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Introductory Microbiology > Structure and Function of Microbial cells > Flashcards

Structure and Function of Microbial cells Flashcards

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1
Q

Agar is

A

A media where bacteria are grown in the lab

It has moisture and nutrients

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2
Q

Paramecium are ( Domain and Kingdom )

A

Eukaryotes

Protozoa

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3
Q

All cells have intercellular composition ____ the outside

A

Different from

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4
Q

Metabolic properties of all cells

A

Cells take up nutrients, transform them, and expel waste

  1. Genetic ( replication, transcription, translation)
  2. Catalytic ( energy,biosynthesis)
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5
Q

What property id this?

Nutrients from the environment are converted into new cell materials to from new cell

A

Growth, all cells

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6
Q

What is the third properties of all cells ( apart from growth and metabolism )

A

Evaluation
Cell evolve to display new properties. Phylogenetic trees capture evolutionary relationships

All organisms evolve or they will die

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7
Q

Creation of the spore is an example of

A

Properties of some cells -> differentiation

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8
Q

Explain how cells interact with each other by chemical messengers

A

Bacteria is able to release atom reducer, as soon as concentration of this reducer is high enough , other bacteria sense it and start to act as if they are surrounded by a lot of bacteria-> formation of the biofilm

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9
Q

What is interesting about the property of exchanging the genetic material in bacteria

A

They can exchange the genetic material not only between mother-daughter cell, but also mother to mother cell

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10
Q

What property is this?

Some cells are capable of self-propulsion

A

Motility

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11
Q

How is the size of the cell usually described?

A

By surface to volume ratio

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12
Q

What is the problem of the surface to volume ratio for unicellular organisms and what is the result of it

A

It is a problem for unicellular organism, because they interact with the environment only through the surface, if they become to large , they cannot function efficiently any more, that is why there is a limit in diameter.
Limit: 0.5 micrometers- 750 micrometers in diameter

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13
Q

What is the typical size for animal cell and bacterial cell

A

Animal cell - 10000 nm

Bacterial cell- 1000 nm to 2000-3000 nm

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14
Q

What structures are shared by both prokaryotes and eukaryotes

A

Cell wall
Cytoplasmic membrane
Cytoplasm
Ribosomes

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15
Q

Name all the main structures present in bacteria

A 
Cell wall
Cytoplasmic membrane
Nucleoid
Cytoplasm 
Plasmid 
Ribosomes
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16
Q

What is the difference between the genetic material storage in eukaryotes and prokaryotes ?

A

Eukaryotes - the genetic material is bound within the nucleus
In prokaryotes the genetic material is not bound in anything -< nucleoid

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17
Q

Name the basic parts of the cell

A 
Cell wall
Cytoplasmic membrane 
Mitochondrion 
Nuclear membrane 
Nucleus 
Ribosomes
Endoplasmic reticulum 
Cytoplasm 
Golgi complex
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18
Q

Why the membrane is so important ?

A

It keeps the inside in and outside out

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19
Q

What are three properties of the membrane

A
  • Permeability barrier ( prevents leakage and functions as a gateway for transport)
  • Protein anchor
  • Energy conservation ( proton motive force )
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20
Q

What is the major source how bacteria create energy?

A

Proton motive force

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21
Q

What is the ratio of proteins/lipids

A

50% or less

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22
Q

Types of the membrane proteins by function

A

Sensors
Adhesins
Transporters
Enzymes

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23
Q

How is the model of the membrane is called

A

Fluid mosaic
Mosaic - because the ratio between the lipids and the proteins
Fluid- because proteins can move

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24
Q

What is the major phospholipid found in bacteria

A

Phosphatidylethanoamine

Glycerol+ 2 FA+ phosphate +ethanolamine

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25
Q

What linkage do archea have in the phospholipid bilayer unlike bacteria

A

Archea- ether C-O-C

Bacteria -ester C-O-C=O

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26
Q

What do archea have instead of FA in phospholipid bilayer

A

Phytanyl that consists of isoprene

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27
Q

How is the polymer of isoprene called?

A

Phytanyl

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28
Q

Why is it an advantage , creating interactions between isoprene units

A

They can create monolayers, it is more tough , more solid-> can survive in extreme environment

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29
Q

What is the name of the tails in phospholipid layer in archea?

A

Biphytanyl

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30
Q

Bacteria have FA and ___ linkages, when archea have ___ and ___linkages

A

Ester linkages
Phytanyl
Ether linkages

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31
Q

How is the lipid bilayer stabalized in eukaryotes?

A

sterol

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32
Q

what is the advantage of sterol?

