Flashcards in Lecture 3 Deck (80):
All the of the chemical processes that take place in a cell.
Is the process by which a cell is formed or grows by converting simple nutritionist from the environment
Is the process by which various
chemicals are broken down and energy is released for use by the cell in other processes, perhaps to drive anabolism
The conservation of energy from chemical
reactions involves oxidation-reduction reactions
Carbon that is totally
reduced is bonded to....
Totally oxidized carbon CO2 is bonded to ..
Totally reduced oxygen H2O is bonded to...
fail to grow in the presence of air or
molecular oxygen (i.e., OR are able to grow in the absence of oxygen
• The growth failure is due to a sensitivity to thepresence of oxygen
Have sufficient levels of the enzymes
superoxide dismutase (SOD) and catalase
to remove the toxic metabolites that result from the incomplete reduction of molecular oxygen, thus they can grow in the presence of air
Require O2 for their energy metabolism;
they cannot carry out fermentation
Obligate anaerobes come in two varieties:
will grow in environments containing nomore than 0.5% O2 and may be brief exposures to air
Can grow in room air or in a 5% incubator BUT GROW BEST IN ANAEROBIC ENVIRONMENT
Can grow either in the presence or absence of oxygen
They have sufficient SOD and catalase or peroxidase but grow best in its presence
Facultative anaerobes can cope with changes in
environmental oxygen levels by
sensing oxygen concentration
and shifting their energy metabolism accordingly
In the presence of the electron acceptors O
or nitrate, E. coli represses some..
Two growth moods......
Some anaerobicaly induced genes
In the absence of inorganic electron acceptors, E. coli carries out
Mixed acid fermentation
It upregulates some of the enzymes of glycolysis and also the enzyme used for fermentative (anaerobic) disposal
Oxygen has toxic metabolites...
Superoxide radicals O2-
Formed during aerobic respiration and in anaerobes when grown in presence of O2
Peroxide anions O2-2 (formed by SOD)
Strict Anaerobes lack the enzyme...
Superoxide Dismutase SOD
Die in the presence of O2
What bacterial cells use to convert H2O2 to non toxic molecules
Obligate anaerobes either lack both or have such a small amount that they die
What does bacteria require to grow ?
They must obtain premade molecules or synthesize molecules for new cells
Ions-to synthesize protein
Why iron is important to the functioning of many enzymes in bacterial metabolism?
Fe is used in ETC
Some bacteria secrete SIDEROPHORES
-special proteins that help them concentrate iron from diluted solutions
And to take iron away from host tissue
What happens to the Fe in mammalian tissues ?
In mammalian tissues Fe is not left freely , it it found tightly bounded in variety different proteins
Where is Iron found?
As Heme (hemoglobin,myoglobin)
As Ferritin within cells
As Transferrin-transport between different tissues
In milk as Lactoferrin,
Also in tears,mucosal secretion (part of defense system)
What does cells require to survive and grow (bacterial metabolism)?
Constant supply of energy
Controlled breakdown of carbohydrate, lipids and proteins (this energy is used in the synthesis of
Cell wall, cell membrane ,cytoplasm nucleoid
Large molecules broken down into smaller subunits---active/passive transport
How is energy provided for medically important bacteria?
What does amino acids, sugars and lipids provide in bacterial metabolism?
They provide reduced carbon that can be oxidized via many catabolic pathways
What is a Key intermediate in several metabolic pathways ?
What can happen to carbon that comes from Pyruvic acid?
It can be catabolized for energy
It can be used in anabolic reactions ;
Synthesis of amino acids
As well as precursors for nucleic acids
What are the pathways that bacteria use to convert glucose to pyruvic acid?
What happens during catabolism of glucose ?(bacterial metabolism)
Chemical energy is captured by the creation of high energy molecules (ATP) or reduced coenzymes
How can energy from reduced coenzymes be used?
It can be used to form proton gradient across the cell via aerobic or anaerobic respiration
What is respiration?
