Final exam Flashcards
6 groups of microbes
Bacteria
Archaea
Fungi
Protozoan
Algae
Small multicellular animals
Bacteria
Unicellular, prokaryote
Cell wall composed of peptidoglycans
- Requires sufficient moisture
- Obtains energy through organic molecules or photosynthesis or inorganic molecules (nitrogen/phosphorus)
Archaea
Unicellular, prokaryote
Cell wall
- Found in extreme conditions
- Not pathogenic to humans
Fungi
Unicellular/multicellular eukaryotes
Obtains energy by decomposing dead organisms
Can be pathogenic (ringworm)
ex: Mold (multicellular) and Yeast (unicellular)
Protozoa
Unicellular eukaryotes
Mobile
Found in water, some live in hosts
AKA: Parasites
Ex: Malaria
Algae
- Unicellular/Multicellular, eukarytotic
- Photosynthetic (chloroplasts)
- Important in ecology/enviornment
- Not usually pathogenic
Algae is not typically _____ but there’s 2 exceptions:
Pathogenic
- An immunosuppressed person
- Algae Bloom
Small Multicellular Organisms
- Multicellular eukaryotes
- Adult worms can be visible to the naked eye, but immature stages are microscopic
What are Koch’s Postulates?
- Suspected causative agent must be found in every case of the disease & absent in healthy hosts
- Agent must be isolated and grown outside of the host
- When agent is introduced to a healthy, susceptible host, the experimental host must get the disease
- Same agent must be found in the diseased experimental host
Pasteur
Disproved the idea of spontaneous generation/abiogenesis
Found what caused fermentation; discovered process now called “pasteurization”
Lister
Antiseptic technique
Jenner
Responsible for 1st vaccination (against smallpox)
He was aware that infection actually produced immunity
Ehrlich
Magic bullets (antibiotics)
Fleming
Discovered the 1st antibiotic to treat disease
Nightingale
Nursing and hygiene
Linneaus
Responsible for the binomial system of nomenclature (naming system)
DKPCOF
Genus
Species
Leeuwenhoek
“Father of Microbiology”
1st to observe live microorganisms (through his magnifying lenses)
Abiogenesis
Spontaneous generation theory that living things came from nonliving matter
Pasteurization
Process of heating it just enough to kill spoilage or pathogenic microorganisms.
Doesn’t alter the quality of food
What are the 4 common processes of all living things?
Growth
Reproduction
Responsiveness
Metabolism
The cell wall of a gram-positive bacteria forms a ____, rigid structure. It has many layers of ________, which refers to a chemical molecule that is part ___ and part _______.
The cell wall of a gram-positive bacteria forms a thick, rigid structure. It has many layers of peptidoglycan molecules, which refers to a chemical molecule that is part protein and part polysaccharide
Gram-positive bacteria:
The peptidoglycan layer also contains teichoic acid and (1) _____ _____. What does (1)______ ___ do?
Lipoteichoic acid
It attaches the cell wall to the cell membrane
Gram-positive bacteria:
The ______ part of peptidoglycan consists of long chains of repeating alternating molecules called ___ and ____. The layers are held together by ______ ________.
polysaccharide
NAG and NAM
tetrapeptide crossbridges
The cell walls of a gram-negative bacteria consist of a ____ ________ ___ surrounded by an outer membrane. Similar to gram-positive bacteria, they have alternating ___ and ____ structures, but they don’t have ______ _____.
The cell walls of a gram-negative bacteria consist of a thin peptidoglycan layer surrounded by an outer membrane. Similar to gram-positive bacteria, they have alternating NAG and NAM structures, but they don’t have lipoteichoic acid
The outer membrane of a gram-negative bacteria is a _______. Its inner layer is composed of _____ molecules and ____.
The outer membrane of a gram-negative bacteria is a bilayer Its inner layer is composed of phospholipid molecules & proteins
Gram-negative bacteria:
The outer layer of the outer _____ is composed of both phospholipid molecules and ________(___). The lipid portion of LPS is known as _____ __
The outer layer of the outer membrane is composed of both phospholipid molecules and lipopolysaccharide (LPS). The lipid portion of LPS is known as lipid A
Where is lipid A found?