A

Polar head
Rigid planar ring structure
Nonpolar hydrocarbon end

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33
Q

Types of sterol in animal cells, fungi , plant cells and protozoa

A

Animal-Cholesterol
Fungi-Ergosterol
Plant cells and Protozoans- stigmasterol

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34
Q

DO bacteria and archea have sterol

A

No, it is almost always absent

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35
Q

How do bacteria stabilize their membrane

A

By hopanoids

Rigid ring structure, the same function , just another molecule

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36
Q

How bacteria and archea store DNA?

A
  • Circular molecule, double stranded
  • Generally haploid ( one copy)
  • Packaged with proteins( H-NS and other histone loke protein) aggregates to form the nucleoid)=the chromosome
  • DNA in the cytoplasm , ribosomal RNA encoded on the chromosome
  • May also contain plasmids
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37
Q

What are plasmids?

A

Smaller circular structures of DNA, genes for function that can be transported very easily, for example antibiotic resistance

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38
Q

How is the gentic material stored in Eukaryotes?

A
  • Linear molecules, double-stranded
  • Generally diploid ( two copies)
  • Packaged with proteins( Histones) to form chromatin fibers=chromosome
  • DNA in the nucleus
  • Nucleolus:( dense DNA that codes for ribosomal RNA, ribosomal proteins , immature ribosome )
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39
Q

What is the difference in gene storage in bacteria and eukaryotes?

A

Bacteria and archea- do not have histones, their gentic material is not bounded ( as in eukaryotes- nucelus )
Eukaryotes do not have plasmids

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40
Q

Three major steps in production of protein from DNA

A
  • Replication , which is mediated by DNA polymerase
  • Transcription, which is mediated by RNA polymerase
  • Translation, which is mediated by ribosome
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41
Q

Parts of ribosomes

A

RNA and proteins

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42
Q

What is the role of ribosomes

A

To translate mRNA into amino acids in order to form proteins

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43
Q

Where are ribosomes in prokaryotes and eukaryotes

A

Prokaryotes- free in the cytoplasm or attached to cytoplasmic membrane

Eukaryotes- free in the cytoplasm or bound to the endoplasmic reticulum

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44
Q

What ribsomes are in prokaryotes and eukaryotes

A

Prokaryotes: 70 S= 30S+50S subunits

Eukaryotes:80 S ribosomes =40S+60S

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45
Q

Why 60S and 80 S are important ?

A

their RNA are used as a genetic markers, these genes have both conserve regions and variable regions ( they are changing to mutation), so we can see how closely related two organisms are

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46
Q

What does S mean in ribosome subunit

A

Svedberg unit, describes the rate of sedimentation of the particle in the centrifuge , how far the particle will move away from the center when exposed to the centrifuge, not linear

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47
Q

How many proteins and what rRNA make the subinits of ribosomes

A

50S->23S rRNA and 5S rRNA, 31 protein
30S->16S rRNA,21 proteins
40S->30 proteins,18S RNA
60S-> 5.8S rRNA,28S rRNA,5S rRNA,40 proteins

48
Q

What are organelles?

A

Compartments made of membranes ( phospholipid bilaeyer and proteins)

49
Q

In what organism is the cell wall present and in what organisms it is absent

A

Plants,algae, fungi- -YES

NO- animals,protozoa

50
Q

What is the cell wall

A

A tough , rigid barrier that helps protect the cell and give its shape

51
Q

The cell wall of eukaryotes is usually composed of___

A

polysaccharides

52
Q

Diversity of cell wall molecules( plants, algae, fungi and others)

A

Plants, algae and some fungi: cellulose ( polymer of glucose )
Fungi:chitin ( polymer of N-acetylglucosamine)
Also cell walls made of galactose, mannose,etc.

53
Q

How the DNA is packed inside of the nucleus

A

DNA wraps around histones, which form loops of DNA called nucleosomes. These nucleosomes coil and stack together to form fibers called chromatin. Chromatin in turn forms larger loops and coils to form chromosomes

54
Q

Two types of chromatin

A

Euchromatin: loosely packed, actively transcribed
Heterochromatin: densely packed, low level of transcription

55
Q

Where does the translation occur if the protein is designated to the cytoplasm

A

Ribosome-mRNA stays free in the cytoplasm

56
Q

What is the golgi body?

A

A set of membrane compartments involved in further processing of proteins and their distribution. Proteins are packaged in vesicles and transported to where they are required

57
Q

What are lysosomes

A

Internal vesicles that contains hydrolytic enzymes required for degradation of materials brought in by phagocytosis and endocytosis

58
Q

What is the structure of mitochondria

A

Porous outer membrane, inner membrane , matrix

59
Q

What is the function of mitochondria?

A

Produce most of the ATP required by the cells

60
Q

The outer membrane is made of

A

Many porin proteins

Very permeable for small molecules

61
Q

The composition of the inner membrane

A

75% proteins
25% lipids
Transport proteins,enzymes,cytochromes,ATPases

62
Q

What is in the matrix of mitochondria?

