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Microbiology > Functional Anatomy of Prokaryotic and Eukaryotic cElls > Flashcards

Functional Anatomy of Prokaryotic and Eukaryotic cElls Flashcards

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1
Q

Describe origin of the words prokaryotes and Eukaryotes? What do they mean?

A

Prokaryotes comes from the Greek word for prenuclues
Eukaryotes comes from the Greek word for True nucleus

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2
Q

Compare and contrast the characteristics for Prokaryotes and Eukaryotes

A

Prokaryotes
-usually one circular chromosome, not membrane closed
-Typically lacks histones
-No organelles
-Bacteria: Peptidoglycan cell walls (some lack)
-Archaea: Some have Pseudomurein cell walls
Binary fission

Eukaryotes:
-Paired chromosomes in nuclear envelope
-Histones
-Organelles
Cells walls found in some protists, and all fungi and plants
-mitosis guided by the mitotic spindle, then division of cytoplasm and organelles

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3
Q

Discuss the cell size, and whether prokaryotes and eukaryotes have a nucleus and ribosomes. What is Svedsburg?

A

Prokaryotes
cell size: 0.2-2.0 um (W) o
NO nucleus
70 S ribosomes
S : Svdedsburg: unit measurement of the rate of centrifugration for sucrose that is used as unit for ribosomes

Eukaryotes:
cell size (10-100 um)
Yes, has a Nucleus
70S + 80s ribosomes (2 sizes of ribosomes because of mitochondria/chloroplast have 70 S)

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4
Q

what kind of shapes do prokaryotic cells have ?

A

Most bacteria are Monomorphic (environmental conditions may alter this)
-A few are genetically pleomorphic (can be multiple shapes, sizes )
ex: Corynebacterium glutamicum (can be bacilli, then cube-shaped)

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5
Q

What are the three Basic prokaryotic shapes? How do you distinguish between spirillum and spirochetes?

A

Bacillus (rod-shaped)
-Coccus (spherical)
-Spiral (one or more twists)
-Vibrio (external, like flagella)
-Spirrillum; FLEXIBLE and thin
-Spirochete: fairly RIGID and thicker with Flagella at ens (move like a wave)

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6
Q

What is the difference between Bacillus and bacillus? Explain the two meanings. What other basic shape names are used as genus names?

A

The scientific name : Bacillus
The shape: bacillus (rod-shape)
ex of basic shape names used as genus names:
Vibriocholera, Spirillum (type of bacteria)

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7
Q

What are four types of unusually shaped prokaryotes? What are examples?

A

Unusually shaped prokaryotes:
-Star-shaped bacteria (ex: Stella species)
-Rectangular Arachaea (ex: Haloarcula species)
-Square archaea (ex: Haloquadratum Walsbyi; seen in salon environment)
-Triangular prokaryotes (exL haloarcula japonica)

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8
Q

What are different cell arrangements that can occur? What are coccobaccili

A

Cell Arrangements (can remain attached after cell division)
Pairs: Diplococci (2 cocci) diplobacilli (2 rod-shape)
Clusters: staphylococci ; Staphylo= Grapelike cluster
Chains: Streptococci, Streptobacilli
*Strepto= TWISTED
Coccobacilli: Very short rod

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9
Q

How are cocci arrangements produced?

A

Cocci arrangements:
1. Plane of Division: examples Diplococic, and Streptococci (splits in half)
2. Tetrad

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10
Q

What kind of cell arrangement occurs in Bacilli?

A

NO arrangement in bacilli; only divide VERTICALLY

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11
Q

What kind of cell division produces the tetrad arrangement? What kind of arrangement are sarcinae and staphyl arrangements ?

A

Cell division in two planes produces the Tetrad arrangement
-The Sarcinae (8) and staphyl arrangements are produced by division in additional planes
sarcinae divide into three planes, have 8 groups

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12
Q

Describe the structure of a prokaryotic cell, differentiating what all bacteria have, and other things not shared

A

Structure of prokaryotic cell:
-Prokaryotic cells LACK cell membrane-enclosed organelles
-All bacteria have Cytoplasm, Ribosomes, Plasma membrane and Nucleoid (containing DNA)*
-Almost all bacteria have cell walls
-

Not all bacteria have capsule, fimbriae, flagella, pilus and plasma

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13
Q

What are the structures external to cell wall?

A

Glycocalyx (capsule) and slime layer, flagella and pili

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14
Q

What Is the glyocalyx and what is it composed of?

A

Gylocalyx (means Sugar coat)
Glycocalyx: general term for a viscous polymer (composed of polysaccharide, polypeptide, or both substances) on the cell surface
-Capsule: organized, firmly attached to the cell, definite boundaries
Slime layer: unorganized, diffuse and easily removed
-Usually sticky
-Chemical composition varies widely from species to species

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15
Q

What are the major functions of Glycocalyx?

