Microbiology Study Guide for Ch 6 Microbial Growth
1. Understand and be able to explain the following terms:
Essential nutrient: PABA is an essential nutrient used by many bacteria in the synthesis of folic acid, a vitamin
that functions as a coenzyme. When sulfanilamide is administered to bacteria, the enzyme that normally
converts PABA to folic acid combines instead
with the sulfanilamide. Folic acid is not synthesized, and the bacteria cannot grow. Because human cells do not
use PABA to
make their folic acid, sulfanilamide can kill bacteria but does not harm human cells. (TB page142)
macronutrients : are/essential nutrients that the body requires in large quantities to provide energy,
maintain structure, and regulate bodily functions./(google) They include:
Carbohydrates: Provide energy and are found in grains, fruits, vegetables, and starchy foods./
Fats: Provide energy, support hormone production, and are found in oils, nuts, seeds, and fatty fish./
Proteins: Build and repair tissues, and are found in meat, fish, eggs, dairy, and legumes./
It's important to consume a balanced diet that includes all three macronutrients in appropriate proportions to
maintain overall health.
Micronutrients Micronutrients are/essential nutrients that the body needs in small amounts for proper growth,
development, and functioning./They include vitamins and minerals. (google)
Autotroph autotrophs (self-feeders) use carbon dioxide (TB page 168)
Heterotroph (feeders on others) require an organic carbon source. Autotrophs are also referred to as lithotrophs
(rock eating), and heterotrophs are also referred to as organotrophs. (TB page 166)
chemoheterotrophs Chemoheterotrophs specifically use the electrons from hydrogen atoms in organic
compounds as their energy source. (TB page 168) Most bacteria, and all fungi, protozoa, and animals, are
chemoheterotrophs.
saprobes A saprobe is an organism that contributes to the decay and decomposition of organic matter in water
bodies, leading to lower oxygen levels and different levels of pollution tolerance among organisms.
(sciencedirect.com)
Saprophytes live on dead organic matter (TB page 166)
log phase phase of growth, after the lag phase, Eventually, the cells begin to divide and enter a period of
growth, or logarithmic increase, called the log phase, or exponential growth phase. (TB page 193)
Parasites derive nutrients from a living host (TB page 166)
Pathogens A disease-causing organism. desease-causing (TB14 and G-15)
Turbid estimating turbidity is a practical way of monitoring bacterial growth. As bacteria multiply in a liquid
medium, the medium becomes turbid, or cloudy with cells. The instrument used to measure turbidity is a
spectrophotometer (or colorimeter) (TB page 198)
binary fission The normal reproductive method of bacteria is binary fission, in which a single cell divides into
two identical cells. (TB page 191)
Diffusion The net movement of molecules or ions from an area of higher concentration to an area of lower
concentration (TB G-7)
Osmosis The net movement of solvent molecules across a selectively permeable membrane from an area of
lower solute concentration to an area of higher solute concentration. (TB G-15)
Isotonic A solution in which, after immersion of a cell, osmotic pressure is equal across the cell’s membrane.
(TB G-12)
Hypertonic A solution that has a higher concentration of solutes than an isotonic solution. (TB G-
11)
Hypotonic A solution that has a lower concentration of solutes than an isotonic solution. (TB G-
11)
facilitated diffusion integral membrane proteins function as channels or carriers that facilitate the movement of
ions or large molecules across the plasma membrane. Such integral proteins are called transporter proteins or
permeases. (TB113)
specificity Percentage of false positive results given by a diagnostic test. (TB G-19)
