question

4 Functions of glycocalyces in bacteria

answer

1. interferes with host phagocytosis
2. prevent dessication (drying out)
3. form biofilm by sticking together
4. Capsular strain variation

question

? Fungi

answer

• Eukaryotic (membrane bound nucleus)
• Obtain food from other organisms
• In mouth from suppressed immune system
• Possess cell walls not a membrane
• Molds and yeasts

question

• Molds description and reproduction

answer

multi-cellular, long filaments; reproduce asexual spores and sexual spores

question

yeasts description and reproduction

answer

uni-cellular, some reproduce sexually, most reproduce asexually by budding

question

? Protozoa

answer

• Similar to animals in nutrient needs and cellular structure
• Live freely in water and some animal hosts
• Mostly asexual but some sexual reproduction
• Malaria a type of deadly protozoa

question

? Algae

answer

• Uni and multicellular eukaryotes
• photosynthetic
• sexual & asexual reproduction
• simple reproductive features
• categorized on the basis of pigmentation, storage products, and composition of cell wall
• Diseases in humans usually arise in fish

question

? Bacteria and Archea

answer

• Unicellular and lack nuclei (prokaryotes)
• Much smaller than eukaryotes
• Found where there is sufficient moisture
• Archea-Ancient bacteria…extreme environments
• Asexual reproduction for both

question

Bacteria – cells walls

answer

contain peptidoglycan (some lack cell walls)

question

Archaea – cell walls

answer

composed of polymers other than peptidoglycan

question

? Small multi-cellular organisms

answer

• Worm diseases in humans
• i.e. In tropics…worm can cause bladder cancer…
• 200 million have it…

question

T/F • A virus can infect a bacterium

answer

True

question

The 4 questions that scientists searched for answers during the golden age

answer

1. Is spontaneous generation of microbial life possible2. What causes fermentation3. What causes disease4. How can we prevent infection and disease?

question

Some philosophers and scientists of the past thought living things arose from three processes:

answer

1. asexual reproduction
2. sexual reproduction
3. from nonliving matter

question

abiogenesis

answer

• living things can arise from nonliving matter

question

decaying meat Experiment

answer

? When decaying meat was kept isolated from flies, maggots never developed
? Meat exposed to flies was soon infested
? As a result, scientists began to doubt Aristotle’s theory

question

beef gravy experiment

answer

placed a broth, or “gravy,” into a bottle

heated the bottle to kill anything inside, then sealed it.

Days later, he reported the presence of life in the broth and announced that life had been created from non-life

In actuality, he did not heat it long enough to kill all the microbes.

question

“swan-necked” flasks experiment

answer

• When the “swan-necked” flasks remained upright, no microbial growth appeared

• When the flask was tilted, dust from the bend in the neck seeped back into the flask and made the infusion cloudy with microbes within a day

question

• The Scientific Method

answer

1) Observation leads to question
2) Question generates hypothesis
3) Hypothesis is tested through experiment(s)
4) Results prove or disprove hypothesis
5) Accepted hypothesis leads to theory/law
6) Reject or modify hypothesis

question

? Fermentation experiment

answer

linked to debate over spontaneous generation

o Proved that the yeasts reproduce and alcohol is produced

question

• Koch’s Postulates

answer

1) Must be able to identify the organism and must be present infected cases, and absent from healthy hosts
2) Must be able to separate the organism from host and grow
3) Must be able to introduce a healthy animal, cause disease,
4) Must be able to extract the same organism from host

question

Can Koch’s Postulates be applied today?

answer

? May not be applied today….but postulates considered framework for science today
? i.e. – nucleic acids did not exist back then
? also some agents cause different diseases

question

Are most bacteria capable of colonizing humans and causing disease?

answer

• Only a few are capable

question

? Pleomorphic aka polymorphic

answer

? Pleomorphic aka polymorphic
• Comes in different shapes

question

? Reproduction of Prokaryotes

answer

• All reproduce asexually
• 3 methods of reproduction in prokaryotic cells: binary fission (most common), snapping division, budding division

question

• Binary fission (most common)

answer

1. Cell replicates DNA in the nucleoid region (no membrane bound nucleus)
2. Cytoplasmic membrane elongates (cell gets bigger), separating DNA molecules
3. Cross wall forms and the membrane invaginated
4. Cross/ septum wall forms completely
5. Daughter cells separate

question

? Budding

answer

• Not common among bacteria but occurs
1. nucleoid replicates
2. new nucleoid moves into a bud
3. young bud eventually becomes a new daughter cell

question

two things responsible for the arrangement and shape of division during binary fission

answer

• Arrangement results from planes in which cells divide

• Separation (AND SPEED) of daughter cell separation

question

Arrangements of Cocci

answer

• Diplococci, streptococci, tetrads, sarcinae, staphylococci

question

Arrangement of Bacilli

answer

• Single bacillus, diplobacilli, streptobacilli, pasisade ( and v-shape

question

? Bacterial endospores

answer

• survival mechanism
• each vegetative cell transforms into one endospore
• each endospore germinated to form one vegetative cell
• produced by GRAM POSITIVE bacteria
• spore has minimal cytoplasm and membrane and some bacterial DNA