A

Glycocalyx Functions:
1. The glycocalyx contains water which INHIBITS drying and nutrient loss
2 Capsules can contribute to virulence (ability of microbe to damage host; cause disease)
-prevent phagocytosis (ex: streptococcus pneumonia, klebsiella pneumonia and bacillus anthraces)
(without capsule, microbes not virulent)
- Facilitate attachment (ex: klebsiella pneumonia-respiratory tract, Streptococcus mutans-teeth, Vibrio cholera- small intestine)

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16
Q

Why is the glycolayx an important component of biofilms? What is EPS and the importance of attachment?

A

Glycoaclyx called extracellular polymeric substance (EPS) helps cells attach to environment and each other (can be mixed populations)
EPSs can be found in capsular material or as dispersed slime in the surrounding environment with no obvious association to one particular cell
*Attachment is also important for non-pathogenic bacteria (rocks in fast moving streams, plant roots, water pipes, etc)

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17
Q

Describe the structure of a flagella and the three things it consists of

A

Flagella:
-Long filamentous appendages outside the cell wall for propulsion
-consists of
-FILAMENT
-BASAL BODY/MOTOR: a rod and series of rings anchoring the flagellum to the wall and membrane. A rotary molecular motor, enabling the flagellum to rotate
(basal body/motor ; complex)
-HOOK: a flexible coupling between the filament and the basal body.

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18
Q

What is filament in the flagellum composed of? what is it is function? Are most prokaryotic filaments covered or not covered?

COME BACK

A

The filament is composed of a globular protein flagellin arranged as intertwining chains that form a helix around a hollow core
filament is responsible for antigenic variation in bacteria
-Flagellin is Highly polymorphic and responsible for bacterial H antigen specificity (E.coli has at least 50 variations/serovars)
(E.coli O157:H7; O: oligosaccharide antigen; H: antigen Flagella )
-Most prokaryotic filaments are NOT covered with a sheath (exceptions: Bdellovibrio and Vibrio cholerae; they have sheath, not antigenic)

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19
Q

What is the structure of bacterial flagellar filament?

A

-Hollow inside, composed of protein

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20
Q

Describe the different arrangements of Bacterial flagella

A

Arrangments of Bacterial Flagella;
1) Monotrichous- 1 flagella
2) Cephalotrichous - tufts (2 or more) at both ends
3) Amphitrichous -(amphi- around; having single flagellum at each of opposite ends)
4) Peritrichous- flagella around (uniformly distributed over the body)
5) Lophotrichous- 1tuft flagella at one end
6) Atrichous: NO flagella

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21
Q

Describe Archaella and what makes it so unique? How was the name proposed?

A

Archaella
-name proposed in 2012 following studies showing archaea flagella to be evolutionary and structurally different bacterial and eukaryotic flagella
-archae don’t code for any of the proteins that are part of flagellum.

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22
Q

Explain how flagella rotates and how discuss which kind of bacteria and prokaryotes are motile

A

Flagella rotate COUNTERCLOCKWISE to move Forward
and CLOCKWISE to TUMBLE (random orientation)
-Bacteria with functional flagella (one or more) are MOTILE
-About half of all known prokaryotic species are motile
-Speed of rotation can also be altered.

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23
Q

What is purpose of running and tumbling that bacteria (with flagella) do? also describe what motile bacteria have that allows them to move and and how their behavior changes.
What happens to bacteria when attractant concentration is higher?

A

Running/tumbling permits directed random movement toward or away from a stimulant
-Motile bacteria have RECEPTORS that recognize chemical stimuli (ex: Oxygen, ribose and galactose )
-Behavior is shaped by temporal changes in chemical environment with that experienced a few moments previously; if the attractant concentration is higher , tumbling is Supressed and the run is longer.

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24
Q

What is taxis and what are the different forms of taxis? What kind of stimulus can bacteria observe?

A

Taxis: bacterial movement towards or away form a stimulus
-Chemotaxis: chemical
-Phototaxis: Light
(also aerotaxis (O2), and thermotaxis(move toward higher or lower temp)

The stimulus can either be an;
Attractant: POSITIVE signal
Repellant: Negative signal

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25
Q

What are Axial Filaments and where are they located? Describe their function and where they are present.

A

Axial Filaments (aka Endoflagella)
-Present in Spirochetes (ex; treponema pallidum (cause syphillis) and Borriella burgdorferi (cause Lyme disease)
-Specialized flagella between cell wall and outer membrane called the “outer sheath”
-anchored at one pole of the cell and wrap around
-These filament bundles rotate to produce movement of outer sheath, propels in spiral motion (corkscrew)

(flagella filament made of flagellin)

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26
Q

how many endoflagela (axial filaments) are made per cell? How would you expect Spirochetes to gram stain?

