question

PCR = Polymerase Chain Reaction

answer

technique where we amplify DNA millions of time to investigate it

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Mycobacterium Tuberculosis

answer

bacteria that causes tuberculosis

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Treponema Pallidum

answer

Bacteria that causes Syphilis. Has a helical shape.

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Glycolcalyx

answer

external polysaccharide (sugar) made inside the cell and excreted outside to form either a capsule or a slime layer

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Role of Capsule

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Organized structured layer that protects the pathogenecity of the cell. Capsules help pathogens escape phagocytosis.
Ex: Streptococcus Pneumonia

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Role of Slim Layer

answer

Non-organized non-structured viscous gelatonous polymer that helps in attachment of pathogen.
Ex: streptococcus mutans (cavities on teeth)

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Flagella

answer

a whip-like structure external to the bacterial cell that is responsible for the movement of the cell by propelling it. Made of filaments, a Hook and Basal Bodies

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Flagella Filaments

answer

Globular proteins called Flagellin

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Flagella Hook

answer

Wide structure composed of different proteins anchored to the cell wall and plasma membrane by the Basal Body

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Flagella Basal Bodies

answer

Disks that anchor the hook

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Axial Filaments

answer

Appendages called Filamentous Fibrilis that wrap themselves around the bacteria and give it a cock-screw like motion

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Fimbria and Pili

answer

Shorter, thinner, straighter hair-like structures than Flagella present all over the cell made of a protein called Pillin.

Some bacteria have sex pilli which are responsible for DNA transfer from one cell to the other.

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Bacterial Cell Wall

answer

Macronetwork complex of Peptidoglycans forming a lettuce

Formed of alternating units of disaccharides (N-Acetylglucosamine and N-acetylmuramic acid) connected by peptide bonds.

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Peptidoglycans

answer

Peptido = peptide
glycans = polysaccharides

Due to the alternating polysaccharides and the peptide bonds that connect them

due to the alternating polysaccharides and pepeti

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Function of Cell Wall

answer

To protect the cell from rupturing when the water pressure inside the cell increases.

Gives shape and rigidity to the cell

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Peptidoglycan structure in Gram + bacteria

answer

a carbohydrate backbone made of alternative polysaccharides of NAG and NAM linked together by tetrapeptide side chains and peptide cross bridges

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Peptidoglycan structure in gram -ve bacteria

answer

Complex structure.

The Peptidoglycan and periplasmic space are sandwhiched in between the plasma membrane and the outer membrane. The peptidoglycan and outer membrane form the cell wall.

The outer membrane is formed of a phospholipid bilayer.

The outer membrane has lipopolysaccharides on its surface, mainly O polysaccharide and Lipid A (endotoxin)

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Cross Bridge Peptide and Tetrapeptide side chain

answer

two types of peptides that link 50-60 units of alternating NAM and NAC together to form the carbohydrate backbone of the cell wall

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Gram Positive Bacterial Cell Wall

answer

Contain many layers of peptidoglycan and Teichoic acid

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Teichoic Acid

answer

Negatively charged phosphtate groups in gram positive bacteria that has two functions

1) Regulating the movement of rations inside and outside the cell
2) contain the antigenic specificity of the organism

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Gram Negative Bacteria Cell Wall

answer

Formed of peptidoglycan and outer membrane

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Outer Membrane of Gram Negative Bacteria

answer

Consists of phospholipids and lipoproteins and porin proteins

Porin proteins act as a channel for material like amino acids and vitamins

Lipopolysaccharides are the O Polysaccharides (contain the antigenic specificity) and Lipid A (endotoxin that causes fever upon infection)

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Which is stronger? gram -ve or +ve?

answer

Gram +ve is rigid and has many layers of peptidoglycans so its stronger than the gram negative which is very fragile.

question

Periplasmic Space

answer

Space between the plasma membrane and outer membrane that contains all enzymes needed to break down nutrient material and generate ATP.

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Describe the Plasma Membrane

answer

Phospholipid bilayer with a hydrophillic phosphorous polar head and hydrophobic lipid content. Proteins in the bilayer allow selective permeability. The Proteins and phospholipid bilayer of the plasma membrane give it a fluid-like mosaic structure.

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Function of the Plasma Membrane

answer

Selective permeability and degredative enzymes that degrade nutrients. Also protects prokaryote by stopping certain antibodies from entering.

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Bacterial Cytoplasm

answer

Viscous semi-transparent material that contains 80% water and enzumes, sugars and inorganic material. Remember that bacteria dont have any membrane bound organelles.

