Microbiology: Cell Structures, Microbial Classification, and Metabolic Processes

What are the six categories of microorganisms identified by Leeuwenhoek?

Bacteria, Archaea, Fungi, Protozoa, Algae, Small multicellular animals, Viruses, Prions.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotes lack a true nucleus and membrane-bound organelles; eukaryotes have a true nucleus and membrane-bound organelles.

What are the two domains of prokaryotic organisms?

Bacteria and Archaea.

What is the primary component of bacterial cell walls?

Peptidoglycan.

How do fungi obtain their food?

By obtaining nutrients from other organisms.

What are the two main types of fungi?

Molds (multicellular) and Yeasts (unicellular).

What are protozoa and where do they typically live?

Single-celled eukaryotes that live freely in water.

What is the role of flagella in protozoa?

Flagella are long, whiplike extensions that aid in locomotion.

What are the main characteristics of viruses?

Acellular, obligate intracellular parasites, and host-specific.

Who is Antoni Van Leeuwenhoek and what was his contribution to microbiology?

A scientist who made simple microscopes and was the first to observe microorganisms.

What are Koch's Postulates?

A set of four criteria to establish a causative relationship between a microbe and a disease.

What is the significance of hemolysis in microbiology?

It refers to the breakdown of red blood cells, often used in identifying bacterial species.

What are the four groups of lipids?

Fats (triglycerides), Phospholipids, Waxes, Steroids.

What are the functions of carbohydrates in living organisms?

Energy storage, structural components, and involvement in cell wall formation.

What are proteins composed of and what are their functions?

Composed of carbon, hydrogen, oxygen, nitrogen, and sulfur; functions include structure, enzymatic catalysis, regulation, transportation, and defense.

What are nucleotides and what do they compose?

Monomers that make up nucleic acids (DNA and RNA).

What is the structure of nucleic acids?

Polymers of nucleotides linked by covalent bonds between phosphate and sugar.

What is ATP and its role in cells?

Adenosine Triphosphate, the main short-term energy supply for cells.

What are the processes of life in microorganisms?

Growth, reproduction, responsiveness, and metabolism.

What distinguishes prokaryotes from eukaryotes in terms of cellular structure?

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

What are glycocalyces and their types?

Gelatinous substances surrounding bacterial cells; types include capsules and slime layers.

What is the function of flagella in bacteria?

To provide motility through rotation.

What are fimbriae and pili used for in bacteria?

Fimbriae are used for adherence, while pili (conjugation pili) are used for DNA transfer between cells.

Why is a pilus considered a type of fimbria?

Because both are used for adherence, but pili are specifically for DNA transfer.

What are the main types of chemical reactions involved in biochemistry?

Synthesis and dehydration synthesis reactions.

What are macromolecules and their basic building blocks?

Large molecules used by all organisms, composed of monomers.

What is the significance of R-groups in organic molecules?

They vary from one molecule to another, affecting the molecule's properties.

What are the two basic types of bacterial cell walls?

Gram-positive and gram-negative.

What color do Gram-positive bacteria appear after staining?

Purple.

What unique chemicals are found in Gram-positive bacterial cell walls?

Teichoic acids and lipoteichoic acids.

What is the characteristic structure of Gram-negative bacterial cell walls?

A thin layer of peptidoglycan surrounded by a bilayer membrane containing phospholipids, proteins, and lipopolysaccharide (LPS).

What color do Gram-negative bacteria appear after staining?

Pink.

What can the Lipid A portion of LPS cause?

Fever, vasodilation, inflammation, shock, and blood clotting.

What are mycoplasmas?

Bacteria that lack cell walls and are often mistaken for viruses.

What is the function of the bacterial cytoplasmic membrane?

Controls the passage of substances into and out of the cell and maintains concentration and electrical gradients.

What is the Fluid Mosaic Model?

It describes the current understanding of membrane structure, composed of lipids and associated proteins.

What are the two types of transport processes in bacterial membranes?

Passive processes (like diffusion and osmosis) and active processes (like active transport and group translocation).

What is plasmolysis?

The shrinking of the cell membrane away from the cell wall due to loss of water.

What is the cytosol?

The liquid part of the cytoplasm, mostly water, containing the cell's DNA.

What are endospores?

Unique structures produced by some bacteria as a defensive strategy against unfavorable conditions.