A

2 to > 100 endoflagella/cell, depending on the species
Spirochetes is expected to stain similar to GRAM NEGATIVE bacteria

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27
Q

Describe the features that both Fimbriae and Pili share

A

Fimbriae and Pili are Hair-like appendages that are both:
1) shorter, straighter and thinner than flagella
2) comprised of pillin arranged helically around a central core
3) present in most gram-negative bacteria (few gram-positive)

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28
Q

What are unique features of fimbriae? What kind of microbes are they necessary for

A

Fimbriae:
-Occur at poles or evenly distributed
-Number from a few to several hundred
-Role: adhere to each other and to surfaces (liquids, glass, rocks, epithelial cells)
Fimbriae are necessary for Neisseria gonoorrhea to colonize mucous membranes

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29
Q

What are the unique features and Roles of pili?

A

Pili:
Usually LONGER Than Fimbrae
-Usally only one or two per cell
Roles:
Sex pili bring two cells together to allow DNA transfer from one cell to another in a process CONJUGATION
Surface motility:
-TWITCHING motility

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30
Q

Describe the twitching motility that pili undergo. Also discuss what of microbes this movement can be seen in.

A

Twitching motility
-observed in Pseudomonas aeruginosa and Neisseria gonorrhoeae and some E.coli strains
-Pilus extends by piling addition, attaches to a surface or another cell, retracts as pilin subnunits are disassembled (also called Grappling hook model )
-Results in short, jerky intermittent movements
(pili tend to twitch forward and backward at both ends of cells)

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31
Q

Discuss how gliding motility works. What is the most studied form of gliding motility?

A

Gliding motility- the ability of certain bacteria to smoothly glide on surfaces independent of flagella or pili
-The gliding mechanism is unclear and might differ between speceis
-Myxobacterial gliding motility is the most studied

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32
Q

What is the structure and function of Cell wall.

A

The cell wall
-Determines cell shape
-Prevents Osmotic lysis
-Anchors flagella
-Made of PEPTIDOGLYCAN (in bacteria)

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33
Q

What is peptidoglycan made of? What is it also known as ?

A

Peptidogylcan (aka murein)
-Polymer of disaccharide:
-N-acetylglucosamine (NAG)
-N-acetylmuramic acid (NAM)
(contains methyl and COOH)

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34
Q

Describe the structure of peptiodglycan

A

Peptidogylcan structure:
-Linear glycan chains (10-65) linked by polypeptides
-although the cross-bridge length and composition varies with bacterial species, TETRAPEPTIDE side chains (attached to NAM) are always included
connect the Lower layer to upper layer)
The tetrapeptide side chain amino acids alternate between D and L amino acids.

(2 NAG make up carb backbone and NAM in middle)

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35
Q

What is the mode of action of penicillin? For Lysozyme?

A

Mode of Action for Penicllin:
-To prevent the final linking of tetra peptide side chains to peptide cross bridges (prevent new synthesis)
Mode of Action for Lysozyme:
-hydrolyze bonds between repeating disaccharide units (NAM and NAG) of peptidoglycan

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36
Q

What part of crosslink varies in different bacteria.

A

LENGTH and COMPOSITION of cross link varies in different bacteria.

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37
Q

Describe the features of Gram-Positive cell walls

A

Gram Positive cell-walls:
-MANY layers of Peptidoglycan
-Contain Teichoic acids (lipoteichoic and wall teichoic acids):
-provide rigidity
-gives the cell a net negative charge. Helps sequester cations (Calcium and Magnesium ; Mg2+) for eventual transport into the cell
-Promote pathogen adherence to host tissues
-Antigenic specificity used to identify gram positive bacteria

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38
Q

What is the Gram-negative cell wall contained of (inside)?

A

Gram- Negative Cell wall:
-contains ONLY one or a few layers of peptidoglycan bonded to lipoproteins

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39
Q

What does the Outer membrane of gram-negative cell consist of?

COME BACK TO THIS

A

Outer membrane of Gram-negative cells
consist of: Periplasm, porin protein, LPS
Forms the periplasm- rich in degradative enzymes
-Strong negative charge is beneficial against phagocytes and complement
-Provides a barrier against harmful substances (antibiotics, lysozymes, etc) but not small metabolites (due to porins)
porins- are beta-barrel proteins that act as chemically selective passive fusion channels (allow passive transfer of specific molecules)
-

porins only found in outer membrane of gram-negative bacteria

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40
Q

What kind of structures have beta-barrel structures in their outer membranes?

A

BACTERIA, MITOCHONDRIA and CHLOROPLASTS

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41
Q

What are the 3 primary parts of Lipopolysacchraide (LPS) and what are their roles?

A

3 primary parts of the Lipopolysaccharide (LPS)
1) Lipid A- released from gram-negative bacteria when they die and is responsible for symptoms associated with their infection (fever, dilation of blood vessels, shock and blood clotting)
(endotoxin- toxin released from cell’s dye)
2) Core Polysaccharide- contains unusual sugars, structural role, provides stability
3) O polysaccharide, antigen useful for distinguishing gram-negative species (ex; E. coli O157:H7)

(great variation in O-side chain composition; at least 20 different sugars known)

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42
Q

What are Acid Fast-cell walls and what kind of cell walls are they? What are they composed of and what kind of species are these cell walls found in?

