Microbiology Modules 5&6
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86 Terms
What is the difference between inorganic and organic nutrients?
Inorganic nutrients generally do not contain carbon–hydrogen bonds. Organic nutrients contain carbon and usually hydrogen.
decomposers that break down dead plants, animals, and microbes, recycling nutrients back into the environment.
What are the four main types of transport across the cell membrane?
Simple diffusion, facilitated diffusion, active transport, and group translocation.
Water moves into the cell, causing it to swell. The cell wall prevents it from bursting and helps maintain its shape.
What is plasmolysis?
occurs when a cell loses water, causing the cytoplasm to shrink and the cell membrane to pull away from the cell wall.
What is endocytosis?
the process by which a cell takes in substances by surrounding them with its cell membrane and forming a vesicle.
What is pinocytosis?
a type of endocytosis in which a cell takes in extracellular fluid and dissolved substances.
What are cardinal temperatures?
temperatures are the minimum, optimum, and maximum temperatures at which a microorganism can grow.
How do thermophiles and hyperthermophiles increase thermostability?
Their proteins have adaptations that help them remain stable at high temperatures, including stabilizing ionic interactions (salt bridges), hydrogen bonds, and hydrophobic interactions.
How do psychrophiles adapt to cold temperatures?
They have specialized efficient enzymes and unsaturated fatty acid tails which help maintain membrane fluidity at low temperatures.
What are the five main categories of microbes based on oxygen requirements?
Obligate aerobes — require oxygen.
Obligate anaerobes — cannot grow in the presence of oxygen.
Facultative anaerobes — grow with or without oxygen, usually better with it.
Aerotolerant anaerobes — do not use oxygen but tolerate it.
Microaerophiles — require lower-than-atmospheric oxygen levels
What is the difference between obligate halophiles and halotolerant microbes?
Obligate halophiles require high salt concentrations to grow. Halotolerant microorganisms can tolerate high salt concentrations but do not require them.
How do phototrophs protect themselves from radiation?
Carotenoid pigments help protect cells against damage from reactive oxygen species. DNA repair enzymes help repair DNA damage caused by ultraviolet radiation.
For it’s extreme resistance to ionizing radiation because it can efficiently repair severe DNA damage.
What is mutualism?
a relationship in which both organisms benefit. It can be obligatory or facultative, depending on the relationship.
What is parasitism?
a relationship in which the parasite benefits while the host is harmed. The parasite obtains resources or a habitat from the host.
What is antagonism?
occurs when one microorganism inhibits or harms another, often by producing substances that prevent the other organism from growing.
What is synergism?
when microorganisms interact so that their combined activities produce a greater benefit or effect than they would individually
What are the stages of bacterial growth in a batch culture?
Lag phase, exponential (log) phase, stationary phase, and death (decline) phase.
What is binary fission?
a type of asexual reproduction in which a bacterial cell replicates its DNA and divides into two daughter cells.
How does a spectrophotometer measure microbial growth?
By measures the turbidity or optical density of a microbial culture. Higher turbidity generally indicates more cells, but it does not directly measure how many cells are alive.
What is PCR (Polymerase Chain Reaction) used for in microbial analysis?
amplifies a specific DNA sequence, producing many copies. Quantitative PCR (qPCR) can estimate the amount of a target DNA sequence in a sample.
What is the difference between simple and conjugated enzymes?
Simple enzymes consist only of protein. Conjugated enzymes contain a protein portion and a nonprotein component needed for function.
What is a cofactor and a coenzyme?
A cofactor is a nonprotein helper needed for an enzyme to function. It can be an inorganic ion or an organic molecule. A coenzyme is an organic type of cofactor.
What is the difference between exoenzymes and endoenzymes?
Exoenzymes are released outside the cell and help break down substances externally. Endoenzymes function inside the cell.
What are regulated enzymes?
They have their production or activity adjusted according to cellular conditions. Inducible enzymes are produced in response to a signal, while repressible enzymes are produced less when a particular signal or product is present.
What is noncompetitive inhibition?
occurs when an inhibitor binds to a site other than the active site and reduces enzyme activity. In the classic case of pure noncompetitive inhibition, the inhibitor reduces the enzyme's maximum reaction rate.
What are the primary electron carrier coenzymes in cells?
NAD⁺ and FAD accept electrons and hydrogen during metabolic reactions, forming NADH and FADH₂, which carry high-energy electrons to other reactions.
What are the three parts of an ATP molecule?
consists of adenine, ribose sugar, and three phosphate groups.
Why does breaking the terminal phosphate bond in ATP release energy?
converts ATP into ADP and inorganic phosphate. The products have lower free energy than ATP under typical cellular conditions, allowing the reaction to release free energy that the cell can use.
What are the three main mechanisms of ATP generation?
Substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation.
What is oxidative phosphorylation?
produces ATP using energy from electrons moving through an electron transport chain. This creates a proton gradient that powers ATP synthase.
What are the three main catabolic pathways for breaking down glucose?
Aerobic respiration, anaerobic respiration, and fermentation.
What is the role of pyruvic acid (pyruvate) in metabolism?
a central metabolic intermediate. In aerobic respiration, it is converted into acetyl-CoA before entering the Krebs cycle. During fermentation, it can be converted into products such as lactic acid or ethanol.
What is the function of the citric acid cycle (Krebs cycle)?
oxidizes acetyl-CoA, releases carbon dioxide, and produces NADH, FADH₂, and ATP or GTP. NADH and FADH₂ carry high-energy electrons to the electron transport chain.
What enzyme catalyzes the terminal step of the electron transport chain?
In many aerobic respiratory chains, cytochrome c oxidase transfers electrons to oxygen, the final electron acceptor. The exact terminal enzyme depends on the organism and respiratory pathway.
What is the difference between aerobic and anaerobic respiration?
Aerobic respiration uses oxygen as the final electron acceptor. Anaerobic respiration uses a different final electron acceptor, such as nitrate or sulfate.
What are the common end products of fermentation?
depend on the organism and pathway. Examples include lactic acid, ethanol, carbon dioxide, and other organic acids or alcohols.
What do lipases do in lipid catabolism?
breaks down triglycerides into glycerol and fatty acids. Glycerol can enter glycolysis after conversion to an intermediate, while fatty acids are broken down through beta-oxidation.
What is the role of proteases in protein catabolism?
break proteins into smaller peptides. Further enzymatic breakdown produces individual amino acids.
What occurs during light-dependent photosynthesis reactions?
capture light energy to produce ATP and NADPH. In oxygenic photosynthesis, water is split and oxygen is released.
What occurs during light-independent photosynthesis reactions?
The Calvin cycle uses ATP and NADPH from the light-dependent reactions to fix carbon dioxide into organic molecules. These molecules can be used to build carbohydrates. The cycle does not directly require light.