question

Formation of Endospore

answer

1. DNA is replicated

2. DNA aligns along the cell's long axis

3. Cytoplasmic membrane invaginates to for FORESPORE

4. Cytoplasmic membrane grows and engulf forespore within a second membrane. Vegetative cell's SNA disintegrates

5. A cortex of calcium and dipicolinic acid is deposited between the membrane

6. Spore coat forms around endospore

7. Maturation of endospore; completion of spore coat and increased resistance to heat and chemicals by unknown process

8. Endospore released from original cell

question

4 processes of life

answer

o Growth, reproduction, responsiveness, metabolism

question

Prokaryotes: describe membrane & nucleus

answer

? No nucleus
? No phospholipid membranes inside…outside membrane exists however
• No compartmentalization
? Composed of bacteria and archaea

question

organelle in typical prokaryotic cell

answer

ribosomes, cytoplasm, nucleoid, cytoplasmic membrane, flagellum, inclusions, and glycocalyx

question

• Glycocalyx

answer

sugar-coating on outside of bacteria

• Composed of polysaccharides, polypeptides or both

question

• Two types of glycocalyces

answer

• Capsule

• Slime Layer

question

• Capsule glycocalyces

answer

? Composed of organized repeating units of organic chemicals
? Firmly attached to cell surface
? May prevent bacteria from being recognized by host

question

• Slime Layer glycocalyces

answer

? Loosely attached to cell surface
? Water soluble
? Sticky layer allows prokaryotes to attach to surfaces

question

composition of flagella

answer

•Not present in all bacteria

filament, hook, basal body

o Basal body anchors filament and hook to cell wall by a rod and creating a series of either 2 or 4 rings of integral proteins

question

Gram-positive flagella

answer

Gram-positive organisms have 2 of these basal body rings, one in the peptidoglycan layer and one in the plasma membrane

question

Gram-negative flagella

answer

Gram-negative organisms have 4 basal body rings. One in the additional ring in 2 in the plasma membrane, and one in the peptidoglycan layer, and one in the outer membrane.

question

• variability names for bacteria flagella numbers

answer

? Monotrichous – one flagella
? Liphotrichous – two or more flagella around same area
? Amphitrichous – flagella at both ends
? Peritrichous – flagella all around (“a” in the figure)

question

function of bacterial flagella

answer

o Rotation propels bacterium through environment
o Rotation reversible; can be counterclockwise or clockwise

question

• Taxis

answer

bacteria can sense things…attracts or repels
? Receptors on bacteria cause attractants and repellants
• Linked to flagella
o Runs
o Tumbles

question

o Fimbriae

answer

• Very external…..come out of glyccolycs
• Sticky, bristlelike projections
• Serve an important function in biofilms
• Shorter than flagella
• Used by bacteria to adhere to one another, to hosts, or substances in the environment

question

• Fimbriae Antigenic Variation

answer

? Antigen (antibody generator)
? Constant change causes variation also to protect against host immune system

question

• Pili

answer

o Longer than fimbriae but shorter than flagella
o Bacteria only have one or two per cell
o New organism created and variation increased
o Bacteria separate fission and conjugation
• Mediate the transfer of DNA from one cell to another
• Can result in Antibiotic resistance from variation in DNA of bacteria

question

• The cell wall of bacteria

answer

o Provide structure and shape and protect cell from osmotic forces
o Assist some cells in attaching to other cells or in resisting antimicrobial drugs
o Not a membrane…more rigid than a membrane
• Prevents itself from rupturing
o Gives bacteria cells characteristic shapes
o Walls can be targeted by antibiotics
o Composed of pepitdoglycan

question

peptidoglycan sugar composition

answer

? Glucose, NAG, NAM
• NAG and NAG glucose derivatives
• They alternate in structure….cross-linked by short peptides

question

o Gram Positive

answer

• Stains PURPLE

2 layers: peptidoglycan layer and cytoplasmic layer

contain unique polyalcohols called Teichoic acids, whcih provide rigidity to the wall

question

Teichoic acids

answer

molecules in GRAM POSITIVE bacteria that provide rigidity

question

Gram negative

answer

• Stains pink

o THIN layer of peptidoglycan
• bilayer membrane outside of pepdidoglycan (cell wall)
• Not easy to treat bc of 3 layers
• Contains, phospholipids, proteins, and LPS
• LPS (lipopolysaccharide)

question

? 3 components of LPS (lipopolysaccharides)

answer

• Lipid A
• Core polysaccharide
• O- Antigen

question

Lipid A

answer

component of gram negative bacteria

known as an endotoxin
o Gets into body, as the bacteria dies, endotoxins released into blood
o Anchored in outer cell membrane

question

• Core polysaccharide

answer

component of gram negative bacteria

question

• O- Antigen

answer

component of gram negative bacteria

(it exhibits variation in length and composition)

question

How antibiotic interferes with synthesis of peptidoglycan

answer

stops cross-linking

question

• lysozyme

answer

o -naturally occurring enzyme found all over the place (even mouth)
o antibacterial that ruptures one of the bonds involved in the synthesis of peptidoglycans
o peptidases, naturally also destroy peptidoglycans
o bacteria can modify the sugar groups on its surface to prevent its destruction from enzymes

question

gram negative cell wall components

answer

a bilayer on the outside, a cell wall in the middle, and a cytoplasmic bilayer inside

question

why membranes form spontaneously

answer

because most energetically stable formation

question

• integral proteins

answer

embedded in the membrane…some trans membrane (span entire membrane)…some only embedded

question

• peripheral proteins

answer

on outside involved with communication purposes

question

6 methods of Transportation in cytoplasmic membrane

answer

1. energy storage
2. selectively and naturally permeable
3. membrane plays a structural role in cell division
4. maintains a concentration and electrical potential
5. Harvest light energy in photosynthetic bacteria
6. Naturally impermeable to most substances

question

o many proteins are +/- charged on inside of the membrane?