A

Acid-fast Cell walls are ATYPICAL Cell Walls
Acid-fast cell walls:
-Waxy lipid (MYCOLIC acid) bound to peptidoglycan
-Found in Mycobacterium and Nocardia species
-Prevents uptake of most dyes (ex: gram stain_
-During acid-fast staining, it RESISTS decolorization with acid-alcohol and retains the initial dye carbon fuchsin

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43
Q

How do the organisms in Acid-fast cell walls gram stain? what do mycolic acids comprise of?

A

They are IMPERVIOUS to gram staining (or stain weakly gram positive)
-Each mycolic acid molecule contains between 60 to 90 carbon atoms

44
Q

What are the features of Mycobacterium tuberculosis ?

A

Mycobacterium tuberculosis:
-Straight or slightly curved 3 x 0.3 um in size
-Size depends on conditions of growth
-Long filamentous, club-shaped, branching forms sometimes seen

45
Q

Which organisms have Atypical cell walls? Describe what they are composed of?

A

organisms with Atypical cell walls:
1) Mycoplasma
-Lack cell walls
-Unique among bacteria due to STEROLS in plasma membrane
2) Archaea
-Wall less Or walls of pseudomurein (N-acetyltalosaminuric acid instead of NAM and cross-links lack the D-amino aids)

46
Q

How do Mycoplasmas and Archaea gram stain?

A

they both appear gram NEGATIVE (they do Not retain peptidoglycan)

47
Q

Discuss cell wall removal terminology that include protoplasts and spheroplasts. What do protoplasts and spheroplasts have in common? What happens when they are intact

A

Cell Wall Removal Terminology:
Protoplasts: cell wall ENTIRELY removed (ex: Lysozyme digestion of gram-positive cells)
-Spheroplasts- cell wall only PARTIALLY removed (ex: lysozyme digestion of gram-Negative cells)
Protoplasts and spheroplasts are BOTH susceptible to OSMOTIC lysis. If they remain intact, they are spherical and remain metabolically active

48
Q

What is EDTA? Why is EDTA necessary for lysozyme to be most effective on gram negative cells ?

A

EDTA- a divalent cation chelator that binds divalent cations like Mg2+ from outer membrane and destabilizes the membrane (have access to peptidoglycan layer)

EDTA is necessary because it will alter ionic interaction in the outer membrane allowing the lysozyme access to peptidoglycan layer.

(EDTA chelator also used to prevent biofilms from forming, remove toxic metals from body)

49
Q

What are L-forms and what do they do?

A

Cell wall removal terminology:
L forms (Lister Institute)- are “cell-wall- deficient” bacteria that can grow as spheroplasts or protoplasts.
-They may form spontaneously or develop in response to penicillin or lysozyme.
-They remain capable of cell growth and division and can return to walled state (can arise from numerous species )
ex: L forms seen in B. subtitles

50
Q

Are L-form bacteria laboratory curiosities of no clinical significance or causes a variety of chronic diseases that include rheumatoid arthritis, chronic fatigue syndrome , Lyme disease and sarcoidosis? COME BACK TO THIS

A

YES

51
Q

Are mycoplasma considered L-forms?

A

No , mycoplasma are NOT considered L-forms, since they are NOT derived from bacteria that normally have cell walls.

52
Q

What is the Plasma membrane (prokaryote) composed of?

A

The Plasma Membrane composition :
1) A phospholipid bilayer contains:
- Peripheral proteins
-integral proteins
-**Transmembrane (most)
-*some form pores
2) The Outer Leaflet also contains glycoproteins and glycolipids
3) Mycoplasma membrane also contain sterols

53
Q

How can you biochemically distinguish peripheral and integral proteins?

A

You can use salt to disrupt the peripheral interactions?
COME BACK

54
Q

What is the Fluid Mosaic model and what are its components?

A

The Fluid Mosaic Model: Describes the cell membrane as a Mosaic of molecules (phospholipids, proteins and carbohydrates) that are constantly moving within the phospholipid bilayer
-Phopholipids rotate and move laterally
-The membrane has a viscosity like olive oil
-Unless ANCHORED, protein move in the membrane to perform their functions

55
Q

What are the major functions of the Plasma Membrane?

A

Major functions of Plasma Membrane:
1) A selectively permeable (semipermeable) barrier:
-Membrane: Ions penetrate membrane slowly while lipid soluble substances (O2, CO2, and non polar organic molecules ) transit more easily
-Channels: transmembrane proteins that provide hydrophilic passage way for ions and small molecules (O2, CO2 an simple sugars) Fixed confirmation but can exclude all but most specific molecules. Channels are DISTINCT from porins
-Transporters: transmembrane proteins that flip between two conformations while transporting specific molecules
2) May contain ATP production enzymes
3) May contain photosynthetic pigments
-In some bacteria (green and purple bacteira), they are found in infoldings of the plasma membrane that extend into the cytoplasm (called CHROMATOPHORES)
ex: rhodospirilum rubrum

56
Q

What kind of cellular structures do Cyanobacteria have? Where are thylakoid membranes also found?