Metabolic process that involves electron transport along a series of membrane associated electron carriers to final electron acceptor
How can bacterial energy metabolism be divided?
Aerobic respiration-molecular oxygen is the final electron acceptor
Anaerobic Respiration -inorganic compound other than O2 is a final electron acceptor NO3- etc
Fermentation- organic molecule is the terminal electron acceptor
How can pyruvic ever be used ?
It can provide fermentation products
It cans serve as an intermediate that enters the TCA cycle
What happens in TCA cycle?
Reduced carbon are completely oxidized to CO2 and the maximum amount of energy is captured in the form of reduced coenzymes
The reduced coenzymes from TCA cycle are re oxidized via the ETC using either Aerobic or Anaerobic respiration
What bacteria use Enter-Doudorff Pathway?
Where does the Glycolitic Pathway occur? For both eukaryotes and bacteria ?
What conditions are required for Glycolytic Pathway to occur?
Both Aerobic and Anaerobic conditions are sufficient.
investment of two moles of ATP for every mole of glucose is required
What is the net product for each more of glucose during Glycolytic Pathway?
2. Moles of Pyruvate
2 Moles of ATP
2 Moles of NADH
Pentose Phosphate Pathway
Also known as hexes-monophosphate shunt
Maybe used at the same time as the other two
Why is Pentose Phosphate Pathway important for biosynthesis and catabolism?
It serves as a function of NADPH for biosynthesis
Functions as a source of 5 carbon sugar
(Ribose-5-Phosphate for nucleic acid synthesis
CAN Yield 1ATP net if used for energy
What are the key points about
Entner -Doudoroff Pathway?
Alternate pathway to catabolize glucose to pyruvate (different set of enzymes)
ONLY DESCRIBED IN PROKARYOTES
Generates; NADH. NADPH PYruvate 1ATP for each mole of glucose
Why in some cases bacteria would prefer Entner-Doudoroff Pathways over Glycolysis? Examples!!
Because they may lack certain enzymes needed for glycolysis.
examples: PSEUDOMONAS AERUGINOSA
What can be done to regenerate NAD+ from NADH?
Either fermentation or respiration
Fermentation: pyruvate or a pyruvate derivative
serves as the terminal electron acceptor with various compounds as waste products; no further ATP is created as the electron transport chain is NOT used
• Respiration: uses a membrane-embedded
electron transport chain and usually an inorganic terminal electron acceptor
Product of Bacterial Fermentation
Streptococcus and Lactobacillus
;lactic acid and acetic acid
Enteric bacteria(E. coli, Salmonella)
;formic acid, acetic acid, ethanol ,lactic acid
Clostridium acetone, ethanol, bugaboo
Propionibacterium propionic acid (cheese)
What is used for complete oxidation of Pyruvate to CO2?
Energy production from TCA cycle?
For each molecule of glucose
What is Biosynthetic function of TCA cycle ?
TCA cycle provides CARBON SKELETON
Some organisms only use part of the reactions
What Happens to the NADH (and FADH2) Created by Glycolysis and the TCA Cycle?
Re oxidation via the ETC
uses O acceptor with formation of H
H+ across the cell membrane
Anaerobic Respiration: could be NO
or CO produces less proton gradient (and hence fewerATPs)-2 as terminal electron acceptor, but then3
When does the ETC occur in Bacterium?