answer

NEGATIVELY

question

• Hypertonic

answer

more solute on outside

? Bacteria tend to live in hypotonic

question

Facilitated diffusion

answer

o High concentration to low with the help of non specific proteins
o Molecules move through a permease specific for one chemical….
• Binding of substrate causes shape change in a channel protein
a. Conduit (channel) from point A to point B
b. Tend to be integral and trans membrane proteins

question

Active Transport

answer

o Use energy to go against concentration gradient with use of ATP

o Can be an uniport, antiport or symport

question

• Uniport

answer

actively transports a molecule or group of molecules across a membrane in the same direction against concentration gradient

question

• Antiport

answer

actively transpoerts 2 molecules across a membrane against a concentration gradient...
ex. Na+ K+ channel

question

• Symport

answer

transports two different molecules across a membrane at the same time.

question

Group Translocation

answer

• As transporting something, the membrane chemically alters it
? i.e- glucose phosphorylated during glycolysis
• traps the glucose in the cell because it’s polar…group translocation

ONLY SEEN IN PROKARYOTES!!!!!

question

• inclusions

answer

molecules that build up inside cell….cell can inhabit the molecules until needed
o some inclusions actually stored for function….ex. gases
o bacterial use magnets to “sense”…example of inclusion

question

• Non-membranous organelles

answer

o ribosomes, cytoskeleton, centrosomes, and proteosomes

question

o Eukaryotic cells vs prokaryotic

answer

Eukaryotic
membrane-bound nucleus, complex cytoskeleton & numerous membrane-bound organelles in their cytoplasm.

Prokaryotic small simple cells that do not have a membrane around their genetic material or membrane-bound organelles in their cytoplasm.

question

T/F Glycocalyx found on eukaryotic cells that have cell wall

answer

False
o Glycocalyx found on eukaryotic cells that do not have cell wall

question

T/F Most eukaryotic glycocalyx are composed of
polysaccharides

answer

True, not peptidoglycans

question

? PELLICLE

answer

the name of the glycocalyx of protozoa

question

protective matrix

answer

o Glycoproteins of the animal and protozoan glycocalyx produce a protective matrix, which protects them from the outside environment

question

GLUCANS and MANNANS

answer

o Cells walls of yeasts are composed of GLUCANS and MANNANS

question

• Fungi cell walls are composed of

answer

mostly Chitin) and sometimes CELLULOSE (plants)

question

• Algae have most complex cell wall composition and a variety of carbohydrates like....

answer

• AGAR, CARRAGEENAN, SILICATES, ALGIN, CALCIUM CARBONATE

question

Describe prokaryotic flagella

answer

? prokaryotic are long, EXTRACELLULAR FILAMENTS THAT ARE COMPLETELY OUTSIDE THE CELL MEMBRANE

question

Describe Eukaryotic flagella

answer

eukaryotic flagella are longer than prokaryotes

? eukaryotic flagella are long, CYTOPLASMIC PROJECTIONS composed of MICROTUBULES that are inside and covered by the CYTOPLASMIC MEMBRANE
• 9+2 in shaft …..9 doublets surrounding 2 singlets microtubules in the center
• eukaryotic flagella are anchored in the CYTOPLASM to a BASAL BODY composed of a triplet of microtubules in a 9+0 arrangement

question

? Eukaryotic flagella generate movement vs prokaryotic

answer

? Eukaryotic flagella generate movement in a wave or whip-like motion….either PULLS the cell in the direction of the flagella or PUSH it forward

• Prokaryotic flagella generally move by ROTATION

question

• Cilia

answer

o Hair-like structures that are shorter than flagella
• Eukaryotic cells contain hundreds of cilia
o Like eukaryotic flagella, the cilia are cell-membrane bound cytoplasmic projections composed of microtubules in a 9+2 arrangement in the shaft and a triplet 9+0 arrangement in basal body
• SAME STRUCUTRE AS EUKARYOTIC FLAGELLA

• Cilia also move in a WHIP-LIKE motion and beat rhythmically together
• Eukaryotic cilia can be used to propel a single cell through a medium or move nutrients over the surface of cell membranes in multicellular organisms

question

? Eukaryotic Cytoplasmic Membrane

answer

• phospholipid bilayer, contains STEROLS and GLYCOPROTEINS
• sterols (steroid + alcohol) make membrane more rigid at high temps and more fluid at lower (by preventing phospholipids from packing together)

question

• membrane glycoproteins in eukaryotes can function as...

answer

recognition molecules, signaling molecules, anchors (glycocalyx), enzymes, cannels, transporters

question

• Prokaryotes lack sterols (except ___________) and contain PEPTIDOGLYCANS (proteins + sugar) instead of glycoproteins

answer

mycoplasma

question

• Primary function of eukaryotic plasma membranes the same as prokaryotic plasma membranes which is...

