MODULE 3 Flashcards
what characteristics eukaryotes and prokaryote both have? (6)
flagella
plasma membrane
cell division
cytoplasm
ribosomes
chromsomes
domain eukaryota or _______ comes from the Greek eu, _______ and karyon, _______
eukarya,
“true” , “
nut” or “kernel“.
(eukaryotic cell structure)
gives strength and give shape to the cell
cell wall and pellicle
eukaryotic cell structure for Photosynthesis—trapping light energy and formation of carbohydrate from CO2 and water
chloroplasts
cell movement
Cilia and flagella
Environment for other organelles, location of many metabolic process
Cytoplasmic matrix
Transport of materials) protein , and lipid synthesis
Endoplasmic reticulum
Packaging and secretion of materials , lysosome formation
Golgi apparatus
Intracellular digestion
Lysosomes
Cell structure and movements, form the cytoskeleton (3)
Microfilaments, intermediate filaments, and microtubules
Energy production through use of the tricarboxylic acid cycle, electron transport, oxidative phosphorylation, and
other pathways
Mitochondria
Ribosomal RNA synthesis, ribosome construction
Nucleolus
Repository for genetic information, control center for cell
Nucleus
Mechanical cell boundary, selectively permeable barrier with transport systems, mediates cell-cell interactions and
adhesion to surfaces, secretion
Plasma membrane
Protein synthesis
Ribosome
Temporary storage and transport, digestion, water balance
Vacuole
Prokaryotes or procaryotes is coined from two Greek words pro_______, and karyon, ________
before, nut or kernel
used to describe unicellular (single-celled) organisms that lack true nucleus and membrane-bound cell organelles. This means that the genetic material is not bound within a nucleus.
Prokaryotes or procaryotes
Prokaryotes are divided into two domains
Bacteria and archaea
Common prokaryotic cell types (3)
cocci (spherical)
bacilli (rod-shaped)
Spirilli (spiral-shaped)
Structures that you can onIy find in either eukaryotic and prokaryotic cell but not in both
Nucleus - E
Cytoskeleton - E
Plasmid - P
• unicellular organisms without nuclei
• No organelles
• Have cell walls
• Lacks peptidoglycan
• DNA is more similar to eukaryotes, denotes lineage.
Archaebacteria
Archaebacteria live in extreme environments. (T/F)
Give examples. (3)
True
No oxygen,
Hot springs,
Deep ocean
Where do archaebacteria get energy?
Chemosynthesis
is the biological conversion of one or more carbon-containing molecules (usually carbon dioxide or methane) and nutrients into organic matter using
the oxidation of inorganic compounds (e.g., hydrogen gas, hydrogen sulfide)
or ferrous ions as a source of energy, rather than sunlight, as in photosynthesis.
What structure of archaebacteria
• protects cell against ion & pH fluctuations, osmotic s tress, degrading enzymes or predacious bacteria.
• helps in maintaining shape & envelope rigidity of the cell.
• it promotes cell adhesion to surfaces
• widely studied recently especially in connection with nanotechnology due to their ability to self assemble protein units without the aid of enzymes
Cell wall
What layer of archaebacteria cell wall could be used technologies such as drug delivery systems & novel detection systems for toxic chemicals?
S-layer
Archaeal cell wall
- S layer composed of either protein or glycoprotein
- most common type of archaeal cell wall
- 20-40 nm thick
- present in some:
Methanogens (METHANOCOCCUS),
Halophiles and
Extreme Thermophiles (SULPHOLOBUS AND PYRODCTIUM)
TYPE 1
Archaeal cell wall
- additional layers of material are present outside the S-layer
- In METHANOSPRILLUM
- there is a protein sheath external to the S-layer
TYPE 2
Archaeal cell wall
- In METHANOSARCINA
-S-layer is covered by a chondroitin like material called as __________
TYPE 3;
methanochondroitin
Archaeal cell wall
- In METHANOTHERMUS and METHANOPYRIS
- S-layer is the outermost layer and is separated from the plasma membrane by a peptidoglycan-like molecule called __________.