The outer cell membrane of a gram-negative bacteria
Lipid A is also called an _______ (this is released when the cell ____ and can cause fever, vasodilation, inflammation, shock, and blood clotting)
Lipid A is also called an endotoxin (this is released when the cell dies and can cause fever, vasodilation, inflammation, shock, and blood clotting)
Tetrapeptide cross-bridges connect..
NAM to NAM
3 appendages can be found on the exterior of bacterial cell walls:
Flagella, Fimbriae, Pili
Flagella
- Used for movement
- Basal body attaches hook to a cell wall and cell membrane
Flagella arrangements
Monotrichous: one
Amphiritichous: two on opposite ends
Lophotrichous: 2+ on the same end
Peritrichous: all around/surrounding
Fimbriae and pili are both used for _____ and are made up of protein molecules called ____. What’s the difference between the two?
Fimbriae and pili are both used for ATTACHMENT and are made up of protein molecules called PILINS.
Pili attachment is for a specific purpose called conjugation.
Types of movement for flagella
Runs (propels foward): counterclockwise
Tumbles: Clockwise
How are ribosomes different in prokaryotes and eukaryotes
Bacteria/prokaryotes have 70S ribosomes while eukaryotes have 80S ribosomes (with 70S only being in mitochondria/chloroplasts)
Glycocalyx functions
Prevents desiccation (drying out), evade phagocytosis, attachment
Glycocalyx are found..
attached to the outermost layer of the cell wall
Glycocalyx:
If the sticky substance is ____ and ____ attached to the bacterial cell wall, the glycocalyx is described as a _____
v.s
If the sticky substance is ____ and ____ attached to the bacterial cell wall, the glycocalyx is described as a _____
Organized and firmly attached = capsule
Unorganized and loosely attached = slime layer
The outer cell membrane of bacteria is made up of a cholesterol-like molecule called a
Hoponoid
4 comparisons between bacterial (prokaryotic) and eukaryotic cells
Bacteria:
No nucleus
Flagella rotate
Cell walls (present in most) contain peptidoglycans
Endospores are present in some
Eukaryotes:
Nucleus
Flagella undulate
Cell walls- present in plants, algae, and fungi- NO peptidoglycans
No endospores
LPS is made up of
a lipid on one end and polysaccharide on the other
Endospores are considered the _________________________ to ______. Many endospores produce toxins that can cause fatal diseases such as ____ and ____.
most difficult biological structure to destroy
anthrax and tetanus
Found in the _______ of some bacteria are endospores, which are used as a ________ strategy against ______ _____, such as when nutrients (especially ___ and ___) are exhausted or if there isn’t sufficient _____.
Found in the CYTOPLASM of some bacteria are ENDOSPORES which are used as a DEFENSE strategy against UNFAVORABLE CONDITIONS, such as when nutrients (especially Carbon and Nitrogen) are exhausted or if there isn’t sufficient MOISTURE.
Where are endospores found?
Cytoplasm
Endospores are formed by a process called _____ which takes between 8-10 ____. Endospores can remain dormant for thousands of years and when conditions become ___ for growth, endospores ___ to produce new _____ ___ (cells that grow and reproduce).
Endospores are formed by a process called SPORULATION which takes between 8-10 HOURS. Endospores can remain dormant for thousands of years and when conditions become FAVORABLE for growth, endospores GERMINATE to produce new VEGETATIVE CELLS
If the color is in the positive ion, these stains are known as
basic dyes
If the color is in the negative ion, these stains are known as
acidic dyes
Bacterial cells are slightly negatively charged. Based on this information, what type of dye is best used to view bacteria?
basic dyes
Since acidic dyes carry negative electric charges, and bacteria cells are also negative, they are not ____ to bacterial cells. As a result, it can’t stain the bacterial cells and instead stains the ________
Since acidic dyes carry negative electric charges, and bacteria cells are also negative, they are not attracted to bacterial cells. As a result, it can’t stain the bacterial cells and instead stains the background
The procedure of a gram stain
1. _______(a basic dye w purple color) is applied and is referred to as a _____
2. Rinsed off the slide with water
3. Slide is then covered with ____, which is a ______ (purpose is to _______)
4. Next, the slide is washed with ____, a _____ ____. This breaks down the ____ of gram ______ cells.
5. It’s then rinsed off the slide with water, and the slide gets stained with ____ (a basic dye with red color). _______ is referred to as a _________ because it has a contrasting color to the primary stain.