answer

• same active and passive processes to move materials as prokaryotes

question

PHAGOSOME

answer

• Pseudopods extend around the particulate matter and fuse together, forming a membrane-bound vesicle in the cell’s cytoplasm called a PHAGOSOME that contains ingested material

question

PHAGOLYSOSOME

answer

• Lysosomes fuse with the phagosome, forming a PHAGOLYSOSOME, which digests the ingested material

question

• Pinocytosis

answer

? INGESTION OF LIQUID materials by a cell
? cell’s pseudopods extend into the liquid medium and fuse together, forming a membrane-bound vesicle in the cell’s cytoplasm that contains the liquid sample

question

o Receptor-mediated Endocytosis

answer

• Ingestion of molecules that are BOUND TO A MEMBRANE RECEPTOR
• Pseudopods extend around the bound molecules and fuse together, forming a vesicle in the cytoplasm that contains the receptor-bound molecules

question

o Exocytosis

answer

o Reverse of endocytosis….
o Vesicles in the cytoplasm fuse with the plasma membrane and release their contents outside the cell.
o Waste materials exit cell via exocytosis

question

• CYTOPLASMIC STREAMING

answer

looks like its constantly moving

• Not observed in prokaryotic cells

question

Eukaryotic and Prokaryotic Ribosome sizes

answer

? Eukaryotic ribosomes have large size 80S ribosomes while prokaryotes have small size 70S ribosomes

? Eukaryotic ribosomes consist of two subunits, which are sizes 60S and 40S

question

? Many antibiotics that inhibit protein synthesis in prokaryotic cells do not affect the eukaryotic cells because ....

answer

because of the larger size of the eukaryotic ribosomes

question

• ribosomes of eukaryotic cells can attach to the _________ and carry out protein synthesis on its membrane

answer

ER

? allows the new polypeptide chain being made to extrude into the ER with it can be packaged into vesicles for transport to another site in the cell or secreted

? these membrane bound structures don’t exist in prokaryotic cells

question

o Skeleton consists of 3 major types of protein structures

answer

• Microtubules

• Microfilaments

• Intermediate Filaments

question

• Microtubules

answer

? Hollow structures that are 25 nm in diameter formed from TUBULIN
? Microtubules also present in flagella, cilia, centrioles

question

• Microfilaments

answer

? Thin filaments 7 nm in diameter that are formed from G-actin
• Protein important in muscle movement
• Enables things to move in the cytoplasm
• centrioles composed of microtubules

question

• Intermediate Filaments

answer

? Long filaments about 10 nm long
? Formed from different monomer depending on the cell type and organelle
• skin and hair composed of microfilament only found in these tissues, and not others

question

Functions of Cytoplasm

answer

• 1. anchors organelles
• 2. enables cytoplasmic streaming and movement of organelles in the cytoplasm
• 3. enables cell contraction
• 4. moves the cell membrane during endocytosis and carries out amoeboid movement
• 5. provides shape in eukaryotic cells

question

T/F some fungi contain centrioles and centrosomes

answer

TRUE

question

? Centrioles and Centrosome

answer

o Animals and SOME FUNGAL cells have TWO large MICTROUBULE structures called CENTRIOLES which lie at RIGHT ANGLES to each other near the cell nucleus in a region of the cytoplasm called the CENTROSOME
o Centrioles participate in mitosis and cytokinesis
o Centrioles are composed of triplet microtubules in a 9+0 arrangement similar to the basal body of EUKARYOTIC flagella and cilia

question

How proteosomes play a key role in adaptive immune responses to intracellular pathogens

answer

• They produce foreign (non-self) peptides from the pathogen that become bound to MHC proteins and are transported to the cell surface for presentation to T cells
• T cells respond to peptides of degraded proteins
o Proteasomes play a key role in adaptive immune responses to intracellular pathogen

question

Which organelles contain DNA?

answer

Nucleus, chloroplast, mitochondria

question

Histones

answer

• Chromosomes are complexed with proteins called Histones and forms threadlike mass called chromatin that is suspended in a semiliquid matrix called nucleoplasm

question

Do all eukaryotic cells contain nuclei?

answer

No

• some eukaryotic cells have MULTIPLE NUCLEI
• some have NO NUCLEI….lose it during maturation process (red blood bells)

question

? Vesicles vs Vacuole

answer

• Small membrane-enclosed sacs are vesicles are used for transport of substances within the cytoplasm of eukaryotic cells

• Large membrane-enclosed sacs are called vacuoles and are used to store chemicals, food (starch), air.

question

Relationship between Active H+ ion transporter and phagolysosome

answer

• An ACTIVE HYDROGEN ION TRANSPORTER is formed in the membrane of PHAGOLYSOSOMES that pumps H+ ions from cytoplasm into phagolysosomes to lower pH and active their hydrolytic enzymes

question

? Peroxisomes

answer

• Membrane-bound organelles in cytoplasm of eukaryotic cells that contain enzymes that decompose poisonous wastes
• Rich in CATALASE that destroys Hydrogen Peroxide (H2O2) and PEROXIDASES which destroy superoxide anion (O2-) and free radicals
• Also DEGRADES FATTY ACIDS
• Peroxisomes numerous in kidney and liver cells

question

Where are peroxisomes numerous?

answer

Kidney and liver cells

question

What part of mitochondria and chloroplasts resembles bacteria?

