Prokaryotic Cell Structures Flashcards

1
Q

Which is simpler: prokaryotic or eukaryotic?

A

Prokaryotic (proteins, nutrients, and DNA)

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2
Q

What are the main components of a Prokaryotic cell?

A

-nucleoid
-cytoplasm
-cell envelope
-surface structures

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3
Q

What do prokaryotic cells not have?

A

a nucleus or other membrane bound organelles

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4
Q

nucleoid

A

a chromatin-dense area within the cytoplasm and contains the bacterial DNA

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5
Q

cytoplasm

A

the gel-like fluid inside the cell

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6
Q

cell envelope

A

complex multi-layered structure that protects the cell contents

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7
Q

surface structures

A

functional proteins on the cell surface

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8
Q

What are the two major types of bacteria?

A
  1. gram-positive (simpler)
  2. gram-negative (more complex)
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9
Q

What do all bacterial cell envelops consist of?

A
  1. cytoplasmic membrane
  2. cell wall
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10
Q

What is the main difference in structure between gram-positive and gram-negative?

A

gram-negative has an outer membrane

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11
Q

Composition of the Bacterial Inner Membrane

A

-cytoplasmic/inner membrane surrounds the cytoplasm
-bilayer: hydrophobic fatty acid “tails” and hydrophilic glycerol + phosphate + other functional groups

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12
Q

What are the hydrophobic and hydrophilic components of a bacterial’s inner membrane connected by?

A

ester linkage

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13
Q

What is the main function of the inner membrane?

A

selective permeability

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14
Q

What kind of components might disrupt the bilayer?

A

detergents

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15
Q

How does temperature affect the inner membrane?

A

-HEAT will make the bilayer more FLUID
-COLD will make the bilayer more RIGID

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16
Q

Composition of the Bacterial Cell Envelope

A

peptidoglycan

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17
Q

Main structures of peptidoglycan

A
  1. polysaccharide backbone
  2. tetrapeptide
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18
Q

polysaccharide backbone

A

-structural component of peptidoglycan
-rigid and provides strength
-2 modified glucose molecules connected by a beta (1,4) bond

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19
Q

tetrapeptide

A

-other structural component of peptidoglycan
-short peptide attached to N-acetylmuramic acid

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20
Q

Amino acids in peptidoglycan

A

L-alanine
D-alanine
D-glutamic acid
L-lysine/diaminopimelic acid (DAP)

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21
Q

Where are peptidoglycan layers crosslinked?

A

DAP and D-alanine

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22
Q

What inhibits the peptidoglycan layer crosslink?

A

penicillin

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23
Q

Who discovered penicillin?

A

Alexander Fleming

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24
Q

How does penicillin inhibit the peptidoglycan crosslink?

A

Penicillin binds to the penicillin binding protein and prevents the protein from forming the crosslink. Thus, bacteria cannot divide or repair the cell wall.

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25
Q

What are two possible ways that bacteria can become resistant to penicillin?

A
  1. Disrupt the binding protein (change binding site)
  2. Disrupt the penicillin
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26
Q

Who discovered lysozyme?

A

Alexander Fleming

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27
Q

What does lysozyme do?

A

-degrades cell walls
-used in many bacterial DNA extraction protocols to break open the cell walls and lyse the cells

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28
Q

Which bacteria type is more vulnerable to lysozymes?

A

gram-positive because they do not have an outer membrane so its inner membrane is exposed to lysozymes

29
Q

What is the target of lysozyme?

A

terminal esters in the polysaccharide backbone

30
Q

Gram-negative outer membrane

A

extra component, contains Lipopolysaccharide

31
Q

Lipopolysaccharide (LPS)

A

-a toxin and unique to bacteria
-Lipid A involves a strong immune response

32
Q

How does LPS induce sepsis?

A

Bacteria can shed LPS which can be detected by the host cell and trigger over-activation of the immune system, leading to Sepsis

33
Q

What are the components of LPS?