A

Cyanobacteria have an internal thylakoid membrane system (separate from the plasma membrane) for photosynthesis
Although Cyanobacteria are prokaryotes, lacking a nuclear membrane and membrane bound organelles, they have INTERNAL membranes
Thylakoid membranes are also present in CHLORPOLASTS

57
Q

Describe the two processes that move materials across a membrane. Differentiate between them

A

1) Passive: cross from HIGH to LOW concentration (no energy required)
-Simple diffusion
-facilitated difffusion
-osmosis
2) Active: cross from LOW to HIGH concentration (energy required)
-active transport
-group translocation

58
Q

What happens in simple diffusion? What is this kind of transport useful for?

A

Simple diffusion: solute moves from high concentration to low concentration
-Used for certain SMALL molecules (O2, CO2)
-continues until equilibrium is reached.

(simple diffusion occur through lipid bilayer)

59
Q

What is facilitated diffusion? What kind of transporter do prokaryotes vs eukaryotes?
COME BACK

A

Facilitated diffusion: solute combines with a channel or transporter protein in the membrane (from high concentration to low concentration)
transporter can be specific or nonspecific
Facilitated diffusion with NON-specific transporter common in prokaryotes; passage of SMALL inorganic ions
-Diffusion through SPECIFIC transporter- common in eukaryotes: passage of LARGER compounds (ex: simple sugars, and vitamins)

60
Q

Why do bacteria release different types of enzymes into the environment? COME BACK

A

Some molecules released by bacteria are too large to enter the cell by transporters, secreted enzymes can break down large molecules.

61
Q

What occurs in Osmosis?

A

Osmosis; The movement of water across a selectively permeable membrane from an area of HIGH water to an area of LOWER water concentration

(at beginning of osmotic pressure experiment, high concentration of water outside sac, which causes water to go into sac and expand it; then eventually water will fill sac and reach equillibrum)

62
Q

What is osmotic pressure?

A

Osmotic pressure: The pressure needed to stop the movement of water across the membrane

63
Q

How does water move across the membrane?

A

Through Simple diffusion
-Facilitated diffusion through aquaporins (water channels)

64
Q

What are the three kinds of osmotic solutions that Bacterial cells experince? What do they all have in common?

A

3 osmotic solutions
1) Isotonic solution: No net movement of water (concentration of water inside = outside cell)
2) Hypotonic solution: Water moves into the cell. If the cell wall is strong, it contains the Swelling. if the cell wall is weak or damaged, the cell BURSTS (osmotic lysis)
3) Hypertonic solution: water moves OUT of the cell, causing the cytoplasm to SHRINK (plasmolysis)

The terms, Isotonic, hypertonic, and hypotonic describe the concentration of solutes Outside the cell relative to inside of cell

65
Q

What occurs during active transport?

A

Active Transport (move from low concentration to high concentration )
-requires a Transporter protein and ATP
-Concentrates materials in the cell
-Generally a different transporter for each substance or closely related substances
-substances not altered by transport

(minerals, sugars, and most amino acids, will move against [ ] gradient with input of energy)

66
Q

What is group translocation? What type of transport is it and what does it require?

A

Group Translocation (way of bacteria uptakes sugar from energy source PEP)
-requires a transporter protein and an organic high energy phosphate compound (ex; PEP; substance in glycolysis)
-Altered during import to make membrane impermeable (ex: Glucose-6-phosphate)
-Exclusive to Prokaryotes
-group transporter is a form of ACTIVE TRANSPORT

67
Q

Describe other types of active movement that occur across the membrane in eukaryotic cells.

A

Some eukaryotic cells (without cell walls) can use pinocytosis, receptor-mediated endocytosis, macropinocytosis and phagocytosis

68
Q

Which structures are integral to the cell wall?

A

Prokaryotic cytoplasm, Nucleoid, Plasmids, Ribosomes Inclusions, and Endospores.

69
Q

What is the prokaryotic cytoplasm? What does it comprise of?

A

Prokaryotic Cytoplasm:
The substance inside the plasma membrane
-80% H2O + proteins, molecules, ions
-Major structures: Nucleoid, ribosomes and inclusions

70
Q

What is a Nucleoid? What does it contain? Discuss features of bacterial chromosome

A

Nucleoid: irregularly-shaped region within the cell of prokaryotes which has nuclear material without a nuclear envelope
Bacterial chromosome (usually 1 circular) :
-attached to plasma membrane (can be spherical, elongated or dumbbell shaped)
-No histones
-how condensed? ; coils like rubber band
-Replication and chromes segregation enzymes are plasma membrane bound

71
Q

What are plasmids and what roles do they play?