TYPE 4;
pseudomurein
Psuedomurein differ from Peptidoglycan in having
___________ instead of N-acetyl muramic acid,
_________ instead of D-amino acids that cross links and _________ glycosidic linkage instead of Beta (1->4) glycosidic linkage.
N-acetyltalosaminuronic acid,
L-amino acids ,
Beta (1->3)
Archaeal cell wall
- in this type, S-layer is absent.
- cell wall is single, thick, homogenous layer resembling Gram positive bacteria.
- These archaea often stain Gram positive.
- present in METHANOBACTERIUM, HALOCOCCUS
TYPE 5
T or F. Prokaryotic cell structure don’t have important consequences for human health.
F
- is a thin layer lining the inner surface
of the cell wall - semipermeable membrane controlling
the flow of metabolites - chemically, consists of Lipoprotein and
carbohydrates - sterols are absent
- fluid-mosaic model
- 40% phospholipid + 60% protein
Bacteria cell membrane
T or F. Both archaea and bacteria have sterols and hopanoids.
False.
no sterols (Archaea and Bacteria)
with hopanoids (Bacteria)
In cell membrane of some species, the opposing phospholipid tails are joined into a single tail, forming a monolayer which ________ the membrane a high temperatures
stabilize
is said to be responsible for the fluidity of the bacterial cell membrane
hopanoids
embedded in or loosely attached to the cell membrane
cell membrane proteins
prokaryotic cell membrane functions (give atleast 5)
- permeability barrier
- regulate movement of materials into and out of cell
- contains proteins that transport nutrients into the cells
and eliminate waste materials - synthesizes cell wall components
- assist with DNA replication (anchors DNA)
- secretes proteins
- carries on cell respiration (ATP synthesis)
- contains bases of flagella
- proteins respond to chemical substances in the
environment
– small molecules like water, oxygen, carbon dioxide, and hydrophobic molecules can move freely (simple diffusion)
– large or charged molecules like proteins, sugars, and ions can not (specific membrane proteins)
selectively permeable cell membrane
passive transport vs active transport
passive transport:
- diffusion
- facilitated diffusion (rarely used by prokaryotes)
- uses channel proteins an carrier proteins
active transport:
- uses energy
cytoplasm is composed of
4/5 water + 1/5 dissolved substances (enzymes, proteins, carbohydrates, lipids, salts, vitamins and various inorganic ions)
- where chemical reactions take place, semifluid substance inside the cell membrane
- colloidal system
- no ER and Mitochondria
- contains mesosomes, inclusions, and vacuoles
cytoplasm (bacteria)
- Vesicular, convoluted invaginations of the
plasma membrane - Prominent in GM+ bacteria
- Principal sites of Respiratory enzymes (helps in respiration and secretion processes)
- Analogous to mitochondria in Eukaryotes
- help to increase the surface area of cell membrane as a result increases the enzymatic content of the cell
mesosomes
T or F. All prokaryotic cells have mesosome for cellular respiration.
True.
- chromosome region
- gel-like region containing the chromosomes and plasmids
nucleoid
- single, circular, double-stranded DNA molecule that contains all genetic information required by a cell
- 1 mm long
- 10% of cell’s total volume
– supercoiled chromosomal DNA
chromosomes
complexed with proteins resembling histone proteins
archaea chromosomes (or bacterial?)