A
  1. Lipid A
  2. Core polysaccharide
  3. O-antigen
34
Q

Lipid A

A

-component of LPS
-anchors LPS in outer membrane (most toxic component)

35
Q

Core polysaccharide

A

-component of LPS
-function is less understood

36
Q

O-antigen

A

-component of LPS
-highly variable between strains; target of immune cell recognition

37
Q

What can O-antigen be used to identify?

A

bacteria strains like E. coli

38
Q

Gram-stain procedure

A
  1. Flood heat-fixed smear w/ crystal violet for 1 minute
  2. Add iodine solution for 1 minute
  3. Decolorize w/ alcohol for 20 sec
  4. Counterstain w/ safranin for 1-2 min
39
Q

What does Step 1 of the gram-stain procedure do?

A

All cells stained purple

40
Q

What does Step 2 of the gram-stain procedure do?

A

Iodine is used as a mordant and binds w/ Crystal Violet to make the stain harder to remove

41
Q

What does Step 3 of the gram-stain procedure do?

A

Alcohol removes stain from gram-negative cells (gram-positive are still purple)

42
Q

What does Step 4 of the gram-stain procedure do?

A

Safranin stains gram-negative bacteria

43
Q

What are the three bacteria cell shapes?

A
  1. Cocci (spherical)
  2. Bacilli (rods)
  3. Spirilla (spiral)
44
Q

Cocci

A

-Streptococcus (strands/gram-positive)
-Staphylococcus (grape-like clusters/gram-positive)
-Neisseria (diplococci/gram-negative)

45
Q

Bacilli

A

-Bacillus (gram-positive)
-Listeria (gram-positive)
-Escherichia (gram-negative)
-Bordetella (gram-negative)

46
Q

Spirilla

A

NO GRAM-POSITIVE
-Treponema pallidum (gram-negative)
-Helicobacter (gram-negative)

47
Q

Define transporters

A

Transporters are responsible for the active import/export of resources and waste

48
Q

What are porins?

A

Beta barrel proteins that permit the simple import diffusion of molecules. Can be selective based on size and charge of molecule. Primarily in gram (-) and Mycobacteria to facilitate transport across the outer membrane or mycolic acid layer.

49
Q

Primary Active Transport

A

uses energy (ATP/GTP) to import or export molecules

50
Q

What type of transporters use primary active transport?

A

ABC (ATP-Binding Cassette) transporters
-Vitamin B-12, Iron-citrate, dipeptides, tripeptides, oligopeptides, essential metals

51
Q

Secondary Active Transport

A

uses ions (H+, Na+, etc) to import or export molecules

52
Q

What are the types of transporters used for Secondary Active Transport?

A
  1. Antiporter
  2. Symporter
53
Q

Antiporter

A

substrate and ion move in different direction

54
Q

Symporter

A

substrate and ion move in same direction

55
Q

What are efflux pumps?

A

They export molecules, especially waste and antimicrobials out of bacterial cells
-five major families

56
Q

What are the cell surface proteins that are involved in motility or attachment?

A
  1. Pilli and Fimbriae
  2. Flagella
57
Q

What do Pilli and Fibriate promote?

A

attachment

58
Q

What does Flagella promote?

A

motility

59
Q

What are Fimbriae?

A

A type of pillus that promotes attachments to surfaces. They can also enable attachment between cells in biofilms.

60
Q

What are sex pilli?

A

A type of pillus that allows for the transfer of genetic information between bacteria

61
Q

What are flagella?

A

Structures that assists in swimming in Bacteria called archaella in Archaea; tiny rotating machines that push or pull through liquid; long, thin appendages anchored in cell at one end

62
Q

What are the different flagella arrangements?

A
  1. Peritrichous
  2. Monotrichous
  3. Lophotrichous
  4. Amphitrichous
63
Q

Monotrichous flagella structure?

A

single flagella on one side

64
Q

Lophotrichous flagella structure?

A

tuft of flagella on one end

65
Q

Amphitrichous flagella structure?

A

single or tuft on both ends

66
Q

Peritrichous flagella structure?

A

flagella throughout the cells

67
Q

Peritrichous flagella movement?

A

Run and Tumble

68
Q

Polar flagella movement?

A

Run