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Bacterial Nucleod Region

answer

One circular DNA chromosome not associated with Histone proteins. It contains all necessary info for organisms to replicate

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Bacterial plasmid

answer

A short piece of DNA that consists of a few genes and replicates on its own. It plays a role in antibiotic resistance and toxiginicity of the bacteria.

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Ribozomes

answer

Is 70S molecular weight and made of two subunits, one 30 S and one 40 S. Its function is in protein translation.

Some antibiotics work on 30S, 40S or 70S ribozome to inhibit bacteria by stopping the translation of mRNA leading to bacterial death.

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Viral and Bacterial destruction

answer

Medicating a viral attack is harder than a bacterial attack since in a viral infection need to destroy living cell while in bacterial infection need to destroy the bacteria.

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Sporulation

answer

process of endospore formation

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Endospore

answer

Formed inside bacteria and released, can survive heating process of food preperation and some disinfectants because of its many membranes. Mainly occurs in gram positive bacteria (Clustridium Botulinum, very potent exotoxin) and some gram negative (coxiella burnetii)

question

S=

answer

svdberg unit, relative sedimentation rate of the unit at ultrahigh speed centrifugation

question

30S Ribozome subunit

answer

Subunit is made up of a protein + 1 molecule of rRNA (Ribozomal RNA)

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40S Ribozome Subunit

answer

Subunit is made up of a protein + 2 molecules of rRNA

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Bacterial inclusions

answer

reserve deposits in cells

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Metachromatic granules

answer

Inclusions: inorganic phosphates for ATP synthesis. Seen as red using Methylene Blue stain

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Polysaccharide granules (sugars)

answer

Inclusions: starch and glycogen, use iodine stain to see

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Sulfur granules

answer

Inclusions: needed for metabolism in some bacteria

question

Carboxysomes

answer

Inclusions: areas inside cell which contain enzyme ribulose-1,5-disphosphate carboxylase. Needed if cell uses carbon monoxide as energy source.

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Gas vacuoles

answer

Area inside cell that maintains buoyancy and keeps the organism floating at a certain depth where theres enough light and nutrients for growth. Mainly for aquatic bacteria.

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Spores

answer

some bacteria form spores, highly durable (can last thousands of years) dehydrated (no water) cells. Also known as resting cells. Sporulation occurs if a nutrient is missing, the bacteria revives if the nutrient is available.

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Eukaryotic flagella and celia

answer

Short hairlike structures. if many, flagella, if few, celia. Gives the cell its wavelike movement

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Eukaryotic cell wall

answer

Mainly sugars, not made of peptidoglycans.
- Algae: cellulose cell wall
- Fungi: cell wall n-acetylglucosamine (NAG) known as chitin
- Yeast: mannan (sugar)

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Eukaryotic Cell membrane

answer

Its structure and function is similar to eukaryotes. Process of endocytosis (phagocytosis for solids and pinocytosis for liquid) and selective permeability

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Eukaryotic Cytoplasm

answer

Complex structure of rods (microtubules) or cylinders (microfilaments) responsible for transport of material inside the cell, cytoplasmic streaming.

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Euakryotic Nucleus

answer

Nuclear envelope is made of double layer and holes. Contains 1 or 2 nuceleoli to synthesize rRNA.

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Eukaryotic DNA

answer

DNA associated with histones and other proteins. If cell is in a resting phase, the DNA and protein are condensed chromatin. If cell is dividing they are uncondensed chromosomes.

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Eukaryotic Endoplasmic Reticulum

answer

Flattened sacks known as 'cisternae' whose function is lipid synthesis. Consists of the Rough Endoplasmic Reticulum (RER, many ribosomes) and the Smooth Endoplasmic Reticulum (SER, no ribosomes)

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Eukaryotic Golgi Apparatus

answer

stack of dishes which receive lipids and proteins, sort them out and excrete them through vesicles

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Eukaryotic Mitochondria

answer

Equivalent to chloroplast in plant cell, it is the energy house of the cell. Check figure. It has its own DNA which replicates from cell DNA without affecting the cell

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Eukaryotic Lysosomes

answer

Prokaryotes and Eukaryotes, powerful digestive enzymes. Only membrane bound organelle that has a single membrane and not a double membrane.

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Eukaryotic vacuoles

answer

In plant cells, vacuoles takes up 90% of cell space. It is the dumping place for waste products and water storage.