- accessory genetic information
- circular, supercoiled, double stranded DNA molecules
- 0.1 – 10% of chromosome size
- contains hundreds of genes (5-100 genes)
plasmids
- consist of ribonucleic acid (rRNA) and
protein (ribosomal protein) - <20,000
- nearly spherical, stain densely, and contain a
large and small subunits - sites for protein synthesis
- the faster the cell is growing, the faster
proteins are produced, the greater the
number of ribosomes - site for antibiotic action (streptomycin and
tetracycline)
ribosomes
Prokaryotic ribosome vs Eukaryotic ribosome
Prokaryotic:
- 70S = 50S (5S and 23S RNA) + 30S (16S RNA)
Eukaryotic:
- 80S = 60S (5S, 5.8S, 28S RNA) + 40S (18S RNA)
photosynthetic bacteria and cyanobacteria has _____ that contains the pigments used to capture light energy for synthesis of sugars
Chromatophores / chlorosomes
bacteria that
– convert nitrogen compounds into plant-useable
form
– house the enzymes used in deriving energy from
oxidation of nitrogen compounds
nitrifying bacteria
Internal Membrane Systems
Chromatophores
nitrifying bacteria
- variety of small bodies within the cytoplasm
- storage of materials that are later use as source of nutrients
- reservoir of structural building blocks
- granules; vesicles
inclusion bodies
Inclusion Bodies examples (2)
granules and vesicles
-storage granules
-gas vesicles (vacuoles)
– intracellular small storage bodies
– vary in size, number, and content
– bacterial cell can use them when environmental
sources are depleted
– i.e. glycogen, poly b-hydroxybutyrate, gas vesicles
for floating, sulfur and phosphate granules
(metachromatic granules), particles of iron oxide
granules and vesicles
accumulations of high molecular weight polymers
synthesized from a nutrient in excess;
contain specific substances densely compacted that do not dissolve in cytoplasm
storage granules
storage granules contain specific substances densely compacted that do not dissovle in cytoplasm (3)
- glycogen
- stored glucose polymer; carbon and energy source - volutin granules/polyphosphate granules (metachromatic granules)
- stored phosphate - others
- storage for elemental sulfur, magnetosomes
- small, rigid protein-bound compartments that provide
buoyancy to the cell - 300-1000 nm x 45-120 nm
- aquatic, photosynthetic bacteria; cyanobacteria
Gas vesicles (vacuoles)
Functions of Cell Wall
- maintain cell shape
- countering the effects of osmotic pressure
- cell division
- provides attachment sites for bacteriophages
- rigid platform for surface appendages (flagella, fimbriae, and pili)
- sites of major antigenic determinants
- resistance of antibiotics
Shape and Arrangement of Bacteria (3)
*Cocci: sphere, 1μm
*Bacilli: rods , 0.5-1 μm in width -3 μm in
length
*Spiral bacteria: 1~3 μm in length and 0.3-0.6
μm in width
Coccus Types (3)
*Diplococci - Neisseriae
*Tetrads - Sarcinae
*Sreptococci - Micrococci and staphylococci
Bacillus Types (5)
*Coccobacilli
*Mycobacteria
*Corynebacteria (palisades arrangement)
*Spore-forming rods
*Streptomycetes (moldlike, filamentous bacteria)
Curved forms: Spirillum/Spirochete (3)
- Vibrios (curved rods)
- Spirilla
- Spirochetes
Cell wall helps withstand pressure and prevents it from osmotic rupture or lysis that is due to _____ (isotonic, hypotonic, or hypertonic solution)
Hypotonic solution
- water moves into cell and may cause the cell to burst if the wall is weak or damaged (osmotic lysis)
- concentrated outside
The bacterial cell wall differs from that of all other organisms by the presence of __________ which is responsible for the rigidity of the bacterial cell wall and for determination of cell shape.