- CRYSTAL VIOLET (a basic dye w purple color) is applied and is referred to as a PRIMARY STAIN
- Rinsed off the slide with water
- Slide is then covered with IODINE, which is a MORDANT (purpose is to INTENSIFY the color of the primary stain)
- Next, the slide is washed with ALCOHOL, a DECOLORIZING AGENT. This breaks down the cell wall of gram-NEGATIVE cells.
- It’s then rinsed off the slide with water, and the slide gets stained with SAFRANIN (a basic dye with red color). SAFRANIN is referred to as a COUNTERSTAIN because it has a contrasting color to the primary stain.
- The slide is rinsed with tap water, blotted dry, and observed under the microscope.
After the primary stain (_____) and the mordant (____) are used…
(crystal-violet)
(iodine)
all cells are stained purple
After the decolorizing agent (____) is used, it removes the _____ ___ from ONLY the ______ ____ _____, making the _____ ______ become ______
alcohol
purple color
gram-negative bacteria (2x)
become colorless
After staining with a counterstain (_____), it turns the ______ gram-____ bacteria ____. Since the gram-____ bacteria retained the original _____ color, they are ___ _______ by the counterstain
After staining with a counterstain (SAFRANIN), it turns the COLORLESS gram-NEGATIVE bacteria PINK. Since the gram-POSITIVE bacteria retained the original PURPLE color, they are NOT AFFECTED by the counterstain.
Acid-Fast Stain
Used for bacteria that have waxy cell walls
Ex: Mycobacterium and Nocardia
Metabolic reactions usually involve the movement of electrons (which are ________ of _____). The molecule that is oxidized is the one to _____ the electron and involves _____. The molecule that is reduced ______ the electron and involves _____.
Metabolic reactions usually involve the movement of electrons (which are carriers of energy). The molecule that is oxidized is the one to donate the electron and involves loss. The molecule that is reduced accepts the electron and involves gain
Phosphorylation is when
ATP is regenerated/recycled from ADP and Pi (inorganic phosphate)
3 ways phosphorylation can be accomplished:
(basically, who provides the energy for the third phosphorus? ADP + P —> ATP)
- Substrate-level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation
transfers Pi from an organic molecule
(the bond gets broken)
Substrate-level phosphorylation
Using energy from the redox reaction to add Pi
(there’s no bond to be broken)
Oxidative phosphorylation
Using light energy to add Pi
(no bond broken)
Photophosphorylation
The overall process of cellular respiration can be summarized as
Glycolysis
Krebs Cycle
Electron Transport Chain
Glycolysis starting molecule:
ending molecule:
starting: Glucose
ending: Pyruvic Acid
What carrier molecule is used during Glycolysis and how many?
NADH, 2
How much ATP is used in Glycolysis? How much is produced? Net amount?
2 ATP is used
4 ATP is produced, 2 net
Summary of Metabolic Stages:
Glycolysis:_______—> ______
The Preparation stage: _____—> ______
The Krebs Cycle: _______—> ______
The Electron Transport Chain: once ______ _____ electrons, it is _____ to form ____
Glycolysis: 1 glucose molecule –> 2 pyruvate molecules
The Preparation stage: each pyruvate molecule—> acetyl CoA molecule
The Krebs Cycle: each acetyl CoA —> CO2
The Electron Transport Chain: once oxygen accepts electrons, it is reduced to form H20
Summary of Energy Yielded:
Glycolysis:
The Preparation Stage:
The Krebs Cycle:
The Electron Transport Chain:
Total:
Glycolysis: 2 ATP, 2 NADH
The Preparation Stage: 2 NADH
The Krebs Cycle: 2 ATP, 2 FADH2, 6 NADH
The Electron Transport Chain: 34 ATP
Total: 38 ATP molecules per glucose molecule
Each molecule of pyruvate coming from glycolysis must first be converted to another chemical called_______
acetyl coenzyme A (acetyl CoA)
Key concepts of the Krebs Cycle:
Starting molecule?
How many molecules of ATP?
What method of phosphorylation?
How many molecules of FADH2?
How many molecules of NADH?
How many molecules of CO2?
Starting molecule?