answer

70 S ribosome...which can replicate

question

Mitochondria

answer

• is a double membrane
• carries out KREBS CYCLE and OXIDATIVE PHOSPHORYLATION
• Inner mitochondrial membrane folded into numerous cristae, which increases surface area and are sites of Electron Transport Chain and Oxidative phosphorylation
• Enzymes in inner mitochondrial membrane
• Cristae contain the electron transport chain
• Contain circular DNA like bacteria

question

? Chloroplasts

answer

• Double membrane structures of photosynthetic eukaryotic cells (plants and algae) use the energy in light to form ATP and convert CO2 into sugars.
o Light pigments present in sacs called thylakoids
• Fluid between the thylakoids and inner membrane called STROMA
• In prokaryotic, the light harvesting pigments and enzymes that carry out photosynthesis are in folds of plasma membrane called photosynthetic lamellae

question

thylakoids

answer

o Light pigments present in sacs called thylakoids

question

STROMA

answer

• Fluid between the thylakoids and inner membrane

question

photosynthetic lamellae

answer

• In prokaryotic, the light harvesting pigments and enzymes that carry out photosynthesis are in folds of plasma membrane called

question

? The Endosymbiotic Theory

answer

• Proposes that mitochondria evolved form small aerobic prokaryotic cell that was ingested by primitive eukaryotic ancestor cell
• Aerobic prokaryote became an internal parasite and developed a symbiotic relationship with eukaryotic host
• Parasite retained a portion of its DNA, ribosomes and cytoplasmic membrane, but lost ability to exist independently from eukaryotic cell
• Eukaryotic cell became dependent on the parasite for ATP production
• Similar relationship between chloroplast in plants and algae

question

o Visible Light

answer

electromagnetic radiation that is detected by the human eye

question

• Electromagnetic radiation

answer

energy without mass given off as waves by decomposing atoms in the sun & stars
? Spectrum of waves from short to long
? Visible light is only a small portion

question

• When light enters glass, the rays bend because ...

answer

glass has a higher refractive index than air
• When light rays enter and exit a curved glass lens, the angle at which they ben upon the lens is affected by the curvature of the lens & refractive index of the glass

o If a lens is curved just right, it will bend light rays to a common focal point, which preserves images formed by the light rays as shown in the figure below.
o The image formed by the light rays gets larger (magnified) as the rays travel away from the focal point of the lens

question

• Quality of a lens depends on...

answer

how well it bends light rays to a common focal point

question

focal point length

answer

o Amount a lens magnifies depends on its focal point length
o Magnification of the image increases as the distance from the focal point increases
o Image we see is reflected light

question

o Numerical Aperture

answer

constant that it is written on the barrel of the lens
• Reflects the efficiency of a lens to collect light

question

o Contrast

answer

difference in intensity between two objects or between an object and its background
• Important determinant of resolution
• Microorganisms are usually colorless and have little contrast in a light microscope field

question

• Compound

answer

uses two sets of lenses in combination called the objective lens and the ocular lens to magify objects

question

o High Magnification light microscope objective lenses (i.e. 100x) also called immersion oil objectives because...

answer

o Immersion Oil has the same refractive index as glass
• When between the lens and glass slide, light rays pass straight through the oil without bending, > more light rays from the object enter the small opening of the oil immersion objective lens

question

• Dark-field microscopy

answer

o Uses a special condenser that passes light rays which travel at a sharp angle to the specimen
o The only light that can enter the objective lens are those that have been refracted into the lens by the specimen
o Specimens are visible without staining and appear as bright objects in a dark field
o Use the same objective and ocular lenses as compound bright field
o Useful for observing microbes that are very small or thin or motile (on a wet preparation of living microbes)

question

Phase Microscopy

answer

– uses a special condenser that passes light waves that are in the same phase
o When phased light waves pass through a specimen on a glass slide, they are slowed by the specimen which changes their phase to varying degrees
o Phase lenses convert the altered phased light into differences in contrast, producing sharp image of cells AND THEIR INTERNAL STRUCTURES without having to stain them

question

2 types of contrast microscopes

answer

• Phase Contrast – produces contrast differences in images
• Differential interferences – produce a 3d appearance

o Both are useful for observing cellular details and motility in wet mounts of living microbes

question

• Fluorescent Microscopy

answer

• Microbes are stained with a fluorescent dye and illuminated with light in a specific wavelength range (EXCITATION WAVELENGTH) that is absorbed by the fluorescent dye
• The fluorescent dye re-emits the absorbed light at a longer wavelength (EMISSION WAVELENGTH)
• Special filters in the oculars pass the re-emitted light, but block the excitation wavelength

• Very useful in the detection of tuburculosis

question

Which Type of microscopy is useful in detection of Tuberculosis?

answer

Fluorescent Microscopy

question

• Immunofluorescence

answer

o A fluorescent dye is coupled to antibodies that react specifically with a specific microbial species
• Labeled antibodies can be used to detect presence of their specific microbe
• If Microbe is present on glass slide, fluorescent dye-labeled antibodies combine with it and the microbes fluoresce

o Combine the sensitivity of fluorescent microscopy with the specificity of antibodies
• Allow specific infectious diseases to be diagnosed rapidly (i.e. 1 hour)
? Critical for rapidly fatal diseases (i.e. bubonic plague)

question

Name two diseases that can be identified with light microscopy

answer

Vaginitis & Meningitis

question

• Vaginitis

answer

common disease in women caused primarily by three organisms
? Yeast (candida albicans), Protozao (Trichomas vaginalis), and a bacterium (Gardnerella vaginalis)
? The yeast & protozoa are readily recognized with light microscopy > if neither is present, likely the bacteria

question

• Meningitis

answer

uncommon, life-threatening infection is a normally sterile site
? Caused by three microbes that Gram Stain Differently from each other
• Neisseria meningitidis – gram-negative coccus
• Streptococcus pneumonia –gram-positve coccus
• Haemophilus influenza – gram-negative rod

question

o Confocal Microscopy

answer

• Uses LASER LIGHT, FLUORESCENT DYE, and COMPUTER to produce a series of sharp, 1 micrometer, single plane images of a specimen
• The plane images are reconstructed by the computer into a 3D image of the specimen that can be rotated at any angle