Peptidoglycan
Peptidoglycan (Mucopeptide) is composed of alternating chains of ________ which is cross linked by _______
N -Acetyl Glucosamine and
N-Acetyl Muramic Acid
PEPTIDE CHAINS
Based on the composition of
cell wall & Staining
bacteria are classified into (2)
“Gram positive” and “Gram
Negative”
- peptide + glycan
- murein
- macromolecule found only in bacteria
- structure varies in Gram-positive and Gram-negative bacteria
Peptidoglycan
are covalently joined to one another to form a glycan chain
* high molecular weight linear chain
* serves as backbone of the peptidoglycan molecule
NAG and NAM subunits (polysaccharide chain)
Peptidoglycan monomer is composed of (3)
NAM
NAG
Tetrapeptide/Pentapeptide
- different bacterial species, different amino acid composition
- is characterized by the presence of a very thick peptidoglycan layer (≈30 layers)
- 90% Peptidoglycan and 10%Teichoic acid
- 20-80 nm thick
- fully permeable to many substances (sugars, amino acids, ions)
- anionic glycopolymers
play crucial roles in cell shape determination, regulation of cell division, and other fundamental aspects of Gram- positive bacterial physiology.
Gram positive cell wall
Interwoven in the cell wall of Gram-positive are _____ and _______covalently bonded to NAM.
Teichoic acids and lipoteichoic acids
contains a thin peptidoglycan layer adjacent to the cytoplasmic membrane
also contains an additional ________ composed by phospholipids and lipopolysaccharide (LPS) which face into the external environment and
________________
Gram negative cell wall;
outer membrane and periplasmic space
(1) __________________
- a bilayer membrane
- “coarse sieve”
- barrier to passage of most molecules and excludes compounds that are damaging to cell
- composed of phospholipids, polysaccharides, and proteins
- contains (2) ________
- attached to the peptidoglycan by
almost continuous layer of (3) ____________
Outer Membrane;
lipopolysaccharide
(LPS)
LIPOPROTEINS (embedded in the outer membrane and covalently bonded to the peptidoglycan)
Outer Membrane has
(1) ______ :
– which is a specialized channel-forming proteins
– channels for low molecular weight substances
(2) and ______:
– which translocate proteins produced to the outside of outer membrane
porins and secretion systems
The LPS (in outer membrane) present on the Gram negative cell wall consists of 3 regions:
- Polysaccharide determining O antigen
- Core Polysaccharide
- Glycolipid portion /Lipid A
- are responsible for the endotoxic activities
- causes a form of Septic shock for which there is no direct treatment
- cause symptoms of disease in animals
- provide for immunological distinction and immunological variation among strains of bacteria
LPS or endotoxin
Lipopolysaccharide (LPS) PARTS
- Lipid A
- O-specific polysaccharide (O-antigen)
- Core polysaccharide
A part of LPS that
– responsible for toxic properties of G-bacteria (endotoxin)
– anchors the LPS in the bilayer
– composition recognizable by body as presence of invading bacteria
– small amounts may elicit defense system response enough to effectively eliminate the pathogen
Lipid A
A part of LPS that is a
– side chain portion of LPS directed away from the membrane
– chains of sugar molecules with varying composition and lengths
– used to identify certain species or strains
– i.e. E. coli O157:H7
O-specific polysaccharide (O-antigen)
- most observed among G- bacteria, rarely in G+ bacteria
- gel-like fluid (periplasm) and protein-filled (secreted proteins)
- very active area of cell metabolism (i.e. nutrient degradation
and transport)
Periplasmic Space
Periplasmic Space contains ________ (destroy potentially harmful substances), ________ (transport metabolites into the bacterial cytoplasm)
digestive enzymes;
transport proteins
- constitute for the major surface antigens
- one of the most important sites for attack by antibiotics
Teichoic acids
In Streptococcus pneumoniae (Gram positive) Teichoic acid bears the
antigenic determinants called the
“Forssman antigen”
one of the most important sites for attack by antibiotics
Teichoic acid?
periplasmic space?
compounds that interfere with the synthesis of peptidoglycan or alters its structural integrity
– penicillin
– enzyme lysozyme
– interfere with peptidoglycan synthesis
– binds to proteins involved in cell wall synthesis
– prevents cross-linking of glycan chains
– more effective against G+ bacteria
– modified to create derivatives that can pass through
porin channels
penicillin
– targets the peptidoglycan
– found in many body fluids
– breaks bond between the NAM and NAG molecules
lysozyme
Differences between cell wall of Gram positive and Gram negative bacteria
Thickness:
Periplasmic space:
Lipids:
Teichioc acid:
Peptidoglycan:
Thickness: (+) Thicker, (-) Thinner
Periplasmic space: (+) Absent, (-) Present
Lipids: (+) Absent or small, (-) Present
Teichioc acid: (+) Present, (-) Absent
Peptidoglycan: (+) 16-18nm, (-) 2nm
The Gram staining method, named
after the Danish bacteriologist who
originally devised it in 1882
(published 1884), _______________, is one of the most important
staining techniques in microbiology.
