Prokaryotic vs. Eukaryotic Cells

• Microbiology studies microorganisms, "micro" means small, and "biology" is the study of living things.
• A microbe is a microscopic organism as a single cell (unicellular), cell clusters, or multicellular, relatively complex organism.
• Microbiology studies microscopic organisms like bacteria, viruses, archaea, fungi, and protozoa.

Types of Microorganisms

• Microorganisms are divided into these seven types: Bacteria, archaea, protozoa, algae, fungi, viruses, and multicellular animal parasites (helminths).
• Each microorganism type has a characteristic cellular composition, morphology, and reproduction.
• They are beneficial in oxygen production, decomposing organic material, nutrient provision for plants and human health maintenance.
• Some microorganisms can be pathogenic, causing diseases in plants and humans.
• Bacteria are unicellular organisms described to be prokaryotic because they lack a nucleus.
• Fungi (mushroom, molds, and yeasts) are eukaryotic cells (with a true nucleus).
• Most fungi are multicellular, and the cell wall consists of chitin.
• Viruses are noncellular entities that consist of a nucleic acid core (DNA or RNA) surrounded by a protein coat.
• Viruses are classified as microorganisms yet are not considered living organisms.
• Parasites are a group of Eukaryotic organisms that include flatworms and roundworms (helminths).
• Parasites aren't microorganisms by definition because they're easily seen with the naked eye, though part of their life cycle is in microscopic form.
• Parasitic helminths are clinically important and often discussed with other microbe groups.
• Algae, also call cyanobacteria (blue-green algae), can be unicellular or multicellular eukaryotes and get nourishment from photosynthesis.
• Algae live in water, damp soil, and rocks to produce oxygen and carbohydrates used by other organisms.
• Cyanobacteria are believed to be the origins of green land plants.
• Protozoa are unicellular aerobic eukaryotes with a nucleus, complex organelles, and obtain nourishment by absorption or ingestion through specialized structures.

Domains of Life

• There are three domains of life: bacteria, archaea, and eukarya.
• Bacteria and archaea are prokaryotes.
• Eukarya are eukaryotes.
• Eukarya include animals, fungi protozoans, and parasites.

Characteristics of Prokaryotic and Eukaryotic Cells

• Prokaryotes are always single-celled organisms and lack a defined nucleus.
• Eukaryotes can be single or multicellular organisms.
• Both cell types conduct the same basic functions.
• Both cell types are surrounded by a plasma membrane, to control what enters and leaves the cell and both are filled with cytoplasm.
• They contain ribosomes for protein production.
• They contain DNA for the general instructions for the cell's life.

Differences Between Prokaryotic Cells and Eukaryotic Cells

• Eukaryotic DNA is in a membrane-surrounded nucleus.
• Prokaryotic DNA is in a nuclear region without a nuclear membrane.
• Eukaryotic cells have paired chromosomes.
• Prokaryotic cells have a single circular chromosome.
• Eukaryotic cells have histone proteins; prokaryotic cells do not.
• Prokaryotic cells do not have membrane-bound organelles.
• The prokaryotic cell wall has peptidoglycan.
• Plant and fungal cells have cellulose and chitin.
• Animal cells don't have cell walls.
• Prokaryotes do not have a cytoskeleton - a network of intercellular protein fibers that help a cell with shape, support, and movement.
• Prokaryotes use asexual reproduction (binary fission).
• Eukaryotes use asexual and sexual reproduction (meiosis and mitosis, respectively).
• Prokaryotes are smaller in diameter, ranging from 0.5 to 2.0 µm and 1.0 - 60 µm in length.
• Smaller surface areas allow nutrients into the inner parts of the cell quicker.
• Eukaryotic cells are larger require specialized organelles to carry out metabolism, provide energy, and transport chemicals throughout the cell.
• Prokaryotic cells are small, being less than 5mm.
• They are always unicellular and have no nucleus or membrane-bound organelles.
• Prokaryotic DNA is circular without proteins.
• The ribosomes in prokaryotes are generally 70S, and there is no cytoskeleton.
• Cell division occurs through binary fission, where the reproduction is always asexual.
• Eukaryotic cells are larger; over 10mm, and are often multicellular.
• Eukaryotes always have a nucleus, and other membrane-bound organelles.
• Eukaryotic DNA is linear and associated with protein to form chromatin.
• The ribosomes are large (80S), and there is always a cytoskeleton
• Cell division occurs through mitosis or meiosis, where the reproduction is asexual or sexual.

Common Bacterial Shapes

• Bacteria are unicellular organisms.
• Bacteria are prokaryotic, and they lack a nucleus.
• Bacteria have a peptidoglycan cell wall; they divide by binary fission and possess flagella for motility.
• Shape classification shapes include bacillus (rod shape), coccus (spherical shape), spirilla (spiral shape), and vibrio (curved shape).
• Cells are Gram-positive or Gram-negative, based on Gram staining.
• Response to gaseous environments include: aerobic (living in the presence of oxygen), anaerobic (living without oxygen), and facultative anaerobes (can live in both environments).
• Bacteria can either be heterotrophs or autotrophs, depending on energy acquisition.
• Autotrophs create their own food using the energy of sunlight or through chemical reactions.
• If autotrophs use chemical reactions, they are categorized to be chemoautotrophs.
• Heterotrophs get energy by consuming other organisms.
• Bacteria that use decaying life forms as a source of energy are called saprophytes.
• Bacteria can have various responses to oxygen.
• Aerobic bacteria require oxygen for growth.
• Obligate aerobic bacteria cannot exist without oxygen
• An example of an obligate aerobic bacteria, is Mycobacterium tuberculosis
• Microaerophilic bacteria require lower concentrations of oxygen between 2-10%.
• An example of microaerophilic bacteria Helicobacter pylori
• Anaerobic Bacteria, do not require oxygen to grow
• Obligate Anaerobic Bacteria; can't survive with oxygen, an example, Clostridium tetani, & C. perfringens
• Facultative Anaerobic Bacteria can grow without oxygen and use oxygen if present, E.coli.
• Aerotolerant Bacteria; cannot use oxygen to grow, by are not harmed by it
• Cocci are spherical or oval-shaped bacteria.
• Bacilli are rod-shaped
• Vibrios are comma-shaped.
• Spirilla are rigid spiral-based forms.
• Spirochetes are flexible spiral forms.
• Actinomycetes are branching filamentous bacteria.
• Cocci arrangements in groups of two are called diplococcus.
• Cocci arrangements in chains are called streptococci.
• Cocci arrangements in clusters are called staphylococci.
• Coccobacilli Bacteria: Gardnerella vaginalis; or causing influenza-like Haemophilus influenzae.
• Diplobacilli Bacteria: Klebsiella rhinoscleromatis causes chronic nasal infection in humans.
• Streptococcus moniliformis is the causative agent of rat-bite fever.
• Palisade bacteria; Corynebacterium diphtheria is the causative agent of diphtheria
• Staphylococcus aureus is an cocci bacterial arrangement in clusters.
• Streptococcus pyogenes bacteria cause acute pharyngitis, accounting for 15-30% of cases in children and 5-10% of cases in adults.
• Streptococcus pneumoniae is gram-positive diplococci that are tapered at the ends, giving the "lancet" shaped appearance.
• Pneumococcus bacteria cause infections in the lungs (pneumonia), ears (otitis), sinuses (sinusitis), brain and spinal cord tissue (meningitis), and blood (bacteremia).
• Gonorrhea is a sexually transmitted disease (STD) caused by infection with the Neisseria gonorrhoeae bacterium.
• N. gonorrhoeae infects the mucous membranes of the cervix, uterus, and fallopian tubes in women and the urethra in women and men
• Bacilli eg Lactobacillus acidophilus is found in the mouth, intestine, and vagina.
• Lactobacillus acidophilus produces lactic acid, helping the body break down food, absorb nutrients, and fight off "bad" organisms that can cause diseases.
• Lactobacilli is a probiotic in yogurts and other fermented foods.
• E. coli normally live in the intestines of healthy people and animals.
• Most types of E. coli are harmless aside from diarrhea. But a few strains, such as E. coli O157:H7, can cause severe stomach cramps, bloody diarrhea and vomiting.
• Individuals may be exposed to E. coli from contaminated water or food, particularly raw produce and uncooked ground beef.
• Adults normally recover from infection with E. coli O157:H7 after around a week, but children and older adults have a greater risk of developing a life-threatening form of kidney failure.
• Klebsiella Pneumoniae Infection causes bacterial pneumonia, and infection occurs in the lungs.

Questions cover cell structures, differences between prokaryotic and eukaryotic cells, and modes of nourishment. Key concepts include cell walls, DNA organization, and nutrient transport