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Eukaryotic Centrioles

answer

Next to nucleus, pair of short axies perpendicular to long axis. Function in mitosis and meiosis and a role in synthesis of flagella and celia.

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Metabolism

answer

The sum of all chemical reactions taking place within an organism

question

Metabolic Chemical Reaction

answer

Catabolic chemical reaction: release energy, degredative, due to breakage of the organic bonds

Anabolic reaction: Acquire energy, biosynthetic, building organic bonds

question

Mechanism of ATP use in Metabolic reactions

answer

Coupling of energy release and energy usage using ATP to build and degrade organic compounds.

Release energy: ATP --> ADP + :P + Energy

Consume Energy: ADP + :P + Energy --> ATP

question

Role of Enzymes

answer

All metabolic reactions can only take place in the presence of enzymes. Catalysts speed up the reaction without themselves being changed. They are specific and mainly consist of proteins.

question

Describe Enzymes

answer

Consist of a protein part (epoprotein or epoenzyme) and Non protein part (metallic ion or complex inorganic molecule)

question

NAD+

answer

Nicotineamide Adenine Dinucleotide. Has an important role in catabolic reactions

question

NADP

answer

Nicotineamide Adenine Diphosphate. Important role in anabolic reactions.

question

NAD+ and NADP are

answer

derivatives of nicotine acid or vitamin B. Both function as electron carriers.

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Carbohydrate Catabolism

answer

Energy releasing pathway (catabolic reaction)that most microorganisms use to oxidize carbohydrates as their main source of energy.

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Respiration

answer

Energy releasing pathway that uses glucose to produce ATP. When balanced, theoretically releases 38 ATP

question

3 classes of molecules that are involved as electron carriers in respiration

answer

Flaviproteins and Flavin (derivatives of B12)

Cytochrome (protein and iron binding for heme molecules)

Coenzyme Q though not a protein carrier

question

Alternative Pathway

answer

Catabolic reaction that is needed for catabolism of 5 carbon sugars needed in synthesis of NADP. Involves the Pentose Phosphase Shunt.

gram -ve bacteria use the Duodordoff pathway

question

Fermentation

answer

A biological pathway that doesnt need oxygen to occur but can occur in its presence. The endpoint can be any other molecule, differs with different species. Number of ATP produced is much less in fermentation than in respiration. . The first step in fermentation is glycolysis, which yields Pyruvic acid.

question

Lipases

answer

Extracellular enzymes produced by microbes that split lipids into other compounds

question

Lipids in metabolic reactions

answer

lipids are made of glycerol and fatty acids. When they are split, they go into Krebs cycle which is involved in the oxidation of glycerol and fatty acids

question

Proteases and Peptidases

answer

Extracellular compounds produced by microbes that split proteins into components (amino acids)

question

Proteins in metabolic reactions

answer

After broken down into amino acids, amino groups undergo deamination where ammonium ions (NH4+) are excreted outside the cell and what remains goes into the kreb cycle

question

Biosynthesis of Carbohydrates

answer

Carbon atoms which are needed for the synthesis of glucose come from intermediates of glycolysis and krebs cycle

question

Metabollic pathways of energy use

answer

anabolic or biosynthetic reactions

question

Glucose to Pyruvic Acid

answer

Glucose --> Glyceraldehyde-3-Phosphate --> Glucose 6 Phosphate ---> Fructose 6 Phosphate --> Pyruvic acid

question

Glucose 6 Phosphate in anabolic reactions

answer

In bacterial cell, Adenosine Diphosphate Glucase (ADPG) synthesizes several units of this compound to form glycogen. This is a form of dehydration synthesis that requires ATP

question

Fructose 6 Phosphate in Anabolic reactions

answer

UDPNA (Uridine Diphosphate Nacetyl Acid) synthesizes severl subunits using UTP to produce peptidoglycan (Bacteria)

question

Lipid biosynthesis

answer

anabolic reaction for the formation of lipids, usually uses precursors of glycolysis

question

Glyceraldehyde 3 Phosphate in lipid biosynthesis

answer

Glyceraldehyde 3 phosphate become dihydroxyacetone phosphate which becomes glycerol and that combines with fatty acids (from pyruvic acid) to form lipids. Requires energy but not necessarily ATP.

question

Biosynthesis of Protein

answer

Some microbes have enzymes necessary to break certain precursors to form the amino acids required (Like E Coli). Microbes that dont have these enzymes cant break down amino acids.

