages
-Archael lipids have isoprenes instead of fatty acids
-Major lipids are phosphoglycerol diethers with phytanyl C20 side chains and diphosphoglycerol tetra
-Many different isoprenoid chains including ring structures

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

Cytoplasmic membrane function

A

-Permeability barrier
* Polar and charged molecules must be transported
* Transport proteins accumulate solutes against concentration gradient
-Protein anchor
*Holds proteins in place
_energy conservation and consumption
* Generation of proton motive force

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

Eukaryotic plasma membrane

A

-Eu and Bac have ester linkages
-Contain Carbohydrates that function as attachment and receptor sites
-Contains Glycoproteins
-Contains sterols
*HUmans contain cholestral while fungal cells contain ergosterol

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

NB antifungal target

A

Ergosterol in membrane

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

Active transport mechanisms

A

-Simple transport
-Group translocation
-ABC system

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

Simple transport

A

-Driven by proton motor force
-Either symport: solute and H+ cotransported in one direction
-Or antiport: Solute and H+ transported in different directions

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

Group translocation

A

-Substance transport is chemically modified
-Energy-rich organic compound (not proton motive force) drives transport
-Best studied

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

E.Translocation

A

Phosphotransferase system in E.coli
-glucose, fructose and mannose
-5 proteins required
-energy from phosphoenolpyruvate

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

ABC transporter system

A

ABC= ATP binding cassette
-200 different systems for organic and inorgnic
-Substrate binding proteins outside of cell have high substrate affinity
-ATP drives uptake
-Binding protein binds to target and brngs it to transporter. Transporter breaks down ATP to transport target across

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

What type of organisms prefer ABC transporters

A

EXtremophiles as they are under stress with limited resources and ABC allow them to find specific substances in small concentrations

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

Cell Wall

A

-Needs to withstand osmotic/turgor pressure to prevent cell lysis
-Maintains cell shape and rigidity
-Bacteria seperated into two groups based off gram stain

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

Gram positive

A

envelope contains cytoplasmic membrane and thick cell wall with many layers of peptidoglycan
stains purple

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

Gram negative

A

Envelope consistes of membrane, thin cell wall with very little peptidoglycan, outermembrane and periplasm
stains pink

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

Bacterial cell wall component

A

It contains glycan tetrapeptide which is made up of:
-Sugar backbone (alternating modiefed glucose made of NAG and NAM joined by B1-4 linkages
-The linkage is what is targeted
-Short peptides are joined to NAM like L-alanine, D-alanine, D-glutamic acid, L-lysine or DAP