Acetyl-CoA
How many molecules of ATP? 2
What method of phosphorylation? Substrate level phosphorylation
How many molecules of FADH2? 2
How many molecules of NADH? 6
How many molecules of CO2? 4
What method of phosphorylation occurs in the Electron Transport Chain?
Oxidative phosphorylation
Electron Transport Chain:
Each NADH creates __ __
Each FADH creates __ __
In total, there are ___ ATP molecules that can be generated from one ____ ____
3 ATP
2 ATP
34 ATP
glucose molecule
Electron transport chain:
In aerobic respiration, ____ is the final electron acceptor. In anaerobic respiration, it’s an ______ _____ that acts as the final electron acceptor
Oxygen
Inorganic molecule
2 main pathways of energy production
cellular respiration
fermentation
Only ____ leads to fermentation, not ____
Only yeast leads to fermentation, not bacteria
End products of fermentation
Lactic acid and ethanol
How much ATP does fermentation produce?
2 atp
When does fermentation occur?
When there is an absence of final electron acceptors (no oxygen, no inorganic molecule)
What acts as a final electron acceptor in fermentation?
Pyruvic acid
Metabolism is divided into two types of chemical reactions:
What’s the difference between these two?
Catabolic: breaks down large molecules into smaller products, exergonic (releases energy), ex: proteins –> a.a
Anabolic: turns smaller products into large molecules, requires energy to make bonds (endergonic), ex: a.a—> protein or fatty acid –> lipid
To move the electrons around (for oxidation-reduction reactions), a carrier is often used. The important ones are:
The electron is usually associated with a _______ atom since it only has _____ ______. So the carriers pick up and drop off the _____
NAD+
NADP+
FAD
The electron is usually associated with a HYDROGEN atom since it only has ONE ELECTRON. So the carriers pick up and drop off the HYDROGENS.
Apoenzyme
The name of the protein portion when the enzyme is combined with other molecules
The apoenzyme is ____ if not bound to nonprotein ______
inactive
cofactors
Cofactors are ____ molecules, like ___ or ___. If the cofactor is an ______ molecule, it’s called a _____.
Cofactors are INORGANIC molecules, like Zn or Fe. If the cofactor is an ORGANIC molecule, it’s called a COENZYME
Important coenzymes:
NAD
FAD
CoA
Holoenzyme
Yields from when apoenzyme binds with its cofactors/coenzymes
3 basic requirements that all cells need for metabolism:
a carbon source, an energy source, and an electron source
Carbon sources and where they get their energy from
Autotrophs- CO2
Heterotrophs- organic
Energy sources and where they get their energy from
Chemotrophs- organic
Phototrophs- light
Electron (H) sources and where they get their energy from
Organotrophs- organic
Lithotrophs- inorganic
Plants and algae are considered
photoautotrophic (CO2 and light)
Humans, bacteria, animals, fungi, etc. are considered
chemoheterotrophs (both organic)
Obligate aerobes
Requires oxygen to live and grow
Oxygen is used as the final electron acceptor when making energy
Obligate anaerobes
Unable to use oxygen for growth because it lacks enzymes (like catalyse)
Oxygen can actually be toxic for them
Facultative anaerobes
Prefers oxygen, but can survive without it
Aerotolerant anaerobes
Has small levels of enzymes but doesn’t use oxygen
Prefers no oxygen but will tolerate it
Microaerophiles
able to survive with low levels of oxygen
Nitrogen Fixation- what is it and why is it important?
When microbes are able to convert the nitrogen in the air (N2) into NH3
This is essential since it’s providing a usable form of nitrogen for other organisms to use
Complex media
Most common, generalized (so most bacteria grow well in complex media)
Ex: Nutrient agar and tryptic soy agar (TSA)
Enriched media is also generalized, but with an added ingredient: blood. Enriched media is used to encourage the growth of a particular bacteria species of interest. It’s typically used to cultivate bacteria from samples such as:
blood, urine, and sputum
Examples of selective media
Sabouraud dextrose agar
MacConkey agar
EMB agar (Eosin-methylene blue agar)
HE agar (Hektoen enteric agar)
Examples of differential media:
MacConkey agar
HE agar
Blood agar
Sabouraud dextrose agar only selects for
the growth of fungi while inhibiting bacterial growth
- supplemented with antibiotics (added ingredient)
MacConkey agar only selects for
gram-negative bacteria while inhibiting the growth of gram-positive bacteria
What inhibits the growth of gram-positive bacteria for MacConkey agar?
