The mechanisms for transporting molecules through the lipid bilayer. Involved in energy generation
The movement of materials through a cell membrane against the concentration gradient using energy
Classes of bacterial active transporters
1. Major Facilitator Superfamily (MFS)
2. ATP- Binding Cassette (ABC)
3. Group Translocation : phosphoenolpyruvate dependent phosphotransferase system (PTS)
Major Facilitator Superfamily
A group of transporters that use proton motive force. 12 -14 transmembrane spanning helices. These are single- polypeptide secondary carriers. eg. Lactose permease
ATP- Binding Cassette
ATP-powered pump. Has 2 halves each with 6 transmembrane a-helices. Has 2 NBDs (cytoplasmic nucleotide binding domains) -- bind to a specific substrate. Can be both importers or exporters. Transport sugars, ions, amino acids, phospholipids and HYDROPHOBIC drugs.
A variation of active transport that occurs only in bacterial cells and only with certain molecules. A molecule is transported into the cell and at the same time it is chemically changed into a slightly different molecule. It requires energy, but the chemical modification prevents the molecule from leaving the cell. in a sense it is a trapping mechanism. phosphorylation ( the addition of a phosphate group) is one variation of how bacteria do this
Advantages of ACTIVE transport
1. Low substrate concentrations
2. Allows cells to accumulate substrate against a concentration gradient.
What do bacteria need to grow?
1. Energy (ATP for catabolic and anabolic reactions)
2. Precursor Metabolites (Building blocks)
3. Reducing Power (NADH/NADPH)
Name the three pathways that produce all 12 precursor metabolites
2. TCA Cycle
3. Pentose Phosphate Pathway
Name the precursor metabolites produced in Glycolysis
3. Triose Phosphate
Name the precursor metabolites produced in TCA
1. Acetyl CoA
3. Succinyl CoA
Name the precursor metabolites in Pentose Phosphate Pathway
Substrate level phosphorylation
Is a type of metabolism that results in the formation and creation of ATP by the direct transfer and donation of a phosphoryl group (Pi) to ADP from a phosphorylated reactive intermediate. Doesnt use ETC, no proton motive force.
Where does substrate level phosphorylation occur?
In the cytoplasm.
Microorganisms that do not require oxygen to function
Microorganisms that require oxygen to function.
Oxidatively decarboxylated to Acetyl CoA, CO2 and NADH catalyzed by the enzyme pyruvate dehydrogenase.
Activated form of acetate with a high energy bond.
Fourth step of glycolysis; four reactions convert BPG into pyruvate; generates 2 ATP per G3P (4 per glucose molecule)
Respiration in which oxygen is consumed and glucose is broken down entirely; water, carbon dioxide, and large amounts of ATP are the final products.
Respiration in the absence of oxygen. This produces lactic acid. ie Fermentation
Flavoproteins, Ubiquinone, Menaquinone
Cytochromes, iron-sulphur proteins
Electron Transport Chain
A series of pumps (or carriers) that are powered by the electrons from the TCA. These pumps take energy from a pair of electrons and uses that energy to pump hydrogen ions into the intermembrane space.
The production of ATP using energy derived from the redox reactions of an electron transport chain.
Proton motive force
The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across biological membranes during chemiosmosis.
Characteristics of ETCs
1. Arrangement of membrane associated electron carriers in order of increasingly more positive redox potential
2. Alternation of electron only and electron plus proton carriers in the chain
3. Generation of a proton motive force
Several membrane proteins found in the bacterial plasma membrane that function in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion concentration gradient to make ATP. ATP synthases provide a port through which hydrogen ions diffuse into the matrix of a mitrochondrion.
DNA Replication; cell elongation; septum formation; completion of septum with formation of distinct walls; cell separation
Mean generation time
The time taken for one cell (therefore the whole population) to divide
No electron transport chain, therefore no proton motive force. Uses substrate level phosphorylation for ATP synthesis
An organism that makes ATP by aerobic respiration if oxygen is present but switches to fermentation under anaerobic conditions.
Require low levels of oxygen.
Require high CO2 conditions
How can O2 be toxic?
It can be converted by metabolic enzymes in to highly reactive derivatives such as the superoxide free radical O2-.
Aerobes and most facultative anaerobes convert superoxide free radicals to.....
Hydrogen peroxide and oxygen
The 3 protective enzymes that aerobes and facultative anaerobes have....
1. Superoxide dismutase
Cardinal temperatures are :
Minimum, Maximum, Optimum
In high concentration of salt/sugar, water is drawn out of cells and causes shrivelling therefore the cell can not go through binary fission
Mircobial cells are 80% water
Fungii can grow at more extremes of Aw, bacteria grow at high Aw
Obtain energy from light
Obtain energy from the oxidation of chemical compounds (organic or inorganic) eg. sugars, amino acids
Utilise only inorganic carbon in the form of CO2
Utilise organic carbon (protein, carbohydrates and lipids)
Most bacteria are....
Temporary storage of specimens being transported.
Should maintain viability of all organisms in the specimen without cell division
Contain only buffers and salts.
Contain general nutrient supplements.
Encourage growth of a particular organism
Encourages growth of some organisms while specifically inhibiting growth of others.
Mannitol salt agar
7.5% Sodium chloride; selective for Staphylococci
Bile salts; selective for gram negative enteric bactetria
Contains indicators that visually distinguish between organisms
Gram Postive bacteria due to the amount of peptidoglycan. Bacillus and Clostridrium species
How long does it take to form endospores?
How long does it take for an endospore to form back into cells?
1. DNA becomes dense
2. Asymmetric cell division
3. Septum forms
4. Larger component engulfs the smaller component
5. Forespore is formed
6. Exosporidium and cortex is formed DEHYDRATION
7. Ca2+ and SASP formation, dipicolinic acid production, coat formation/layers formed
8. Maturation of layers
9. Lysis of cell and release of endospore.
1. Core (DNA and ribosome)
2. Cortex (Peptidoglycan less cross linked)
3. Spore Coat (Large, several protein layers)
4. Exosporidium (Lipid, carb, protein coat, thin layer)
Name the 4 Physical control methods
1. Moist heat
2. Dry Heat
Describe depth Filter
A random array of fibers made with asbestos, glass or paper.
Particles get trapped. is used when a large volume is to be prefiltered due to the filter absorbing a lot of liquid.
Describe membrane filtration
Most commonly used methos of filtration. Thin like paper material made with cellulose acetate. Has a regular and even pore size. Functions like a sieve but does tend to clog up.
Describe nucleopore filter
This filter has few pores and is only used in electron microscopy.
Examples of solutions that are filtered
1. Tissue culture media
3. Anitbiotic solutions
5. Filtered beer
High Efficiency Particulate Air filter. Found in laminar flow hoods and class 2 biological saftey cabinets.
Explain non ionising radiation
eg. Ultra violet radiation. Wave length 260nm damages DNA in the cell by forming pyrimidine dimers or by direct protein damage.
Applications of non ionising radiation
Sterilisation of benches and air. Gram negative bacteria most sensitive, gram postive less sensitive and endospores are most resistant
Explain ionising radiation
Indirectly kills cells by breaking molecules into ions. Induces reactive chemical radicals (free radicals). Carry more energy than non ionising radiation
Advantage of ionising radiation
Ionising radiation is penetrating therefore used to sterilise products even after they have been packaged
Disadvantage of ionising radiation
Expensive to operate, requires elaborate safety precautions.