question

• Electron Microscopy

answer

? Uses a BEAM OF ELECTRONS instead of visible light rays to form images
• e- have a much shorter wavelength than visible light
• therefore, electron microscopes have a much greater resolving power and magnification than light microscopes
? Used to obtain detailed views of very small things

question

2 types of electron microscopy

answer

Scanning and TEM
both need vacuums

question

SEM

answer

o Has a resolving power of 20 nm and magnification range of 1000X and 10,000X
o Provides a 3D views of the SURFACE of small objects such as viruses and bacteria

question

TEM

answer

o Has resolving power of 2.5nm and a magnification range of 10,000 – 100,000X
o Used to obtain detailed views of EXTERNAL AND INTERNAL CELLULAR STRUCTURES, VIRUSES and LARGE MOLECULES
o To observe internal cellular structure, specimens must be embedded in plastic and cut into thin sections….or FREEZE ETCHING

question

2 Types of Probe Microscopy

answer

• Scan Tunneling Microcopes

• Atomic Force Microscope

question

• Atomic Force Microscope

answer

o Pass a tungsten probe back and forth over surface of specimen to measure the deflections in a laser beam
o Distance as small as 0.01nm are detected, revealing details at the atomic level
o Unlike scan tunneling, this scope allows use of LIVING SPECIMENS b/c they do not use an electron beam or vacuum / do not require specimen to be electrically conductive

question

• Scan Tunneling Microscopes

answer

o Passes a sharp pointed tungsten probe back and forth above the surface of a specimen, measures the flow of e- between the probe tip and specimen surface
o Distance as small as .01 nm detected, revealing details of atomic level….specimens must be ELECTRICALLY CONDUCTIVE

question

o Preparing Microbes for Light Microscopy

answer

• Mount on glass slide
? Making a wet mount if LIVING microbes are going to be examined for
• A liquid suspension of microbes under a cover slip on a glass slide
• Wet mounts also used to determine if microbes are MOTILE
• Observations for wet mounts best if done with a PHASE-CONTRAST MICROSCOPE
• When observing, Brownian motion must be distinguished from true motility

question

o Brownian motion

answer

presumably random moving of particles suspended in a fluid (a liquid or a gas) resulting from their collision by the fast-moving atoms or molecules in the gas or liquid.
o Microbes usually carry a net negative charge….attracts positive basic dyes

question

Microbes usually carry a net _____ charge

answer

negative....attracted to basic dyes

question

• Bacteria are readily stained with basic dyes because ...

answer

their surface is normally negatively charged

question

Simple Staining Type

answer

? Aqueous or alcohol solution of a Single basic dye
? Dye solution placed over smear on glass slide for 30-60 seconds, then washed away with water
? Allow to dry, then examine
• Examples are CRYSTAL VIOLET, SAFARANIN, and METHYLENE BLUE

question

Negative Staining Types

answer

? ACIDIC or BLACK PARTICLES (India Ink)
• The BACKGROUND IS STAINED, not MICROBE
• Microbe appears as a light silhouette against a dark background
• Commonly used to determine if a microbe produces a CAPSULE
o Capsules are important VIRULENCE FACTORS for many pathogenic microbes
• Factors are molecules that are expressed and secreted by pathogen

question

Different Stains

answer

• Stains that react differently with different groups of bacteria
• Provides a quick means of distinguishing the detected bacterial groups from each other
• Gram Stain
? Most commonly used stain in microbiology
? Distinguishes 2 major groups of bacteria

question

• Method of Gram Staining (REMEMBER THESE STEPS!!!!)

answer

1. Prepare a smear to be stained on glass slide

2. Heat fixation

3. Cover smears with CRYSTAL VIOLET for 30 sec, and rinse with water (both gram + and – are purple)

4. Cover smears with GRAM IODINE for 30 Seconds
(Iodine forms insoluble complex with crystal violet with is retained by gram + but easily washed away with alcohol by gram -)

? Iodine is considered a MORDANT
? Enhances staining

5. Cover smears with Gram Decolorizer for 15 sec, rise with water (Gram – now colorless)

6. Cover smears with GRAM SAFARNIN stain for 30 sec, rinse with water (gram negative stains pink)

question

o Acid Fast Staining

answer

• used to detect bacteria in genus Mycobacteria
? they need to be heated in order to properly stain
? stains red
? used in the ID of organisms that cause TUBERCULOSIS & Leprosy

question

o Schaeffer-Fulton Endospore Stain

answer

• used to detect bacteria that form endospores
• vegetative cells stain RED
• endospores are impermeable to most chemicals and don’t stain well with other methods
? i.e.- anthrax

question

o Special Stains

answer

• Used to visualize bacterial structures or components
? Ex. Flagella, capsules, chromatin
• Can be used with or without counterstains

question

o Electron Microscope Stains

answer

• Contain e- absorbing heavy metals such as lead, osmium, tungsten
• Can be used as negative stains which stain the backgrounds or positive, which bind to specific molecules or structures in the microbe

question

? Metabolic Processes Guided by Eight Elementary Statements

answer

i) Every cell acquires nutrients
ii) Metabolism requires energy from light or from catabolism of nutrients
iii) Energy is stored in adenosine triphosphate (ATP)
iv) Cells catabolize nutrients to form precursor metabolites
v) Precursor metabolites, energy from ATP, and enzymes are used in anabolic reactions
vi) Enzymes plus ATP form macromolecules
vii) Cells grow by assembling macromolecules
viii) Cells reproduce once they have doubled in size