Hans Christian Gram
reflects fundamental
differences in the
biochemical and
structural properties of
bacteria.
The Gram reaction
- most frequently used differential stain
- devised by Hans Christian Gram in 1884
Gram Stain
Gram Staining
primary stain:
mordant:
decolorizer:
counterstain:
- crystal violet
- iodine
- 95% ethanol
- safranin
Cell Wall-Less Bacteria
- variable shape
- have sterols in their cell membranes (stability)
Mycoplasma species
cell wall appendages (protrude out from the main body)
- Glycocalyx (+/-)
- Capsule
- Slime layer - S-layer
- Surface proteins - Flagella
- Fimbria
- Pili
is a general term for any network of
polysaccharide (and small proteins) lying outside the cell
- consists largely of water and small content of 2% solids (could be complex polysaccharide or protein)
- bacteria may appear moist and glistening
- thick or thin; flexible or rigid
- few have repeating units of one or two amino acids (D-amino acids)
GLYCOCALYX
type of glycocalyx
– if the glycocalyx is loosely bound
to the cell wall of bacteria
– is irregular, nonuniform in density, and can easily be removed from the bacterial cell wall.
– less discrete structure or matrix which
embeds the cell ; diffuse and irregular
slime layer
type of glycocalyx
– when glycocalyx is tightly bound to the cell wall of bacteria
– It is gelatinous in nature, closely surrounds the bacterium, and cannot be easily stained and removed from the bacterial cell wall
– discrete detectable layer of polysaccharides deposited outside the cell wall; distinct and gelatinous (thicker and more rigid)
capsule (true capsule)
- Antiphagocytic, thus contribute “Virulence”
- protects against “Lysozyme”
- Promote attachment of bacteria to surface (e.g. Streptococcus mutans)
- Permits bacteria to adhere to Medical
Implants & Catheters. - helps trap nutrients near the cell
- protect soil bacteria from desiccation
- reserves of carbohydrates
- mediate adherence of cells to surfaces
- protect bacterial cells from engulfment
- capsules protect soil bacteria from desiccation
- when overproduced may become reserves of carbohydrate
- helps trap nutrients near the cell
- bind cells together and float themselves as colonial masses in their environments
Capsules
Disease: It is a virulence factor in most bacteria, and it contributes to
their ability to cause diseases in their host.
Protection: protects bacteria from antibiotics, chemicals
and against the lytic and phagocytic activities of host’s white blood
cells.
Adherence to surfaces: Its sticky nature of the enables bacteria to attach themselves firmly to the surface of their host. Streptococcus mutans, the causal agent of tooth decay adheres to the surface of decaying teeth with the help of _____.
Avoidance of desiccation: (especially capsule) contains water as its constituent. This help to prevent dryness of the bacterial cell.
In cell-cell recognition: The ________ carries receptors on their surface that allows them to bind to other cells of close species.
Glycocalyx
The ____________ of Gram+ STREPTOCOCCUS MUTANS allows it to accumulate on tooth enamel and one of the causes of cavities. Other bacteria in the mouth become trapped in the slime and form a biofilm & eventually a buildup of plaque.
slime layer
Capsule and Slime Layer
- some enables bacteria to adhere to specific surfaces and grow
as a _____. - polysaccharide-encased mass of bacteria coating a surface (i.e. Streptococcus mutans and dental plaque)
BIOFILM