question

Amination

answer

Addition of an amino group to organic acids

question

trans-amination

answer

Amino group added from another amino acid

question

Biosynthesis of Nucleic Acids

answer

RNA and DNA are made up of nucleotides, purines and pyramidines (the C and N atoms come from amino acids glycine, glutamine, and aspartate) and pentose (sugar) and phosphorous group (from ATP)

question

Amphoteric Pathway

answer

Whenever a pathway has a dual function in catabolism and anabolism

question

Generation time

answer

time to double the number of bacteria in a culture

question

Binary Fission

answer

an inward dip in plasma membrane and cell wall

1- Elongation of cell and replication of DNA
2- The cell wall and plasma membrane move inward to region where DNA was replicated
3- Complete separation of DNA and cell wall
4- 2 daughter cells are identical to the mother

question

Budding

answer

Some bacteria replicate by budding, which is a small outgrowth on one side of the cell which keeps it growing till the outgrowth is identical to the mother cell. Cell wall and plasma membrane expand.

question

Spore Formation

answer

some bacteria, particularly filamentous bacteria, make spores at the end of or underneath the filament (spore chain). These spores grow up to form new bacteria.

question

Ways of bacterial reproduction

answer

-Binary Fission
-Budding
-Spore Formation

question

REMINDER

answer

study eam question on page 2 of notes OCT30

question

Stages of Bacterial Growth

answer

1) the Lag Phase
2) Log Phase
3) Stationary Phase
4) Death Phase or Decline

question

Lag Face

answer

First stage of bacterial growth: From 1 hr to 3 hr, the number of bacteria stay the same. Bacteria is undergoing intensive metabollic activities particularly synthesizing DNA and enzymes

question

Log phase

answer

Second phase of bacterial growth, T=4.5 hrs, number of bacteria start to increase

question

Constant Phase

answer

Number of bacteria become constant, stage of equilibrium where number of dividing cells equals the number of dying cells.

question

Death Phase

answer

Toxic waste excreted from dying cells, pH becomes very acidic and very few bacteria grow in an acidic medium

question

Chemical Requirements for Bacterial Growth

answer

Water, oxygen, carbon, minerals (sulfer, phosphorous), organic growth factors, and trace elements

question

Physical requirements for Bacterial Growth

answer

Temperature, pH, osmotic pressure

question

Affect of Temperature and Bacterial Growth

answer

- -10o --> 10/20o => cold loving bacteria or Psychrophiles

- 20o --> 40-50o => Moderate, mesophiles

- 50o --> 70o => heat loving bacteria, theriophiles

- 70o --> 100-120o Hypothermophiles/volcanic activities, hot springs. these bacteria usually need sulfur for metabolism.

Best temperature is body temperature, 37oC

question

Effect of pH on Bacterial Growth

answer

Optimal pH is 6.5-7.5 in the neutrality zone, plus phosphate buffers to maintain pH.

question

Acidophilic Bacteria

answer

grow at a very low pH
in stomach, pH=2, enterobacteria
in coal mines, pH=1

question

Effect of Osmotic Pressure on Bacterial Growth

answer

Plasmolysis occurs when concentration of solutes outside the cell is more than enside, so water leaves the cell to the environment causing cell shrinkage.

question

Important Chemicals for Bacterial Growth

answer

- Water
-CO2 needed as a source of Carbon for the carbon backbone
- Ammonium ion needed as a source of nitrogen for protein synthesis and amino acid source
- Sulfate, some bacteria need sulfur
- Phosphorous needed for ATP, phospholipids, purines and pyrmadines from Phosphate ion

question

importance of Trace Elements in Bacterial Growth

answer

trace elements Zn, Fe, Cu and Mg mainly work as cofactors.

question

Organic Growth Factors

answer

- Trigger growth of the cell, provided from environment,
- used in synthesis of vitamins and some amino acids.

question

Strict Anaerobic Bacteria

answer

Don't need oxygen at all to grow and will die in the presence of oxygen

question

Aerotolerant bacteria

answer

Mainly grow at bottom, in the absence of oxygen, but can be found on the surface

question

Facultative Bacteria

answer

Can grow in the presence or absence of Oxygen, though they prefer O2. if its not available, they can use other.

question

Microaerophillic Bacteria

answer

Need O2 but less concentration than aerophillic so usually found in the middle

question

Culture Media

answer

Nutrient material used for the growth of microbes in the lab

question

Agar

answer

A nutrient material (extracted from seaweed) that acts as a solidifying agent for the growth of bacteria

question

Advantages of using Agar:

answer

1) Very few bacteria degrade Agar
2) Becomes solid at 40o and remains solid at 100o
3) When poured on innoculum, doesnt hurt or kill bacteria

question

Chemical Media

answer

Well-defined chemicals that only need hydration (addition of water). The media provides a source of energy and all required nutrients for bacterial growth

question

Complex Media

answer

Made up of yeast extract, meat extract, peptones (short chains of amino acids) and provides a source of energy and nutrients.