What is the significance of the endosymbiotic theory?

It suggests that eukaryotes formed from the union of small aerobic prokaryotes with larger anaerobic prokaryotes.

What type of ribosomes do prokaryotes have?

70S ribosomes.

What are the main components of eukaryotic cell walls?

Various polysaccharides, including cellulose in plant cell walls and chitin in fungal cell walls.

What is the role of glycocalyces in bacteria?

They function in the formation of biofilms and help adhere cells to one another and to surfaces.

What are the three main parts of bacterial flagella?

The basal body, hook, and filament.

What is the function of ribosomes in cells?

They are the site of protein synthesis.

What is the difference between phagocytosis and pinocytosis?

Phagocytosis involves the uptake of solid substances, while pinocytosis involves the uptake of liquids.

What is MRSA?

Methicillin-resistant Staphylococcus aureus, a multi-drug-resistant strain that can cause serious infections.

What is the role of the mitochondria in eukaryotic cells?

They produce most of the cell's ATP and contain their own DNA and ribosomes.

What are the two types of bacteria based on their oxygen requirements?

Aerobic (like Bacillus) and anaerobic (like Clostridium).

What is the significance of the G+C content in bacterial classification?

It helps in the classification of bacteria based on their genomic content.

What are the implications of bacterial biofilms?

They can contribute to the persistence of infections and resistance to treatment.

What is diphtheria?

A dangerous upper respiratory tract infection caused by exotoxins, particularly lethal in children with a mortality rate of up to 40%.

What vaccines are used for diphtheria prevention?

DTaP vaccine for children and TDaP for adults.

What is metabolism?

Controlled biochemical reactions that take place in cells.

What is catabolism?

The process of breaking down large molecules into smaller products, releasing energy (exergonic).

What is anabolism?

The process of synthesizing large molecules from smaller products of catabolism, requiring energy (endergonic).

What are the two main types of metabolic pathways?

Aerobic and anaerobic pathways.

What is phosphorylation?

The addition of a phosphate group to a molecule, crucial for ATP production.

What is substrate-level phosphorylation?

A direct transfer of phosphate between two substrates, resulting in ATP production.

What is oxidative phosphorylation?

The process where ATP is produced using energy from a proton gradient created by the electron transport chain.

What are redox reactions?

Reactions that involve the transfer of electrons, where oxidation (loss of electrons) is paired with reduction (gain of electrons).

What are the three important electron carriers in cellular metabolism?

NAD+ (converted to NADH), NADP+ (converted to NADPH), and FAD (converted to FADH2).

What is the role of enzymes in metabolism?

Enzymes catalyze chemical reactions in cells, reducing the activation energy required for reactions.

What factors affect enzyme activity?

Temperature, pH, ionic concentration, substrate concentration, and presence of inhibitors.

What are competitive and noncompetitive inhibitors?

Competitive inhibitors prevent substrate binding at the active site, while noncompetitive inhibitors bind to an allosteric site, altering enzyme activity.

What is glycolysis?

The process of converting glucose into two molecules of pyruvic acid, producing a net gain of 2 ATP and 2 NADH.

What are the stages of cellular respiration?

Synthesis of Acetyl-CoA, Krebs cycle, and electron transport chain.

What is the Krebs cycle?

A series of reactions that transfer energy from Acetyl-CoA to electron carriers, producing ATP, NADH, and FADH2.

What is the electron transport chain?

A series of proteins in the membrane that transfer electrons, creating a proton gradient for ATP synthesis.

What is fermentation?

A metabolic process that partially oxidizes sugars using an organic molecule as an electron acceptor, regenerating NAD+.

What is the net gain of ATP from glycolysis?

2 ATP per molecule of glucose.

How many NADH are produced in glycolysis?

2 NADH per molecule of glucose.

What is the final electron acceptor in aerobic respiration?

Oxygen (O2).

What is the fate of pyruvic acid in fermentation?

Converted to another organic compound, such as lactate or ethanol, to regenerate NAD+.

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration uses oxygen as the final electron acceptor, while anaerobic respiration uses other molecules.

What is the role of ATP synthase?

To synthesize ATP using the energy from the proton gradient established by the electron transport chain.

What is the significance of coenzymes in enzymatic reactions?

Coenzymes assist enzymes in catalyzing reactions, often acting as carriers for chemical groups.