A

Plasmids: autonomously replicating, independent chromosomes (DNA)
-contain 5 to 100 genes
-NOT crucial for survival under normal environmental conditions
-associated with plasma membrane proteins

72
Q

Describe the structure and function of prokaryotic ribosome. What is the size?

A

Prokaryotic Ribosome: large and long ribosomal RNA with a lot of proteins bound
-Protein synthesis
-70 S (size of ribosome)
-50S+ 30S subunits (cannot add them up, since it depends on the shape)
-each subunit contains multiple polypeptides and rRNA
-Common targets for antibiotics
(small subunit is 30S; Large subunit is 50s (common target for antibiotics) to form a complete 70s ribosome)

73
Q

what are inclusions and where are they seen inside the cell? What are some examples?

A

Inclusions- (material heals inside a cell); some are widespread, others limited to few species
-Metachromatic granules: phopshate reserves for ATP (membrane bound)
The color they give off are different from the stain they apply (Ex: if use blue stain, they will appear red)
-Polysaccharide granules- energy reserves (glycogen/starch)
-Lipid inclusions: Energy reserves
-Sulfur granules; Energy reserves
-Carboxysomes: protein shells containing the enzyme Ribulose 1,5-diphosphate carboxylase for CO2 fixation
-Gas vacuoles: protein-covered cylinders
-Magnetosomes: Iron oxide (membrane bound; orient bacteria to geomagnetic fields) (may protect from H2O2)

74
Q

What is the purpose of Gas vacuoles?
COME BACK ????

A

Gas vacuoles;
Is sulfur an energy source?

75
Q

What are endospores? Describe their structure and function. Where are true endospores found?

A

Endospores: Resting cell (don’t carry out metabolic reactions) with thick walls and additional layers that are resistant to desiccation, radiation, heat and chemicals
-contain only DNA, small amounts of RNA, ribosomes, enzymes a few important small molecules (ex; Dipicolinic acid)
-can remain dormant for thousands of years
-Prior to 1984, endospore bacteria were classified in either the Bacillus or Clostridium genera (anaerobic) (due to no access to RNA sequencing)
-Although true endospores are only found in Gram-POSITIVE bacteria, an endospore-like body is found n gram-negative organism Coxiella brunette

76
Q

Can endospores survive pasteurization? Boiling? Autoclaving?

A

Yes, endospores can survive pasteurization, and boiling , but NOT Autoclaving(heat will be above boiling point to kill the spores)

77
Q

Define the terms sporulation and germination. What triggers sporulation or germination?

A

Sporulation; Endospore FORMATION
Germination; RETURN to vegetative state
Vegetative cells are triggered to sporulate when key nutrient (carbon or nitrogen source) becomes Scarce or unavailable
-Endospore germination occurs when more favorable growth conditions are present and is triggered by high heat or small triggering molecules (two germinates known to date are alanine and inosine )

78
Q

Where can endospores be located?

A

Endospores location is species-dependent, either terminal, subterminal or central
(they are located in different areas in the cell)

79
Q

Discuss the process of Sporulation

A

Sporulation: The formation of spores and endospores
Process:
1. Asymmetric Cell Division: A sporangium (spore cell ) divides asymmetrically to form Forespore and Mother cell
2. Engulfment - Then mother cells Engulfs the foreshore and forms a spore coat around foreshore (double membrane)
3. Late Sporulation - the peptiodgylcan cortex is formed in between the outer forespore membrane and inner forespore membrane
4. Mother Cell lysis - mother cell lyses to release the forespore into the environment
5. Germination - spores can quickly germinate and return back to vegetative growth in response to nutrients.

1 cell produces 1 endospore.

80
Q

What occurs in spores from prokaryotic and eukaryotic organisms?

A

Spores formed by prokaryotic Actinomycetes and Eukaryotic algae and fungi detach from parent and develop into another organism.
-They represent Reproduction!

81
Q

Describe the structure of Flagella and Cilia. Where are they located in the cell? How do they differ?

A

Flagella and Cilia (Structure):
-bundle of nine fused pairs of microtubule DOUBLETS surrounding two central Single microtubules “9+2 array”
-Encased within the cell’s plasma membrane
-Anchored to the plasma membrane by a basal body
Flagella: FEW and long
Cilia: Numerous and SHORT

82
Q

Compare and contrast how eukaryotic vs prokaryotic flagella move

A

Eukaryotic flagellum moves in a WAVELIKE manner
Prokaryotic flagellum ROTATES

83
Q

Discuss which eukaryotic organisms lack cell walls or have cell walls, including what their structure is made of. How does this compare to importance of cell wall in bacteria?

A

Animal cells and Protozoans LACK cell walls (protozoans have a FLEXIBLE outer protein coat, called PELLICLE)
-When the cell wall is present in organisms, the cell wall is quite simple:
-NO Peptidoglycan
-Algae and Plant cells: cell wall made usually of CELLULOSE (glucose polymer)
-Fungi: cell wall usually made of CHITIN
-Molds: Chitin (NAG polymer) and/or cellulose
-Yeasts; Glucan, mannan, and small amount of chitin

As with bacteria, cell wall structure contributes to the cell shape and helps resist osmotic lysis

84
Q

What is Glucan molecule?