A

Enzymes ( citric acid cycle),DNA,ribosomes(70S)

63
Q

Where does the proteins for the mitochondria come from?

A

Mitochondria are able to synthesize some of their proteins, the remaining ones are imported from the cytoplasm of the cell( they are encoded in the genome)

64
Q

Structure of the chloroplast

A

Outer membrane->porins similar to mitochondria
Inner membrane
Stroma
Thylokoid

65
Q

What is in the stroma?

A

Circular DNA
70S ribosomes
enzymes of the Calvin cycle

66
Q

What is the thylakoid?

A

Closed system of interconnecting sacks and tubules
Contain enzymes and pigments that harvest light energy and the membrane-bound ATPases that use this energy to produce ATP

67
Q

Where does the protein from the chloroplast come from?

A

Chloroplasts are able to synthesize some of their own proteins ( their own circular DNA), the remaining ones are imported from the cytoplasm of the cell

68
Q

Where do photosynthetic prokaryotes have their proteins

A

Cytoplasmic membrane

69
Q

Why chloroplast and mitochondria have two layers and 70S ribosomes

A

Acquisition of mitochondria and chloroplasts by eukarya cells at some point of time

70
Q

What is the cytoskeleton?

A

A complex network of protein filaments that helps organize the cytoplasm and give the cell its shape

71
Q

Microtubules consist of

A

alpha and beta tubulin

72
Q

Actin filament consists of

A

Actin

73
Q

Intermediate filament consist of

A

Keratin
Desmin
Vimentin

74
Q

The role of microtubules

A

Serve as a highway for transporting vesicles and organelles around the cell
Move cell via flagella and cilia
Participation in cell division

75
Q

The role of intermediate filaments

A

To anchor the nucleus

Maintain the cell shape

76
Q

The role of actin filaments

A

To keep the shape to the cell
move cell via mucle contraction
Move organelles and cytoplasm in plants,fungi, and animals

77
Q

What helps microtubules to transport the organelles around the cell

A

Kinesin and dynein are two proteins that attach to vesicles or organelles and walk on microtubules, transporting their cargos to where they are required

78
Q

How much time does it take to transport the vesicle across the cell with microtubules?

A

Max 5s

79
Q

What is the formula of the cilia

A

9 sets of doublets + 2 in the center

80
Q

In what organisms flagella is covered with the plasma membrane?

A

Eukaryotes, but not prokaryotes

81
Q

How is the movement created in the cilia?

A

The dynein arms slide the doublets past each other

82
Q

The base of the flagellum is called

A

The basal body

83
Q

The basal body of the gram-negative

A 
L ring(LPS)
P ring (Peptidoglycan)
MS ring ( membrane superficial)
C ring (cytoplasm)
84
Q

The basal body of the gram-positive

A

P, MS and C rings

85
Q

MS and C rings are covered with

A

Motor protein

86
Q

The flagella is moved by

A

the proton motive force, the difference in charge creates a potential energy

Outside- positive

Inside the cytoplasmic membrane - negative

The mechanical force is created by allowing the protons to flow through the mot protein and allowing rotation in the motor protein, which will cause the turn of the central axes and the whole flagellum will rotate

87
Q

What is the difference in flagellum in eukaryotes and prokaryotes

A

The flagellum is anchored in the cytoplasmic membrane, but not covered with it -> in bacteria
In eukaryotes the flagellum is surrounded by the cytoplasmic membrane

88
Q

How the flagellum is assembled

A

1) MS/C ring first
2) Motor proteins are assembled around MS/C ring
3) Then P and L ring
4) Formation of the early hook ( early, because it does not have a cap yet)
The cap helps the flagellum subunits to assemble
5) Assembling flagellum subunits

89
Q

How do the subunits come to the tip for the growth of the filament

A

Through the channel inside

90
Q

The direction of the flagellum

A

Peritrichous ( in all direction)
Monotrichous
Lophotrichous (in one direction, but more than one)

91
Q

How does the peritrichous movement work

A

Bundled flagella in counter clockwise direction (CCW)
Then when working in the clockwise direction , the flagella fell apart and the bacteria and reorient to start moving in the other direction,
And then CCW direction

92
Q

How does polar flagella movement work

A 
Reversible flagella
In CCW rotation-> movement forward 
CW rotation-> reverse direction
Unidirectional flagella
CW direction-> forward
Cell stops, reorients 
Moves in the other direction, only forward direction
93
Q

What is the other way to move around

A

Gliding motility

94
Q

Types of gliding motility

A

a) secretion of mucus behind-. movement forward
b) Type IV pilus-dependent-> retraction of the pilus->movement forward
c) glide protein -> the protein glide in one direction and the cell moves in the other

95
Q

What is taxis and their types ?