Summary of ATP production
If aerobic respiration available --glycolysis produces 8ATP
Complete conversion of Pyruvate to CO2
(30 ATP with aerobic respiration )
Total--38ATP per glucose molecule
Bacterial growth-Binary Fission
1. cell elongates & DNA is replicated; note attachment of daughter chromosomes to cell membrane
• 2. cell wall & plasma membrane begin to divide cell in half between the two DNAs
• 3. cross wall completely
separates two daughter DNAs
• 4. cells separate
How do we if the cell will be spherical or rod?(bacterial growth,)
If they synthesize peptidoglycan at the same rate, then the cell is spherical
if the cross-septum enzymes are slower than those at the cell's side, then the cell is a rod
Methods to Identify Microbial Agents of Disease
▫ Direct microscopic visualization of the organism
▫ Cultivation and identification of the organism
▫ Serological and cytological methods to:
Detect microbial antigens
Detect the host's immune response, either a response of the innate or specific immune system
▫ Detection of microbial DNA or RNA
Glass or quartz lenses refract (bend) light because the glass is optically more dense than the surrounding air
Convex lenses refract light and can focus light on a focal point
This permits magnification (enlargement) of an image at distances farther away from the focal point
note that the magnified image is reversed and
only oblique,scattered light reaches the specimen
This causes the specimen to appear
bright against a dark background
and increases the resolving power
of the microscope to 20nm vs.200nm for the brightfield
What is Darkfield Microscopy good for?
useful for visualization of the
very thin spirochetes that cause
syphilis (Treponema pallidum) or
leptospirosis (Leptospira spp.)
Phase contrast microscopy
An optical microscopy
illumination technique in which
small phase shifts in the light
passing through a transparent
specimen are amplified to create
a 3D image. It enables
visualization of the internal
structures of unstained cells
contrast microscopy (DIC),
also known as Nomarski
Interference Contrast (NIC) or
Nomarski microscopy, is an
optical microscopy illumination
technique used to enhance the
contrast in unstained,
Short wavelength Uv light
Employs a fluorescent dye linked to an antibody .
The antibody directly binds the target antigens
The tagged antibody is second antibody it binds another antibody that actually binds the target antigen
Electron Microscopy - Transmission (TEM)
Magnetic coils focus beams of
electrons from a tungsten
filament onto or through
specimens for electron
microscopy. The electrons create
an image on a detector screen.
Electron Microscopy - Scanning (SEM)
In SEMs the surface of
the specimen is coated with a thin layer of a heavy metal and the electron beam scans across its surface rather than passing thorugh the specimen
Wet mounts,Bacterial motility
To detec flung in tissue use solution of 10'5 KOH----lactophenol cotton blue
The KOH dissolves mammalian cells and
non-cellular material leaving the resistant fungal cell walls to be visualized
Negative staining: India Ink
consists of carbon particles suspended in a fluid; it can be used to visualize the thick capsule that is characteristic of Cryptococcus neoformins in freshly obtained cerebrospinal fluid (CSF)
coryne- is a prefix applied to a
rod-shaped cell that is wider at one end than the other (e.g., club-shaped bacilli in diptheroids)
diplococci and chains for
streptococci, grape-like clusters for staphylococci, palisades & v-shapes for diptheroids (look similar to Corynebacterium diphtheriae)
have a positive charge and bind to
negatively charged molecules such as nucleic acids, many proteins, and the surfaces of bacterial cells
Methylene blue, crystal violet
have negatively charged groups and
bind to positively charged cell structures
▫ eosin, rose bengal, acid fuchsin
single agent is used so can
only tell cell shape, size and cell arrangements
divide bacteria into separate
groups based on staining properties
Acid fast stain
stain with crystal violet, use a mordant, decolorize with alcohol, counterstain with safranin ⇨.
purple Gram positive &
red Gram negative;
used for many bacteria
Acid fast stain
heat with basic fuchsin and phenol,
decolorize with HCl-alcohol, counterstain with methylene blue ⇨
red acid-fast cells with all others
important for a restricted group of bacteria
Acid fast stain is used for...
Used to stain cells of genus Mycobacterium and
Nocardia and oocysts of certain protozoa
stains the background and
can show true cell size; also used to demonstrate capsules
drive malachite green into
vegetative cells and endospores with heat,
rinsewith water and counterstain with safranin
⇨green endospore and red vegetative cell
staining in a color that is different
than that of the dye used to
create the stain
Albert's stain can be used
to detect volutin (black granules) within green Corynebacterium cells