A

A GLUCAN molecule is any polysaccharide of D-glucose monomers

85
Q

What is the role of glycocalyx and where is it located?

A

Eukaryotic cells, including animal cells will often be surrounded by a GLYCOCALYX (gel-like layer) which can extend from either the cell wall or plasma membrane
-In cells lacking a cell wall, the sticky carbohydrates are bonded to either..
strengthen cell surface, help cells attach to each other and help cell-cell recognition

86
Q

Discuss the structure of eukaryotic plasma membrane and how it is similar in structure to bacteria, but also has differences. What makes Eukaryotic plasma membrane function different from bacteria?

A

The Plasma Membrane:
-Similar in basic structure to bacteria
-Phospholipid bilayer,
-Peripheral, integral, transmembrane proteins
-Glycocalyx carbohydrates.
**Sterols (help resist osmotic lysis) (UNIQUE to eukaryotes, except for Mycoplasma (prokaryotes) who have them.

Eukaryotic PM Similar in Function (to bacteria) :
-membrane transfer by same mechanisms but..
Eukaroytic PM LACKS group translocation
-have PINOCYTOSIS, Receptor mediated Endocytosis and Phagocytosis .

87
Q

Differentiate between Cytoplasm, Cytosol, Cytoskeleton and Cytoplasmic Streaming in Eukaryotes. What is the cytoskeleton made of?

A

Cytoplasm: a substance that consists of all the contents inside plasma membrane and outside the nucleus
Cytosol: the fluid portion of the cytoplasm NOT contained within membrane bound organelles.
Cytoskeleton: Complex internal structure that provides support, shape and assists in transport through cell.
Cytoskeleton has 3 fibers:
-Microfilaments (red)
-Intermediate filaments
-microtubules (green)
Cytoplasmic Screening: Movement of cytoplasm throughout the cell
(helps distribute nutrients and move the cell over a surface)

88
Q

What is the role of ribosomes in Eukaryotes? Distinguish between the different kinds of ribosomes in eukaryotic cell structures. Where are 80 S, 70S and free ribosomes located?

A

Ribosomes:
-Used for Protein Synthesis
-80 S(60 S + 40S)
-Membrane-bound: Attached to nuclear outer membrane and ER (endoplasmic reticulum)
-Free ribosomes: in cytoplasm
-two subunits assemble individually in nucleolus, exit the nucleus and then join for translation
-70 S (50S + 30 S)
in Chlorplasts and mitochondria
-translate chloroplast/mitochondrial mRNAs

89
Q

**What are the membrane organelles that ALL Eukaryotes have? What are their functions? (know this detail in textbook)

A

Membrane Bound Organelles (ALL Eukaryotes)
-Nucleus: Contains chromosomes
-ER(endoplasmic reticulum): Transport network, Smooth and Rough
-Golgi Complex: Membrane formation and Secretion
-Lysosome: Digestive enzymes
-Vacuole: Diverse functions: storage (energy sources, toxins wastes), endocytosis role and plant rigidity.

90
Q

**Discuss the organalles that Some Eukaryotes have, including their roles (know level of detail given in textbook)

A

Organelles that Some Eukaryotes have:
-Most have Mitochondria: Cellular respiration
-Chloroplast: Photosynthesis
-Peroxisome: Oxidation of Fatty acids; destroys H2O2
-Centrosome: region consisting of a pericentriolar center (protein fibers) and a pair of centrioles; involved in the formation of the mitotic spindle

91
Q

What does the Eukaryotic Nucleus consist of?

A

The Eukaryotic Nucleus:
-contains most of the cellular DNA
- Nuclear envelope (membrane that surrounds inner nucleus )
-Nuclear pores (protein complex with aqueous channel; used for transport)

92
Q

What is the structure and function of the Nucleolus?

A

Nucleolus:
-NOT membrane bound
-Formed around tandem repeats of rRNA genes (humans have 200 copies of rRNA genes on 5 chromomses )
-UNCONDENSED:
-chromosome regions (no histones)
-Site of assembly for small and large cytosolic ribosomes subunits

93
Q

Describe the Endoplasmic Reticulum and its role in the cell. What are the two forms of ER?

A

Endoplasmic Reticulum:
Two forms of ER: Rough ER (contains ribosmes) and Smooth ER
-The ER lumen is continuous with the perinuclear space (2 membranes between nuclear envelope)
-Phospholipid synthesis occurs here
-Processing and sorting center
-entry point for the vesicular pathway
(transporting vesicles from ER to Golgi)
-carbohydrates and phospholipids may be attached to proteins

94
Q

what is the role of the Golgi complex?