Both bile salts and crystal violet
EMB agar only selects for
the growth of gram-negative bacteria while inhibiting the growth of gram-positive bacteria
What inhibits the growth of gram-positive bacteria for EMB agar?
Eosin and methylene blue
HE agar selects for
the growth of gram-negative bacteria ONLY while inhibiting the growth of gram-positive bacteria due to its chemical ingredients
What ingredient inhibits gram-positive bacteria for HE agar?
only bile salt
MacConkey agar differentiates whether the bacteria can _______ ______. What color change occurs?
ferment lactose = turns pink (G-)
do not ferment lactose = cream (G-)
HE agar differentiates based on
lactose fermentation and sulfur utilization
What color does lactose-fermenting gram-negative bacteria turn on HE agar?
What about non-lactose fermenting gram-negative bacteria?
- salmon-orange
- retains blue-green color
HE agar can differentiate bacteria based on their ability to utilize ____. When hydrogen sulfide reacts with iron, it forms ____ ____ on the HE agar.
sulfur
black precipitates
Eosin-Methylene blue is both a selective and differential media. It assesses for lactose fermentation: positive will look ____/____/metallic while negative will have ___ ____/media
positive will look purple/black/metallic while negative will have no color/media
What is a biofilm?
A complex relationship among numerous microbes
Binary fission steps:
Chromosome _____ (attaches to cell membrane)
Cell ______, ______chromosome
____ cell wall/cell membrane form ____
____ is completed, separating into___ _____ microbes.
Chromosome REPLICATES (attaches to cell membrane)
Cell ELONGATES, SEPARATING chromosome
NEW cell wall/cell membrane form SEPTUM
SEPTUM is completed, separating into 2 IDENTICAL microbes.
4 phases of bacterial growth
lag phase
log phase
stationary phase
death phase
Lag Phase
- Little change in # of microbes
- Adapting to environment
- Lasts hours to days
Log Phase
- Exponential growth (2^n)
- Cells most active
- Best time to gram stain
- Best time to assess effectiveness of antibiotics
Stationary Phase
- Growth slows
- Deaths = divisions- equilibrium
Death Phase
- Deaths > divisions
- Accumulation of wastes, depletion of nutrients, change in pH
3 groups based on the preferred temperature of a microbe
Which is most likely to be pathogenic and why?
Psychrophiles- likes cold
Mesophiles- in between
Thermophiles- likes heat
Mesophiles because they like human temperatures the best
Care must be taken when culturing a microorganism otherwise contamination may occur. The goal is to culture an Axenic culture. What does axenic mean?
Pure
Control plate and nothing grows on it
axenic and aseptic
Control plate has growth, but only one species of bacteria is growing:
axenic but not aseptic
Fastidious bacteria are
hard to grow
Quorum sensing in a biofilm is responsible for what 4 things?
- Communication between microbes
- Able to determine population and species of microbes
- Helps to control certain genes within each microbe
- Microbes assume specific functions to benefit community
Blood agar differentiates bacteria based on red blood cell _____, in other words, whether or not a bacteria can _____ (break down) red blood cells.
hemolysis
hemolyze
Alpha-hemolysis
partially hemolyze (green/gray media)
Beta-hemolysis
completely hemolyze
(clear)
Gamma-hemolysis
unable to hemolyze (no change)
Basically, with each division of binary fission, the population ____. This is represented as __ (indicates _____ growth)
n = generation
Basically, with each division of binary fission, the population doubles. This is represented as 2^n (indicates exponential growth)
n = generation
Generation Time
The time required for a bacterial cell to double (divide)
Most have a doubling time of 1-3 hours
What is a plasmid?
a small DNA molecule that replicates independently of the other chromosomes often carrying information required for replication.
4 different types of plasmids
Fertility
Resistance
Bacteriocin
Virulence
Fertility
instructions for conjugation
Resistance
antibiotic resistance
Bacteriocin
kills competitors
Virulence
enzymes/toxins that enable pathogenicty
Plasmids do not ________________
Plasmids do not control normal metabolism