question

Selective Media

answer

Suppress growth of certain bacteria and allow for the growth of needed bacteria

Bismuth Sulfate in media will suppress gram +ve and only allow gram -ve interic bacteria

Sabouroid Dextrose allows only the growth of fungi at pH 5.6

question

Differential Media

answer

Differentiates between closely related bacteria and allows bacteria to grow but allows you to differentiate between them.

Bloos Agar allows the growth of all streptococcus but differentiates between Strep. Pyogenes from others since only this bacteria hemolysis the blood

question

Selective and Differential Media

answer

Selects growth of certain microorganisms and also differentiates between others

MacConkey suppresses the growth of gram +ve and allows gram -ve to grow
+ bile and crystal violent --> only allows the growth of enteric gram -ve

+ Lactose
If bacteria ferments lactose --> pink color
If bacteria doesn't ferment lactose --> colorless colony

question

Enrichment Media

answer

Used when the desired microorganism is present in small numbers. Selective and increases the number of microorganisms every time they are subcultured in a solution media.

question

Reducing Media

answer

Made for Anaerobic bacteria.

Uses Sodium Thioglycolate which reacts with oxygen and removes it from the media. Provides an anaerobic atemosphere for the growth of anaerobic bacteria

question

Characteristics of a Culture Media

answer

- Right nutrient and right amount of nutrient
- Sufficient moisture
- Provide sufficient O2 is aerobic growth is required
- Properly adjusted pH
- STERILE

question

Deep Freeze Bacteria Culture

answer

Suspend pure bacteria in culture in suitable media. Freeze quickly at -50o-->-90o and the bacteria can survive for years while frozen. Thaw the specimen and culture it again-->bacterial growth

question

Lyophilization

answer

Freeze dry the bacteria and freeze it at -70o, then vaccuum out air and water through a special pump and seal it with high temperature. This powderizes the culture so it can survive for many years and be recultured.

question

Preservation of Viruses

answer

Liquid Nitrogen

question

Sterilization

answer

Destruction of all forms of life including endospores. Best method is using heat.

question

Disinfection

answer

The destrcution of the vegetative pathogens (all the bacteria except endospores) using a disinfecting agent

question

Antisepsis

answer

When the killing of vegetative pathogens is applied to living tissues using an antiseptic agent.

question

Degerming

answer

Mechanical removal of germs from an area using an alcohol swab

question

Sanitization

answer

Reducing the number of organisms to minimize infection using sanitizing agent.

question

Requirements of effective microbial treatment

answer

- Degree of contamination
- Time of exposure
- Type of microorganism
- Environmental factors: pH, temperature, presence of organic matter

question

Heat as a method of control of Bacterial Growth

answer

Dry Heat (open flame) and Moist Heat (Autoclave)

question

Moist Heat

answer

Boiling for 10 minutes is enough to kill most microbes but not endospores.

As the pressure increases the temperature the microbes are exposed to increases.

question

Autoclave

answer

Sterilizes using pressurized steam, especially used on surgical equipments and when theres an AIDS patient

question

Pasterization

answer

Different degrees of heat to sterilize

Classic 63o for 30 mins
HTST (High Temp Short Time) 72o for 15 mins
Ultra High 100o for 1 minute

question

Thermal Death Time

answer

Length of time to kill all microbes using dry heat

question

Thermal Death Point

answer

The temperature at which all bacteria are killed within 10 minutes

question

Low Temperature in Bacterial Growth

answer

Doesnt kill but inhibits growth of microbes

question

HEPA - High Efficiency Particulate Air

answer

Machine used in hospitals to filter out bacteria and viruses depending on the filter used, especially for patients in isolation unit.

question

Plasmolysis as a Growth Control

answer

Injcrease of salt in a solution with bacteria causes plasmolysis and cell shrinkage but not death

question

Dessication to control bacterial growth

answer

Remove water to control growth of bacteria

question

Radiation to control bacterial growth

answer

Very effective way of killing bacteria using Xray, gamma waves or UV light

question

Chemical means to control growth of bacteria

answer

Ethylene Oxide is a penetrating chemical mainly used on AIDS patients

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