A

Golgi Complex;
-receive transport vesicles from ER
-proteins/lipids move from cistern-to-cistern via transfer vesicles
-enzymatic reactions yield gylcolipids, glycoproteins and lipoproteins
-Cargo containing vesicles leave for plasma membrane, lysosomes, etc.

95
Q

Describe the structure and function of lysosomes. What is the pH inside a lysosome and why is this low pH beneficial to the cell?

A

Lysosomes
-enclosed by a single membrane
-contain digestive enzymes to break down cell components no longer needed as well as molecules or even bacteria that are ingested by the cell
-The interior of a lysosome is moderately acidic (pH 5)
-The Low pH is beneficial to the cell because it is used a safety mechanism. if NOT at a low temperature, you can lose the function of enzymes that degrade things (enzymes need an acidic environment to stay active and have proper functioning)

96
Q

Where are vacuoles located and what are their different functions ?

A

Vacuoles:
-Enclosed by ER/golgi-derived membrane-bound sac (tonoplast)
-generally small in animals cells but can occupy 90% of the cell volume in plants
-has diverse functions depending on the cell. Some…
act as storage organelles for proteins, sugars, organic acids and inorganic ions
-acts a degradative compartments
-store metabolic wastes and poisons
-in plants, they can take up water to give rigidity to leaves and stems.

(vacuole are located within cytoplasm in the cell wall, surrounded by plasma membrane next to a nucleus )

97
Q

Describe the components of Nucleus, ER, Golgi complex, Lysosome and Vacuole.

A

Nucleus: Contains chromosomes (that form through nuclear division), also contains nuclear envelope (double membrane that has nuclear pores and nucleoli) and nucleus contains almost all of cells Hereditary information (DNA)

98
Q

What is the role of mitochondria? What are they composed of?

A

Mitochondria:
-Has two membranes (inner (respiratory chain) and outer membranes)
-# of mitochondria varies greatly
-Generates ATP
-contains chromosome (DNA)
-70S Ribosomes.

(mitochondria also have cristae (increase SA to synthesize ATP) and matrix (where protons are pumped out)

99
Q

Where are chloroplasts seen and and what do they contain? What do they have in common with mitochondria and bacteria?

A

Chloroplasts:
-seen in Algae and Green plants
-have THREE membranes (outer membrane, inter membrane space and inner membrane)
Like Mitochondria, chloroplasts contain 70s ribosomes and Divide like bacteria

100
Q

What are other structures located in the chloroplast? What major process occurs in chloroplast?

A

Chlorplasts contain:
-THYLAKOIDS (sac-like photosynthetic membranes)
-stroma (aqueous fluid)
-Granum (stack of thylakoids)
-lumen
PHOTOSYNTHESIS occurs in the chloroplast (where sunlight is converted into food and energy for plants

101
Q

Describe the. structure and function of the Peroxisome

A

Peroxisome:
Spherical, single membrane, smaller than lysosomes
-contain enzymes that oxidize organic compounds for normal metabolism (amino acids and fatty acids { Beta-oxidation}) or detoxification (alcohol)
-Catalase converts H2O2 generated in the peroxisome to H2O and O2.
(seen in Indian Mutjac Deer and Skin fibroblast cells)

Peroxisomes in image: green, F-actin: red and Nuclei: blue

102
Q

Where is the centrosome located and what are their roles?

A

Centrosome: located near the nucleus
1) in Nondividing cells, they are the center for building and organizing center microtubule formation
2) During cell division, duplicates and migrates to opposite poles of the cell to form mitotic spindles (that separate chromosomes)
Consists of two components:
1) pericentriolar area : a cytosolic region composed of a dense network of small protein fibers
2) centrioles

103
Q

What are Centrioles composed of and how are they aligned?

A

Centrioles: (made of microtubules like flagella, cilia)
-A pair of centrioles within pericentriolar region (of centrosome)
-Each centriole consists of 9 sets of triplet microtubules in a “9 + 0” array
- the centrioles are at RIGHT ANGLES to each other

104
Q

Describe the Endosymbiotic theory.
COME BACK TO THIS

A

Endosymbiotic Theory: belief that progenitor cell came from Ancient archeon
-The ancient arches had no cell wall and began with the invagination of Plasma Membrane, which derived nucleus.
The nucleus then formed nuclear envelope and produced ER (endoplasmic reticulum)
-Once nucleus and ER formed, the prokaryote engulfed the cellular mitochondria and photosynthetic prokaryote, which led to formation of plastid with mitochondria.

(Endosymbiotic theory explains that some eukaryotic organelles like mitochondria and plastids evolved from free-living prokaryotes)

105
Q

What is the supporting evidence for the Endosymbiotic Theory?

A

Supporting Evidence for Endosymbiotic Theory:
-Like bacteria, ribosomes are similar (70s bacteria, mitochondria)
-Size and shape of mitochondria are similar to bacterial size
-Ribosomes in mitochondria target bacteria
They divide

COME BACK TO THIS

Microbiology (18 decks)

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