question

• Three important electron carriers

answer

o Nicotinamide adenine dinucleotide (NAD+)
o Nicotinamide adenine dinucleotide phosphate (NADP+)
o Flavine adenine dinucleotide (FAD) > FADH2

question

• Glucose catabolized by two processes:

answer

o Cellular respiration
o Fermentation

question

? Glycolysis

answer

• Occurs in cytoplasm of most cells
• Involves splitting of a six-carbon glucose into two three-carbon sugar molecules
• Substrate-level phosphorylation-direct transfer of phosphate between two substrates
• Net gain of two ATP molecules, two molecules of NADH, and precursor metabolite pyruvic acid
• Divided into three stages involving 10 total steps
• Energy-investment stage
• Lysis stage
• Energy-conserving stage

question

• Cellular Respiration

answer

• Resultant pyruvic acid completely oxidized to produce ATP by series of redox reactions

question

• Three stages of cellular respiration

answer

1. Synthesis of acetyl-CoA
2. Krebs cycle
3. Final series of redox reactions
(electron transport chain)

question

• Synthesis of acetyl-CoA in cellular respiration results in...

answer

• Two molecules of acetyl-CoA
• Two molecules of CO2
• Two molecules of NADH

question

o Six types of reactions in Krebs cycle

answer

• Anabolism of citric acid
• Isomerization reactions
• Hydration reaction
• Redox reactions
• Decarboxylations
• Substrate-level phosphorylation

question

o The Krebs cycle results in:

answer

• Two molecules of ATP
• Two molecules of FADH2
• Six molecules of NADH
• Four molecules of CO2

question

• Electron Transport Chain

answer

o Most significant production of ATP occurs from series of redox reactions known as an electron transport chain (ETC)
o Series of carrier molecules that pass electrons from one to another to final electron acceptor
o Energy from electrons used to pump protons (H+) across the membrane, establishing a proton gradient
o Located in cristae of eukaryotes and in cytoplasmic membrane of prokaryotes

question

• Aerobic respiration:_____ serves as final electron acceptor

answer

Oxygen

question

How do bacteria get E to use for anabolism?

answer

• Bacteria secrete enzymes (hydrolytic) into the environment
o The degraded materials are imported through the membrane
o Breakdown continues within the cell
o The energy from these Nitrogen containing compounds is used for anabolism

question

o Clostridium Difficile

answer

• Bacterial resistant
• High mortality rate
• Fecal transplant to restore the good bacteria…CURE

question

• Fructoolgosaccharides (FOS)

answer

• Polymer of fructose
• Added to probiotics bc humans cant digest
• Way to enhance the effect of good bacteria

question

? Certain bacteria can keep away disease by...

answer

just being there and using all the resources

question

Ways that bacteria are helpful

answer

• They metabolize things
• They also can make vitamins that we need
• Maybe help against obesity
• inflammation
• also outside of the body
o fermented foods can be healthy
• create lactic acid, ethanol which keeps competitors away
• energy extraction process
• makes the food more stable…
o i.e - pickles last longer than cucumber

question

aggregates

answer

name given to the colonies that bacteria grow in

question

• Two groups of organisms based on source of energy

answer

1. Chemotrophs
2. Phototrophs

question

2 types of chemotrophs

answer

• aerobic
? start with sugar, glycolysis, e- transport
? end product CO2 and water
• anaerobic
? much less E is produced
? linked to fermentation
• lactic acid and alcohol, which is toxic

question

• Oxygen is essential for obligate ______

answer

aerobes

question

Oxygen is deadly for obligate ________

answer

anaerobes
o Toxic forms of oxygen are highly reactive and excellent oxidizing agents
o Resulting oxidation causes irreparable damage to cells

question

o Four toxic forms of oxygen

answer

• Singlet oxygen
• Superoxide radicals
• Peroxide anion
• Hydroxyl radical

question

• Singlet oxygen (O2)

answer

molecular oxygen with e- that have been boosted to a higher E state during aerobic metabolism. Phagocytic cells use it to oxidize microbes.

question

• Superoxide radicals (O2-)

answer

they form during the incomplete reduction of O2 during e- transport. They are very reactive. Superoxide dismutase combines 2 O2's and 2 protons to form H2O2 and O2. Anaerobes lack super oxide dismutases.

question

• Peroxide anion (O2-2)

answer

Peroxide anion (O2-2) formed during super oxide dismutases reactions. (H2O2 contains peroxide anion). Catalase convert H2O2 to H2O + O2
Peroxidase converts H2O2 to H2O

question

• Hydroxyl radical (OH)

answer

result from ionizing radiation and incomplete radiation of H2O2. As the most reactive of the toxic O2 species

question

• Facultative Anaerobes

answer

can survive in the presence of O2 and use it

question

• Aerotoleratant Anaerobes

answer

can tolerate O2…doesn’t kill them

question

• Microaerophiles

answer

Likes small amount of O2…only grow in O2 concentrations much less than air

question

Describe the effect of temperature on lipid-containing membranes of cells and organelles

answer

o If too low, membranes become rigid and fragile
o If too high, membranes become too fluid