A

Directed movement toward or away from a gradient of chemical or physical agents

Chemotaxis ( chemicals,nutrients)
Phototaxis light ( photographic)
Aerotaxis :oxygen
Osmotaxis :ionic strength ( high/low concentration)

96
Q

How the bacteria move to the attractant

A

The bacteria will run and tumble and run when there Is no attraction
If there is an attractant, the cell is not able to sense the attractant , because it is too small to sense the difference across its length, the cell needs to compare, it starts to run more in the direction of the attractant and the tumbles will become less frequently , the bacteria needs to test out different locations, so it won’t go straight to the attractant , it will still go back and forth, but the ultimate movement will be in the right direction, just not in the most efficient manner

97
Q

Two proteins required for the assembly of the fimbriae

A

The chaperone and the usher

98
Q

How does the assembly of the fimbriae occur in gram-negative bacteria

A

Subunits are brought from cytoplasm to periplasm . With the help of chaperon, the proteins do not unfold or digradate and manage to make it to the usher, which is a part of the pore in the outer membrane, the usher get the proteins from the cover ( like a sausage from the package)
That assembles the proteins in the right order
Pieces are not covalently bound , they just fit into each other like puzzle pieces

99
Q

Adhesion of the fimbriae to the surface is performed by

A
  • The main subunits

- Specialized subunit at the tip ( as in the case with the P fimbriae-type 1 pillus on the tip of the fimbriae)

100
Q

How does fimbriae adhesion of gram-positive occur

A

The adhesion to surfaces is carried out by surface adhesins, consisting of only one protein

101
Q

How does fimbriae of the gram-positive bacteria occur

A

Subunits of the fimbriae are assembled by sortases and attached to peptidoglycan

102
Q

The fimbriae of the gram-positive bacteria are anchored in ___, when in gram-negative ____

A

Peptidoglycan

The outer membrane

103
Q

The fimbriae in gram-positive composed of ____, and in gram-negative composed of ___

A

Pilin proteins

104
Q

How do the fimbriae subunits bound to each other

A

IN gram-positive -> covalently-linked

in gram-negative -> not covalently bound to one another( strand exchange)

105
Q

Fimbriae assembled by

A

in gram-positive-> enzymatically by sortases

IN gram-negative-> by chaperon and the usher, that are coded with the fimbriae pilin genes

106
Q

What is the endosperm

A

Highly differentiated cells that are extremely resistant to harch environment : heat,chemicals,radiation,nutrient depletion,dessication

107
Q

For how long does the endosperm can remain dormant, what environment conditions are needed to “wake” it and how the endosperm is dispersed

A

The endosperm is dispersed by wind, water , animal digestive system

They can remain dormant for 100s of years

Need water and 37 degrees celcius are needed for germination

108
Q

Another way of dormant phase and explain it

A

Other bacteria have found other solution:VBNC( viable , but not culturable state) that occurs when the bacteria is not dead, but not actively metabolizing, using very little energy to stay alive, but not enough to reproduce
VBNC susceptible to -> desiccation , some antibiotics require division to work, so they will not influence VNBC, VNBC heat resistant , nutrient depletion resistant, resistant to radiation

109
Q

The layers of the endosperm and their characteristics

A 
Inside out
DNA inside
Cortex-peptidoglycan
Core wall- used to be cytoplasm. Have Calcium, dipicolinic acid (DPA)-only in spores,SASPs(small,acid soluble proteins). Have proteins for germination 
Spore coat - have keratin
Exosporium- a layer of proteins
110
Q

What does DPA, Ca and SASPs do

A

SASPs bind to DNA and help protect against damage (UV light)

DPA+Ca bind water and help in dehydration

111
Q

How the endosperm forms

A

Usual vegetative cycle , when things are good

When become stressful in nutrients, the cell might decide to enter sporulation stage

The first stage of the endosperm formation: assymetric cell division and formation of the prespore , which is separated from the mother cell by septum

Then the engulfment occurs and a spore surrounded by a mother cell

The next stage is cortex formation, and there are three layers formed: cytoplasmic membrane, cell wall, cortex

Then the spore coat takes up Ca,SASPs and dipicolinic acid from the cytosol

And then the spore mature and the mother cell lysis

112
Q

What are cell inclusions

A

In bacteria and archea, energy reserves and building blocks are sometimes stored in granules or inclusions

Storing the nutrients the time when they are going to be not so abundant

113
Q

How are the cell inclusions surrounded

A

Can be enclosed with a single layer (phospholipid, protein, glycoprotein)

114
Q

What can be a cell inclusion

A

Carbon
Sulfur
Polyphosphate
Magnetite (that allow to respond to magnetic field and know the direction)

115
Q

How does the cell inclusion help cyano bacteria

A

They help the inclusions to float (buoyancy), so they can stay near the place with the sunshine

Introductory Microbiology (21 decks)

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