chapter 6 Flashcards
microorganisms need what
- nutrients (carbon, nitrogen, oxygen, hydrogen, phosphate, sulfur, etc)
- energy sources (sunlight, organic compounds, etc.)
- gases (carbon dioxide, and oxygen)
- proper temperature and pH levels
essential nutrient:
essential nutrient: any substance that must be provided to an organism
micronutrients
macronutrients
micronutrients: present in much smaller amounts and are involved in enzyme function and maintenance of protein structures
- also known as trace elements
- examples: manganese, zinc, nickel
macronutrients: are required in relatively large quantities and play principal roles in cell structure and metabolism: (carbon, hydrogen, oxygen)
inorganic nutrients
- an atom or simple molecule that contains a combination of atoms other than C and H
- found in the earth’s crust, bodies of water, and the atmosphere
- metals and their salts (magnesium sulfate, ferric nitrate, sodium phosphate)
- gases (oxygen, carbon dioxide) and water
organic nutrients
- contain carbon and hydrogen atoms and are usually the products of living things
- simple organic molecules such as methane
- large polymers (carbohydrates, lipids, proteins, nucleic acids)
what microbes eat
1) where they get their carbon
- heterotroph: an organism that must obtain its carbon in an organic form
- autotroph: an organism that uses inorganic CO2 as its carbon source:
- has the capacity to convert CO2 into organic compounds
- not nutritionally dependent on other living things
2) where they get their energy
- phototroph: microbes that photosynthesize
- chemotroph: microbes that get its energy from chemical compounds
chemoheterotrophs
- derive both carbon and energy from organic compounds
- process these molecules through cellular respiration or fermentation
saprobes
- free-living organisms that feed on organic detritus from dead organisms
- decomposers of plant litter, animal matter, and dead microbes
- recycle organic nutrients
heterotrophs and their energy sources: parasites
- derive nutrients from the cells or tissues of living hosts
- Pathogens: cause damage to tissues of even death
- range from viruses to helminths
- ectoparasites: live on the body
- endoparasites: live in the organs and tissues
- intracellular parasites: live within cells
- Obligate parasites: unable to grow outside of the living host
- leprosy bacillus and syphilis spirochete
essential nutrients - carbon
Among the common organic molecules that can satisfy this
requirement are proteins, carbohydrates, lipids, and nucleic
acids. In most cases, these molecules provide several other
nutrients as well.
essential nutrients - hydrogen
Hydrogen is a major element in all organic and several inorganic
compounds, including water (H2O), salts (Ca[OH]2), and certain
naturally occurring gases (H2S, CH4, and H2). These gases are
both used and produced by microbes. Hydrogen helps cells
maintain their pH, is useful for forming hydrogen bonds between
molecules, and also serves as a source of free energy in
respiration.
Carbon is what of the essential nutrients
- it is our backbone
- Carbon likes to be with 4 hydrogens
essential nutrients - oxygen
Because oxygen is a major component of organic compounds
such as carbohydrates, lipids, nucleic acids, and proteins, it
plays an important role in the structural and enzymatic functions
of the cell. Oxygen is likewise a common component of inorganic
salts such as sulfates, phosphates, nitrates, and water. Free
gaseous oxygen (O2) makes up 20% of the atmosphere.
essential nutrients - nitrogen
The main reservoir of nitrogen is nitrogen gas (N2), which makes up
79% of the earth’s atmosphere. This element is indispensable to the
structure of proteins, DNA, RNA, and ATP. Such compounds are the
primary nitrogen source for heterotrophs, but to be useful, they must first be degraded into their basic building blocks (proteins into amino acids; nucleic acids into nucleotides). Some bacteria and
algae utilize inorganic nitrogenous nutrients (NO3–, NO2–, or NH3). A
small number of bacteria and archaea can transform N2 into compounds usable by other organisms through the process of
nitrogen fixation. Regardless of the initial form in which the
inorganic nitrogen enters the cell, it must first be converted to NH3,
the only form that can be directly combined with carbon to synthesize amino acids and other compounds
essential nutrients - phosphate
The main inorganic source of phosphorus is phosphate (PO4^3–),
derived from phosphoric acid (H3PO4) and found in rocks and
oceanic mineral deposits. Phosphate is a key component of
nucleic acids and is therefore essential to the genetics of cells
and viruses. Because it is also found in ATP, it serves in cellular energy transfers. Other phosphate-containing compounds are
phospholipids in cytoplasmic membranes and coenzymes such
as NAD+.
essential nutrients - sulfur
Sulfur is widely distributed throughout the environment in
mineral form. Rocks and sediments (such as gypsum) can
contain sulfate (SO4^2–), sulfides (FeS), hydrogen sulfide gas
(H2S), and elemental sulfur (S). Sulfur is an essential
component of some vitamins (vitamin B1) and the amino acids
methionine and cysteine; the latter help determine shape and
structural stability of proteins by forming unique linkages called
disulfide bonds.
other important nutrients
Potassium (K): essential to protein synthesis and
membrane function
* Sodium (Na): important for certain types of cell transport
* Calcium (Ca): stabilizer of cell wall and endospores of
bacteria
* Magnesium (Mg): component of chlorophyll and a
stabilizer of membranes and ribosomes
* Iron (Fe): important component of the cytochrome proteins
of cell respiration
* Zinc (Zn): essential regulatory element for eukaryotic
genetics
How microbes eat: transport mechanisms
Transport of necessary nutrients occurs across the
cytoplasmic membrane, even in organisms with cell walls
* The driving force of transport is atomic and molecular
movement
Diffusion
define diffusion
the phenomenon of molecular movement, in
which atoms or molecules move in a gradient from an area
of higher density or concentration to an area of lower
density or concentration
the movement of water: osmosis
Osmosis: 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
endocytosis
- cell encloses the substance in its membrane
- simultaneously forms a vacuole and engulfs the substance
phagocytosis
- accomplished by amoebas and white blood cells
- ingest whole cells or large solid matter
pinocytosis
- ingestion of liquids such as oils or molecules in solutions
minimum temperature
- the lowest temperature that permits a microbe’s continued growth and metabolism; below this temperature, its activities stop
maximum temperature
Maximum temperature: the highest temperature at which
growth and metabolism can proceed before proteins are
denatured
optimum temperature
- Optimum temperature: an intermediate between the
minimum and the maximum that promotes the fastest rate
of growth and metabolism