question

Categories of microbes based on temperature

answer

• Psychrophiles, mesophiles, thermophiles, hyperthermophile

question

Psychrophiles

answer

microbes grow optimally at low temperature

question

mesophiles

answer

microbes grow optimally in the human body

question

thermophiles

answer

microbes that grow moderately at high temperature

question

hyperthermophile

answer

microbes that grow at very high temperatures

question

o Neutrophiles

answer

microbes grow best in a narrow range around neutral pH

question

o Acidophiles

answer

microbes grow best in acidic habitats
• found in yogurt
• can live in the stomach
• when messing with H bonding, can interfere with the structure of DNA

question

o Alkalinophiles

answer

live in alkaline soils and water

question

o Two physical effects of water

answer

• Osmotic pressure
• Hydrostatic pressure

question

Many microbes require _____ to perform many metabolic reactions

answer

water

question

• Osmotic pressure

answer

o The pressure exerted on a semipermeable membrane by a solution containing solutes that cannot freely cross membrane

o Jelly---lots of sugar…hypertonic environment….preserve better….bacteria can’t survive…they shrink and their cell walls
o Salts preserve food, create hypertonic environment

question

o Halophiles

answer

microbes that love salt

question

o Barophiles

answer

microbes that love high pressure

question

• Hydrostatic pressure

answer

o Water exerts pressure in proportion to its depth
o Barophiles live under extreme pressure
• Their membranes and enzymes depend on pressure to maintain their three-dimensional, functional shape

question

extracellular matrix development in biofilms is beneficial in what 4 ways?

answer

• Adheres cells to one another
• Allows attachment to a substrate
• Sequesters nutrients
• May protect individuals in the biofilm

question

quorum sensing

answer

respond to the density of nearby microorganisms
• forms groups and work together to survive
? produce ligands that bind to receptors…activating new genes, enzymes,
? represent 10% of all bacteria

question

Synergic relationship

answer

the sum of the whole system is greater than the sum of its parts; 1 + 1 = 3

question

Medium vs Inoculum

answer

• medium is what the microbe will grow on…the gel or liquid
o inoculum the material that we start with
• i.e.- a drop of urine to try to isolate an organism
? could be pure or impure

question

• Cultures composed of cells arising from.....

answer

A single progenitor unit

o Progenitor is termed a CFU
o CFU – colony forming unit….homogenous colon

question

• Aseptic technique

answer

prevents contamination of sterile substances or objects

question

• Two common isolation techniques for pure cultures

answer

o Streak plates

o Pour plates

question

o Streak plates

answer

• Jelly material is AGAR…take a sterile loop (fire)

• Streak the most dilute portion on #1 and streak it onto #2
• Dilution allows increase change of finding what we’re looking for since it’s very dilute
• Looking for an axenic culture (no foreign contaminates)

question

axenic culture

answer

(no foreign contaminates)

question

o Pour plates

answer

• Serial dilutions (in a series)
? Take out a sample, put in broth (doesn’t contain agar), and continually dilute the solution 10-fold
• At some point take it out some and put on plate

question

fastidious

answer

word describing the fact that bacteria have strict requirements in order to grow in a particular environment

question

o Defined media

answer

have known quantities of all ingredients. For microorganisms, they consist of providing trace elements and vitamins required by the microbe and especially a defined carbon source and nitrogen source.

question

o Complex media

answer

• Take a bunch of stuff that support life and put it all together
• i.e- blood….all kinds of good things in blood to support life
• yeast can perform the same things and support the growth of the microbe
• enzymatic digestive proteins also used in these complex media

question

o Selective media

answer

• Put something in the medium that selecets for something you’re looking for
? i.e- salt…if bacteria has high selection for salt…or if it doesn’t need it
• can also leave things out to help find what you’re looking for
? can put in antibiotics to look for antibiotic resistance

question

• Saboraud

answer

kind of medium with a lower pH…actually selects for fungus
• By lowering pH, you kill bacteria and select for fungi

question

Difference between selective and differential media

answer

? Selective allows it to grow better
? Differential allows you to see the difference by looking at it

o some media can be selective and differential

question

3 kinds of hemolysis

answer

• alpha
? parital discoloration in area of blood cells
• beta
? complete discoloration - -see a clear zone
• gamma
? no hemolysis….no change

question

Slant tube containing solid media

answer

• Aerobic will grow in slant area
• Anaerobic will grow in butt area

question

MacConkey agar

answer

agar as a selective AND differential medium

is a culture medium designed to grow Gram-negative bacteria and differentiate them

question

3 ways of preserving a culture

answer

• Refrigeration
• Stores for short periods of time

• Deep-freezing
• Stores for years

• Lyophilization
o Stores for decades

question

o Generation Time of bacterial growth

answer

• Time required for a bacterial cell to grow and divide
• Dependent on chemical and physical conditions
geometric progression

question

• generation time

answer

how long it takes bacteria to reproduce

question

4 phases of bacterial life

answer

Lag phase - adjusting to new environment

Log phase - growing, forming new cell walls (best time to give antibiotic)

Stationary phase - plateau

Death phase

question

DIRECT methods to measure microbial reproduction

answer

serial dilution and viable plate counts

membrane filtration

most probable number

electronic counter

question

INDIRECT methods to measure microbial reproduction

answer

• Metabolic activity
? Can tell by metabolism how many cells there are
? Do during lag phase
Dry Weight

Turbidity (cloudiness)
? Use spectrophotometer
? Correlate the wavelength to the amount of bacteria

question

GENETIC method to measure microbial reproduction

answer

o Isolate DNA sequences of unculturable prokaryotes
o Used to estimate the number of these microbes
• If you look at patterns in DNA, you can see how much is there
• Can be associated with color changes, bubbles
• Use differentials along the way

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