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

NAG

A

N-acetylglucosamine

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

NAM

A

N-acetylmuramic acid

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

DAP

A

diaminoplimelic acid

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

Go over diagram of gram positive

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

DIagram of Gram negative

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Acid fast cell walls
Cells contain a high percentage of mycolic acid -Hydrophobic waxy lipid Forms a layer outside of the tin peptidoglycan layer -Causes cells to stick together -Is detected by acid fast stains
26
Archael cell walls
-Lack peptidoglycan and outer membrane -Most lack polusaccharide wall and instead of S-layer (protein shell)
27
Archael cell wall makeup
-pseudomurein cell wall -similar to peptidoglycan -Alternating NAg and NAT -B1-3 glycosidic bonds instead of B1-4 -Amino acids all L-stereoisomer
28
NAT
N-acetyltalosaminuronic acid
29
Arachael sensitivity to lysosmes
Enzymes are specific to B1-4 bonds instead of B1-3
30
Eu cell walls
Plants contain cellulose Fungi contain chitin which is a polymer of NAG units and is an important antifungal drug target Yeast cell walls contain glucan and mannan
31
Outer membrane structure of gram negative
second bilayer external to cell wall -Outer membrane contains polysaccharides covalently bound to lipids: lipopolysaccharide layer (LPS) -Facilitates surface recognition, important virulence factors and add strength -Contains porins
32
LPS
lipopolysaccharide layer -Contains core polysaccharide and O-polysaccharide -Lipid bond sto divalent cations (Mg2+) and adds strength -Lipid A portion -LPS replaces most of phospholipids in outer half of membrane
33
Braun lipoprotein
ANchors outer membrane to peptidoglycan
34
Endotoxin
Lipid A, toxic component of LPS when cell dies responsible for symptoms associated with infection
35
core polysaccharide
Attached to lipid A and provides structural stability
36
O polysaccharide
Functions as antigen and is useful for distinguishing between different strains antibodis bind here
37
S-layer
paracrystalline structure consisting of protein or glycoprotein -Always outermost layer -functions: strenght, protection from lysis, conferring shape, creating periplasmic-like space, facilitting cell surface interactions, promoting adhesion, protecting cell from host defences
38
Mycoplasms
tough cell membrane in Bac without cell wall
39
Thermoplasm
Tough cell membrane in Archae that lack cell walls
40
Capsule and slime layer component
sticky polysaccaride coat outside cell envelope
41
Capsule
If tightly attached, tight matrix; visible if treated with INdia ink
42
Slime layer
Loosely attached, eaily deformed and is easier to wash off than capsuleC
43
Capsule and Slime functions
Assist in attachment to surfaces Roles in development and maintanence of biofilms Contribute to infectivity ( capsule pieces kill macrophages)( prevents antibiotic from reaching target) Prevent dehydration/desiccation
44
Surface structures
Hair like appendages shorter than flagella made of pillin include fimbriae and Pili
45
Fimbria
Can occur all over the cell Numbers in 100s involved in biofilm formation and colonisation
46
Pilus
Longer than fimbriae only few per cell Functions: -Motility by twitching and glidng -DNA transfer (conjugation)
47
Hamus/Hami
Archael grappling hooks that assist in surface attachment and forming biofilms -structurally resemble type IV pili except for barbed termini, which attaches cells to surfaces or each other
48
Cell inclusions
Function as energy reserves, carbon or phosphorus reservoirs and or have special fucntions -enclosed by thin protein membrane -reduce osmotic stress
49
Carbon storgae polmers
-synthesised when carbon in excess -broken down as carbon or energy sources if needed -glycogen is a glucose polymer
50
Phosphate granules
Inorganic phosphate elemental sulfur accumulates in periplasmic granules and oxidised to sulfate (SO4)
51
Sulfur granules not found in Gram positive
Thick layer prevents periplasmic layer from expanding as much which reduces storage space
52
Magnetosomes
Allow bacteria to orient within magnetic field -Biomineralised magnetic iron oxides -Allow cell to undergo magnetotaxis: migration along magnetic field lines
53
Gas vesicles
Conical-shaped, gas filled structures made of two proteins
54
Endospores
Dormant, tough and non-reproductive structure produced by certain bacteria (usually gram positive) -Formation triggered by lack of nutrients -Able to survive for millions of years through hasrh conditions and structures are not metabolically active
55
exosporium
Outer layer -interacts with environment or host organism and may contain spore antigens which trigger an immune response
56
Spore coat
Resistant to many toxic molecules and may also contain enzymes involved in germination
57
Cortex
Beneath the spore coat and consists of peptidoglycan and makes the endospore resistant to temperature
58
core wall
provides endospore resistance to UV light and harsh chemicals
59
Core
Contains spore chromosomal DNA -Encased in chromatin -like proteins known as SASPs -SASPs protect spore DNA from UV radiation and heat -DPA further stabilises protein and DNA -Also contains normal cell structure such as ribisomes and other enzymes
60
SASP
small acid-soluble spore proteins
61
DPA
Dipicolinic acid
62
Endosprulation
Insert
63
Endospore germination
INsert
64
how to kill endospores
-destroyed by burning or autoclaving (takes several hours) -Prolonged exposure to ionising radiation -A 10% sodium hypochlorite solution where contact time exceeds 10 minutes -Hospitals use ethylene oxide which is a low-temp sterilant
65
Flagella
-assists in swimming in Bac and Archae -Long thin appendages (15-20nm wide) anchored in cell -Different arrangements -Increase or decrease rotational speed relative to strenght of proton motive force
66
Polar/monotrichous
single flagellum at 1 pole
67
Lophotrichous
Tuft of flagella at one pole
68
Amphitrichous
Flagella at both poles
69
Peritrichous
Flagella all over
70
Amphilophotrichous
Tuft of flagella at both ends
71
Flagella structure
Filament composed of flagelin protein -hook -basal body * G-Neg have 2 sets of rings (one to cell wall and one to plasma membrane) *G-Pos only have inner set of rings
72
Flagella synthesis
Several genes MS ring made first Anchoring proteins, hook, cap are made next Filament forms with flagellin exported through export apparatus
73
Movement with bundeled flagella
74
MOvement with single flagella
75
Archaella
proteins unrelated to flagella, more closely related to type IV pili -smaller than bacterial flagella -Move by rotation driven by ATP hydrolysis (move slower)
76
Twitching motility
Requires Type IV pili extend from one cell pole, attach to surface, retract to pull cell forward -Energy from ATP hydrolysis
77
Gliding motility
smooth, continuous motion along long axis without external structures -Only bacteria -helical intracellular protein track, gliding motors and adhesion proteins
78
Taxis
Directed movement in response to chemicl or physical stimuli enhances access to resources and allows avoidance of death
79
Chemotaxis
Chemicals
80
Phototaxis
Light
81
Run and tumble behaviour
Run: smooth motin, flagellar motion rotates counterclockwise Tumble: stops and jiggles because flagellar motor rotates clockwise, flagellar bundle comes apart -after tumble another run beings in a random direction
82
Biased random walk
Bacterial respond to temporal and not spatial differnce in chem concentration increaed chem gradient results in longer lenght of run
83
Osmotaxis
ionic strength
84
Hydrotaxis
water
85
Aerotaxis
Oxygen
86
Magnetotaxis
Magnetic current It is used to wim toward or away from O2
87
Scotophobotaxis
Response to absence of light enetering darkness causes cells to tumble and head back to light
88
Mitochondria
respiration and oxidative phosphorylation for aerobic Eu number varies surrounded by 2 membranes -Cristae:folded internal membranes -contain enzymes needed for respiration and ATP production -Matrix: inermost area and contains citric acid enzymes
89
Chloroplasts
Contains chlorophyll site of photsynthesis double membrane innermemrane surrounds stroma and contains large amounts of RuBisCO for Calvin cycle Thylakoids are flattened membrane discs containing chlorophyll and ATP synthetic components and form proton motive force
90
Cytoskeleton
Microtubules -Hollow tube that have 25nm diamters and are composed of alpha and beta tubulin -Maintain cell shape, motility, move chromosomes and organelles Microfilaments -7nm in diamter and are polymers of actin protein -Maintain and change cell shape; involved in amoeboid motility and cell division Intermediate filaments -8-12nm in diameter; fibrous keratin proteins -Maintain cell shape and position organelles
91
Endoplasmic reticulum
Rough contains ribisomes while smooth does not Smooth participates in synthesis of lipis and carb metabolism Rough produces glycoproteins and new membrane material
92
Golgi Complex
Stacks of membrane-bound sacs modifying ER products
93
Lysosmes
Membrane enclosed compartments containing digestive enzymes and recycling cell components
94
Flagella and Cili
Cilia are shorter than Flagella and beat in synchrony Eu flagella are long and propel through whiplike motion protein called dynein found in them

Microbiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions