6 Microbial Nutrition and Transport Mechanisms Flashcards
process by which chemical substances (nutrients) are acquired from the environment and used for cellular activities
Nutrition
any substance that must be provided to an organism
*Chemicals that are necessary for particular organisms, which they cannot manufacture by themselves
*Carbon, hydrogen, oxygen, phosphate, and sulfur (CHONPS)
Essential nutrient
Two categories of essential nutrients:
– Macronutrients
– Micronutrients or Trace elements
required in relatively large quantities and play principal roles in cell structure and metabolism
- carbon, oxygen, nitrogen, and hydrogen
Macronutrients:
also known as trace elements
- present in much smaller amounts
* involved in enzyme function and maintenance of protein structure
- manganese, zinc, nickel, cobalt, molybdenum, and
copper
only required in small amounts; usually found in sufficient quantities in tap water
Micronutrients:
- contain carbon and hydrogen atoms and are the products of living things
- simple organic molecules such as methane
- large polymers (carbohydrates, lipids, proteins, nucleic acids)
Organic nutrients
- an atom or simple molecule that contains a combination of atoms other than carbon and hydrogen
- found in the crust of the earth, bodies of water, and the atmosphere
Inorganic nutrient
- is a fundamental macronutrient for bacteria and serves as the primary building block for all cellular components
- needed for the skeleton or backbone of all organic molecules and molecules serving as sources normally also contribute both oxygen and hydrogen atoms
*Bacteria utilizes this for various essential processes, including energy
production, synthesis of cellular structures, and metabolism.
Carbon
- Main reservoir is its gas counterpart (N2)
- 79% of earth’s atmosphere is N2
*is part of the structure of proteins, DNA, RNA & ATP – these are the primary source of N for heterotrophs - Some bacteria & algae use its inorganic nutrients
- Some bacteria can fix N2
- Regardless of how N enters the cell, it must be converted to NH3, the only form that can be combined with carbon to synthesis amino acids, etc
Nitrogen
- major component of carbohydrates, lipids and proteins
- plays an important role in structural & enzymatic functions of cell
- component of inorganic salts (sulfates, phosphates, nitrates) & water
- makes up 20% of atmosphere
- essential to metabolism of many organisms
Oxygen
- major element in all organic compounds & several inorganic ones (water, salts & gases)
- gases are produced & used by microbes
- roles:
–maintaining pH
–forming H bonds between molecules
–serving as the source of free energy in oxidation reduction reactions of respiration
Hydrogen
- is a component of phospholipid membranes, DNA, RNA, ATP, and some proteins
- key component of nucleic acids, essential to genetics
- serves in energy transfers (ATP)
Phosphorous
- widely distributed in environment, rocks, sediments contain sulfate, sulfides, hydrogen sulfide gas and sulfur
- is a component of sulfur-containing amino acids, disulfide bonds critical to tertiary structure of proteins (a.a. methionine& cysteine) , and in vitamins (thiamin and biotin)
- contributes to stability of proteins by forming disulfide bonds
Sulfur
nutrient that is important for certain types of cell transport
Sodium (Na):
nutrient that is a stabilizer of cell wall and endospores of bacteria
Calcium (Ca):
nutrient that is a component of chlorophyll and a stabilizer of
cell membranes and ribosomes
Magnesium (Mg):
nutrient that is an important component of the cytochrome proteins of cell respiration
Iron (Fe):
nutrient that is an essential regulatory element for eukaryotic genetics
Zinc (Zn):
necessary organic chemicals that
cannot be synthesized by certain organisms (vitamins,
certain amino acids, purines, pyrimidines, cholesterol,
NADH, and heme)
§Growth factors
Organic compounds, required in very
small amount and then only by some cells (3)
(1)amino acids,
(2) purines and pyrimidines
(3) vitamins
are needed for protein synthesis,
Amino acids
for nucleic acid
synthesis.
Purines and pyrimidines
are small organic molecules that
usually make up all or part enzyme cofactors,
and only very small amounts are required for
growth
Vitamins
*Nutritional types of microorganisms
Carbon source (2)
Autotroph
Heterotroph
*Nutritional types of microorganisms
Energy Source (2)
– Phototroph
– Chemotroph
*Nutritional types of microorganisms
- Electron (Reduction potential) Source
– Organotroph
– Lithotroph
Two Kinds of Bacterial Heterotrophs:
Saprobes and
Parasites
- free living organisms that feed on organic detritus from dead organisms
- decomposers of plant litter, animal matter, and dead microbes
- recycle organic nutrients
Saprobes
- derive nutrients from the cells or tissues of a living host
- pathogens: cause damage to tissues or even death
- range from viruses to helminths
- ectoparasites: live on the body
- endoparasites: live in the organs and tissues
Parasites
live within cells such as the
leprosy bacillus and the syphilis spirochete
intracellular parasites:
unable to grow outside of a living host
- less strict parasites can be cultured artificially
* if provided with the correct nutrients and environmental conditions
obligate parasites:
The vast majority of microbes causing human disease
are ____
chemoheterotrophs
- The process of moving molecules into or out of cells
- Transport of necessary nutrients occurs across the cell membrane, even in organisms with cell walls
- The driving force of transport is atomic and molecular movement
Transport Mechanisms
transport–do not require energy, substances exist in a gradient and move from areas of higher concentration towards areas of lower concentration
–Diffusion
–Facilitated diffusion –requires a carrier
- Osmosis -water
Passive transport
–require energy and carrier proteins, gradient independent
–Carrier-mediated active transport
–Group translocation –transported molecule chemically altered
–Bulk transport –endocytosis, exocytosis, pinocytosis
is the transport of solute molecules to higher concentrations, or against a concentration gradient, with the use of metabolic energy input.
Active transport
– Movement of substances directly across a phospholipid bilayer, with no need for a transport protein
– Movement from high ® low concentration
– No energy expenditure (e.g. ATP) from cell
– Small uncharged molecules may be transported via this process, e.g. H2O, O2, CO2
- All molecules (solid, liquid, or gas) are in continuous movement
- As temperature increases, molecular movement becomes faster
- In any solution, including cytoplasm, these moving molecules cannot travel very far without having collisions with other molecules
- As a result of these collisions, the directions of colliding molecules are altered and unpredictable
- If the solute is more concentrated in one area than another, the thermal movement will eventually distribute the molecules evenly
- ____ of molecules across the cell membrane is largely determined by the concentration gradient and permeability of the substance
simple diffusion
– Movement of substances across a membrane with the assistance of a transport protein
– Movement from high ® low concentration
– No energy expenditure (e.g. ATP) from cell
– Two mechanisms: Channel & Carrier Proteins
facilitated diffusion
The rate of diffusion across selectively permeable membranes is greatly increased by the use of carrier proteins, sometimes called ____, which are embedded in the plasma membrane.
permeases,
the diffusion of water through a selectively, or differentially, permeable membrane
- has passageways that allow free diffusion of water, but block certain other dissolved molecules
- when the membrane is placed between solutions of differing concentrations of solute and the solute cannot pass through the membrane, water will diffuse at a faster rate from the side that has more water to the side that has less water
- this will continue until the concentration of water is equalized on both sides of the membrane
- Living membranes generally block the entrance and exit of larger molecules and permit the free movement of water
- Most cells are surrounded by some free water and the amount of water entering or leaving has a major impact on cellular activities and survival
Osmosis
Transport of one substance from a low ® high concentration as another substance is simultaneously transported from high ® low.
co transport systems
A molecule is
transported while being chemically modified.
group translocation system
The best-known group translocation system is the ____, which transports a variety of sugars into procaryotic cells while Simultaneously phosphorylating them using phosphoenolpyruvate (PEP) as the phosphate donor.
phosphoenolpyruvate: sugar
phosphotransferase system (PTS)
Active transport systems in bacteria
carrier mediated active transport
group translocation systems
bulk transport
- processes that involve the movement of large particles, macromolecules, or fluids into (endocytosis) or out of (exocytosis) a cell by engulfing them in vesicles formed from the cell membrane.
- transport of large molecules, particles, liquids, or other cells across the cell membrane requiring the expenditure of energy
- cell encloses the substance in its membrane
- simultaneously forms a vacuole and engulfs the substance
Bulk transport: Endocytosis and Exocytosis
- accomplished by amoebas and white blood cells
- ingest whole cells or large solid matter
Phagocytosis
ingestion of liquids such as oils or molecules in solution
Pinocytosis:
